Malaria is a serious illness caused by parasites and transmitted to humans through the bites of infected mosquitoes. It can lead to severe health complications if not promptly diagnosed and treated. This article explores its current status in the United States, contrasting its historical presence with today’s reality.
Malaria’s Presence in the United States
Malaria is not common in the United States today. The Centers for Disease Control and Prevention (CDC) indicates that approximately 2,000 malaria cases are reported each year in the U.S. These cases primarily occur in individuals who have traveled to regions where malaria is widespread and then returned to the U.S., highlighting that local transmission within the United States is rare.
Eradication Efforts and Ongoing Surveillance
The rarity of malaria in the U.S. is a result of extensive public health campaigns and environmental changes implemented over many decades. Malaria was eliminated from the country by 1951, following a concerted national effort. This included widespread application of insecticides like DDT, drainage of mosquito breeding sites, and other environmental modifications. Improved housing conditions also reduced human exposure to mosquitoes.
Although the malaria parasite has been largely eliminated from the local transmission cycle, the Anopheles mosquito, which can carry the parasite, still exists in many parts of the United States. Public health agencies maintain ongoing surveillance systems to monitor for any re-establishment of the disease. The CDC continues to track cases and assist with prevention both domestically and internationally.
How Cases Still Arise
Despite its eradicated status, malaria cases in the U.S. primarily arise through “imported” infections. These occur when individuals contract the disease while traveling in malaria-endemic countries and then develop symptoms after returning home. In 2023, a significant increase in imported cases was noted in southern border cities, with many occurring among new arrivals who had traveled through endemic regions.
In very rare instances, “local transmission” can occur, meaning a person contracts malaria within the U.S. without a history of international travel. This happens when a local Anopheles mosquito bites an infected individual (often an imported case) and then transmits the parasite to another person nearby. In 2023, for the first time in 20 years, ten such locally acquired cases were identified across Florida, Texas, Maryland, and Arkansas. These rare events underscore the importance of rapid public health responses to prevent broader outbreaks.
Protecting Yourself When Traveling
Given that most malaria cases in the U.S. are travel-related, taking precautions when visiting malaria-endemic areas is important. Consulting a healthcare provider before travel is advisable to discuss antimalarial medications, which can prevent infection. These medications are typically taken before, during, and after a trip.
While traveling, personal protective measures against mosquito bites are effective. This includes using insect repellents containing active ingredients such as DEET, picaridin, or oil of lemon eucalyptus. Wearing long-sleeved shirts and long pants, especially from dusk to dawn when mosquitoes are most active, can also reduce exposure. Sleeping under insecticide-treated bed nets can provide additional protection in areas where mosquitoes are prevalent.
Upon returning home, it is important to be aware of malaria symptoms, such as fever, chills, and flu-like illness. Symptoms can appear days, weeks, or even months after exposure. Seeking prompt medical attention if these symptoms develop after travel to an endemic area is important.