West Nile virus infections set record numbers

As of Aug. 22, there are 82 people in various counties in Mississippi that have been affected with West Nile virus, combining with five other states to make 2012 one of the worst years for the disease.

Seventy-five percent of the cases reported this year have been reported from five states: Texas, Mississippi, Louisiana, Oklahoma and Illinois.  To date, analysts with the Center of Disease Control in Atlanta, Ga. say that only Alaska, Hawaii and Vermont have no reported cases of West Nile virus this year.

The West Nile virus is one of the mosquito-borne illnesses that affects birds, animals and humans, causing flu-like symptoms in people who are bitten by infected mosquitoes. 

Only certain types of mosquitoes carry viruses of concern to people. A mosquito must first become infected by feeding on a bird that has the virus, then bite a human or animal in order to pass the disease along. 

In Mississippi, West Nile has been reported in horses, birds, mosquitoes and humans. In humans, the infection can lead to dangerous conditions such as meningitis or encephalitis. Anyone is susectible to getting the virus, but people over 50 years of age are affected more severely. 

Approximately three percent to 15 percent of people with WNV die from the virus. Unlike other mosquito-borne illnesses, horses and certain species of birds (especially crows and blue jays) can also get sick and die from the disease.

Nevertheless, mosquito-borne illnesses can be prevented by eliminating places where mosquitoes breed and by protecting yourself from mosquito bites when outside. 

Repellents, clothing, netting and other personal protection measures can help prevent mosquito bites and the diseases they carry. Insect repellents are also effective and safe when properly used. 

DEET, been in public use since 1957, is toted as the best insect repellant on the market.

There has been twenty years worth of testing of more than 20,000 other chemical compounds and the testing has not resulted in another product that has the effectiveness and duration of protection of DEET. This repellent comes in lotion, spray and other forms.

Concentrations of DEET range from about five percent all the way up to 100 percent. Products with higher concentrations should repel insects longer. However, after a certain point, higher concentrations do not guarantee greater protection. 

For example, 50 percent DEET provides about four hours of protection against mosquitoes, but increasing the concentration to 100 percent gives only about one extra hour of protection.

DEET must be used with proper precautions, however. 

Over the years, there have been complaints associated with DEET use such as minor skin and eye irritation. A few severe reactions have been reported, especially in children, either after swallowing or prolonged skin application. Reactions have included headaches, nausea, disorientation, confusion and in some cases, convulsions or death. If DEET is used according to the directions, these risks should be minor if any. 

The American Academy of Pediatrics recommends that repellents used on children should contain no more than 30 percent DEET. While higher concentrations of DEET may be safe, the Mississippi Department of Health generally recommends using repellents with 10 percent or less on children. 

Picaridin is an effective alternative to DEET products and also provides long-lasting protection against mosquito bites. This repellent has been used worldwide since 1998. 

Compared to DEET, Picaridin is practically odorless, does not cause skin irritation, and has no adverse effect on plastics. However, it may not provide protection as long as DEET. One field study showed that there were five hours of protection against mosquitoes by Picaridin versus seven hours of protection by DEET.

However, products with the ingredient picaridin are expected to provide better and longer-lasting protection than plant-based repellents.

For example, oil of lemon eucalyptus has been tested against mosquitoes found in the United States and provides protection similar to repellents with low concentrations of DEET.

Repellents derived from plants such as citronella, geranium, basil, garlic and peppermint generally provide only temporary protection from mosquitoes. 

Citronella candles are mildly effective mosquito repellents. Normally, people who have a citronella candle burning will have fewer mosquito bites, but it is not 100 percent effective. 

Products with the product permethrin, which is a pesticide rather than a repellent, work good on clothing to repel mosquitoes. It is not intended for use on the skin. 

Normally, permethrin products are sold in lawn, garden or sporting goods stores. Permethrin can retain its potency for at least two weeks. It can be applied to clothing, tent walls, and mosquito nets. In Africa, permethrin-sprayed mosquito nets have been used successfully in malaria prevention campaigns in Africa.

The combination of Permethrin-treated clothing and DEET-treated skin creates almost a 100 percent complete protection against mosquito bites. 

 For more information, call Mississippi’s West Nile Hotline at 877-978-6453 or visit the Mississippi Department of Health’s website at www.msdh.state.ms.us/.