Florida and Texas have reported a combined total of five cases, noting the patients are ‘improving’ from their symptoms.
County officials in Florida have announced “aerial treatments” to kill mosquitoes after malaria was detected in the southern United States for the first time in 20 years.
Noting “increased disease activity in the area”, Sarasota County issued a statement on Tuesday saying it would deploy aeroplanes and trucks overnight to spray pesticides as part of an effort to stem the spread of the mosquito-borne disease.
The move comes a day after the US Centers for Disease Control and Prevention (CDC) issued a health advisory for malaria.
While thousands of cases are reported each year in the US – primarily by travellers returning from abroad – the last time the country had a locally-transmitted outbreak was in 2003, when eight cases were reported in Florida.
The latest cases were likewise identified in Florida, with a cluster of four patients identified in Sarasota County, south of Tampa along the Gulf of Mexico.
A further case was found in Texas’s Cameron County, which is also situated on the Gulf coast. The Texas Department of State Health Services noted that the patient was a local resident who “spent time working outdoors” and had no recent experiences travelling out of state.
The last time Texas reported a local incident of malaria, the agency said, was in 1994.
Though the five patients in Texas and Florida “have received treatment and are improving”, the CDC warned doctors and residents – particularly in warm, mosquito-friendly areas – to be on the lookout for the disease.
“Malaria is a medical emergency and should be treated accordingly,” the CDC said in its health advisory on Monday.
A potentially life-threatening disease, malaria is primarily spread through bites from the female Anopheles mosquito, which can carry Plasmodium parasites.
An infected bite can lead to fevers and chills in the mildest form of the disease but in severe cases, patients can experience convulsions, laboured breathing, abnormal bleeding and jaundice.
Before the coronavirus pandemic, the US documented approximately 2,000 cases of “travel-related” malaria per year. Only 300 were severe.
The first confirmed case in the US this year was announced on May 26. As with the Texas case, the Florida Department of Health explained that the patient had “spent extensive time outdoors” and called on residents to use mosquito repellent or wear long sleeves.
Summer in the US coincides with the rainy season for many southern states, which generally stretches from May through October. Mosquitoes can breed in the warm, standing water left behind after downpours.
Experts fear climate change may exacerbate the spread of mosquitoes and with them, diseases typically associated with warmer areas.
The World Health Organization estimates there were 247 million cases of malaria in 2021, more than half of which occurred in four African countries: Nigeria, the Democratic Republic of the Congo (DRC), Tanzania and Niger.
Of that year’s cases, 619,000 people died from the disease.