New Jersey health officials said they are investigating what could be the state’s first locally acquired case of malaria in more than three decades.

The New Jersey Departments of Health (NJDOH) and Environmental Protection (NJDEP) announced on Monday that they are looking into a case of malaria reported in a Morris County, N.J. resident who has no recent history of traveling outside the United States.

While approximately 100 cases of malaria are reported in New Jersey each year, the Morris County resident would be the first locally acquired case reported in the state since 1991.

The state health officials said they are working closely with the U.S. Centers of Disease Control and Prevention (CDC) “to investigate potential sources of infection,” but “it is possible the resident was infected with malaria in New Jersey.”

Malaria is transmitted by Anopheles mosquitoes and is caused by a parasite. The disease can be transmitted when a mosquito bites an infected person, acquiring the parasite, and then bites another person, infecting them.

Anopheles mosquitos are found in New Jersey, but health officials said the risk to the general public of non-travel related malaria remains low. The disease is widespread in tropical regions.

“While risk to the general public is low, it’s important to take the necessary precautions to prevent locally acquired malaria in New Jersey. The most effective ways are to prevent mosquito bites in the first place and to ensure early diagnosis and treatment of malaria in returning travelers,” acting health commissioner Jeff Brown said in a statement.

“Anyone traveling to countries with widespread malaria should take appropriate steps to prevent malaria while traveling and monitor for symptoms,” he added.

“I urge the public to continue taking steps to eliminate standing water around their properties, which will go a long way to reducing the risk of mosquito breeding,”

Environmental protection commissioner Shawn LaTourette encouraged the public to guard against mosquito bites by eliminating or covering standing water like birdbaths and pools.

“As the summer winds down, taking this simple but necessary step will help ensure quality of life and protect public health,” LaTourette said.

Malaria often causes fever, chills, headache, muscle aches and fatigue, and it can also cause nausea, vomiting and diarrhea. Symptoms usually appear within seven to 30 days of exposure to the disease. There are prescription antimalarial drugs but, if not treated quickly, the disease can be life-threatening.

The development of malaria vaccines has been slow, but the World Health Organization (WHO) began recommending widespread use of a vaccine in children who live in sub-Saharan African and other regions with high transmission.