US health authorities are advising people to take precautions and protect themselves from infection by mosquitoes carrying the West Nile Virus (WNV), as in many affected states a wet spring is turning into a wet summer bringing with it the usual increase in mosquito populations.
Some states, such as Alabama and Ohio, have had a dry spring and are expecting a dry summer and a fall in WNV prevalence since the mosquito that carries the virus and infects humans through bites will have fewer places to breed.
However, as Tim Ingram, commissioner of the Hamilton County General Health District in Cincinnati, Ohio, said in yesterday’s Community Press, even without wet weather, mosquitoes still remain a threat, and he urges everyone to continue to “drain, dunk and protect” to reduce the risk of WNV for everyone this summer and fall.
Drain means go round your yard and eliminate standing water that can collect in places like tyres, flower pots and wading pools. Mosquitoes use these undisturbed pools for breeding.
Dunk means apply mosquito larvicide or “dunks” to standing water areas that you can’t drain. These chemicals are safe for the environment and don’t harm your pets, says Ingram. You can get them at your local hardware store.
Protect means protect yourself and reduce ways the mosquito can enter your home. Make sure window and door screens fit well with no gaps or tears, wear long sleeves and pants when you go out at dawn and dusk, the times when the mosquito is flying about. Trim your shrubs and cut the grass.
Protect your skin with an Environmental Protection Agency-registered insect repellent that contains DEET, picaridin or oil of lemon eucalyptus. Observe the instructions on the package, particularly if you have allergies.
Meanwhile Illinois state department of public health has reported one human case of WNV to the Centers for Disease Control and Prevention (CDC) ArboNET surveillance system, and says a woman from Cook County is their second WNV victim this year.
Department of Public Health Director, Dr Eric E. Whitaker said in a press release that:
“So far this year there are only three counties reporting West Nile virus positives in Illinois, compared with 21 counties this time last year. However, this is the second human West Nile virus case of 2007.”
“Even though we have not seen widespread mosquito activity, you still need to protect yourself against mosquito bites,” he cautioned.
They issued a similar list of “drain, dunk, protect” precautionary measures as that advised by Ingram in Ohio, except they didn’t call it such.
And in Texas, where rain seems to have been falling all spring and now summer as well, Scott Sawlis, an entomologist for the Dallas County Department of Health and Human Services, speaking to the Dallas Morning News yesterday, urged people not to panic and to keep a sense of perspective. As long as it keeps raining, the mosquito is being controlled. Until the rain stops and the sun comes out to warm up stagnant water, the mosquitoes won’t be so much of a problem, and “if it rains all summer, who knows?” he said.
However, the authorities are still urging people to take the usual precautions and stock up on insect repellent. Sawlis said that 75 per cent of the people who fell ill with WNV in the past weren’t using it. They also recommend you “turn off porch lights before stepping outside to prevent bugs from entering your home”.
The CDC’s ArboNET surveillance system has received reports of WNV infections in birds, animals and mosquitoes from the following states so far this year: Arizona, California, Florida, Idaho, Illinois, Indiana, Missouri, Mississippi, North Dakota, Nebraska, Ohio, Oregon, Pennsylvania, South Dakota, Tennessee, Texas, Utah, and Virginia.
And the following states have reported human cases in 2007: Arkansas (1 case), California (1 case), Illinois (1 case), Iowa (1 case), Mississippi (6 cases, one of which was fatal), Nebraska (2 cases), North Dakota (1 case), South Dakota (5 cases), and Texas (1 case).
Of the 19 total human WNV cases reported to the CDC this year, 6 reported encephalitis/meningitis and 13 reported fever.
Not all cases of human infection are reported to the CDC, and there is sometimes a time delay between an announcement by a state health authority reporting cases and the official report to the CDC, which may account for some of the discrepancies between the CDC figures on a state and the figures from that state’s own health authority.
Add to this the fact that only severe cases of infection are reported at all, and only 2 out of 10 people infected with WNV experience symptoms, one can see how difficult it must be to compile a nationwide assessment of the virus’s prevalence.
WNV first appeared in the United States in the New York metropolitan area in the fall of 1999.
WNV is a disease that affects the central nervous system and symptoms usually appear between 3 and 14 days after being bitten by a WNV carrying mosquito.
If you get bitten by a WNV infected mosquito your chances of getting ill are still quite low. 80 per cent of people infected with WNV have no symptoms.
Severe illness affects about 1 in 150 infected people, and in very rare cases can progress to permanent neurological damage and death.
Symptoms of severe illness can last several weeks and include: headache with high fever, stiffness of the neck, convulsions, feeling disoriented, coma, tremors, weak muscles, loss of vision, numbness and paralysis.
2 out of every 10 persons bitten by the mosquito are more likely to have milder symptoms for a few days (and occasionally longer) which include fever, headache, body aches (like having the flu), nausea, vomiting, sometimes a skin rash on the chest, stomach and back, and swollen lymph glands.
Written by: Catharine Paddock
Writer: Medical News Today