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U.S. Malaria Cases Point To Need for Aggressive Infection Prevention

Cases of malaria have been found in the U.S.
A mosquito biting a person's skin.

Cases of malaria in Florida and Texas highlight the need for more aggressive prevention measures to help stop the spread of infectious diseases. While it has been nearly 20 years since the last cluster of locally acquired malaria cases occurred in the U.S., the disease is still prevalent and deadly in other parts of the world.

“We need to put more focus on tackling diseases where they are occurring and infecting people on a day-to-day basis,” said Yale New Haven Hospital Infectious Disease Specialist Sunil Parikh, MD, MPH, associate professor of epidemiology at Yale School of Public Health. “Malaria is endemic in most of Africa, leading to staggering disease and death, yet only when it hits our doorsteps do we give it the attention it deserves.”

Malaria is an infection caused by a parasite transmitted by mosquitoes and there are five species known to infect and cause disease in humans. The group of mosquitoes that transmit malaria are different from the mosquitoes known to transmit other illnesses like dengue, zika or West Nile. Once someone is bitten the parasite infects the liver before entering the bloodstream and it can take a week or longer for symptoms to finally appear.

Malaria symptoms

Common symptoms associated with malaria include:

  • Fevers
  • Chills
  • Sweats

In areas where malaria is endemic, it causes serious illness in those who are immunocompromised, young children and those who are pregnant. However, in areas where malaria is not common, nearly everyone is at risk for developing more severe disease. While most cases are treatable with a combination of medications, a species of mosquito called Plasmodium vivax can hang out in the liver for months to years and cause disease down the line. So far, all the cases identified in the U.S. are from that species.

Historically, malaria cases in the U.S. occur in people who have recently traveled to other parts of the world where malaria is present. We also know that there are mosquitoes capable of transmitting malaria throughout much of the southern United States. Locally transmitted cases can occur when these species of mosquitoes bite an infected person, and then bite another individual.

The best way to prevent malaria is by doing the same thing you would do to prevent other mosquito-borne illnesses. Limit spending time outside in the early evening when mosquitos feed, wear long sleeves outdoors, drain puddles or areas where water can collect and use CDC recommended insect repellants.

Dr. Parikh says it is unlikely malaria cases will appear farther north in Connecticut, however anytime malaria is present it should be taken seriously, as the disease can be severe.

“We’re more connected to geographic areas that have a lot of malaria,” Dr. Parikh said. “Over the last six to seven years we haven’t been able to make a tremendous impact on reducing the number of malaria cases globally and in some countries the numbers have increased. I wouldn’t be surprised if more travel related cases occur and that’s always going to be a risk.” As temperatures warm, mosquito numbers will increase and be present for longer periods of the year.

Additionally, Dr. Parikh points to the importance of recognizing malaria symptoms. While rare, clinicians treating patients who present with fever, chills and sweats should consider malaria as a possibility so patients can get the appropriate treatment. Hospitals and pharmacies should also make sure to have diagnostic tests and drugs on hand, so as not to delay appropriate care.