Not long ago, Shannon, an exceptional laboratory tech at the hospital where I work, joined a group of medical professionals from her church to volunteer in a small hospital in Haiti. A few days after her return home, I met Shannon in the hospital elevator. She looked exhausted and described the almost primitive conditions under which she had lived and worked in Haiti—grueling hours in 100-degree temperatures and incessant biting of mosquitoes and stinging ants. Realizing where my mind was going, she assured me that she had gotten the proper immunizations before her trip and had also taken chloroquine, the antimalaria medication that is commonly used as a preventive therapy. I was glad to hear that she had taken those steps but also knew that there had been reports of chloroquine not working. I warned Shannon to keep an eye on any symptoms that might develop.

So unless you’re headed to Haiti, why should Shannon’s saga matter to you? Even though more than 600,000 die of malaria worldwide each year, it’s rare in the US, with only about 2,000 cases annually. But travelers to many places, such as Africa and South Asia, are prime targets. There are literally dozens of countries where an American could contract malaria—even if all the proper precautions are taken.

Now back to Shannon. Within moments of getting off the elevator, she developed chills—a common symptom of malaria. Once she reached the lab, she calmly asked a colleague to draw her blood and prepare several slides to examine under the microscope. Shannon’s blood sample showed that she was indeed infected with one of the tiny parasites that causes malaria. A proper diagnosis is imperative so that the parasite is killed and the patient doesn’t get worse because the wrong drugs are used. With further lab analysis, we were able to tailor Shannon’s therapy with confidence.

After being admitted to the hospital, Shannon was seen by an infectious disease specialist and started receiving a combination of antimalarial medications. Even so, she ran high fevers and soaked her bed linens several times with perspiration. Without IV fluids, such sweating would have caused dehydration. Fortunately, Shannon improved dramatically over the next 48 hours and was sent home on oral medication. She’s now back to excellent health. Shannon was lucky to have been back in the US when she got sick, since the medical facilities in Haiti are sorely lacking. Even more important, Shannon knew enough to not dismiss her symptoms as “just a virus”—a potentially deadly mistake made by many people, since malaria symptoms mimic a number of seemingly benign illnesses, such as influenza or food poisoning.

Lessons Learned: Even if you’ve taken precautions before traveling, remember that no preventive medication is 100% effective against any disease. Always consult the CDC travel website, CDC.gov/travel, before visiting any underdeveloped country, and give yourself plenty of time to prepare—learn what symptoms you could develop if you get sick (with malaria, an infected person might get sick within seven days or up to a year later), and ask a travel professional for practical advice on how you would deal with a medical crisis if one occurred while you were still away. With a deadly disease like malaria, there’s no time to spare!