Despite drought, mosquitos continue to spread West Nile Virus this summer

Extension Disaster Education Network offers advice from the Centers for Disease Control and Prevention to prevent West Nile Virus disease.

Outbreaks of West Nile virus occur across the country every summer, but this year some areas have reported a significant increase in infections occurring in people, birds and mosquitos. Through the end of July, 42 states had reported a total of 241 cases of West Nile Virus disease, including four deaths, the highest number of cases reported for the same time frame since 2004. At the end of July, Texas, Mississippi and Oklahoma account for 80 percent of reported cases with Texas actually doubling their previous case numbers this year with 75 percent of the cases being neuro-invasive, the most serious form of the disease.

Mosquitos that carry the West Nile Virus tolerate drought extremely well and can reproduce in small amounts of water.

Michael Kaufman, Michigan State University associate professor and mosquito expert, explained in a recent Michigan Radio interview that Culex pipiens, the mosquito breed in Michigan that carries the West Nile Virus (WNV), really likes our recent hot, dry weather and have been reproducing earlier than usual because of it.

So far this year, the Michigan Department of Community Health (MDCH) has confirmed four human cases of WNV. In 2011, MDCH reported 34 serious cases of West Nile Virus in humans and two fatalities.

West Nile Virus primarily affects birds, but may be transmitted by certain species of mosquitos from infected birds to humans, horses and other mammals including cattle, dogs and cats. Only one bite form an infected mosquito is all it takes to contract the disease.

The best approach to protect oneself from contracting WNV is to avoid mosquito bites. The Centers for Disease Control and Prevention (CDC) suggests using insect repellents when outdoors, wearing long sleeves and pants when outdoors at dawn and dusk, installing or repairing screens on windows and doors, and emptying  standing water from items outside your home such as flowerpots, buckets and toddler swimming pools.

Alternative repellents containing oil of lemon eucalyptus as well as well-known commercial products such as DEET and Picardin can be used effectively.

These precautions are especially important for populations at high risk for WNV including pregnant women, transplant patients, diabetics, individuals with high blood pressure or a history of alcohol abuse as well as those over age 50.   

As mosquitos are most active dusk to midnight, limiting your time outdoors during those hours is recommended. Some communities have instigated public mosquito control programs targeting locations where people congregate in the evening such as ball fields and picnic grounds.  Taking personal precautions and following the above recommended steps will further reduce one’s risk.

The incubation period in humans for WNV is usually two to 15 days with symptoms lasting from a few days to several weeks for the most severe cases, some of whom may incur permanent neurological effects.

Most people who are infected with WNV will have absolutely no symptoms, but 20 percent will develop West Nile Fever resulting in fever, headache, tiredness, body aches, occasionally a skin rash on the trunk of the body and swollen lymph glands.  A very small number of people infected with WNV, 1 in 150, will develop a more severe West Nile neuro-invasive disease such as West Nile encephalitis, West Nile meningitis orWest Nile poliomyelitis. Symptoms can include high fever, headache, neck stiffness, stupor, disorientation, tremors, convulsions, coma, muscle weakness and paralysis. 

There is no treatment for West Nile Virus and those with West Nile Fever generally recover on their own, though medication to relieve headache and body aches may be helpful. Individuals with the more severe neuro-invasive forms of the disease often need hospitalization, IV fluids and respiratory support.

For more information about West Nile Virus, visit the Extension Disaster Education Network (EDEN) website or the CDC website.

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