Locally transmitted malaria in the US could be a harbinger of rising disease risk in a warming climate – 5 questions answered

• The Centers for Disease Control and Prevention reported on June 26, 2023, that five cases of locally transmitted malaria had been identified – four in Florida and one in Texas – since May 2023.
• These are the first cases of locally acquired mosquito-borne malaria in the U.S. since 2003.

1. What is malaria and how did these people become infected?

• Malaria is a serious and sometimes life-threatening disease caused by the bite of a female mosquito from the genus Anopheles, the vector that transmits malaria.
• The most common symptoms are fever, chills, headaches, muscle aches and fatigue.
• These symptoms typically occur from 10 to 15 days after people are infected with the parasite.

2. Why might these cases be surfacing now?

• For one, climate change is causing a shift in weather patterns, some of which can worsen malaria conditions.
• A higher average surface temperature from global warming could lead to higher mosquito migration in areas that were previously uninhabitable by Anopheles mosquitoes.
• Given these changes in local conditions, more cases could occur in populations that were previously “immunologically naïve” to malaria.
• This drives up the number of drug-resistant cases, the severity of the illness and the possibility of larger outbreaks.

3. How can people help prevent malaria transmission?

• Precautions also include what’s known as “drain and cover” – in other words, draining standing water to prevent mosquitoes from multiplying and using screens to prevent mosquitoes from entering through doors and windows.
• Health departments also note that it’s important to drain or discard containers that can collect rainwater, such as flower pots, old tires and buckets.

4. What are the available malaria treatments?

• There are several medicines used to prevent and treat malaria.
• The choice of medication typically depends on the type of malaria, whether a malaria parasite is resistant to a medicine, the weight or age of the person infected with malaria and whether the person is pregnant.
• These kill malaria parasites by damaging their proteins and are usually the most effective treatment against malaria.

5. Are vaccines against malaria available?

• Therefore, in October 2021, the World Health Organization began recommending the widespread use of a malaria vaccine known as RTS,S/ASOI for children who live in moderate- to high-risk areas.
• Trials show that the vaccine can significantly reduce malaria, including severe malaria, among young children.
• While new malaria vaccines will be a major boost for curbing malaria worldwide, it will be critical for health departments to continue emphasizing other preventive strategies, especially in newly affected areas like Florida and Texas.