CDC Commentary: Clues to Diagnosis in the Patient With Posttravel Illness

Phyllis Kozarsky, MD


June 21, 2010

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Hello, this is Phyllis Kozarsky from the Travelers' Health Branch at CDC.

I'd like to take a few minutes today to talk to you about diagnosing illnesses in patients who have recently traveled. Fever is a common complaint among returning travelers and an important clue to finding the right diagnosis.

Returning international travelers could potentially host a number of exotic infections, but recent studies indicate that a significant proportion of febrile illnesses among this population are the result of common infections such as bacterial pneumonia and pyelonephritis. Even so, fever in returning travelers can signal the presence of travel-related infection, ranging from common post-travel problems, such as travelers' diarrhea, to life-threatening infections of public health significance, such as malaria, dengue, or tuberculosis. Keep in mind that individuals who have traveled to the developing world are more likely to present with more serious and potentially preventable travel-related illnesses, like malaria and typhoid fever.

One of the most critical steps in determining the cause of illness is to gather the complete travel history of the patient. The patient's travel history includes not only destinations but also:

  • Level of accommodation while abroad;

  • Pre-travel medical history;

  • Adherence to prescribed medicines; and

  • Activities during travel.

These details may provide vital clues to the cause of certain conditions. Make sure you ask about details from their travels that may reveal probable sources of exposure to infectious agents.

If the patient visited malaria-endemic areas like sub-Saharan Africa, specifics about their accommodations such as the presence of window screens, air conditioning, and bed nets are useful. If the patient has traveled to a malaria-risk area and has a fever, assume a malaria diagnosis until you have ruled it out. Malaria is the most common cause of acute, undifferentiated fever after travel to some malarious areas. Do not rule out this diagnosis for patients with a history of malaria chemoprophylaxis. Poor compliance with antimalarial medication is very common.

Malaria can progress rapidly, so prompt diagnosis and treatment are vital to the patient's health. Patients may present with intervals of flu-like symptoms, including headache, muscle pain, and malaise. They may even be afebrile at the time of evaluation but will typically report a history of fever and chills. These symptoms can develop in as few as 7 days but usually take at least 10 - 14 days from the initial exposure to appear. Be aware that symptoms of malaria can develop several months to a year or more after exposure.

When detected early, malaria can be treated effectively. Blood smear microscopy is the best method for diagnosing malaria, determining the species of malaria parasite, and quantifying the parasitemia. If you suspect malaria, consult an infectious disease physician or a provider who has specialized tropical or travel medicine expertise who can confirm the diagnosis and suggest treatment options. It may take several blood smears spaced in time by hours to make the diagnosis. Treatment is urgent.

While malaria is being ruled out, consider the geography of the exposure along with the incubation period and the patient's health history to develop a differential diagnosis. For example,

  • A patient who has traveled to a tropical area and who develops a fever within 1 week of exposure may have dengue fever. Dengue is the most common tropical disease causing fever in travelers returning from the Caribbean, the Americas, and Asia.

  • An unvaccinated traveler who develops fever approximately 1 month after exposure might have Hepatitis A.

During your assessment, bear in mind other potential sources of illness:

  • If you are practicing in the northern hemisphere, remember that the flu can be transmitted year-round in tropical areas and from April through August in the Southern Hemisphere.

  • Measles, though seen rarely in the United States, should be a consideration in patients with fever and a rash, as should rickettsial infections, which are common in travelers returning from South Africa.

  • Do not discount sexually transmitted diseases such as acute HIV or bacterial infections as causes for infection.

  • Other diseases, such as leptospirosis and meningococcemia, are seen more rarely in travelers, but always consider them because they require rapid and precise treatment.

Also, be careful not to overlook non-infectious health problems that may be due to exacerbations of chronic illness or related to travel, such as pulmonary emboli, particularly in those who have been immobile. Finally, stay abreast of current research on travel medicine and infectious diseases.

There are a number of resources available to help you in your evaluation of international travelers. The American Society of Tropical Medicine and Hygiene Web site includes a listing of providers who care for individuals who are ill post-travel.

When you are seeing a post-travel patient, remember to also think about infection control, public health implications, and requirements for reportable diseases.

For more information about post travel consultations and fever, visit the CDC Travelers' Health Web site at

Thank you and good health.

Web Resource

CDC Travelers' Health. Available at: Accessed June 10, 2010.

Phyllis Kozarsky, MD, is an expert travel health consultant for CDC's Travelers Health and Animal Importation team, whose focus is to promote travelers' health and to prevent introduction of diseases related to animal importation to the US. She is an editor of CDC's Health Information for the International Traveler, also known as the Yellow Book."

Dr. Kozarsky began her CDC career in 2001. She is also medical co-director at TravelWell, an Emory Healthcare affiliated program aimed at providing pre-and post-traveler health services to international travelers, and at Grady Memorial Hospital's Immigrant and Refugee clinic. Current research efforts have primarily focused on issues in clinical tropical medicine and travelers' health, including the epidemiology of travel- related infections.

She received her bachelor's degree from Hobart and William Smith Colleges in Geneva, New York. She went to Medical College of Pennsylvania in Philadelphia, and received her medical degree from Albert Einstein College of Medicine in New York.

She is the author of many peer-reviewed articles, and is a member many professional organizations, including the International Society of Travel Medicine and the American Society of Tropical Medicine and Hygiene.

To request an interview, call CDC's Division of Media Relations at (404) 639-3286, or e-mail us at


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