The Centers for Disease Control and Prevention (CDC) has reported the largest number of malaria cases detected in the United States since 1971. The rise in infections mainly stems from travelers inadequately following preventative measures when they visit regions of the world where malaria remains endemic, the CDC concluded in their Morbidity and Mortality Weekly Report.

“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. “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 confirmed 1,925 malaria cases occurred in the United States in 2011, which marks a 14 percent increase since 2010. Of the majority of cases who acquired the parasite overseas, 69 percent were imported from Africa, with two-thirds of those stemming from West Africa. Interestingly, once you break it down to individual countries, the single most cases didn't come from an African country; they cam from India.

The vectors of choice for malaria are female mosquitoes, which become infected with the unicellular microorganism. A bite introduces the organism into the body’s circulatory system via the insect’s saliva. The ultimate destination of these organisms is the liver where thrive by maturing and reproducing.

“Malaria is preventable. In most cases, these illnesses and deaths could have been avoided by taking recommended precautions,” said Laurence Slutsker, 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.” The rise in malaria is a reminder of why the CDC exists in the first place; the institution was originally founded in 1946 to specifically combat widespread cases of malaria that struck the Southeastern portion of United States in particular.

Despite drastic improvements in public health systems and carrying out preventative measures in the United States, such as draining swamps, travel seems to be the Achilles heel of keeping the disease entirely at bay. But travel likely isn't the only reason malaria is spreading. For example, global warming, which is thought to expand the territory in which the mosquito vectors can thrive (as explained in Al Gore’s movie, “An Inconveneint Truth”), is another potential suspect in the spread of the disease. Ultimately, the complexity of this environmental aspect, as Michael Lemonick explained in Climate Central, makes it difficult to say whether a warmer, more welcoming climate will really make a difference in how malaria spreads in the United States – especially since the country was already hospitable to the disease spreading insects.