The West Nile virus is having a great summer in New York City. Health officials this week reported that at least two people have recently contracted the viral illness, while a record number of mosquitoes are estimated to be carrying it currently. Officials are warning people to use repellant and wear protective clothing during peak mosquito activity, and they’re actively spraying high-risk areas.
Mosquitoes are the deadliest animal in the world to humans, thanks to the many diseases they can spread to us. But relative to other, hotter countries, the US is less affected by mosquito-borne maladies (indeed, ticks are actually the top source of illness spread by insects and arachnids here). But since its arrival here over 20 years ago, West Nile virus has become the most common mosquito-borne illness in the states. And while birds are a natural reservoir of West Nile, the virus has routinely been extremely deadly for certain North American species.
West Nile is a nationally notifiable disease in the US, meaning that doctors are obliged to report any known cases to health departments. But most cases aren’t caught, in large part because about 80% of people infected with West Nile never develop noticeable symptoms. Those who become sick tend to experience symptoms like fever, headache, rash, and fatigue, the latter of which can last for weeks or even months before complete recovery. More rarely, in about one out of 150 cases, the virus can infect the nervous system, causing much more serious problems like swelling of the brain or its protective layers. Neuroinvasive West Nile can lead to paralysis, tremors, and even coma, and about 10% of sufferers of this form of the disease ultimately die as a result.
New York City was the epicenter of the first known West Nile outbreak in the US in 1999. It’s since been found in all 48 landlocked states, but NYC remains a popular summer destination for West Nile. On Tuesday, health officials reported that two people had recently contracted West Nile, one in Brooklyn and the other in Queens. Perhaps more alarming is that the virus has been found in an unprecedented number of local mosquito pools, meaning samples collected from trapping a large group of mosquitoes and testing them all at once for the virus. So far, there have been 1,068 mosquito pools positive for West Nile documented across the five boroughs, far above the 779 positive pools reported this time last summer.
Nationwide, according to health officials, there have been 54 cases and four deaths attributed to West Nile this year. And since 1999, there have been more than 25,000 cases of neuroinvasive West Nile and nearly 2,500 deaths reported in the country. The chances of becoming severely sick or dying from West Nile are relatively small, but mosquitoes are annoying enough as it is, and their peak level of activity won’t die down until at least October—so it’s still prudent to take whatever precautions you can, especially since West Nile won’t be going away in the US anytime soon.
“We are in the height of West Nile virus season, but there are things you can do to decrease your risk of being bitten,” said NYC Health Commissioner Ashwin Vasan in a statement. “Use an EPA registered insect repellent, wear long sleeves and pants, especially when outside at dusk and dawn when the types of mosquitoes that transmit WNV are most active. In addition, you can stop mosquitoes from laying eggs in the water by emptying outdoor containers that hold water or calling 311 if you see standing water that you cannot empty. Help keep you and your loved ones safe with these actions during WNV season.”