As Michiganders deal with outbreaks of West Nile virus it is pertinent to understand a little about the disease and how it can be slowed or prevented. West Nile virus is a group of encephalitic viruses that can cause illness and even death if contracted. Sin Nombre virus is the specific virus in the West Nile group that we have seen in New York in 1999 and in points west through 2002. The transmission cycle for this virus is similar to most other forms of encephalitis. The virus is maintained in over 110 species of birds with the crow being the most noted. The Northern House mosquito (C. pipiens) will take a blood meal off of the various bird reservoirs thus housing the virus primarily in it’s salivary glands. This cycle by itself does not have much impact on humans however the Northern House mosquito (C. pipiens) will also take blood meals from humans and horses as well as birds. This interaction can result in the virus being spread to us. Humans and horses are dead-end hosts which means that if an uninfected mosquito feeds on an infected human or horse the viral agents can not be accumulated in sufficient quantities in the mosquito to pass the disease onto another human.

Only about 20% of humans with this virus will become symptomatic. The symptoms of this viral infection are wide ranged. Mild symptoms include fever, headache, body aches. Severe symptoms can include a high fever, stiff neck, coma, tremors or paralysis. About 1 in 150 people who are infected with this virus will display severe symptoms and unfortunately some advanced neurological effects maybe permanent.

The prevention or control of mosquitoes can be accomplished through a combination of mosquito management techniques. One of the most important management tool that can affect negatively affect mosquito populations is breeding source reduction. Standing water such as water in bird baths, tires, sagging tarps, and clogged gutters can offer a breeding source for the Northern House mosquito. Reducing or eliminating standing these pools of water where mosquito larvae develop can help to reduce the populations of mosquitoes in particularly the Northern House mosquito. Another tool in the mosquito management arsenal is the application of larvicide products to standing pools of water. These larvicide products offer a control method using a bacteria to attack the larva stage of the mosquito. One more method of mosquito control is adulticiding. This consists of using an insecticide which is applied close to the resting places of adult mosquitoes. The use of insecticides to kill adult mosquitoes is still a very useful tool when used with a combination of the above mentioned control methodologies. When used according to label directions the insecticide products used during the treatment of adult mosquitoes can be a beneficial contributor to your overall program.

There are many websites that offer information on West Nile virus and mosquito control techniques. A few are: