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Diseases Spread by Insects and Ticks

​Infectious diseases spread by insects are a major cause of illnesses to children and adults worldwide. Here are 4 diseases spread by insects.

West Nile virus

West Nile virus is spread by mosquitoes. In the United States, West Nile virus and outbreaks of various types of encephalitis (brain swelling) get plenty of media coverage.


  • Most cases of West Nile virus infection are mild. People may have no symptoms or mild symptoms such as fever, headache, and body aches.

  • Less common symptoms, occurring mostly in older adults, may include a severe headache, a high fever, a stiff neck, confusion, seizures, sensitivity to light, muscle weakness, and loss of consciousness.

Zika virus

Zika virus is primarily spread by mosquitoes. Zika virus infection during pregnancy can cause fetuses to have a birth defect of the brain called microcephaly. Zika virus outbreaks are currently happening in many countries and territories. For up-to-date information about the virus and outbreaks, go to


  • Many people won't have symptoms or will have only mild symptoms.

  • Symptoms may include fever, rash, joint pain, or red eyes.

Lyme disease

Lyme disease is spread by deer ticks. Deer ticks are tiny, black-brown arachnids about the size of a poppy seed. They are not insects because they have 8 legs (like spiders). Lyme disease is an important health concern in certain regions of the country; the following areas are where most infections occur: Northeast, from Virginia to Maine; north-central states, mostly Wisconsin and Minnesota; and West Coast, particularly northern California.


Often the first and most obvious symptom of Lyme disease is a localized rash that begins as a pink or red circle at the site of tick attachment. This circle expands over time and may become several inches or larger. A classic bull's-eye appearance, with concentric rings, appears in some people. The rash generally occurs 1 to 2 weeks after the tick bite but ranges from 3 days to 30 days.
A rash may occur without any other symptoms or may be associated with

  • Headache

  • Chills

  • Fever

  • Fatigue

  • Swollen glands, usually in the neck or groin

  • Aches and pains in the muscles or joints

If you live in an area of the country endemic to Lyme disease and your child develops a suspicious rash with or without any of these symptoms, call your child's doctor.

Rocky Mountain spotted fever

Rocky Mountain spotted fever is spread by ticks. Despite the name, Rocky Mountain spotted fever currently occurs mostly in other regions of the United States, including North and South Carolina, Oklahoma, and Tennessee.


Most people get a red, dot-like rash that begins on the wrists and ankles and spreads toward the center of the body. The illness may be severe or fatal in some people.

  • Other symptoms may include severe headache, fever, muscle aches, nausea, or vomiting.

If your child has been bitten by an insect and shows any of the symptoms of West Nile virus infection, Zika virus infection, Lyme disease, or Rocky Mountain spotted fever, call your child's doctor.

Children need and love to be outdoors. The chance of your children becoming infected by insects and ticks is quite low, especially when you take steps to reduce the risk of bites. If you have any concerns about insect or tick bites, talk with your child's pediatrician.

More information

Last Updated
Insect Repellents: What Parents Need to Know (American Academy of Pediatrics Copyright © 2019)
The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.
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