The transmission of malaria was wiped out in the United States decades ago, but that isn't stopping the disease from adding to the country's healthcare costs. A study in the American Journal of Tropical Medicine and Hygiene found that malaria generated about half a billion dollars in healthcare costs over a 15-year period.
The disease's impact on the American healthcare system was attributed to a steady stream of travelers returning home with the mosquito-borne disease, leading to a count of deaths and hospitalized patients eclipsing those of other travel-related illnesses.
Diana Khuu, PhD, MPH, a scientist at the University of California, Los Angeles, and the lead author of the study, said in a statement that more Americans are traveling to areas in which malaria is common, and aren't taking preventative measures such as applying mosquito repellents and anti-malarial medications.
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Khuu and her colleagues looked for malaria patients in a database maintained by the federal Agency for Healthcare Research and Quality that tracks hospital admissions nationwide. The researchers found that between 2000 and 2014, about 22,000 people were admitted to U.S. hospitals due to complications from malaria. Moreover, 4,823 patients were diagnosed with severe malaria, which means they suffered from problems like renal failure, coma or acute respiratory distress that significantly increase the risk of death; 182 of these patients died.
The associated burden from these cases is substantial. The researchers found that the average cost per patient was about $25,800, and that the total bill for treating malaria patients in the U.S. from 2000 to 2014 was about $555 million.
Overall, the scientists estimated that each year there are about 2,100 people in the U.S. suffering from malaria, since about 69 percent require hospital treatment. That count would exceed the high end of the official estimate from the Centers for Disease Control and Prevention of 1,500 to 2,000 cases per year. Khuu attributed the difference to the fact that CDC's malaria count is based on reports submitted to the agency by hospitals or physicians, and hospital admission records that were used in her study may capture additional cases that have not been reported to the CDC.
While those admissions' records did not include travel history, the researchers believe the malaria infections they documented most likely were acquired during travel to parts of Africa, Asia, and Latin America, where malaria is still common. Over the last 15 years, a blitz of malaria interventions -- including insecticide-treated bednets and increased access to highly effective malaria drugs -- has been accompanied by an estimated 37 percent drop in malaria incidence and a 60 percent drop in malaria deaths globally.
Meanwhile, although malaria was eliminated from the United States in the 1950s, there are sporadic reports of locally-acquired malaria infections, presumably caused by a mosquito that either fed on an infected traveler or hitched a ride on a flight or ship coming from a malaria-endemic region.
Malaria hospitalizations were more common in the United States than hospitalizations for many other travel-associated diseases. For example, during the same period, dengue fever, which is common in Mexico, Puerto Rico and throughout Latin America, has caused small, local outbreaks in south Florida and Texas generating on average 259 hospitalizations a year, compared with 1,489 for malaria.
But Khuu said mosquitoes capable of carrying malaria are common in many parts of the U.S., and increases in the number of travelers coming home with the disease increases the risk of malaria re-establishing itself in the United States. According to the study, the majority of malaria hospitalizations occurred in states along the Atlantic seaboard. Malaria's last domestic stronghold was in the Southeast.
Twitter: @JELagasse