For the Birds Radio Program: West Nile Virus, Part II

Original Air Date: Sept. 27, 2001 Rerun Dates: June 27, 2002

Why is the CDC trying to find a vaccination for West Nile virus to help crows and sparrows?

Duration: 4′40″


Earlier this month, I talked about West Nile Virus on this program. The disease is in the news because the first cases in Wisconsin were recently documented in Milwaukee.

West Nile virus can kill human beings, so in many areas people are applying pesticides in hopes of destroying the mosquitoes that transmit the disease from infected people and animals to healthy ones. The problem is, the pesticides are even more dangerous than the disease. In New York State, researchers studied the carcasses of 80,000 birds found dead of unknown causes. Some of the birds had indeed died of West Nile virus, but the majority had died of pesticide poisoning. And the disease continues to break out even in areas where pesticides had been applied. This is because so many of the species of mosquitoes that transmit the disease breed in gutters, old tires, buckets, and other standing water in our own backyards. Applying pesticides in healthy wetlands to kill the mosquitoes makes about as much sense as discovering a mold spot on the surface of a block of cheddar cheese and, instead of just cutting the mold off, lacing the entire cheese with poison.

A new disease is terrifying. I can remember the publicity and fear when AIDS was first discovered, and then Lyme disease. Now Lyme disease is rather under control. We can be vaccinated, and if we notice an inflamed area at the site of a tick bite, we can prevent or cure the disease itself with antibiotics. AIDS continues to be a scourge that is still taking an enormous human toll, and after two decades of research we still don’t have a proven vaccination or a cure.

West Nile virus is nowhere near as fatal to humans as AIDS is, though it’s dangerous indeed. According to the CDC, most people infected with West Nile Virus do not become ill. If someone does get sick, symptoms usually occur 5–15 days after a West Nile virus infected mosquito bites him or her. People with a mild infection may come down with fever, headache, eye pain, muscle aches, joint pain, a rash on the trunk, and swollen lymph nodes. In severe cases, symptoms include extreme muscle weakness, inflammation of the brain, or encephalitis, paralysis, and coma. In rare cases, the infection may be fatal, particularly in the elderly, and in people with other medical conditions, but assuming the patient recovers, prior infection with West Nile virus can provide lifelong immunity to the virus.

The Centers for Disease Control are hard at work perfecting a vaccination against West Nile virus for humans. The thoroughbred horse industry has developed a vaccination for horses that’s fairly effective, and I just learned that the CDC is working with the American Bird Conservancy to develop one for birds. At this point they’re testing an injectable vaccine, which even if it’s 100 percent effective can only work on captive birds and exotic zoo specimens. But the American Bird Conservancy hopes that in the future, they’ll be able to develop an oral vaccine that could be administered in birdseed. Their short-term goal is to immunize birds such as crows and House Sparrows that live in urban habitats.

People might complain that crows and sparrows aren’t exactly valuable species, and that the effort might be better spent figuring out how to protect rarer or more useful birds. But protecting a few abundant species will at least lower the transmission rate for all, humans and animals, since mosquitoes have to have bitten an infected animal or person in order to pass the disease to a healthy one.

West Nile virus has close to a one-hundred-percent mortality rate in birds, including such hardy species as crows, so this disease is extremely dangerous. Birds and humans share many attributes. It’s sad that one of them had to be vulnerability to a disease.