In 2011, 1,925 malaria cases were reported in the United States, according to data published in a supplement of the Morbidity and Mortality Weekly Report (MMWR) released last week by the Centers for Disease Control and Prevention (CDC). This number is the highest since 1971, more than 40 years ago, and represents a 14% increase since 2010. Five people in the U.S. died from malaria or associated complications.

Almost all of the malaria cases reported in the U.S. were acquired overseas. More than two-thirds (69%) of the cases were imported from Africa, and nearly two-thirds (63%) of those were acquired in West Africa. For the first time, India was the country from which the most cases were imported. Cases showed seasonal peaks in January and August.

A word interconnected by travel

“Malaria isn’t something many doctors see frequently in the United States thanks to successful malaria elimination efforts in the 1940s,” said CDC Director Tom Frieden, M.D, M.P.H. “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.”

Symptoms and effects

Malaria is caused by a parasite transmitted by the bite of an infective female Anopheles mosquito. In 2010, it caused an estimated 660,000 deaths and 219 million cases globally. The signs and symptoms of malaria illness are varied, but the majority of patients have fever. Other common symptoms include headache, back pain, chills, increased sweating, muscle pain, nausea, vomiting, diarrhea, and cough. Untreated infections can rapidly progress to coma, kidney failure, respiratory distress, and death.

“Malaria is preventable. In most cases, these illnesses and deaths could have been avoided by taking recommended precautions,” said Laurence Slutsker, M.D., M.P.H., director of CDC’s Division of Parasitic Diseases and Malaria. “We have made great strides in preventing and controlling malaria around the world. However, malaria persists in many areas and the use of appropriate prevention measures by travelers is still very important.”

Drugs and protective clothing can help

Travelers to areas with malaria transmission can prevent the disease by taking steps such as use of antimalarial drugs, insect repellent, insecticide-treated bed nets, and protective clothing.

Travelers in the United States should consult a health-care provider prior to international travel to receive needed information, medications, and vaccines. CDC provides advice on malaria prevention recommendations on-line (www.cdc.gov/malaria/travelers/drugs.html). If a traveler has symptoms of malaria, such as fever, headaches, and other flu-like symptoms, while abroad or on returning home, he or she should immediately seek diagnosis and treatment from a health-care provider.