How to minimize exposure to West Nile virus Published Sept. 12, 2012 By Capt. Michael Renkas 81st Aerospace Medicine Squadron KEESLER AIR FORCE BASE, Miss. -- Keesler Air Force Base is currently experiencing normal mosquito populations. However, our mosquitoes are not immune to West Nile virus or other mosquito-borne viruses. It is imperative people understand how WNV is transmitted, the symptoms and treatment of the virus, the risk of infection and countermeasures for reducing that risk of infection. Following are some general questions and answers to increase understanding of West Nile virus, along with proven protective measures to reduce mosquito exposure: How is WNV transmitted? The West Nile virus is naturally carried by birds. As mosquitoes feed on infected birds, they become a potential vector for infecting humans or other animals. WNV has also been isolated in ticks. What are the symptoms of and treatment for WNV infection? Symptoms may develop within two to 14 days after being bitten by an infected mosquito. A specialized treatment for WNV does not exist, however infection does lead to immunity. Mild symptoms include fever and aches which typically pass without direct medical attention, but these symptoms may persist, even in healthy individuals, for weeks to months. Other moderate to mild symptoms may include headache, nausea, vomiting and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. Medical attention should be considered at the individual's discretion. Severe symptoms can last several weeks and result in irreversible neurological damage. Someone hospitalized with a severe case will receive supportive care in the form of IV fluids, respiratory assistance and recuperative care. Anyone recently bitten by mosquitoes or ticks who begins to experience the following symptoms must immediately seek medical attention: High fever, severe headache, neck stiffness, stupor, confusion, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. Approximately 80 percent of those infected with WNV will not exhibit any symptoms, 20 percent will exhibit moderate to mild symptoms and fewer than one percent will experience severe symptoms. If infected, persons age 50 and over are more likely to develop severe symptoms. Pregnant or nursing mothers who feel they are symptomatic for WNV should consult their medical provider. What is the risk of WNV infection? There is no direct person-to-person transmission of WNV from casual contact. Although the risk is extremely low, person-to-person transmission has been identified with blood transfusions, organ transplants and possibly mother to child. Both the American Red Cross and the Keesler Blood Donor Center have their blood processed through laboratories which screen for WNV. This may not be the case in third-world countries. People working or playing outdoors are at an increased risk of contracting WNV simply due to their increased exposure to mosquitoes, especially those outside at dawn, dusk and throughout the night. Several species of female mosquitoes will fly more than a mile to collect a blood meal for their young. What can be done to prevent being bitten by a mosquito? Everyone can do their part at home or at work to help reduce mosquito breeding environments. Mosquitoes require as little as an inch of standing water to lay their eggs. In fact, mosquitoes are known to lay eggs on a dry water line within a receptacle in anticipation it will collect rain water. Residential or building occupants must ensure gutters properly drain and excessive run-off is carried away to natural drainage ditches or reabsorbed into the ground. Old tires, cans, open garbage bins, bird baths, potted plants or other receptacles which could retain rain water for extended periods should be dumped, covered, moved or removed. These measures may not be an option for those who live near natural bodies of water where the most effective defense is reducing time outdoors at dawn, dusk and at night. For those working outdoors or outside during these times, the best practice is to treat exposed skin with insect repellant containing DEET (20 percent) or Picaridin. Permethrin is also recommended by the Centers for Disease Control and Prevention and registered with the Environmental Protection Agency for the treatment of clothing, shoes, bed nets and camping gear. Some retail stores have begun selling clothing pre-treated with permethrin for those who work outdoors or are outdoor enthusiasts. For more information call (228) 376-3163 or refer to the following sources: CDC West Nile Home Page: http://www.cdc.gov/ncidod/dvbid/westnile/index.htm CDC Insect Repellents Page: http://www.cdc.gov/ncidod/dvbid/westnile/RepellentUpdates.htm CDC Q&A WNV Cats and Dogs: http://www.cdc.gov/ncidod/dvbid/westnile/qa/wnv_dogs_cats.htm