Centers for Disease Control -- Fight the Bite

Public Health Confronts the Mosquito

West Nile Virus Here To Stay

Mosquitoes have always been a nuisance but with the spread of West Nile virus, they have also become an important public health concern. Although the West Nile virus mainly infects birds, it can be transmitted to humans and other animals by certain species of mosquitoes that take blood meals from both birds and humans. The bite from just one infected mosquito is all that is needed to transfer the disease. In humans, West Nile virus disease symptoms vary from no visible effect to flu-like symptoms, paralysis, or even death. All age groups are susceptible, but the elderly and those with weakened immune systems are more likely to experience severe forms of the disease. More on symptoms

Public mosquito control programs have been started in many cities and towns across the country. Even the best community mosquito control program will only reduce the risk from West Nile virus and thus wherever you live, personal protection against mosquito bites is your best safeguard.

Since 1999, in the United States more than 60 mosquito species have been found in West Nile virus positive mosquito pools.  These are pools from which West Nile virus was isolated, West Nile RNA detected, or West Nile antigen was detected using a variety of diagnostic tests.  Although a mosquito species found positive for the virus in nature may potentially be a carrier, further tests are usually needed to determine if the species is efficient in transmitting the virus to humans.  It is important to know which mosquitoes are efficianet carriers of the virus in your state or local community.

Tracking positive mosquito pools in the United States

Adult female mosquitoes need blood to produce eggs and perpetuate their species.Although they can survive by feeding on sugary liquids, it is only after a blood meal that they start producing eggs. Only female mosquitoes bite. Male mosquitoes feed on sugars found in fruits and flowers.

Mosquitoes looking for a blood meal are mainly attracted to carbon dioxide in the breath, body heat, and sweat of humans. Lactic acid and numerous other scents emitted by the human skin have also been found attractive to mosquitoes. Individuals who produce more body heat, sweat, carbon dioxide, and lactic acid will be more attractive to mosquitoes.

Entomology

Arboviruses (short for arthropod-borne viruses) such as the West Nile virus, western equine encephalitis virus, and Saint Louis encephalitis virus are perhaps the most important microorganisms that mosquitoes transmit in the United States. In other parts of the world, mosquitoes are carriers of parasites that cause human malaria, filariasis, dengue fever, Japanese encephalitis, yellow fever, and others.

The West Nile virus is a disease that primarily affects birds. It may be transmitted by mosquitoes from infected birds to other hosts such as humans or horses. The West Nile virus has not been shown to be transmitted from human to human, horses to humans, or horses to horses. Thus, the West Nile virus is carried by various species of birds and spread by mosquitoes.

Insect Repellent Use and Safety

Recommendations for Outdoor Workers

Controlling Mosquitoes Around the Home and Yard

Insect repellents are recommeded as the best way for one to protect themselves from mosquito bites when involved in outdoor activities.  Repellents act by making a person "undesirable" for feeding or in other words the repellent masks the gases and scents known to be attractive to mosquitoes.

DEET and Picaridin are recommended to be applied to the skin and permethrin applied on the clothing. DEET and Picaridin repel mosquitoes while permethrin actually kills mosquitoes on contact.

Using DEET or Picaridin alone or permethrin alone will not be as effective as using the two in combination. However, using DEET or Picaridin alone may be sufficient for most outdoor activities such as going to the park, mowing the lawn, gardening, or relaxing in the backyard. Individuals who will be outdoors for an extended period of time, like hunters and campers, are encouraged to use the combination of DEET or Picaridin and permethrin.

There are alternative repllents such as combinations of soybean oil, geranium oil and coconut oil and lemon eucalyptus that have been shown to repel mosquitoes, but only for short periods of time. Before using any repellent read and follow all label directions.

Mosquitoes lay their eggs in standing water. Limit the number of places around your home for mosquitoes to breed by getting rid of items that hold water. Repair broken screens and windows on your home.

Support your community mosquito control programs.