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Beware Disease-Spreading Mosquitoes ... and Other Blood-Sucking Pests!

preading Mosquitoes .

preading Mosquitoes ... and Other Blood-Sucking Pests!

(ARA) - Few words strike more fear in outdoor enthusiasts than West Nile virus or encephalitis. Understanding more about these diseases can help you protect yourself and your family when you’re enjoying time outdoors.

West Nile virus and encephalitis viruses come in many forms, but have two things in common - a nonhuman primary host and an infected blood-feeding arthropod, such as a mosquito or tick, according to Dr. Fabio Del Piero, DMV, assistant professor of pathology at the University of Pennsylvania.

Dr. Del Piero says there are five main arboviral agents of encephalitis in the United States that are transmitted by mosquitoes: West Nile virus (WNV), eastern equine encephalitis (EEE), western equine encephalitis (WEE), St. Louis encephalitis (SLE), and La Crosse encephalitis (LAC). Another virus, Powassan, is a minor cause of encephalitis in the northern United States, and is transmitted by ticks. Most encephalitis cases occur from June through September, when these pests are most active.

A majority of human infections are asymptomatic or result in flu-like symptoms. In a very few cases infection may lead to encephalitis, which can be fatal or lead to permanent neurological damage.

Currently, neither antibiotics nor antiviral drugs are considered effective for these viruses. Treatment is primarily supportive. There are no commercially available human vaccines for these U.S. diseases. However, there are some vaccines available for horses that may be susceptible to some of the viruses.

West Nile virus facts

West Nile virus (WNV) is a flavivirus that can infect humans, birds, mosquitoes, horses and other mammals. WNV first appeared in the United States in 1999, causing illness and death in birds, horses, and humans. Dr. Del Piero, also a Diplomate of the American College of Veterinary Pathology and a noted expert in WNV, points out that while the initial outbreak of this disease was limited to the northeastern United States, the virus had an inexorable migration across the continental United States over the next several years, causing significant losses among affected species.

Horses have been most affected by the recent WNV epidemic in the United States. Losses to the equine industry have been large and unprecedented. An equine vaccine for WNV has been available since 2001 and appears to be effective in limiting the incidence of disease in well-vaccinated populations. A second approved vaccine has recently been marketed for use in horses. No WNV vaccine is available for humans.

WNV infections have also been documented in other mammals, including dogs and llamas, as well as endangered wild and captive bird populations.Do not handle any of these dead animals with bare hands and be sure to contact your local health department for instructions on reporting and disposing of the bodies.

In temperate zones, WNV encephalitis cases occur primarily in the late summer or early fall. In the southern climates, West Nile virus can be transmitted year round. In a very small number of cases, WNV also has been spread through blood transfusions, organ transplants, breastfeeding and even during pregnancy from mother to baby. While anyone is susceptible to WNV, persons over 50 have the highest risk of severe disease.

Symptoms in people can vary from mild to severe. Approximately 80 percent of people who are infected with WNV will not show symptoms. Symptoms can last for as short as a few days to several weeks. Severe symptoms may include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. Neurological effects can be permanent.

People typically develop symptoms between three and 14 days after they are bitten by an infected mosquito. In horses, as in humans, fever may precede the onset of central nervous system signs, or may be the only evidence of infection. Treatment for horses is supportive and owners should call their veterinarian.

Prevention is the best policy

You can prevent WNV and encephalitis in two ways: personal protection and through public health measures that reduce mosquito populations. Personal measures include reducing time outdoors, particularly in early morning or evening hours, wearing long pants and long-sleeved shirts, and applying insect repellents containing DEET (N, N-diethyl-meta-toluamide) to exposed skin. Good window and door screens also help keep mosquitoes out.

Eliminating mosquito breeding sites is also important. Empty standing water from flower pots, buckets and barrels. Change the water in pet dishes. Replace water in bird baths weekly. Drill holes in tire swings so water drains out. Keep children's wading pools empty and on their sides when not use.

Many public health departments spray insecticides to kill adult mosquitoes and larvae. Aerial spraying is the preferred method in emergency situations.

For more information about these diseases, visit www.acvp.org/news.

Courtesy of ARA Content

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