According to the Centers for Disease Control and Prevention, rising numbers of malaria cases documented in the U.S. are a warning to travelers to countries with malaria: plan ahead and take the necessary steps to protect yourself against this deadly disease.

The health agency’s latest malaria report reveals that about 2,000 cases of malaria were diagnosed and treated in the U.S. in 2011 — nearly all were acquired overseas in areas with malaria transmission. This is the biggest number documented since 1971. Among the individuals who acquired malaria five died from the disease.

Annually, millions of U.S. residents journey to countries where malaria is transmitted. Most travelers who acquire malaria either did not take an antimalarial drug to prevent the illness or did not take the right drug or dose.

A majority of the cases were in people who had traveled to sub-Saharan Africa. Although India is often thought of as a region with low risk of malaria for travelers, it is the individual country from which the most cases were brought into the U.S.

“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 obtained by LiveScience. “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.”

The CDC offers the following tips for protecting yourself from malaria when traveling into a region where the disease is prevalent:

• Go see your doctor several weeks before you travel.
• Purchase your malaria pills prior to your trip.
• Take your malaria pills exactly as the directions say.
• Sleep under an insecticide-treated bed net at night, wear long sleeves and long pants, and utilize insect repellent.
• If you experience malaria symptoms, visit a physician as soon as possible

According to the CDC, a person dealing with a classical malaria attack will experience a cold stage, hot stage and a sweating stage. A person suffering a more severe malaria attack will experience abnormalities in blood coagulation, low blood pressure, and acute kidney failure among other symptoms.