US Army specialist Steve Richards captures mosquitos for testing
After a week or two of relative calm, the mosquito-borne illness is back in the headlines. The virus took the life of a 73-year-old Queens man Monday who died after two days in the hospital. In Georgia, concerns are mounting over organ donations and blood bank supplies after four organ recipients were treated for symptoms of the virus. One of the recipients died from brain swelling associated with the disease. Overall, this has been a tough year as far as West Nile virus is concerned; when it first appeared during the summer of 1999, it was contained to New York City, Connecticut and New Jersey. Since then, cases have sprung up around the country, as far west as South Dakota and in southern states like Florida. This year, the CDC has confirmed more than 600 cases of West Nile Virus; 31 of them have been fatal. Between 1999 and 2001, there were 18 deaths linked to the virus.
Does this new information mean we're back in the figurative woods? Should we all start hoping for an early frost and an end to mosquito season? As with many news stories, things on the West Nile front aren't nearly as bad as they may seem.
TIME.com spoke with Dr. Stephen Zinner, an infectious disease physician and chair of dept of medicine at Mount Auburn Hospital in Cambridge Mass. He is also a professor at Harvard Medical School:
TIME: It looks like West Nile virus is sticking around. How nervous should we be?
Dr. Stephen Zinner: I don't think there's any reason to panic. People should not live in fear of this virus. Just keep mosquito prevention in mind. As we've all been hearing, most healthy adults are not at great risk.
It's important to remember that most people [around 80 percent] who are infected by the virus by a mosquito show no recognizable symptoms. Of the 20 percent who do have some recognizable illness, most of it is extremely mild, a "flu-like" symptom, nausea, maybe mild rash, some fatigue. These are symptoms that appear in viral infections in general.
Maybe 1 in 150 [less than one percent] of those who are infected might have manifestations in their central nervous systems. The most obvious risk for that is older age (50+). When a severe illness does occur, you get typical signs of encephalitis.
TIME:And what are those signs?
Zinner: West Nile encephalitis looks a lot like any other encephalitis: Infection and inflammation in the brain leads to headache, fever, confusion, maybe seizures. In the worst cases, it can lead to coma or death.
TIME: Should we be concerned by the rise in confirmed cases (and deaths) this summer?
Zinner: I don't believe so — what we're seeing is a natural effect of the virus spreading geographically. As the virus moves west, as we've seen this summer, more susceptible adults are exposed. And that means we see more cases.
I predict we'll see the virus in California by late this year and early next year. There is an upside to the diffusion of West Nile: whenever a virus like this spreads, most people who are exposed to it will develop immunity and the rate of infection will decline. This is the usual expectation, and it seems to hold for this virus — three years ago we saw an outbreak in New York City, then last year, the infections spread south, and this year it's moving west.
TIME: Is there a cure or vaccine for West Nile virus? Will we see one soon?
Zinner: At this point there is no specific anti-viral agent proven to be clinically effective against West Nile virus. There are a few candidates, and while they've only just begun clinical trials, the prospect for future vaccines or treatments is good.
TIME:Let's say you?re living in a WNV hotspot, like Louisiana, and you don't feel great. When should you go to doctor?
Zinner:Certainly a mosquito bite should not prompt a call to a physician. Most of these cases have come on fairly suddenly, with fever and nausea, usually. The only way to confirm the virus is with a blood test. If people are worried that their symptoms are West Nile-related, they can ask a doctor for a blood test. That said, there is no specific treatment; we can only treat the symptoms.
TIME:Okay, tell us what we should be doing to minimize our risk of contracting the virus.
Zinner:It's everything you've heard all year: Use DEET, wear long-sleeve shirts and long pants, clear standing water and avoid going outside at dusk. It's really important that people take mosquito protection seriously.
TIME:Does end of summer mean we'll see fewer cases of WNV?
Absolutely. That's happens each year. Cases diminish when mosquitoes die off in cooler weather.
TIME:Should we be concerned about recent news stories suggesting a link between transplanted organs and the West Nile virus?
Zinner:These cases are all under investigation, so we don't really know yet exactly what's happened. But with most self-limiting viruses, like this one, the virus clears itself out of the bloodstream when the patient recovers. So it's possible the donor was incubating the virus but wasn't manifesting symptoms, and the organ recipients ended up with symptoms because their immune systems were compromised. But I want to emphasize that we won't know anything for sure until we see more information.
TIME:Now that we've encountered this possible transmission pathway, should we include West Nile virus in routine screenings at blood banks?
Zinner:Again, we're going to have to wait and see what happens in these investigations before we take action. It's not clear at this point whether screenings would actually prove useful in preventing the virus.