Chikungunya (pronounced, chik-en-gun-ye,) virus is transmitted to people by the mosquitoes, Aedes aegypti and Aedes albopictus. These pests bite in the daytime and are the same ones that spread dengue fever.
Until recently, the disease was primarily seen in Africa, Asia, and the Indian subcontinent. However in 2013, the first cases of local (not imported by travelers) chikungunya virus infections were found in the Americas, including in the Caribbean. Since then almost 2 million cases have been reported. To date, there have been 13 locally transmitted cases in the United States. However, there have been over 3,700 travel associated cases in the continental US reported since 2014.
The most common symptoms of chikungunya infection are fever and joint pain, which usually begins three to seven days after the mosquito bite. Other symptoms may include headache, muscle pain, joint swelling, and rash. Most symptoms resolve in one week; however, in some people, joint pain may persist for months. The symptoms of chikungunya, Zika, and dengue viruses may be difficult to tell apart, but dengue can be more severe and has a higher risk of death.
Although the risk of death with chikungunya is not high, symptoms may be quite severe and disabling. Because chikungunya virus is new to the Western Hemisphere, many clinicians are not aware of this virus and do not consider it as a diagnosis, which may lead to unnecessary testing for other diseases.
Anyone who has not already been infected with chikungunya is at risk.
People at risk for more severe disease include
- newborns infected around the time of birth;
- older adults (≥65 years); and
- people with underlying health problems such as weakened immune systems, diabetes, heart disease, and high blood pressure.
Spread of the virus from mother to infant at the time of giving birth is rare. Also, in theory, transmission can occur from a blood transfusion, but this has not been reported.
Avoiding mosquito bites is the main way to prevent infection. No specific treatment is available. Alleviating symptoms is the mainstay of care, similar to treating a severe flu-like illness with rest, drinking plenty of fluids, and using medications such as acetaminophen (Tylenol) and ibuprofen (Motrin, Advil) to relieve the fever and pain. When seeking care, people should tell the doctor if they have been traveling, especially overseas.
Tips to prevent mosquito bites:
- Use an Environmental Protection Agency (EPA)-registered insect repellent with one of the following active ingredients: DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol, or 2-undecanone. Always follow the product label instructions.
- Wear long sleeved shirts and long pants.
- Treat clothing and gear with permethrin.
- Apply sunscreen first, then the insect repellent; don’t apply repellent to skin that will be under clothes.
- Use air-conditioning when available, or use screens on windows and doors. Repair holes in screens to keep mosquitoes outside.
- Keep mosquitoes from laying eggs in and near standing water. Once a week, empty and scrub, turn over, cover, or throw out items that hold water, such as tires, buckets, planters, toys, pools, birdbaths, flowerpots, or trash containers. Check inside and outside your home.
Even if you do not feel sick, travelers returning to the United States from an area with chikungunya, dengue, and Zika should take steps to prevent mosquito bites for 3 weeks so they do not spread virus to mosquitoes that could spread the virus to other people.
- Chikungunya infection is spreading throughout the world and has spread to over 60 countries since 2013.
- Infected mosquitoes spread the virus and avoiding bites is the best way to avoid infection.
- Although risk of death is low, the illness can be severe and debilitating.
- Newborns, the elderly, and people with underlying health problems are especially at risk for severe disease.
About five days ago, Kristin returned from a Habitat for Humanity trip to the Dominican Republic where she was building houses in a rural community. Buckets of water for cooling down were kept at the site. On the last day of the project, she forgot to apply insect repellent and she recalls having multiple mosquito bites. She is 24 years old and has had juvenile-onset diabetes since she was 4 years old.
Last night before bed she felt achy, had a headache, and nausea. Upon awakening this morning she had a fever, vomiting, worsening muscle aches, and joint pain. She couldn’t stand up straight because of severe back pain, so her roommate drove her to the doctor. During the visit, the doctor noticed a red rash all over Kristin’s neck, chest and back, and palms and swelling in the joints on her hands and feet. With her recent overseas travel, the doctor was concerned she might have chikungunya, Zika, or possibly dengue, so she ordered blood tests. Kristin’s lymphocyte count, one of the kinds of infection fighting white blood cells, was very low and her blood sugar was also low. Because of her diabetes and vomiting, Kristin was admitted to the hospital for supportive care, including IV fluids. Polymerase chain testing (PCR) identified the chikungunya virus in Kristin’s blood.