As the eyes of the world turn to Rio de Janiero for the 2016 Summer Olympics, the spread of the Zika virus in Brazil is a growing concern — but Zika is not the only disease that mosquitoes can spread to humans.

“Mosquitoes in the Aedes family can transmit not only the Zika virus, but also dengue and chikungunya,” says dermatologist Jose Dario Martinez, MD, an American Academy of Dermatology International Fellow and chief of the internal medicine clinic at the university hospital of the Universidad Autónoma de Nuevo León. “All three diseases are a potential health threat to anyone traveling to regions where these insects thrive.”

According to Dr. Martinez, Aedes mosquitoes are prevalent in Mexico, South and Central America, and some regions of Asia and Africa. In the U.S., he says, these insects have been found in states along the Mexican border, as well as some parts of Florida and Puerto Rico. Since other types of mosquitoes can’t carry dengue, chikungunya and Zika, he says, the risk of these conditions among U.S. residents is mainly limited to those traveling to affected areas.

All three diseases are characterized by a high fever, rash and joint pain, Dr. Martinez says, although most of those infected don’t experience any symptoms. Although these conditions are similar, each has its own unique characteristics.

Dengue has been around for many years, Dr. Martinez says, while chikungunya and Zika emerged more recently. Each disease carries the risk of different complications, he says: Dengue can cause severe bleeding, which may lead to shock; chikungunya can cause severe joint pain and chronic arthritis; and Zika may lead to Guillain-Barré syndrome, a disorder in which the immune system attacks the nerves.

Unlike dengue and chikungunya, which are transmitted through mosquito bites, Zika can be transmitted from an infected person to another person via sexual intercourse and blood transfusions, Dr. Martinez says. Moreover, he says, Zika infections in pregnant women may spread to the fetus, resulting in birth defects like microcephaly, a condition in which a baby is born with an abnormally small head; women may pass the disease to an unborn child after contracting it from an infected mosquito or via unprotected sex with a person who has the virus.

“Zika may be the most dangerous of the conditions transmitted by Aedes mosquitoes,” Dr. Martinez says. “However, all three diseases are serious threats to public health, particularly because many of those infected won’t experience any symptoms and therefore won’t know they’re carrying the virus.”

There are no U.S. Food Drug Administration-approved vaccines for these conditions, he says, and the only available treatment option is acetaminophen to control pain and fever. According to Dr. Martinez, the best way to fight these diseases is prevention. He says those traveling to regions where dengue, chikungunya and Zika are prevalent should protect themselves from mosquito bites by avoiding the outdoors at dawn and dusk, wearing long-sleeved shirts and pants, and using an insect repellant that contains the active ingredient DEET.

Dr. Martinez also recommends that pregnant women avoid traveling to Zika-infected countries and suggests that travelers returning from these countries get tested for Zika before donating blood. Additionally, anyone who develops a high fever, rash or joint pain after returning from countries affected by any of these conditions should see a doctor as soon as possible, he says.

“It’s important to be vigilant when traveling to areas where you could be bitten by a mosquito carrying dengue, chikungunya or Zika,” Dr. Martinez says. “By taking preventive measures and monitoring your health when you return, you can protect yourself and help limit the spread of Zika to others.”

American Academy of Dermatology