Vector-borne illnesses are diseases that spread through bites of infected insects, such as mosquitoes, ticks, biting flies, or fleas. These insects pick up viruses or bacteria and pass them to people when they bite.

Several vector-borne illnesses can affect pregnant women, especially in certain parts of the world:

• Dengue virus is spread through the bite of infected Aedes mosquitoes. It is common in tropical and subtropical regions and is one of the most common vector-borne illnesses worldwide. It can cause a high fever, body aches, and in severe cases, bleeding and hospitalization.

• Zika virusis also carried by Aedes mosquitoes. In addition, it can be passed through sexual contact and from mother to fetus. Most people have mild symptoms or none at all, but Zika during pregnancy can cause serious birth defects.

• Oropouche virus is spread through the bites of tiny flies called midges. It is found in South and Central America and the Caribbean. The virus causes symptoms like fever, headache, and joint pain.

• Chikungunya virus is also spread through the bite of an infected Aedes mosquito. It causes fever and severe joint pain that may last for weeks or months.

Vector-borne illnesses are transmitted anywhere in the world where biting insects are active, especially in warmer climates and during the warmer seasons. In the United States, your risk is higher during spring, summer, and early fall, especially in states and jurisdictions with warmer climates, such as Florida, Texas, Southern California, Arizona, Hawaii, Puerto Rico and the US Virgin Islands. The risk also increases when traveling to tropical climates where these illnesses are more common, including Central America, South America, the Caribbean, parts of Africa, and South/Southeast Asia.  

But because of more travel and changes in the climate, some of these diseases are now found in areas where they weren’t seen before. Also, since Aedes mosquitoes can carry more than one virus, it’s possible to be infected with multiple illnesses at the same time or at different times in your life.

Yes. Some vector-borne illnesses can lead to serious health problems during pregnancy. For example, dengue infection may increase the risk of hospitalization, heavy bleeding, or the need for intensive care. Other illnesses, like chikungunya and zika, are usually milder but can still cause symptoms such as fever, joint pain, or fatigue, which may contribute to pregnancy complications. Depending on the illness, risks may include preterm birth, low birth weight, stillbirth, or other delivery-related concerns.

Yes. Many vector-borne illnesses can be passed from the pregnant person to the fetus. This is called a congenital infection. In some cases, these infections can lead to birth defects. For example, Zika virus has been linked to microcephaly, a condition where the fetal brain is smaller than normal. This can cause long-term problems with brain development, as well as hearing and visual impairment and cognitive disorders.

The risk of birth defects and their severity can vary depending on specific illnesses and the stage of pregnancy when the infection occurred. For more information, you can visit the Centers for Disease Control and Prevention (CDC) resources on Chikungunya, Dengue, Oropouche, and Zika viruses.

Currently, there are no vaccines available to prevent illness caused by the Oropouche and Zika virus. The vaccine against dengue, Dengvaxia, is not available in the United States, and it is not recommended during pregnancy. Due to low global demand, the manufacturer plans to stop making Dengvaxia in late 2026.

There is one vaccine approved to prevent Chikungunya virus in the United States called called VIMKUNYA. This vaccine is generally not recommended during pregnancy but may be an option after delivery or in situations where the risk of infection is high. New recommendations for the VIMKUNYA vaccine during pregnancy and breastfeeding are currently under review. You can talk to your healthcare provider if getting vaccinated after pregnancy is right for you, especially if you live in or plan to travel to areas where chikungunya is common.

Take the following precautions to protect yourself against the bites of disease-carrying vectors:

Before Travel

• When making international travel plans, visit the CDC’s Travel Destinations List to see whether travel preparations are recommended for your destination of interest.

•  Avoid nonessential travel to high-risk areas for vector-borne illnesses. Check out the CDC’s Travel Health Notices for the latest information.

• Use the CDC’s Pregnant Travelers Page for general preparation tips.

During Travel

• Wear long sleeves and long pants when outdoors.

• Apply Environmental Protection Agency (EPA) registered insect repellents to skin and clothing.

• Avoid outdoor activity during dusk and dawn when mosquitoes are most active.

• Minimize exposure to open water sources outside and at home, which are breeding grounds for vectors.

• Keep your doors or windows closed or utilize fans, mosquito nets, or mesh screens on windows and doors to prevent contact with vectors.

After Travel

• If you develop any symptoms, such as a fever, headache, joint pain, or rash, see a healthcare provider as soon as possible.

One way to protect yourself is to use EPA-registered insect repellents. These repellents are both safe and effective, even during pregnancy. Look for products that contain:

• N, N-diethyl-meta-toluamide (DEET)

• Oil of lemon eucalyptus

• Picaridin

• Para-menthane-diol

• IR353

You may see natural products like wristbands, lotion, patches, or candles that use essential oils (such as peppermint, citronella, rosemary, or lemongrass). While these may seem like safer options, they are not EPA-registered and haven’t been proven to protect against mosquito-borne disease. 

Since vaccines are not available for all vector-borne illnesses, protecting yourself during pregnancy can also include avoiding nonessential travel. Before booking your trips, make sure to check the CDC’s Travel Health Notices, which can inform you of areas to avoid traveling to.