Mosquito season is here - protect against West Nile virus

“Expect to see the mosquitoes a lot sooner,” said Dave Benth, director of Vector Control, last week. And wow, was he right! With the recent moisture they seem to have multiplied overnight.

When there are 75 to 100 mosquitoes in traps in the city limits, adult spraying will be added to the strategy of controling the mosquitoes, Benth explained in an interview with the Herald last week. He said the traps were showing a count of less than 20 at that time.

A 12-hour period on Monday night collected a count of 220 mosquitoes in the south east part of the city. A trap at the Riverview Cemetary contained 136, and by the river outside of the city revealed a count of 520 hungry blood suckers.

You can protect yourself from mosquito-borne illnesses. Mosquito-borne illnesses include West Nile virus (WNV), St. Louis encephalitis, and Eastern Equine encephalitis. These illnesses affect birds, animals and humans, causing flu-like symptoms in people who are bitten by infected mosquitoes. Occasionally, illness can be severe, leading to meningitis or encephalitis.

The transmission of the West Nile virus is high at peak mosquito season. North Dakota Department of Health reported 137 cases in 2006 with 34 of those cases requiring hospitalization. This year four cases of WNV have been reported already in the state of Miss.

In most cases, persons infected with West Nile Virus either show no symptoms or have very mild flu-like symptoms, called West Nile fever. These mild cases of West Nile fever normally last only a few days and are not believed to cause any long-term effects.

According to the Center for Disease Control (CDC), severe cases have resulted in “West Nile encephalitis,” an inflammation of the brain, “West Nile meningitis,” inflammation of the membrane around the brain, or “West Nile meningoencephalitis,” an inflammation of the brain and the membrane around it. The typical time from infection to the onset of signs and symptoms is 3 to 14 days. The signs and symptoms of severe disease may last several weeks and may have permanent neurological effects.

Signs and symptoms of the milder illness, West Nile fever, include headache, fever, body aches, sometimes swollen lymph nodes, sometimes a skin rash on the body.

The CDC reports that with more severe infection (West Nile encephalitis or meningitis), the signs and symptoms include headache, high fever, stiffness in the neck, disorientation (in very severe cases, coma), tremors and convulsions, muscle weakness (in very severe cases, paralysis).

Most documented human cases in the U.S. have resulted from mosquito bites. Just one mosquito bite can transmit West Nile virus or other diseases. The risk of getting infected with WNV can often be reduced or eliminated with use of preventive measures that minimize or eliminate mosquito bites.

To lessen the chances of mosquito bites, reduce or eliminate mosquito populations by disrupting mosquito breeding grounds. Get rid of sources of stagnant or standing water weekly, for mosquitoes can breed in any stagnant puddle that lasts more than four days.

Benth encouraged residents to do what they can to keep the number of mosquitoes lower on their property.

“Get rid of standing water, anything holding standing water can be breeding grounds for mosquitoes. Keep your yard trimmed and keep your shrubs trimmed,” he said.

Benth added there are a number of products effective for deterring the insects from yards. Retailers can advise you what works, Benth said.

You should also cover as much of the skin as possible by wearing shirts with long sleeves, long pants and socks whenever possible, and use insect repellents containing DEET. According to the Center for Disease Control, the most effective repellents contain DEET (N, N-diethyl-m-toluamide or N, N-diethyl-3-methylbenzamide).

“Mosquito repellents with DEET are good products. The higher content of DEET, the longer-lasting they are,” Benth, of Vector Control said.

Use repellent containing DEET carefully. Repellents containing DEET are very safe for adults and children when used according to directions. Products with a higher percentage of DEET (up to 50 percent) give longer protection.

“Percentage levels for children are lower,” said Benth. The Center for Disease Control recommends repellents containing no more than ten percent DEET for children under the age of six. Repellents with DEET should not be used on infants less than 2 months old.

Parents should choose the type and concentration of repellent to be used by taking into account the amount of time that a child will be outdoors, exposure to mosquitoes, and the risk of mosquito-transmitted disease in the area. Don't put repellent on kid's hands because it may get in their mouth or eyes.

In order to avoid reaction to DEET or other ingredients of insect repellents, it is important that you read and follow the directions on all insect repellent before use. Repellents should not be applied to skin that is already irritated, or to cuts/lacerations.

For detailed information about prevention and repellent use go to www.cdc.gov/westnile or www.ndwnv.com for the North Dakota Department of Health West Nile Virus home page.

Jodi McPherson can be reached at jmcpherson@willistonherald.com