Mosquitos can transmit serious diseases

Learn how to avoid becoming ill during the active mosquito season.

As summer kicks into full gear, hungry mosquitos may be unwelcome guests at picnics and other outdoor events. They also may find their way into your bedroom at night looking for their food of choice—-human blood. In addition to being irritated by their red, blotchy, itchy bites or having your sleep disrupted by these noisy, dive-bombing insects, there are more serious consequences you may face if bitten by a mosquito.

There are several viral and parasitic diseases that mosquitos carry and transmit to their bite victims. The Centers for Disease Control and Prevention (CDC) monitors outbreaks and cautions travelers about visiting countries where diseases such as malaria, yellow fever, dengue, several types of encephalitis, and Rift Valley Fever are widespread. Currently, most of these mosquito-borne diseases tend to be found in Africa, Asia, South America and the Caribbean. While those traveling abroad need to be especially vigilant about protecting themselves from mosquito bites, even here in the United States, transmission of at least two diseases by mosquito bites has been confirmed. Since 1999, outbreaks of West Nile have been reported every summer in all states except Alaska and Hawaii. Though most people infected with West Nile do not even exhibit symptoms, about 20 percent will develop a fever and may experience a headache, body aches, joint pains, vomiting, diarrhea, or a rash. Fatigue and weakness can linger for weeks or months but most people will eventually make a complete recovery. About 1 percent of those infected, however will develop more serious neurological illness that can have permanent results. Symptoms may include headache, high fever, neck stiffness, disorientation, coma, tremors, seizures, or paralysis. If you suspect you or a family member may have contracted West Nile, seek medical attention immediately.

The other mosquito-borne disease that has more recently established itself in the United States is chikungunya. In December 2013, the World Health Organization (WHO) reported finding mosquito-borne chikungunya in the Caribbean island of Saint Martin, the first reported incidence of the disease in the Americas. Like West Nile, the most common symptoms of chikungunya are fever and joint pain but can include headache, muscle pain, joint swelling, and rash. Most people recover in a week but some individuals have experienced joint pain that lasts for months or years. Those older than 65, women in the late stages of pregnancy, and individuals with arthritis, high blood pressure, heart disease, or diabetes are at higher risk for more serious reactions to chikungunya due to their weaker immune systems.

The incidence of chikungunya in the United States has grown to the level that it is now a nationally notifiable disease with cases being reported to the CDC by local and state health departments. As of June 2, 157 cases from 30 different states had been reported to ArboNet, the CDC’s national surveillance system.

How do large outbreaks of these mosquito-borne diseases occur? First, a mosquito bites an infected person, thereby becoming infected themselves, and then pass on infection to other people they subsequently bite. According to health officials, the most effective approach to preventing mosquito-borne diseases is to reduce your exposure to mosquitos.

Specific actions that can help you avoid being bitten include:

  • Applying an Environmental Protection Agency (EPA)-registered insect repellent on exposed skin before heading outdoors. Look for products that contain active ingredients recommended by both CDC and EPA such as DEET, picaridin, IR3535, or plant-based oil of eucalyptus.
  • Wearing a long-sleeved shirt, long pants, hat, and socks when outdoors
  • Use permethrin-treated clothing, footwear, and tents. You can purchase items that have already been treated or apply the spray yourself. Clothing can be washed several times before the permethrin loses its effectiveness and needs to be re-applied.
  • Eliminate areas of standing water around your home that could be breeding sites for mosquitos including tires, bird baths, and children’s wading pools.
  • Make sure all doors and windows in your home have screens that fit snugly and are free of holes, tears, or loose screening. As needed, repair or replace those screens that might allow mosquitos entry indoors.
  • Encourage and support efforts by your home owners association or local community to engage in a mosquito control program.

In addition to the above actions, those traveling to the Caribbean or other areas of the globe where mosquitos are known to be prevalent are cautioned to stay and sleep in screened in or air-conditioned rooms. If the sleeping area is exposed to the outdoors, make sure to use a bed net.

For more information about keeping yourself and your family healthy and safe, visit the Michigan State University Extension website where you will find articles on a variety of topics, details about hours of operation and staff housed at your county Extension office, and access to Extension experts who can help address questions you might have.


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