Maryland has recorded its first case of locally acquired malaria in four decades, setting off concern among public health officials about the mosquito-borne disease known as a major global killer.
The person infected lives in the Washington, D.C., suburbs and is recovering at home after being hospitalized, said state health officials, who provided no other information.
They said the person did not travel recently outside of the United States or to other states with locally acquired cases. The U.S. Centers for Disease Control and Prevention confirmed the case Friday, and the agency has confirmed at least eight cases in Florida and Texas since May.
“Malaria was once common in the United States, including in Maryland, but we have not seen a case in Maryland that was not related to travel in over 40 years,” said Dr. Laura Herrera Scott, state health secretary. “We are taking this very seriously and will work with local and federal health officials to investigate this case.”
Maryland typically reports about 200 travel-related cases of malaria a year, according to state health figures.
The U.S. Centers for Disease Control and Prevention reports the number of annual cases across the country is about 2,000 — also almost entirely travel related.
The Maryland case involves a strain that is different from the strain seen so far in Florida and Texas, and can be more severe, said Dr. David Blythe, director of the Maryland Department of Health’s Infectious Disease Epidemiology and Outbreak Response Bureau, in a Friday afternoon news conference.
He said its primary symptom is fever, which residents should be on the lookout for. Symptoms usually appear about seven to 30 days after someone is bitten by a mosquito carrying a parasite. It can cause high fever, chills, body aches, diarrhea and vomiting.
The officials said the risk to public health remains low from locally acquired malaria, though risk is higher for children and those with underlying health conditions. Blythe urged people to take precautions to prevent mosquito bites, such as using repellent with DEET, covering exposed skin with clothing, closing doors and windows or using properly working screens, and emptying standing water weekly to prevent mosquitoes from laying eggs.
Officials also recommended understanding risks from travel and speaking with a health care provider about prescription medications to prevent malaria.
Malaria is still a big threat, particularly in African countries that have a disproportionate share of the approximately 250 million annual cases. In 2021, there were close to 620,000 deaths, about 80% of those children, according to the World Health Organization.
There are now effective treatments and a new malaria vaccine that officials have been working to administer in African countries.
Better mosquito control measures in the United States have lowered the incidence of malaria and other mosquito-borne diseases such as West Nile. Blythe, however, said the anopheles mosquito responsible for the infection is common in Maryland.
He said the health department is looking out for increased rates of locally transmitted malaria in the future due to climate change.