Nearly 2,000 people were diagnosed with malaria in the U.S. in 2011, a 40-year high for the infection, health officials reported Thursday.
Most were among U.S. residents or citizens and virtually all cases were brought back from other countries, the U.S. Centers for Disease Control and Prevention reported. People need to watch out for the mosquito-borne infection, the CDC cautioned.
“In 2011, 1,925 malaria cases were reported in the United States,” CDC said in a statement.
“This number is the highest since 1971, more than 40 years ago, and represents a 14 percent increase since 2010. Five people in the U.S. died from malaria or associated complications.”
In 1970, 4,247 malaria cases were reported in the U.S., almost all of them among U.S. military personnel. That was the height of the Vietnam War. In 1971, 3,180 cases were reported.
In 2011, just 91 cases were in military personnel. Soldiers, sailors, marines and airmen deployed in malaria-ridden zones are now given drugs to prevent infection. New York City had the most cases in 2011, with 238 cases, the CDC team said.
Almost all the cases were imported, 69 percent of them from African countries where malaria is common. One of the infected people got the parasite through a blood transfusion, two babies were born infected and one case cannot be explained.
The malaria parasite is spread by mosquitoes and can live for years in the human body. When a mosquito bites an infected person it can pick up parasites and then transmit them to someone else – meaning malaria can be introduced by an infected traveler. It also means blood transfusions can transmit infections – that’s happened in 97 cases since 1963, CDC says.
“Malaria isn’t something many doctors see frequently in the United States thanks to successful malaria elimination efforts in the 1940s,” CDC director Dr. Tom Frieden said in a statement.
“The increase in malaria cases reminds us that Americans remain vulnerable and must be vigilant against diseases like malaria because our world is so interconnected by travel.”
Malaria killed 660,000 people globally in 2010. Symptoms include fever, headache, back pain, chills, sweating, muscle pain, nausea, vomiting, diarrhea and cough.
“Malaria is preventable. In most cases, these illnesses and deaths could have been avoided by taking recommended precautions,” said Dr. Laurence Slutsker, director of CDC’s division of parasitic diseases and malaria.
Another drug, mefloquine hydrochloride, sold under brand names including Lariam, Mephaquin or Mefliam, can cause severe side effects including hallucinations and is considered a drug of last resort. The Food and Drug Administration strengthened warnings about the pill in July.