Nature's hazards: Mosquito-borne diseases

  • Published
  • By Greg Chadwick
  • Air Force Materiel Command Health and Wellness Team
Mosquito bites can be annoying, but they can also cause serious viral diseases, such as Zika, West Nile, Chikungunya and Dengue. If an infected mosquito bites a bird or mammal, including humans, it can transmit the illness to them.

According to the Centers for Disease Control and Prevention, West Nile virus is the most common disease spread by mosquitoes in the United States. West Nile virus has been detected in all lower 48 states. The largest outbreaks (1999-2014) have occurred in California, Texas, Colorado and Illinois. West Nile is transmitted to humans primarily through the bite of infected mosquitoes. In a very small number of cases, the virus has been spread through blood transfusions, organ transplants and from mother to baby during pregnancy, delivery or breast feeding.

Most people (70-80 percent) who become infected with West Nile do not develop any symptoms. About one in five people who are infected will develop flu-like symptoms, which include headache, fever, body aches, joint pains or rash. Less than one percent of people who are infected will develop a serious neurologic illness such as encephalitis or meningitis. In rare cases, West Nile can be fatal.

Serious illness from West Nile can occur in people of any age. However, people over age 60 who become infected with West Nile virus are at higher risk of developing serious symptoms of the disease. West Nile virus is diagnosed through clinical symptoms and blood test results. There are no medications to treat or vaccines to prevent West Nile virus infection.

An emerging mosquito-borne disease is caused by the Zika virus. Zika is primarily transmitted through mosquito bites. Other, less common ways people can get Zika are through sexual contact, from a pregnant woman to her fetus, and through a blood transfusion.

No mosquito-borne Zika virus disease cases have been reported in the US, but there have been travel-associated cases. A travel-associated case of Zika virus is when a person travels to an area with active Zika virus transmission, gets bitten by an infected mosquito, and returns to the US. These travel-associated cases could result in local transmission of the virus in some areas of the country. Local transmission of the Zika virus is when a mosquito bites an infected person and the mosquito gets infected with the virus. The infected mosquitoes can then bite healthy people and spread infection.

Many people infected with Zika virus won't have symptoms or will only have mild symptoms. Common symptoms of Zika are fever, headache, muscle pain, rash, joint pain and conjunctivitis (pink eye).

CDC scientists recently announced the Zika virus is a cause of microcephaly in newborns and other severe fetal brain defects. Microcephaly is a birth defect in which a baby's head is smaller than expected when compared to babies of the same sex and age. Zika is diagnosed based on a person's recent travel history, symptoms, and with blood tests. There is no specific medicine to treat Zika or vaccine to prevent it.

How to protect yourself from mosquito bites:

· Mosquito-proof your home by using screens on windows and doors. Repair or replace all torn screens in your home. Close windows and doors, then use air conditioning when available.
· Drain water where mosquitoes grow. Mosquitoes can grow in containers that hold water for more than a week such as pop cans, buckets, bottles and discarded tires. Keep rain gutters clean. Fill holes that hold water with gravel or dirt.
· Wear long-sleeved shirts, long pants and socks to create a barrier between you and mosquitoes.
· Apply insect repellent on exposed skin when you go outdoors. Use Environmental Protection Agency-registered insect repellants containing DEET, picaridin, IR535 or oil of lemon eucalyptus.

Civilian Health Promotion Services will be offering educational briefings on summertime safety during June and July. For more information, click here or contact your local CHPS team. Comprehensive information on preventing mosquito-borne diseases can be found on the Centers for Disease Control and Prevention website.