The Centers for Disease Control and Prevention reported last week that more people in the United States. have shown symptoms of infection with West Nile virus at this point in 2012 than at this time in any year since the virus was first detected in 1999. As of Aug. 21, 1,118 people had been diagnosed with the virus and 41 have died.
The vast majority of cases (about 75 percent, the CDC reports) have occurred in five states (Texas, Mississippi, Louisiana, South Dakota and Oklahoma); nearly half of the cases have occurred in Texas alone.
West Nile virus has made a far smaller showing in this part of the country so far this year, with Maryland reporting 11 cases (including 1 death) according to Kimberly Mitchell, chief of rabies and vector-borne disease at the Maryland Department of Health and Mental Hygiene. The CDC reports two cases (and no deaths) in Virginia and none in the District, though the virus has been found among mosquitoes in D.C. (The CDC's tally for Maryland hasn't caught up to the state's records, noting just 10 cases.)
The CDC notes that only about 20 percent of those who are bitten by infected mosquitoes will show signs of illness. Among those who do experience symptoms, most will have mild cases characterized by fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. Such cases may or may not require medical treatment.
Severe cases, with symptoms such as high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis, affect about 1 in 150 of those infected and may require hospitalization.
Symptoms typically appear three to 14 days after a person has been bitten by an infected mosquito, according to the CDC.
Those who are outdoors a lot are of course at increased risk of contracting West Nile virus. People over age 50 are at increased risk of developing more severe forms of the disease.
There is no vaccine for West Nile; nor are antibiotics appropriate for treating this kind of infection, as antibiotics combat bacterial, not viral, infections.
Mitchell says that Maryland’s experience this year has been “pretty routine. It’s been fairly consistent with what it’s been in the past two years,” Mitchell says, noting that in the past few years Maryland has seen between one and 23 cases annually.
Mitchell notes that virus’s presence in the Northeast has waned in recent years, for reasons that vary from the amount of rainfall (mosquitoes breed in pools of water, so more rain means more breeding spots) to the presence of different species of mosquitoes (whose feeding habits alter the way the virus is transmitted) and human behavior (including whether people take steps to drain standing water and whether they’re diligent in their use of mosquito repellant.
So, is Mitchell taking steps to protect herself? “I have my own can of Deep Woods OFF that I’m pretty religious about putting on,” she says. “Preventive measures are the key thing.”
The Journal of the American Medical Association has published a patient's guide to West Nile virus. And the CDC offers tips for protecting against the virus – most of them aimed at preventing against mosquito bites. Here they are:
When you are outdoors, use insect repellent containing an EPA-registered active ingredient. Follow the directions on the package.
Many mosquitoes are most active at dusk and dawn. Be sure to use insect repellent and wear long sleeves and pants at these times or consider staying indoors during these hours.
Make sure you have good screens on your windows and doors to keep mosquitoes out.
Get rid of mosquito breeding sites by emptying standing water from flower pots, buckets and barrels. Change the water in pet dishes and replace the water in bird baths weekly. Drill holes in tire swings so water drains out. Keep children's wading pools empty and on their sides when they aren't being used.
How worried are you about contracting West Nile virus? Are you taking steps to protect yourself and your family?