West Nile virus in Australia
West Nile virus in Australia
West Nile virus in Australia
West Nile virus in Australia
West Nile virus in Australia
West Nile virus in Australia
West Nile virus in Australia
West Nile virus in Australia
West Nile virus in Australia
West Nile virus in Australia
Report West Nile Virus
Report unusual disease signs, abnormal behaviour or unexplained deaths in livestock and other animals. Ring the 24 hour EAD hotline on 1800 675 888.
West Nile Virus infection - clinical
West Nile Virus (WNV) is a mosquito-borne virus in the Flavivirus family. A strain known as Kunjin virus, WNV is endemic to parts of Australia and has been present for many years. Other viruses in this family include dengue, Japanese encephalitis, Murray Valley encephalitis, and Zika.
WNV occurs on every continent except Antarctica. In Australia, WNV is only rarely linked to human illness. However, in 2011 a variant of the Australian strain caused a major outbreak of neurological disease in horses in south-eastern Australia.
Disease information
What does West Nile Virus look like?
In Australia, disease has been limited to horses, although several cases have been suspected (though not confirmed) in dogs and alpaca. Many animals infected with WNV do not develop any clinical signs. Unlike North American strains, Australian strains of WNV have not caused disease in birds.
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
Other nervous signs may include:
- Facial paralysis
- Muscle tremors/fasciculation
- Hyperaesthesia
- Circling
- Blindness
- Recumbency or inability to stand
- Hind limb weakness
- Multiple limb paralysis
- Altered mental state
- Hypermetria
- Depression
Fever is an inconsistent finding, usually as a result of the late onset of neurological signs relative to the time of infection. It is important to differentiate the illness from Hendra virus infection particularly in areas where flying foxes are abundant and to take appropriate precautions.
The majority of affected horses recover uneventfully within a few days to a few weeks. In the 2011 WNV outbreak, about 10% of horses showing clinical signs died.
What should I do if I suspect West Nile Virus?
Notify suspected West Nile virus immediately by:
- Calling the Emergency Animal Disease Hotline on 1800 675 888 (24 hours), or
- Calling your Local Land Services office on 1300 795 299 (during work hours), or
- Emailing a completed NSW notifiable animal disease form PDF, 166.38 KB
How is it diagnosed?
Diagnosis of West Nile virus in live horses is routinely based on detecting an immune response to the virus. Collection of paired clotted blood samples is recommended. The first (acute) sample should be taken as soon as possible after clinical signs have been observed. A second convalescent sample should be collected approximately 21 days later. The acute samples should be submitted to the laboratory soon after collection as a high proportion of horses will give significant results in the WNV IgM assay at the time clinical signs are first observed.
If cerebrospinal fluid (CSF) has been collected, it should also be submitted for testing for both the virus by qRT-PCR and for antibody detection. Although WNV can be detected in the central nervous system of acutely infected horses, it is not possible to detect viral RNA in blood samples.
If the horse dies or is euthanased, both fresh and fixed brain, CSF and upper cervical spinal cord samples should be taken. The brain should be cut in half longitudinally to ensure that representative areas are available fresh for virus detection and fixed for histopathology. The risk of Hendra virus infection should be considered prior to tissue collection.
Keep all samples chilled but do not freeze.
NSW DPIRD covers the cost of laboratory testing of samples collected by a veterinarian to confirm or exclude suspected WNV infection in animals.
For further information on submitting laboratory samples see: Laboratory Services
How is it spread?
WNV is maintained in a mosquito-bird cycle where mosquitoes act as vectors and birds act as natural hosts (Figure 1). The species of mosquito (Culex annulirostris) that most frequently spreads WNV breeds in fresh water. Wading birds are key natural reservoirs of WNV in Australia. Horses, people and a variety of other animals may become infected through a bite from an infected mosquito. There is no further spread of the virus from an infected mammal.
WNV is endemic in northern Australia. While Culex annulirostris is common throughout NSW, very large populations develop in the Murray Darling River basin and Macquarie Marshes areas of NSW. Asymptomatic infection occurs intermittently in these areas and can be detected serologically in sentinel chickens or other animals, particularly dogs and horses.
In 2011, cases of disease in horses in NSW were initially detected in south western and central western NSW but became widely distributed west of the Great Dividing Range from northern NSW to the Murray River in the south and throughout the Hunter Valley and Sydney basin.
Does West Nile Virus affect people?
Yes, West Nile Virus is Zoonotic. For further information regarding West Nile virus infections in people visit NSW Health.
Other key information and resources
Treatment
There is no specific treatment available for WNV infections. Supportive treatment with intravenous fluids and anti-inflammatory drugs may be required.
Prevention
Reducing exposure of horses to mosquitoes is the most effective measure to minimise the risk of infection with WNV. Mosquitoes are usually most active at dusk and dawn, so reducing time outside at these times may help. Insecticides and physical barriers, such as rugs for horse, may also be useful.
Further Information
For further information regarding West Nile virus infection in wildlife visit Wildlife Health Australia (fact sheets, various species of animals).
Email the NSW DPI Biosecurity team at animal.biosecurity@dpi.nsw.gov.au or call your Local Land Services office .
Reporting animal biosecurity emergencies
Some animal pests and diseases, or residues in animal products or stock feed can have serious consequences for trade, production or human health. By remaining vigilant and acting quickly if you suspect a significant animal pest, disease, or residue you may be able to prevent these consequences. Don’t delay! Contact Local Land Services or ring the 24 hour hotline:
Emergency Animal Disease Hotline (24 hours) on 1800 675 888.
Contact us
If you have a general query or concern about animal diseases, please email staff in Animal Biosecurity at animal.biosecurity@dpird.nsw.gov.au
Report West Nile Virus
Report unusual disease signs, abnormal behaviour or unexplained deaths in livestock and other animals. Ring the 24 hour EAD hotline on 1800 675 888.
West Nile Virus infection - clinical
West Nile Virus (WNV) is a mosquito-borne virus in the Flavivirus family. A strain known as Kunjin virus, WNV is endemic to parts of Australia and has been present for many years. Other viruses in this family include dengue, Japanese encephalitis, Murray Valley encephalitis, and Zika.
WNV occurs on every continent except Antarctica. In Australia, WNV is only rarely linked to human illness. However, in 2011 a variant of the Australian strain caused a major outbreak of neurological disease in horses in south-eastern Australia.
Disease information
What does West Nile Virus look like?
In Australia, disease has been limited to horses, although several cases have been suspected (though not confirmed) in dogs and alpaca. Many animals infected with WNV do not develop any clinical signs. Unlike North American strains, Australian strains of WNV have not caused disease in birds.
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
Other nervous signs may include:
- Facial paralysis
- Muscle tremors/fasciculation
- Hyperaesthesia
- Circling
- Blindness
- Recumbency or inability to stand
- Hind limb weakness
- Multiple limb paralysis
- Altered mental state
- Hypermetria
- Depression
Fever is an inconsistent finding, usually as a result of the late onset of neurological signs relative to the time of infection. It is important to differentiate the illness from Hendra virus infection particularly in areas where flying foxes are abundant and to take appropriate precautions.
The majority of affected horses recover uneventfully within a few days to a few weeks. In the 2011 WNV outbreak, about 10% of horses showing clinical signs died.
What should I do if I suspect West Nile Virus?
Notify suspected West Nile virus immediately by:
- Calling the Emergency Animal Disease Hotline on 1800 675 888 (24 hours), or
- Calling your Local Land Services office on 1300 795 299 (during work hours), or
- Emailing a completed NSW notifiable animal disease form PDF, 166.38 KB
How is it diagnosed?
Diagnosis of West Nile virus in live horses is routinely based on detecting an immune response to the virus. Collection of paired clotted blood samples is recommended. The first (acute) sample should be taken as soon as possible after clinical signs have been observed. A second convalescent sample should be collected approximately 21 days later. The acute samples should be submitted to the laboratory soon after collection as a high proportion of horses will give significant results in the WNV IgM assay at the time clinical signs are first observed.
If cerebrospinal fluid (CSF) has been collected, it should also be submitted for testing for both the virus by qRT-PCR and for antibody detection. Although WNV can be detected in the central nervous system of acutely infected horses, it is not possible to detect viral RNA in blood samples.
If the horse dies or is euthanased, both fresh and fixed brain, CSF and upper cervical spinal cord samples should be taken. The brain should be cut in half longitudinally to ensure that representative areas are available fresh for virus detection and fixed for histopathology. The risk of Hendra virus infection should be considered prior to tissue collection.
Keep all samples chilled but do not freeze.
NSW DPIRD covers the cost of laboratory testing of samples collected by a veterinarian to confirm or exclude suspected WNV infection in animals.
For further information on submitting laboratory samples see: Laboratory Services
How is it spread?
WNV is maintained in a mosquito-bird cycle where mosquitoes act as vectors and birds act as natural hosts (Figure 1). The species of mosquito (Culex annulirostris) that most frequently spreads WNV breeds in fresh water. Wading birds are key natural reservoirs of WNV in Australia. Horses, people and a variety of other animals may become infected through a bite from an infected mosquito. There is no further spread of the virus from an infected mammal.
WNV is endemic in northern Australia. While Culex annulirostris is common throughout NSW, very large populations develop in the Murray Darling River basin and Macquarie Marshes areas of NSW. Asymptomatic infection occurs intermittently in these areas and can be detected serologically in sentinel chickens or other animals, particularly dogs and horses.
In 2011, cases of disease in horses in NSW were initially detected in south western and central western NSW but became widely distributed west of the Great Dividing Range from northern NSW to the Murray River in the south and throughout the Hunter Valley and Sydney basin.
Does West Nile Virus affect people?
Yes, West Nile Virus is Zoonotic. For further information regarding West Nile virus infections in people visit NSW Health.
Other key information and resources
Treatment
There is no specific treatment available for WNV infections. Supportive treatment with intravenous fluids and anti-inflammatory drugs may be required.
Prevention
Reducing exposure of horses to mosquitoes is the most effective measure to minimise the risk of infection with WNV. Mosquitoes are usually most active at dusk and dawn, so reducing time outside at these times may help. Insecticides and physical barriers, such as rugs for horse, may also be useful.
Further Information
For further information regarding West Nile virus infection in wildlife visit Wildlife Health Australia (fact sheets, various species of animals).
Email the NSW DPI Biosecurity team at animal.biosecurity@dpi.nsw.gov.au or call your Local Land Services office .
Reporting animal biosecurity emergencies
Some animal pests and diseases, or residues in animal products or stock feed can have serious consequences for trade, production or human health. By remaining vigilant and acting quickly if you suspect a significant animal pest, disease, or residue you may be able to prevent these consequences. Don’t delay! Contact Local Land Services or ring the 24 hour hotline:
Emergency Animal Disease Hotline (24 hours) on 1800 675 888.
Contact us
If you have a general query or concern about animal diseases, please email staff in Animal Biosecurity at animal.biosecurity@dpird.nsw.gov.au
Report West Nile Virus
Report unusual disease signs, abnormal behaviour or unexplained deaths in livestock and other animals. Ring the 24 hour EAD hotline on 1800 675 888.
West Nile Virus infection - clinical
West Nile Virus (WNV) is a mosquito-borne virus in the Flavivirus family. A strain known as Kunjin virus, WNV is endemic to parts of Australia and has been present for many years. Other viruses in this family include dengue, Japanese encephalitis, Murray Valley encephalitis, and Zika.
WNV occurs on every continent except Antarctica. In Australia, WNV is only rarely linked to human illness. However, in 2011 a variant of the Australian strain caused a major outbreak of neurological disease in horses in south-eastern Australia.
Disease information
What does West Nile Virus look like?
In Australia, disease has been limited to horses, although several cases have been suspected (though not confirmed) in dogs and alpaca. Many animals infected with WNV do not develop any clinical signs. Unlike North American strains, Australian strains of WNV have not caused disease in birds.
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
Other nervous signs may include:
- Facial paralysis
- Muscle tremors/fasciculation
- Hyperaesthesia
- Circling
- Blindness
- Recumbency or inability to stand
- Hind limb weakness
- Multiple limb paralysis
- Altered mental state
- Hypermetria
- Depression
Fever is an inconsistent finding, usually as a result of the late onset of neurological signs relative to the time of infection. It is important to differentiate the illness from Hendra virus infection particularly in areas where flying foxes are abundant and to take appropriate precautions.
The majority of affected horses recover uneventfully within a few days to a few weeks. In the 2011 WNV outbreak, about 10% of horses showing clinical signs died.
What should I do if I suspect West Nile Virus?
Notify suspected West Nile virus immediately by:
- Calling the Emergency Animal Disease Hotline on 1800 675 888 (24 hours), or
- Calling your Local Land Services office on 1300 795 299 (during work hours), or
- Emailing a completed NSW notifiable animal disease form PDF, 166.38 KB
How is it diagnosed?
Diagnosis of West Nile virus in live horses is routinely based on detecting an immune response to the virus. Collection of paired clotted blood samples is recommended. The first (acute) sample should be taken as soon as possible after clinical signs have been observed. A second convalescent sample should be collected approximately 21 days later. The acute samples should be submitted to the laboratory soon after collection as a high proportion of horses will give significant results in the WNV IgM assay at the time clinical signs are first observed.
If cerebrospinal fluid (CSF) has been collected, it should also be submitted for testing for both the virus by qRT-PCR and for antibody detection. Although WNV can be detected in the central nervous system of acutely infected horses, it is not possible to detect viral RNA in blood samples.
If the horse dies or is euthanased, both fresh and fixed brain, CSF and upper cervical spinal cord samples should be taken. The brain should be cut in half longitudinally to ensure that representative areas are available fresh for virus detection and fixed for histopathology. The risk of Hendra virus infection should be considered prior to tissue collection.
Keep all samples chilled but do not freeze.
NSW DPIRD covers the cost of laboratory testing of samples collected by a veterinarian to confirm or exclude suspected WNV infection in animals.
For further information on submitting laboratory samples see: Laboratory Services
How is it spread?
WNV is maintained in a mosquito-bird cycle where mosquitoes act as vectors and birds act as natural hosts (Figure 1). The species of mosquito (Culex annulirostris) that most frequently spreads WNV breeds in fresh water. Wading birds are key natural reservoirs of WNV in Australia. Horses, people and a variety of other animals may become infected through a bite from an infected mosquito. There is no further spread of the virus from an infected mammal.
WNV is endemic in northern Australia. While Culex annulirostris is common throughout NSW, very large populations develop in the Murray Darling River basin and Macquarie Marshes areas of NSW. Asymptomatic infection occurs intermittently in these areas and can be detected serologically in sentinel chickens or other animals, particularly dogs and horses.
In 2011, cases of disease in horses in NSW were initially detected in south western and central western NSW but became widely distributed west of the Great Dividing Range from northern NSW to the Murray River in the south and throughout the Hunter Valley and Sydney basin.
Does West Nile Virus affect people?
Yes, West Nile Virus is Zoonotic. For further information regarding West Nile virus infections in people visit NSW Health.
Other key information and resources
Treatment
There is no specific treatment available for WNV infections. Supportive treatment with intravenous fluids and anti-inflammatory drugs may be required.
Prevention
Reducing exposure of horses to mosquitoes is the most effective measure to minimise the risk of infection with WNV. Mosquitoes are usually most active at dusk and dawn, so reducing time outside at these times may help. Insecticides and physical barriers, such as rugs for horse, may also be useful.
Further Information
For further information regarding West Nile virus infection in wildlife visit Wildlife Health Australia (fact sheets, various species of animals).
Email the NSW DPI Biosecurity team at animal.biosecurity@dpi.nsw.gov.au or call your Local Land Services office .
Reporting animal biosecurity emergencies
Some animal pests and diseases, or residues in animal products or stock feed can have serious consequences for trade, production or human health. By remaining vigilant and acting quickly if you suspect a significant animal pest, disease, or residue you may be able to prevent these consequences. Don’t delay! Contact Local Land Services or ring the 24 hour hotline:
Emergency Animal Disease Hotline (24 hours) on 1800 675 888.
Contact us
If you have a general query or concern about animal diseases, please email staff in Animal Biosecurity at animal.biosecurity@dpird.nsw.gov.au
Report West Nile Virus
Report unusual disease signs, abnormal behaviour or unexplained deaths in livestock and other animals. Ring the 24 hour EAD hotline on 1800 675 888.
West Nile Virus infection - clinical
West Nile Virus (WNV) is a mosquito-borne virus in the Flavivirus family. A strain known as Kunjin virus, WNV is endemic to parts of Australia and has been present for many years. Other viruses in this family include dengue, Japanese encephalitis, Murray Valley encephalitis, and Zika.
WNV occurs on every continent except Antarctica. In Australia, WNV is only rarely linked to human illness. However, in 2011 a variant of the Australian strain caused a major outbreak of neurological disease in horses in south-eastern Australia.
Disease information
What does West Nile Virus look like?
In Australia, disease has been limited to horses, although several cases have been suspected (though not confirmed) in dogs and alpaca. Many animals infected with WNV do not develop any clinical signs. Unlike North American strains, Australian strains of WNV have not caused disease in birds.
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
Other nervous signs may include:
- Facial paralysis
- Muscle tremors/fasciculation
- Hyperaesthesia
- Circling
- Blindness
- Recumbency or inability to stand
- Hind limb weakness
- Multiple limb paralysis
- Altered mental state
- Hypermetria
- Depression
Fever is an inconsistent finding, usually as a result of the late onset of neurological signs relative to the time of infection. It is important to differentiate the illness from Hendra virus infection particularly in areas where flying foxes are abundant and to take appropriate precautions.
The majority of affected horses recover uneventfully within a few days to a few weeks. In the 2011 WNV outbreak, about 10% of horses showing clinical signs died.
What should I do if I suspect West Nile Virus?
Notify suspected West Nile virus immediately by:
- Calling the Emergency Animal Disease Hotline on 1800 675 888 (24 hours), or
- Calling your Local Land Services office on 1300 795 299 (during work hours), or
- Emailing a completed NSW notifiable animal disease form PDF, 166.38 KB
How is it diagnosed?
Diagnosis of West Nile virus in live horses is routinely based on detecting an immune response to the virus. Collection of paired clotted blood samples is recommended. The first (acute) sample should be taken as soon as possible after clinical signs have been observed. A second convalescent sample should be collected approximately 21 days later. The acute samples should be submitted to the laboratory soon after collection as a high proportion of horses will give significant results in the WNV IgM assay at the time clinical signs are first observed.
If cerebrospinal fluid (CSF) has been collected, it should also be submitted for testing for both the virus by qRT-PCR and for antibody detection. Although WNV can be detected in the central nervous system of acutely infected horses, it is not possible to detect viral RNA in blood samples.
If the horse dies or is euthanased, both fresh and fixed brain, CSF and upper cervical spinal cord samples should be taken. The brain should be cut in half longitudinally to ensure that representative areas are available fresh for virus detection and fixed for histopathology. The risk of Hendra virus infection should be considered prior to tissue collection.
Keep all samples chilled but do not freeze.
NSW DPIRD covers the cost of laboratory testing of samples collected by a veterinarian to confirm or exclude suspected WNV infection in animals.
For further information on submitting laboratory samples see: Laboratory Services
How is it spread?
WNV is maintained in a mosquito-bird cycle where mosquitoes act as vectors and birds act as natural hosts (Figure 1). The species of mosquito (Culex annulirostris) that most frequently spreads WNV breeds in fresh water. Wading birds are key natural reservoirs of WNV in Australia. Horses, people and a variety of other animals may become infected through a bite from an infected mosquito. There is no further spread of the virus from an infected mammal.
WNV is endemic in northern Australia. While Culex annulirostris is common throughout NSW, very large populations develop in the Murray Darling River basin and Macquarie Marshes areas of NSW. Asymptomatic infection occurs intermittently in these areas and can be detected serologically in sentinel chickens or other animals, particularly dogs and horses.
In 2011, cases of disease in horses in NSW were initially detected in south western and central western NSW but became widely distributed west of the Great Dividing Range from northern NSW to the Murray River in the south and throughout the Hunter Valley and Sydney basin.
Does West Nile Virus affect people?
Yes, West Nile Virus is Zoonotic. For further information regarding West Nile virus infections in people visit NSW Health.
Other key information and resources
Treatment
There is no specific treatment available for WNV infections. Supportive treatment with intravenous fluids and anti-inflammatory drugs may be required.
Prevention
Reducing exposure of horses to mosquitoes is the most effective measure to minimise the risk of infection with WNV. Mosquitoes are usually most active at dusk and dawn, so reducing time outside at these times may help. Insecticides and physical barriers, such as rugs for horse, may also be useful.
Further Information
For further information regarding West Nile virus infection in wildlife visit Wildlife Health Australia (fact sheets, various species of animals).
Email the NSW DPI Biosecurity team at animal.biosecurity@dpi.nsw.gov.au or call your Local Land Services office .
Reporting animal biosecurity emergencies
Some animal pests and diseases, or residues in animal products or stock feed can have serious consequences for trade, production or human health. By remaining vigilant and acting quickly if you suspect a significant animal pest, disease, or residue you may be able to prevent these consequences. Don’t delay! Contact Local Land Services or ring the 24 hour hotline:
Emergency Animal Disease Hotline (24 hours) on 1800 675 888.
Contact us
If you have a general query or concern about animal diseases, please email staff in Animal Biosecurity at animal.biosecurity@dpird.nsw.gov.au
Report West Nile Virus
Report unusual disease signs, abnormal behaviour or unexplained deaths in livestock and other animals. Ring the 24 hour EAD hotline on 1800 675 888.
West Nile Virus infection - clinical
West Nile Virus (WNV) is a mosquito-borne virus in the Flavivirus family. A strain known as Kunjin virus, WNV is endemic to parts of Australia and has been present for many years. Other viruses in this family include dengue, Japanese encephalitis, Murray Valley encephalitis, and Zika.
WNV occurs on every continent except Antarctica. In Australia, WNV is only rarely linked to human illness. However, in 2011 a variant of the Australian strain caused a major outbreak of neurological disease in horses in south-eastern Australia.
Disease information
What does West Nile Virus look like?
In Australia, disease has been limited to horses, although several cases have been suspected (though not confirmed) in dogs and alpaca. Many animals infected with WNV do not develop any clinical signs. Unlike North American strains, Australian strains of WNV have not caused disease in birds.
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
Other nervous signs may include:
- Facial paralysis
- Muscle tremors/fasciculation
- Hyperaesthesia
- Circling
- Blindness
- Recumbency or inability to stand
- Hind limb weakness
- Multiple limb paralysis
- Altered mental state
- Hypermetria
- Depression
Fever is an inconsistent finding, usually as a result of the late onset of neurological signs relative to the time of infection. It is important to differentiate the illness from Hendra virus infection particularly in areas where flying foxes are abundant and to take appropriate precautions.
The majority of affected horses recover uneventfully within a few days to a few weeks. In the 2011 WNV outbreak, about 10% of horses showing clinical signs died.
What should I do if I suspect West Nile Virus?
Notify suspected West Nile virus immediately by:
- Calling the Emergency Animal Disease Hotline on 1800 675 888 (24 hours), or
- Calling your Local Land Services office on 1300 795 299 (during work hours), or
- Emailing a completed NSW notifiable animal disease form PDF, 166.38 KB
How is it diagnosed?
Diagnosis of West Nile virus in live horses is routinely based on detecting an immune response to the virus. Collection of paired clotted blood samples is recommended. The first (acute) sample should be taken as soon as possible after clinical signs have been observed. A second convalescent sample should be collected approximately 21 days later. The acute samples should be submitted to the laboratory soon after collection as a high proportion of horses will give significant results in the WNV IgM assay at the time clinical signs are first observed.
If cerebrospinal fluid (CSF) has been collected, it should also be submitted for testing for both the virus by qRT-PCR and for antibody detection. Although WNV can be detected in the central nervous system of acutely infected horses, it is not possible to detect viral RNA in blood samples.
If the horse dies or is euthanased, both fresh and fixed brain, CSF and upper cervical spinal cord samples should be taken. The brain should be cut in half longitudinally to ensure that representative areas are available fresh for virus detection and fixed for histopathology. The risk of Hendra virus infection should be considered prior to tissue collection.
Keep all samples chilled but do not freeze.
NSW DPIRD covers the cost of laboratory testing of samples collected by a veterinarian to confirm or exclude suspected WNV infection in animals.
For further information on submitting laboratory samples see: Laboratory Services
How is it spread?
WNV is maintained in a mosquito-bird cycle where mosquitoes act as vectors and birds act as natural hosts (Figure 1). The species of mosquito (Culex annulirostris) that most frequently spreads WNV breeds in fresh water. Wading birds are key natural reservoirs of WNV in Australia. Horses, people and a variety of other animals may become infected through a bite from an infected mosquito. There is no further spread of the virus from an infected mammal.
WNV is endemic in northern Australia. While Culex annulirostris is common throughout NSW, very large populations develop in the Murray Darling River basin and Macquarie Marshes areas of NSW. Asymptomatic infection occurs intermittently in these areas and can be detected serologically in sentinel chickens or other animals, particularly dogs and horses.
In 2011, cases of disease in horses in NSW were initially detected in south western and central western NSW but became widely distributed west of the Great Dividing Range from northern NSW to the Murray River in the south and throughout the Hunter Valley and Sydney basin.
Does West Nile Virus affect people?
Yes, West Nile Virus is Zoonotic. For further information regarding West Nile virus infections in people visit NSW Health.
Other key information and resources
Treatment
There is no specific treatment available for WNV infections. Supportive treatment with intravenous fluids and anti-inflammatory drugs may be required.
Prevention
Reducing exposure of horses to mosquitoes is the most effective measure to minimise the risk of infection with WNV. Mosquitoes are usually most active at dusk and dawn, so reducing time outside at these times may help. Insecticides and physical barriers, such as rugs for horse, may also be useful.
Further Information
For further information regarding West Nile virus infection in wildlife visit Wildlife Health Australia (fact sheets, various species of animals).
Email the NSW DPI Biosecurity team at animal.biosecurity@dpi.nsw.gov.au or call your Local Land Services office .
Reporting animal biosecurity emergencies
Some animal pests and diseases, or residues in animal products or stock feed can have serious consequences for trade, production or human health. By remaining vigilant and acting quickly if you suspect a significant animal pest, disease, or residue you may be able to prevent these consequences. Don’t delay! Contact Local Land Services or ring the 24 hour hotline:
Emergency Animal Disease Hotline (24 hours) on 1800 675 888.
Contact us
If you have a general query or concern about animal diseases, please email staff in Animal Biosecurity at animal.biosecurity@dpird.nsw.gov.au
Report West Nile Virus
Report unusual disease signs, abnormal behaviour or unexplained deaths in livestock and other animals. Ring the 24 hour EAD hotline on 1800 675 888.
West Nile Virus infection - clinical
West Nile Virus (WNV) is a mosquito-borne virus in the Flavivirus family. A strain known as Kunjin virus, WNV is endemic to parts of Australia and has been present for many years. Other viruses in this family include dengue, Japanese encephalitis, Murray Valley encephalitis, and Zika.
WNV occurs on every continent except Antarctica. In Australia, WNV is only rarely linked to human illness. However, in 2011 a variant of the Australian strain caused a major outbreak of neurological disease in horses in south-eastern Australia.
Disease information
What does West Nile Virus look like?
In Australia, disease has been limited to horses, although several cases have been suspected (though not confirmed) in dogs and alpaca. Many animals infected with WNV do not develop any clinical signs. Unlike North American strains, Australian strains of WNV have not caused disease in birds.
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
Other nervous signs may include:
- Facial paralysis
- Muscle tremors/fasciculation
- Hyperaesthesia
- Circling
- Blindness
- Recumbency or inability to stand
- Hind limb weakness
- Multiple limb paralysis
- Altered mental state
- Hypermetria
- Depression
Fever is an inconsistent finding, usually as a result of the late onset of neurological signs relative to the time of infection. It is important to differentiate the illness from Hendra virus infection particularly in areas where flying foxes are abundant and to take appropriate precautions.
The majority of affected horses recover uneventfully within a few days to a few weeks. In the 2011 WNV outbreak, about 10% of horses showing clinical signs died.
What should I do if I suspect West Nile Virus?
Notify suspected West Nile virus immediately by:
- Calling the Emergency Animal Disease Hotline on 1800 675 888 (24 hours), or
- Calling your Local Land Services office on 1300 795 299 (during work hours), or
- Emailing a completed NSW notifiable animal disease form PDF, 166.38 KB
How is it diagnosed?
Diagnosis of West Nile virus in live horses is routinely based on detecting an immune response to the virus. Collection of paired clotted blood samples is recommended. The first (acute) sample should be taken as soon as possible after clinical signs have been observed. A second convalescent sample should be collected approximately 21 days later. The acute samples should be submitted to the laboratory soon after collection as a high proportion of horses will give significant results in the WNV IgM assay at the time clinical signs are first observed.
If cerebrospinal fluid (CSF) has been collected, it should also be submitted for testing for both the virus by qRT-PCR and for antibody detection. Although WNV can be detected in the central nervous system of acutely infected horses, it is not possible to detect viral RNA in blood samples.
If the horse dies or is euthanased, both fresh and fixed brain, CSF and upper cervical spinal cord samples should be taken. The brain should be cut in half longitudinally to ensure that representative areas are available fresh for virus detection and fixed for histopathology. The risk of Hendra virus infection should be considered prior to tissue collection.
Keep all samples chilled but do not freeze.
NSW DPIRD covers the cost of laboratory testing of samples collected by a veterinarian to confirm or exclude suspected WNV infection in animals.
For further information on submitting laboratory samples see: Laboratory Services
How is it spread?
WNV is maintained in a mosquito-bird cycle where mosquitoes act as vectors and birds act as natural hosts (Figure 1). The species of mosquito (Culex annulirostris) that most frequently spreads WNV breeds in fresh water. Wading birds are key natural reservoirs of WNV in Australia. Horses, people and a variety of other animals may become infected through a bite from an infected mosquito. There is no further spread of the virus from an infected mammal.
WNV is endemic in northern Australia. While Culex annulirostris is common throughout NSW, very large populations develop in the Murray Darling River basin and Macquarie Marshes areas of NSW. Asymptomatic infection occurs intermittently in these areas and can be detected serologically in sentinel chickens or other animals, particularly dogs and horses.
In 2011, cases of disease in horses in NSW were initially detected in south western and central western NSW but became widely distributed west of the Great Dividing Range from northern NSW to the Murray River in the south and throughout the Hunter Valley and Sydney basin.
Does West Nile Virus affect people?
Yes, West Nile Virus is Zoonotic. For further information regarding West Nile virus infections in people visit NSW Health.
Other key information and resources
Treatment
There is no specific treatment available for WNV infections. Supportive treatment with intravenous fluids and anti-inflammatory drugs may be required.
Prevention
Reducing exposure of horses to mosquitoes is the most effective measure to minimise the risk of infection with WNV. Mosquitoes are usually most active at dusk and dawn, so reducing time outside at these times may help. Insecticides and physical barriers, such as rugs for horse, may also be useful.
Further Information
For further information regarding West Nile virus infection in wildlife visit Wildlife Health Australia (fact sheets, various species of animals).
Email the NSW DPI Biosecurity team at animal.biosecurity@dpi.nsw.gov.au or call your Local Land Services office .
Reporting animal biosecurity emergencies
Some animal pests and diseases, or residues in animal products or stock feed can have serious consequences for trade, production or human health. By remaining vigilant and acting quickly if you suspect a significant animal pest, disease, or residue you may be able to prevent these consequences. Don’t delay! Contact Local Land Services or ring the 24 hour hotline:
Emergency Animal Disease Hotline (24 hours) on 1800 675 888.
Contact us
If you have a general query or concern about animal diseases, please email staff in Animal Biosecurity at animal.biosecurity@dpird.nsw.gov.au
Report West Nile Virus
Report unusual disease signs, abnormal behaviour or unexplained deaths in livestock and other animals. Ring the 24 hour EAD hotline on 1800 675 888.
West Nile Virus infection - clinical
West Nile Virus (WNV) is a mosquito-borne virus in the Flavivirus family. A strain known as Kunjin virus, WNV is endemic to parts of Australia and has been present for many years. Other viruses in this family include dengue, Japanese encephalitis, Murray Valley encephalitis, and Zika.
WNV occurs on every continent except Antarctica. In Australia, WNV is only rarely linked to human illness. However, in 2011 a variant of the Australian strain caused a major outbreak of neurological disease in horses in south-eastern Australia.
Disease information
What does West Nile Virus look like?
In Australia, disease has been limited to horses, although several cases have been suspected (though not confirmed) in dogs and alpaca. Many animals infected with WNV do not develop any clinical signs. Unlike North American strains, Australian strains of WNV have not caused disease in birds.
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
Other nervous signs may include:
- Facial paralysis
- Muscle tremors/fasciculation
- Hyperaesthesia
- Circling
- Blindness
- Recumbency or inability to stand
- Hind limb weakness
- Multiple limb paralysis
- Altered mental state
- Hypermetria
- Depression
Fever is an inconsistent finding, usually as a result of the late onset of neurological signs relative to the time of infection. It is important to differentiate the illness from Hendra virus infection particularly in areas where flying foxes are abundant and to take appropriate precautions.
The majority of affected horses recover uneventfully within a few days to a few weeks. In the 2011 WNV outbreak, about 10% of horses showing clinical signs died.
What should I do if I suspect West Nile Virus?
Notify suspected West Nile virus immediately by:
- Calling the Emergency Animal Disease Hotline on 1800 675 888 (24 hours), or
- Calling your Local Land Services office on 1300 795 299 (during work hours), or
- Emailing a completed NSW notifiable animal disease form PDF, 166.38 KB
How is it diagnosed?
Diagnosis of West Nile virus in live horses is routinely based on detecting an immune response to the virus. Collection of paired clotted blood samples is recommended. The first (acute) sample should be taken as soon as possible after clinical signs have been observed. A second convalescent sample should be collected approximately 21 days later. The acute samples should be submitted to the laboratory soon after collection as a high proportion of horses will give significant results in the WNV IgM assay at the time clinical signs are first observed.
If cerebrospinal fluid (CSF) has been collected, it should also be submitted for testing for both the virus by qRT-PCR and for antibody detection. Although WNV can be detected in the central nervous system of acutely infected horses, it is not possible to detect viral RNA in blood samples.
If the horse dies or is euthanased, both fresh and fixed brain, CSF and upper cervical spinal cord samples should be taken. The brain should be cut in half longitudinally to ensure that representative areas are available fresh for virus detection and fixed for histopathology. The risk of Hendra virus infection should be considered prior to tissue collection.
Keep all samples chilled but do not freeze.
NSW DPIRD covers the cost of laboratory testing of samples collected by a veterinarian to confirm or exclude suspected WNV infection in animals.
For further information on submitting laboratory samples see: Laboratory Services
How is it spread?
WNV is maintained in a mosquito-bird cycle where mosquitoes act as vectors and birds act as natural hosts (Figure 1). The species of mosquito (Culex annulirostris) that most frequently spreads WNV breeds in fresh water. Wading birds are key natural reservoirs of WNV in Australia. Horses, people and a variety of other animals may become infected through a bite from an infected mosquito. There is no further spread of the virus from an infected mammal.
WNV is endemic in northern Australia. While Culex annulirostris is common throughout NSW, very large populations develop in the Murray Darling River basin and Macquarie Marshes areas of NSW. Asymptomatic infection occurs intermittently in these areas and can be detected serologically in sentinel chickens or other animals, particularly dogs and horses.
In 2011, cases of disease in horses in NSW were initially detected in south western and central western NSW but became widely distributed west of the Great Dividing Range from northern NSW to the Murray River in the south and throughout the Hunter Valley and Sydney basin.
Does West Nile Virus affect people?
Yes, West Nile Virus is Zoonotic. For further information regarding West Nile virus infections in people visit NSW Health.
Other key information and resources
Treatment
There is no specific treatment available for WNV infections. Supportive treatment with intravenous fluids and anti-inflammatory drugs may be required.
Prevention
Reducing exposure of horses to mosquitoes is the most effective measure to minimise the risk of infection with WNV. Mosquitoes are usually most active at dusk and dawn, so reducing time outside at these times may help. Insecticides and physical barriers, such as rugs for horse, may also be useful.
Further Information
For further information regarding West Nile virus infection in wildlife visit Wildlife Health Australia (fact sheets, various species of animals).
Email the NSW DPI Biosecurity team at animal.biosecurity@dpi.nsw.gov.au or call your Local Land Services office .
Reporting animal biosecurity emergencies
Some animal pests and diseases, or residues in animal products or stock feed can have serious consequences for trade, production or human health. By remaining vigilant and acting quickly if you suspect a significant animal pest, disease, or residue you may be able to prevent these consequences. Don’t delay! Contact Local Land Services or ring the 24 hour hotline:
Emergency Animal Disease Hotline (24 hours) on 1800 675 888.
Contact us
If you have a general query or concern about animal diseases, please email staff in Animal Biosecurity at animal.biosecurity@dpird.nsw.gov.au
Report West Nile Virus
Report unusual disease signs, abnormal behaviour or unexplained deaths in livestock and other animals. Ring the 24 hour EAD hotline on 1800 675 888.
West Nile Virus infection - clinical
West Nile Virus (WNV) is a mosquito-borne virus in the Flavivirus family. A strain known as Kunjin virus, WNV is endemic to parts of Australia and has been present for many years. Other viruses in this family include dengue, Japanese encephalitis, Murray Valley encephalitis, and Zika.
WNV occurs on every continent except Antarctica. In Australia, WNV is only rarely linked to human illness. However, in 2011 a variant of the Australian strain caused a major outbreak of neurological disease in horses in south-eastern Australia.
Disease information
What does West Nile Virus look like?
In Australia, disease has been limited to horses, although several cases have been suspected (though not confirmed) in dogs and alpaca. Many animals infected with WNV do not develop any clinical signs. Unlike North American strains, Australian strains of WNV have not caused disease in birds.
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
Other nervous signs may include:
- Facial paralysis
- Muscle tremors/fasciculation
- Hyperaesthesia
- Circling
- Blindness
- Recumbency or inability to stand
- Hind limb weakness
- Multiple limb paralysis
- Altered mental state
- Hypermetria
- Depression
Fever is an inconsistent finding, usually as a result of the late onset of neurological signs relative to the time of infection. It is important to differentiate the illness from Hendra virus infection particularly in areas where flying foxes are abundant and to take appropriate precautions.
The majority of affected horses recover uneventfully within a few days to a few weeks. In the 2011 WNV outbreak, about 10% of horses showing clinical signs died.
What should I do if I suspect West Nile Virus?
Notify suspected West Nile virus immediately by:
- Calling the Emergency Animal Disease Hotline on 1800 675 888 (24 hours), or
- Calling your Local Land Services office on 1300 795 299 (during work hours), or
- Emailing a completed NSW notifiable animal disease form PDF, 166.38 KB
How is it diagnosed?
Diagnosis of West Nile virus in live horses is routinely based on detecting an immune response to the virus. Collection of paired clotted blood samples is recommended. The first (acute) sample should be taken as soon as possible after clinical signs have been observed. A second convalescent sample should be collected approximately 21 days later. The acute samples should be submitted to the laboratory soon after collection as a high proportion of horses will give significant results in the WNV IgM assay at the time clinical signs are first observed.
If cerebrospinal fluid (CSF) has been collected, it should also be submitted for testing for both the virus by qRT-PCR and for antibody detection. Although WNV can be detected in the central nervous system of acutely infected horses, it is not possible to detect viral RNA in blood samples.
If the horse dies or is euthanased, both fresh and fixed brain, CSF and upper cervical spinal cord samples should be taken. The brain should be cut in half longitudinally to ensure that representative areas are available fresh for virus detection and fixed for histopathology. The risk of Hendra virus infection should be considered prior to tissue collection.
Keep all samples chilled but do not freeze.
NSW DPIRD covers the cost of laboratory testing of samples collected by a veterinarian to confirm or exclude suspected WNV infection in animals.
For further information on submitting laboratory samples see: Laboratory Services
How is it spread?
WNV is maintained in a mosquito-bird cycle where mosquitoes act as vectors and birds act as natural hosts (Figure 1). The species of mosquito (Culex annulirostris) that most frequently spreads WNV breeds in fresh water. Wading birds are key natural reservoirs of WNV in Australia. Horses, people and a variety of other animals may become infected through a bite from an infected mosquito. There is no further spread of the virus from an infected mammal.
WNV is endemic in northern Australia. While Culex annulirostris is common throughout NSW, very large populations develop in the Murray Darling River basin and Macquarie Marshes areas of NSW. Asymptomatic infection occurs intermittently in these areas and can be detected serologically in sentinel chickens or other animals, particularly dogs and horses.
In 2011, cases of disease in horses in NSW were initially detected in south western and central western NSW but became widely distributed west of the Great Dividing Range from northern NSW to the Murray River in the south and throughout the Hunter Valley and Sydney basin.
Does West Nile Virus affect people?
Yes, West Nile Virus is Zoonotic. For further information regarding West Nile virus infections in people visit NSW Health.
Other key information and resources
Treatment
There is no specific treatment available for WNV infections. Supportive treatment with intravenous fluids and anti-inflammatory drugs may be required.
Prevention
Reducing exposure of horses to mosquitoes is the most effective measure to minimise the risk of infection with WNV. Mosquitoes are usually most active at dusk and dawn, so reducing time outside at these times may help. Insecticides and physical barriers, such as rugs for horse, may also be useful.
Further Information
For further information regarding West Nile virus infection in wildlife visit Wildlife Health Australia (fact sheets, various species of animals).
Email the NSW DPI Biosecurity team at animal.biosecurity@dpi.nsw.gov.au or call your Local Land Services office .
Reporting animal biosecurity emergencies
Some animal pests and diseases, or residues in animal products or stock feed can have serious consequences for trade, production or human health. By remaining vigilant and acting quickly if you suspect a significant animal pest, disease, or residue you may be able to prevent these consequences. Don’t delay! Contact Local Land Services or ring the 24 hour hotline:
Emergency Animal Disease Hotline (24 hours) on 1800 675 888.
Contact us
If you have a general query or concern about animal diseases, please email staff in Animal Biosecurity at animal.biosecurity@dpird.nsw.gov.au
Report West Nile Virus
Report unusual disease signs, abnormal behaviour or unexplained deaths in livestock and other animals. Ring the 24 hour EAD hotline on 1800 675 888.
West Nile Virus infection - clinical
West Nile Virus (WNV) is a mosquito-borne virus in the Flavivirus family. A strain known as Kunjin virus, WNV is endemic to parts of Australia and has been present for many years. Other viruses in this family include dengue, Japanese encephalitis, Murray Valley encephalitis, and Zika.
WNV occurs on every continent except Antarctica. In Australia, WNV is only rarely linked to human illness. However, in 2011 a variant of the Australian strain caused a major outbreak of neurological disease in horses in south-eastern Australia.
Disease information
What does West Nile Virus look like?
In Australia, disease has been limited to horses, although several cases have been suspected (though not confirmed) in dogs and alpaca. Many animals infected with WNV do not develop any clinical signs. Unlike North American strains, Australian strains of WNV have not caused disease in birds.
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
Other nervous signs may include:
- Facial paralysis
- Muscle tremors/fasciculation
- Hyperaesthesia
- Circling
- Blindness
- Recumbency or inability to stand
- Hind limb weakness
- Multiple limb paralysis
- Altered mental state
- Hypermetria
- Depression
Fever is an inconsistent finding, usually as a result of the late onset of neurological signs relative to the time of infection. It is important to differentiate the illness from Hendra virus infection particularly in areas where flying foxes are abundant and to take appropriate precautions.
The majority of affected horses recover uneventfully within a few days to a few weeks. In the 2011 WNV outbreak, about 10% of horses showing clinical signs died.
What should I do if I suspect West Nile Virus?
Notify suspected West Nile virus immediately by:
- Calling the Emergency Animal Disease Hotline on 1800 675 888 (24 hours), or
- Calling your Local Land Services office on 1300 795 299 (during work hours), or
- Emailing a completed NSW notifiable animal disease form PDF, 166.38 KB
How is it diagnosed?
Diagnosis of West Nile virus in live horses is routinely based on detecting an immune response to the virus. Collection of paired clotted blood samples is recommended. The first (acute) sample should be taken as soon as possible after clinical signs have been observed. A second convalescent sample should be collected approximately 21 days later. The acute samples should be submitted to the laboratory soon after collection as a high proportion of horses will give significant results in the WNV IgM assay at the time clinical signs are first observed.
If cerebrospinal fluid (CSF) has been collected, it should also be submitted for testing for both the virus by qRT-PCR and for antibody detection. Although WNV can be detected in the central nervous system of acutely infected horses, it is not possible to detect viral RNA in blood samples.
If the horse dies or is euthanased, both fresh and fixed brain, CSF and upper cervical spinal cord samples should be taken. The brain should be cut in half longitudinally to ensure that representative areas are available fresh for virus detection and fixed for histopathology. The risk of Hendra virus infection should be considered prior to tissue collection.
Keep all samples chilled but do not freeze.
NSW DPIRD covers the cost of laboratory testing of samples collected by a veterinarian to confirm or exclude suspected WNV infection in animals.
For further information on submitting laboratory samples see: Laboratory Services
How is it spread?
WNV is maintained in a mosquito-bird cycle where mosquitoes act as vectors and birds act as natural hosts (Figure 1). The species of mosquito (Culex annulirostris) that most frequently spreads WNV breeds in fresh water. Wading birds are key natural reservoirs of WNV in Australia. Horses, people and a variety of other animals may become infected through a bite from an infected mosquito. There is no further spread of the virus from an infected mammal.
WNV is endemic in northern Australia. While Culex annulirostris is common throughout NSW, very large populations develop in the Murray Darling River basin and Macquarie Marshes areas of NSW. Asymptomatic infection occurs intermittently in these areas and can be detected serologically in sentinel chickens or other animals, particularly dogs and horses.
In 2011, cases of disease in horses in NSW were initially detected in south western and central western NSW but became widely distributed west of the Great Dividing Range from northern NSW to the Murray River in the south and throughout the Hunter Valley and Sydney basin.
Does West Nile Virus affect people?
Yes, West Nile Virus is Zoonotic. For further information regarding West Nile virus infections in people visit NSW Health.
Other key information and resources
Treatment
There is no specific treatment available for WNV infections. Supportive treatment with intravenous fluids and anti-inflammatory drugs may be required.
Prevention
Reducing exposure of horses to mosquitoes is the most effective measure to minimise the risk of infection with WNV. Mosquitoes are usually most active at dusk and dawn, so reducing time outside at these times may help. Insecticides and physical barriers, such as rugs for horse, may also be useful.
Further Information
For further information regarding West Nile virus infection in wildlife visit Wildlife Health Australia (fact sheets, various species of animals).
Email the NSW DPI Biosecurity team at animal.biosecurity@dpi.nsw.gov.au or call your Local Land Services office .
Reporting animal biosecurity emergencies
Some animal pests and diseases, or residues in animal products or stock feed can have serious consequences for trade, production or human health. By remaining vigilant and acting quickly if you suspect a significant animal pest, disease, or residue you may be able to prevent these consequences. Don’t delay! Contact Local Land Services or ring the 24 hour hotline:
Emergency Animal Disease Hotline (24 hours) on 1800 675 888.
Contact us
If you have a general query or concern about animal diseases, please email staff in Animal Biosecurity at animal.biosecurity@dpird.nsw.gov.au
Report West Nile Virus
Report unusual disease signs, abnormal behaviour or unexplained deaths in livestock and other animals. Ring the 24 hour EAD hotline on 1800 675 888.
West Nile Virus infection - clinical
West Nile Virus (WNV) is a mosquito-borne virus in the Flavivirus family. A strain known as Kunjin virus, WNV is endemic to parts of Australia and has been present for many years. Other viruses in this family include dengue, Japanese encephalitis, Murray Valley encephalitis, and Zika.
WNV occurs on every continent except Antarctica. In Australia, WNV is only rarely linked to human illness. However, in 2011 a variant of the Australian strain caused a major outbreak of neurological disease in horses in south-eastern Australia.
Disease information
What does West Nile Virus look like?
In Australia, disease has been limited to horses, although several cases have been suspected (though not confirmed) in dogs and alpaca. Many animals infected with WNV do not develop any clinical signs. Unlike North American strains, Australian strains of WNV have not caused disease in birds.
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
The early stages of disease may be mistaken for colic. Initially horses may appear depressed and reluctant to move but these signs are soon followed by neurological signs. The most commonly encountered signs are those of ataxia (including stumbling, staggering, wobbly gait, or incoordination).
Other nervous signs may include:
- Facial paralysis
- Muscle tremors/fasciculation
- Hyperaesthesia
- Circling
- Blindness
- Recumbency or inability to stand
- Hind limb weakness
- Multiple limb paralysis
- Altered mental state
- Hypermetria
- Depression
Fever is an inconsistent finding, usually as a result of the late onset of neurological signs relative to the time of infection. It is important to differentiate the illness from Hendra virus infection particularly in areas where flying foxes are abundant and to take appropriate precautions.
The majority of affected horses recover uneventfully within a few days to a few weeks. In the 2011 WNV outbreak, about 10% of horses showing clinical signs died.
What should I do if I suspect West Nile Virus?
Notify suspected West Nile virus immediately by:
- Calling the Emergency Animal Disease Hotline on 1800 675 888 (24 hours), or
- Calling your Local Land Services office on 1300 795 299 (during work hours), or
- Emailing a completed NSW notifiable animal disease form PDF, 166.38 KB
How is it diagnosed?
Diagnosis of West Nile virus in live horses is routinely based on detecting an immune response to the virus. Collection of paired clotted blood samples is recommended. The first (acute) sample should be taken as soon as possible after clinical signs have been observed. A second convalescent sample should be collected approximately 21 days later. The acute samples should be submitted to the laboratory soon after collection as a high proportion of horses will give significant results in the WNV IgM assay at the time clinical signs are first observed.
If cerebrospinal fluid (CSF) has been collected, it should also be submitted for testing for both the virus by qRT-PCR and for antibody detection. Although WNV can be detected in the central nervous system of acutely infected horses, it is not possible to detect viral RNA in blood samples.
If the horse dies or is euthanased, both fresh and fixed brain, CSF and upper cervical spinal cord samples should be taken. The brain should be cut in half longitudinally to ensure that representative areas are available fresh for virus detection and fixed for histopathology. The risk of Hendra virus infection should be considered prior to tissue collection.
Keep all samples chilled but do not freeze.
NSW DPIRD covers the cost of laboratory testing of samples collected by a veterinarian to confirm or exclude suspected WNV infection in animals.
For further information on submitting laboratory samples see: Laboratory Services
How is it spread?
WNV is maintained in a mosquito-bird cycle where mosquitoes act as vectors and birds act as natural hosts (Figure 1). The species of mosquito (Culex annulirostris) that most frequently spreads WNV breeds in fresh water. Wading birds are key natural reservoirs of WNV in Australia. Horses, people and a variety of other animals may become infected through a bite from an infected mosquito. There is no further spread of the virus from an infected mammal.
WNV is endemic in northern Australia. While Culex annulirostris is common throughout NSW, very large populations develop in the Murray Darling River basin and Macquarie Marshes areas of NSW. Asymptomatic infection occurs intermittently in these areas and can be detected serologically in sentinel chickens or other animals, particularly dogs and horses.
In 2011, cases of disease in horses in NSW were initially detected in south western and central western NSW but became widely distributed west of the Great Dividing Range from northern NSW to the Murray River in the south and throughout the Hunter Valley and Sydney basin.
Does West Nile Virus affect people?
Yes, West Nile Virus is Zoonotic. For further information regarding West Nile virus infections in people visit NSW Health.
Other key information and resources
Treatment
There is no specific treatment available for WNV infections. Supportive treatment with intravenous fluids and anti-inflammatory drugs may be required.
Prevention
Reducing exposure of horses to mosquitoes is the most effective measure to minimise the risk of infection with WNV. Mosquitoes are usually most active at dusk and dawn, so reducing time outside at these times may help. Insecticides and physical barriers, such as rugs for horse, may also be useful.
Further Information
For further information regarding West Nile virus infection in wildlife visit Wildlife Health Australia (fact sheets, various species of animals).
Email the NSW DPI Biosecurity team at animal.biosecurity@dpi.nsw.gov.au or call your Local Land Services office .
Reporting animal biosecurity emergencies
Some animal pests and diseases, or residues in animal products or stock feed can have serious consequences for trade, production or human health. By remaining vigilant and acting quickly if you suspect a significant animal pest, disease, or residue you may be able to prevent these consequences. Don’t delay! Contact Local Land Services or ring the 24 hour hotline: