The United States Centers for Disease Control and Prevention (CDC) issued an alert after five locally-acquired malaria cases were reported in Florida and Texas, the first in the last 20 years.

Officials revealed that four people in Sarasota County, Florida, and one person in Cameron County, Texas, were infected by the mosquito-borne illness. This comes as Cameron County is the southernmost county in Texas and is roughly 1,300 miles away from Sarasota, Florida.

First Malaria Cases in the US in the Last 20 Years

All of the patients from Florida have been "treated and have recovered," as noted by a statewide mosquito-borne illness advisory issued by the state's Department of Health on Monday. Furthermore, residents were advised to take precautionary measures by applying bug spray, avoiding areas with high mosquito populations, and wearing appropriate clothing.

The health department added that these measures are even more essential during sunrise and sunset when mosquitoes are most active. The new cases come as the last locally-acquired Texas cases were reported in 1994 and, in the case of Florida, in 2003 in Palm Beach, as per ABC News.

Malaria is caused when a person is bitten by an infected mosquito that carries malaria parasites and is known to be non-contagious, meaning it cannot be spread from person to person. Symptoms of this illness include fever, chills, muscle aches, nausea, headache, and anemia. The health agency warned that it can also sometimes result in fatalities if left untreated.

The disease was once common in the United States, but a campaign in 1947 conducted by southeastern states, where they sprayed insecticides and drained breeding grounds, eliminated the transmission of the illness.

The CDC said that roughly 2,000 malaria cases are reported yearly but mostly diagnosed in people who caught the disease abroad. The threat of malaria to most people who acquired the infection locally is extremely low.

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Possibility of Spreading Illness

The health agency noted that there was no evidence to suggest that the cases from Florida and Texas were related. Last week, according to NBC News, the Texas Department of State Health Services announced the detection of a local malaria case in a person who was working outdoors and was now known to have traveled outside the country or the state.

On the other hand, the Florida Department of Health issued a statewide mosquito-borne illness advisory on Monday. The recent cases in the United States are caused by a parasite that infects mosquitoes known as P. vivax.

While the parasite is not as deadly as some others that cause malaria, it can lie dormant in the body and cause chronic infections months or years after the initial illness. The CDC noted that symptoms of the illness typically appear ten days to four weeks after a mosquito bites a person.

While the majority of malaria cases, roughly 95%, are found in Africa, climate change threatens to break the norm. According to CNN, scientists have continuously warned people that the illness could become more common in the United States as temperatures continue to rise.

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