The West Nile virus is a seasonal epidemic which is common in North America as warm weather approaches. Although traces of the virus are appearing early this year, causing researchers to be on the alert, the usual time frame of concern is generally summer and into the fall. The culprit which brings this unwanted visitor is the mosquito, which becomes infected with the virus after coming in contact with a bird carrying the disease, and subsequently bites humans. It would not be unusual for mosquitoes to be seen on Memorial Day weekend, if the conditions are right.
The West Nile virus was first reported in New York in 1999 and was identified again in Texas in 2002. Recently, residents in Dallas, Texas, were warned to be vigilant as reports that the first mosquito trap testing showed a positive result for the West Nile virus. Since 2002, Illinois has also identified cases of the disease over the years, which has contributed to the deaths of 133, and has caused illness to 2,137 people.
Through the coordinated efforts of researchers for the Centers for Disease Control (CDC) and the National Center for Atmospheric Research (NCAR), studies yielded information regarding the connection between the influence of weather and the breeding of the mosquitoes carrying the virus. This type of information can be used to validate any predictions of the West Nile virus outbreaks made by scientists. Further, mosquito control agencies find this information valuable to determine the number of needed seasonal workers, and the public can become more aware of the risk factors through health alert messages.
Mosquitoes carrying the disease are most noticeable in rainy weather; however, they breed well in hot weather and are often found in the stagnant water of street ditches and catch basins. From 2004 to 2012, researchers analyzed how precipitation and temperature impacted the disease in counties across the nation. The documented differences noted higher than average West Nile cases in the East, even though the fall and spring were very dry. In the West, the virus cases were higher, even though these seasons were wetter than normal.
Some people may have no symptoms of this mosquito-born virus as is the case in 80 percent of those bitten. On the other hand, mild symptoms include joint pains, vomiting, diarrhea, and body aches, which occur most often in 20 percent. According to the U.S. Center for Disease Control, symptoms of weakness and fatigue may be present for weeks or months. The more severe cases may happen in one in 150 of those infected, and in those rare cases, a neurological illness develops that has the potential for causing death. At the present time, there is no vaccine for this mosquito-born condition.
Health experts have discussed some precautionary measures. Rainwater left in a container has the potential for breeding mosquitoes, which can carry the West Nile virus. The amount of water in the container is not important, but emptying the standing water from street containers may remove the risk. Additionally, be alert to unattended pet water dishes, swimming pools, tire swings, birdbaths, and flower planters.
It was noted that mosquitoes are very active at dusk and dawn. Wearing garments that cover the arms and legs as well as using an insect repellent is also highly advisable. With the weather changes, such as heavy rainfall or droughts, the infection rate of mosquitoes with the West Nile virus has given health care workers and researchers a cause to be on the alert and to warn of the outbreak of this virus to at-risk areas immediately.
Written by Marie A. Wakefield
The Dallas Washington News – First Mosquito Carrying West Nile Virus Reported in Dallas County
CBS Chicago – With Warmer Weather, Risks Increase For West Nile Virus, Lyme Disease
Time – Scientists Find a Way to Predict West Nile Outbreaks
www.cdc.gov/westnile – West Nile Virus (WNV) Fact Sheet
Photo Courtesy of Sanofl Pasteur’s Flickr License – Creative Commons License