Florida and Texas are seeing some local cases of malaria – the first spread of the mosquito-borne disease inside the United States in 20 years, officials warned in a health warning. Strong.

It says the risk of malaria in the United States remains very low.

All five patients – four in Floridaone of Texas – is currently being treated.

Malaria is caused by being bitten by an infected mosquito. People can’t catch it from each other. But the insects catch it from infected people – and the cycle continues.

It is common in large areas of Africa, Asia, and Central and South America but not in the United States.

However, Anopheles mosquitoes, found in many parts of the United States, can transmit malaria, if they feed on the blood of an infected person.

The risk is higher in these areas:

Infected people may experience fever, sweating, and chills. Malaria is an emergency and must be treated quickly with medication to kill the parasites causing the infection.

Using insect repellent and covering with blankets can help protect against mosquito bites.

The CDC says it is working with the Florida and Texas health departments and that those recently diagnosed and treated “are improving.”

U.S. physicians are advised to consider malaria in any person with a fever of unknown cause, regardless of international travel history, particularly if they have visited or lived in affected areas of Florida or Texas.

Florida has issued a mosquito-borne disease warning after cases were detected in Sarasota County and Manatee County, warning residents to drain standing water where mosquitoes can breed and to wear long-sleeved shirts and pants.