Anthony S. Fauci, the former top U.S. infectious-disease expert, was hospitalized last month with the mosquito-borne West Nile virus. On Monday, Maryland announced its first confirmed case of the disease this year. And the biting insects seem to be everywhere in the Washington region.
Attention on West Nile, the most common disease spread by mosquitoes, is high with more than three weeks of hot, humid D.C. summer still ahead of us.
Mosquitoes carry other diseases, such as eastern equine encephalitis, which killed an adult in New Hampshire this month and is seen rarely in our region – typically once every five to eight years. Locally, experts say, cases of mosquito-borne illness such as Zika, malaria and dengue fever are isolated and usually imported by people who traveled internationally.
The good news, experts say, is most people infected with West Nile never know it and there are ways to prevent bites besides hiding indoors until fall.
“We’re not telling people not to go out,” said Joy McFarlane Mills, a supervisory biologist at the D.C. Department of Health. “Go out and enjoy yourself, but use … prevention mechanisms as needed.”
– – –
What is West Nile virus?
West Nile is most commonly transmitted to humans by the bites of mosquitoes infected after feeding on birds that have the virus, according to the Centers for Disease Control and Prevention. It was first detected in the United States in 1999.
Eighty percent of people who are infected with West Nile show no symptoms at all, public health experts say. The other 20 percent will show symptoms such as fever, headache, body aches, vomiting, diarrhea or rash.
A small number, less than 1 percent, develop severe disease including neurological symptoms such as encephalitis.
Those with cancer or diabetes or are otherwise immunosuppressed may be at increased risk for severe disease, as are older adults because the risk begins to increase at age 50.
There are no vaccines to prevent or medicines to treat West Nile virus disease in people.
– – –
How common is it in the Washington, D.C., region?
West Nile is the most common mosquito-borne disease in the D.C. region and across the United States, but serious cases are rare.
Maryland reported its first confirmed case of the disease Monday in the Baltimore area, said David Crum, the state public health veterinarian. There are an additional three confirmed or probable cases, according to CDC data from Tuesday afternoon. Last year, Maryland reported a total of seven cases, meaning more are likely.
Virginia has had an annual average of six or seven cases for the past five years. The state has three cases so far this summer, with the initial case occurring in June, which is unusually early, said Julia Murphy, the state public health veterinarian and head of the mosquito team.
District officials are currently investigating two presumptive cases, said McFarlane Mills, supervisory biologist at D.C. Health’s Division of Animal Services. There was one case each in 2023 and 2022 and six in 2021, she said.
As of Tuesday afternoon, Texas had reported the most cases so far this year, with more than 40 confirmed or probable cases, followed by Nevada, Nebraska, Louisiana and Mississippi, each of which had more than 20, according to a CDC tracker.
– – –
Is it worse than usual?
Time will tell. The typical season runs from July through September, and officials are tracking cases carefully.
Environmental factors impacting the life of mosquitoes can be complicated depending on the landscape and conditions, but weather is thought to be a key factor that can affect transmission of West Nile virus, Murphy said.
A mild winter followed by a hotter-than-average summer, like the one we’ve had this year, tends to increase the risk of West Nile, she said.
Studies show dryer-than-normal conditions could also mean more West Nile.
– – –
How can I protect myself?
Public health officials think of two fronts in the war against West Nile: preventing mosquito bites and eliminating breeding areas.
“If you’re feeding them, you’re breeding them,” Crum of Maryland said.
Culex pipiens, the common house mosquito, is the main driver of West Nile in the D.C. region, and the insects often breed in containers of water found in urban, suburban and rural settings, Murphy said.
That’s why public health officials advise residents to “tip and toss” potted plant trays, buckets, toys, birdbaths and other receptacles that collect water at least once a week to interrupt the breeding cycle. Rain gutters, drain pipes and tires could also be culprits.
If standing water can’t be removed, it can be treated with larvicide, such as Dunks, Murphy said.
Those strategies will prevent mosquito larvae from maturing into adult bloodsuckers. But to prevent bites, experts advise residents to stay indoors at dusk if possible, wear long sleeves and pants when outside and treat bare skin and clothing with an EPA-registered repellent as directed, such as DEET. The CDC maintains a list of products that will do the trick.
“It’s about staying conscientious,” McFarlane Mills of DC Health said. “The way we carry hand sanitizer, carry your spray, especially if you’re an outdoorsy person. Make sure you’re preventing any potential exposure.”
(c) Washington Post
The Compost is not telling us how this little runt is still alive.