QUESTION: I saw a report on the news about West Nile Virus and they mentioned that dead crows may be a sign of the virus. I’ve seen several dead crows in the Palisades and they don’t have any signs of trauma. Should we be worried about West Nile Virus? What are the symptoms of the virus?
Dr. Raskin: Your question reminded me of Alfred Hitchcock’s 1963 horror film “The Birds”; but, instead of ravenous crows attacking a schoolhouse, there are numerous dead birds falling from the sky! To demystify the situation, let me give you all the details of the lifecycle of the West Nile virus. West Nile is most commonly transmitted to humans from getting bitten by mosquitos that are infected with the virus. There are very rare cases of transmission via blood transfusions, organ transplants,and pregnancy, but these are very uncommon. The mosquitos often feed on birds, and they can get infected as well. In fact most birds survive without any problems, but for some reason crows and jays can frequently die from the disease. Mosquitos can become infected when they feed on the infected birds, and then they can bite a human.
The good news about West Nile Virus is that most people (70-80%) who get infected have no symptoms at all and never know that they had an infection. About one-fifth of humans who are infected develop headaches, body and joint aches, diarrhea and vomiting, but most resolve completely. There are some cases where patients can feel fatigue and weakness for several weeks. A very small number (less than 1%) of those infected will go on to develop severe neurologic illness including seizures, coma, paralysis, and even death. The incubation period is about 2 to 6 days after getting the bite, and the condition can be diagnosed by lab tests with blood or spinal fluid.
Unfortunately, there are no vaccines to prevent West Nile yet, and there are no specific treatments other than supportive care for those severely ill who may require intravenous hydration and pain relievers. The best way to combat this disease is to prevent the mosquito bites in the first place. Wearing insect repellant and protective clothing around high risk times (higher risk from dusk to dawn and from June through September), and reducing the possibility of mosqitos in the home can be very helpful. Repairing screens on doors and windows and removing any standing water near the house where mosquitos like to breed, such as birdbaths, poolcovers or buckets are also wise measures to take.
There is no evidence that a person can get infected by handling a live or dead bird, even if they are infected with the virus. Nonetheless, I recommend handling the dead birds with gloves only or using the inside of a plastic garbage bag to pick them up. If you happen to see a lot of dead crows, you can report this to the state health department or state wildlife agency, and they will often investigate to see if the cause of death is West Nile or other diseases such as Avian Flu.
Accoding to the CDC website, there have only been 23 cases of West Nile found in Los Angeles county so far in 2014, so chances are very low that you need to be too worried.
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