What you need to know about malaria in the U.S.

Roughly 2,000 cases of malaria are diagnosed annually in the United States, which are usually connected to international travel. But within the past two months, there have been several locally acquired cases of malaria in Texas and Florida.

These locally acquired cases are the first in the United States in 20 years, according to the Centers for Disease Control and Prevention (CDC).

Naomi Hauser, assistant clinical professor of infectious diseases at UC Davis Health, answers questions about what you need to know about malaria in the U.S.

Should people be concerned about malaria spreading in the U.S.?

The recent cases of malaria in the United States are a concern, but overall, the disease is still very rare here.

Malaria infection is usually travel-related and with travel increasing as COVID-19 slows, the spread of malaria is something we need to keep an eye on. Additionally, climate change is altering habitats and where mosquitoes and ticks can live, so there is a risk of spread of diseases we have seen rarely or not at all.

What are the symptoms of malaria?

The symptoms of malaria are like the flu. These include fever, chills, headaches, muscle aches, abdominal pain, fatigue and nausea. If you think you have been exposed to malaria, let your health care provider know so you can get tested.

How is malaria typically spread?

When a mosquito bites someone who has malaria, the mosquito becomes infected. When that mosquito bites someone else, it transfers the parasite to the other person’s bloodstream.

Is malaria contagious from person-to-person?

No, malaria cannot be passed from one person to another. It must be spread through a mosquito go-between, which is what we call a vector.

How can people protect themselves to prevent malaria?

The key is protecting yourself from mosquito bites. When you are going outside around dusk or dawn, which is the most appealing times for mosquitos, make sure you dress yourself in long sleeves and long pants.

There are repellents (most common are DEET and Picaridin) that protect against mosquitos, ticks and other flies. DEET-containing repellents are effective and safe, but in children, we do not want to use a concentration of more than 30% DEET.

Learn more about different types of repellents from the U.S Environmental Protection Agency.

You can also check your yard to ensure there is no standing water, which can attract mosquitos.

How can people reduce the risk of getting malaria if they are travelling to Texas, Florida or other parts of the world with recent cases?

People should take the previously noted steps to protect themselves from mosquito bites.

Also, some areas in the world have such a high risk of malaria that people travelling there can be given malaria prophylaxis antibiotics before they travel. If you think you might be travelling to one of those places, you should speak with your health care provider to see if there are antibiotics that would be appropriate for you to take.

Is there a vaccine for malaria?

No, there is not a vaccine for malaria. There are vaccine studies in the works, but nothing is available currently.

How is malaria treated?

Malaria is treated with prescription drugs to kill the parasite. Several things influence the choice of medicine including:

• Which type of malaria parasite you have
• The severity of your symptoms
• Your age
• Whether you're pregnant

Is climate change contributing to this increase in new malaria cases?

Currently, I do not think the increase in cases of malaria in the United States is due to climate change. The places where cases have been seen have had malaria before, house the right vectors and have the right climate for spread of the disease.

But climate change is going to change where those vectors can live and for how long they can survive in certain and is something we need to be aware of moving forward.