Cases of Malaria in the U.S. are at a 40-year high and almost all cases being acquired overseas, according to new data from the Centers for Disease Control and Prevention (CDC).

In 2011, about 2,000 cases of malaria were diagnosed and treated in the U.S., with 70 percent of cases coming from Africa. In just about every instance of the illness, the person had recently traveled to an area where malaria is present.

This is not uncommon, as millions of American travelers visit countries known to transmit malaria. Still, the amount of malaria cases in the U.S. is the highest total since 1971. Of the nearly 2,000 cases, five have been fatal.

Even though India was believed to be a low risk country for malaria, it lead all other single countries in malaria transmissions. Anyone who travels to an area where malaria is present is at-risk, but most instances of illness occur when a person did not take the proper dosage of an antimalarial drug or no treatment at all.

"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 is commonly transmitted via mosquito. Aside from antimalarial drugs, the best preventative action against the disease is insect repellent, protective clothing and insecticide-treated bed nets.

The CDC has a detailed chart for malaria prevention by country, but also recommended five simple tips for preventing and dealing with malaria.

1. "Visit your doctor 4-6 weeks before you travel."

2. "Buy your malaria pills before your trip."

3. "Take your malaria pills exactly as prescribed."

4. "Avoid mosquito bites by sleeping under an insecticide-treated bed net, wearing long sleeves and long pants, and using repellent."

5. "If you become sick with malaria symptoms such as fever and chills during or after your travel, make sure it is not malaria by seeing a doctor right away."