Finding Birds with West Nile Virus

If I find a dead bird, how do I know if it has West Nile Virus, and what does that mean for my family and pets?

West Nile Virus is a disease that first came into the US in 1999. It is spread by mosquitoes and has been found in birds, horses and humans. New reports have shown that squirrels, bats, and other mammals can get West Nile Virus and the disease has just recently been reported in reptiles.

Some birds, especially blue jays, crows and raptors are seriously affected. Birds with West Nile virus can show signs of disorientation, weakness, unable to fly or eat, weight loss, eye problems, seizures, tremors, paralysis and eventually death. Other birds may be infected but do not show any signs and recover. No vaccine is currently available for birds.

Horses are very sensitive to the West Nile Virus and up to 20% to 30% of the infected horses can die, however there is a vaccine available for horses.

Studies have found that a person's risk of getting West Nile is low. "Many people that are exposed to the West Nile virus exhibit flu-like symptoms or no symptoms at all. Those at highest risk are the elderly and people with weakened immune systems: it is important, however, for all people to protect themselves from mosquito bites to minimize the risk of infection." from The National Biological Information Infrastructure website at

The following is from the Massachusetts Dept. of Public Health's web site

The best way to protect yourself is to keep mosquitoes from biting you. Follow these steps every summer if you live in or visit an area with mosquitoes:

  • Avoid outdoor activities between dusk to dawn, if possible, as this is the time of greatest mosquito activity.
  • If you must be outdoors when mosquitoes are active, wear a long-sleeved shirt and long pants. Use a mosquito repellent that contains DEET (the chemical N-N-diethyl-meta-toluamide) and follow the directions on the label. DEET can be poisonous if overused. Never use DEET on infants. Avoid using repellents with DEET concentrations above 10-15% for children and with concentrations above 30-35% for adults. Cream, lotion or stick formulas are best for use on the skin. Avoid products with high amounts of alcohol because these may be absorbed through the skin.
  • Take special care to cover up the arms and legs of children playing outdoors. When you bring a baby outdoors, cover the baby's carriage or playpen with mosquito netting.
  • Fix any holes in your screens and make sure they are tightly attached to all your doors and windows.

If you find a dead bird, pick it up with either rubber gloves or by placing a plastic bag over the bird, then using the bag as a mitt, pull the bird into the bag and tie it up. Though the West Nile Virus is not spread by direct contact dead, birds can have other bacteria and parasites that you want to avoid. The following is information from the Massachusetts Department of Public Health on what to do if you find a dead bird in Massachusetts. Keep the dead bird in a cool area and call the state lab.

Dead Bird Reports:
The MDSP ( Mosquito-borne Disease Surveillance Program) will collect dead bird reports, including the location where the bird was found and the species of bird, from local and state officials and the public. The Massachusetts State Lab will request that some of the dead birds, primarily crows and blue jays, be submitted for testing, and state lab will provide a pickup service from designated regional repositories to assist local communities in transport of specimens. Because WNV causes death in birds, and the mortality rate from infection for the American crow is high, we expect that dead birds, and especially crows, will be the first warning of WNV activity in an area. The state lab will record and analyze dead bird reports, which will be used to identify areas for intensified surveillance of virus activity including bird testing, mosquito trapping and active disease surveillance. Reports of dead birds will be taken via a toll-free telephone number at the State Laboratory Institute (866 MASS WNV, which is 866-627-7968). These reports will be summarized daily and provided to local health agents, the public and the media, via a public website (

Testing dead wild birds for West Nile virus:
MDSP will collect and test dead birds, primarily American crows and blue jays, for WNV. Based on reports of dead birds, testing may be increased to assess virus transmission among the bird and mosquito populations. Once infection of a bird population in an area is established, a limited sample of dead birds may be tested to confirm that additional deaths are the result of WNV infection. All bird deaths should be reported to the MDSP on the toll-free telephone line, which may be used by local officials and the public. At the time of the report, the MDSP staff person will record information and enter the report into the surveillance database. The caller will be informed if the reported bird is to be tested, and arrangements made for pickup and delivery. Otherwise the caller will be informed of proper disposal procedures for the dead bird.

The risks of West Nile on our pets are best answered from the following excepts from the web site provided by APHIS. APHIS is the Animal and Plant Health Inspection Service of the U.S. Dept. of Agriculture (

Q. Are animals other than birds and horses affected by the virus?
A. Experimental tests suggest that sheep, chickens, and pigs could be affected by WNV. Two cases of illness caused by WNV were detected in sheep in the United States in 2002. In tests, the virus caused pregnant sheep to abort. Cows may show antibodies to the virus, which means they have contracted it without showing any clinical signs or becoming ill.

Q. Are dogs and cats affected by the virus?
A. It is unlikely that dogs or cats will show signs of clinical illness, although any mammal or bird could potentially be exposed to the virus through mosquito bites. A survey of blood samples from dogs and cats in the New York City epidemic area showed low infection rate.

Q. What precautions can be taken to protect animals from WNV?
A. Preventing animals' exposure to mosquitoes is essential. The best way to do this is by removing any potential sources of water in which mosquitoes can breed. Dispose of any water-holding containers, including discarded tires. Drill holes in the bottom of containers that are left outside. Clean clogged roof gutters on an annual basis. Turn over wading pools or wheelbarrows when not in use, and do not allow water to stagnate in bird baths. Aerate ornamental pools or stock them with fish. Clean and chlorinate swimming pools that are not in use and be aware that mosquitoes can breed in the water that collects on swimming pool covers. Use landscaping to eliminate standing water that collects on your property; mosquitoes can breed in any puddle that lasts more than 4 days. Thoroughly clean livestock-watering troughs on a monthly basis. Local mosquito-control authorities can help in assessing the mosquito-breeding risks associated with your property.

"WNV represents a new challenge for North American diagnosticians, wildlife rehabilitators, wildlife biologist, zoological staff, and others involved with wild birds and mammalian species. Although it is widely recognized that crows and other corvids are highly susceptible to this newly emergent disease, many other species are also exposed." (Vet Pathology 40:6, 2003 West Nile Virus Infection in Eastern Fox Squirrels)

New findings are being collected and analyzed day by State, Federal and private organizations. More information on West Nile Virus can be found on the following web sites: