In the summer of 2002 I was still a fairly new attending physician, leading groups of residents around the hospital while our patients taught us about medicine and humanity. The public hospital where I was rounding was in constant financial trouble, so I took off for the suburbs before I was forced to. My new hospital was in a different county, one with many lakes and wetlands, and something strange was going on. I had a bunch of people on my service with strange constellations of symptoms: headache, fever, weakness, confusion. In many of the patients the disease looked like nothing so much as polio. Most of the sickest patients were old, but a few were younger. Neurologists would label them with a variety of rare neurologic diseases such as transverse myelitis, Wilson’s disease, delirium tremens, CIDP. None of these really explained what was happening, and a virus new to North American was slowly flying cross-country.
Around the same time, I would go for hikes with my parents, and often find dead crows on the trail. The CDC and state health department had warned that corvid birds such as crows and jays seemed to be especially affected by the new virus and likely served as a reservoir for human infection.
We didn’t have great ways to test for West Nile Fever at that point. We would take samples of spinal fluid and send them to a specialty lab along with as much of a travel and vaccine history as we could pry out of a delirious patient. The tests weren’t specific for WNV so we had to use the patient’s history to narrow down the diagnosis. But we did diagnose it, and frequently. Beyond diagnosis, though, there wasn’t much we could do.
Since 2002, WNV has become endemic to the area, but severe human cases are now rare, perhaps due to more human immunity or climate or behavior factors, but this year, we’ve seen a surge. Very few people actually become ill when infected and the 20% or so who do feel like they have the flu. A very small percentage of those develop severe disease.
Like all mosquito-borne diseases, we can help prevent infection, but we probably can’t eliminate all risks. Unlike malaria, whose hosts are limited to people and mosquitoes, WNV also infects birds, so we’re pretty much stuck with this virus for the foreseeable future.
Mosquitoes that carry WNV like to bite at dusk and dawn. Avoid going outside then, and if you do, cover up well in light colors and use insect repellant with 30% DEET. Find standing water on your property, such as tires, old flower pots, birdbaths, and empty them—mosquitoes need standing water to breed. Also make sure your screens are all intact. You can’t get WNV if you don’t get bitten.
Late summer/early fall is a beautiful season, with leaves starting to change, warm days cool nights. Enjoy them, but do so safely.