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Tropical Infections in Critical Care
MAJ Robert Wood-Morris
Infectious Diseases, B.C. Internal Medicine, Walter Reed Army Medical Center, Washington, D.C., U.S.A.LTC Michael Zapor
Infectious Diseases Service, Walter Reed Army Medical Center, Washington, D.C., U.S.A.David R. Tribble
Enteric Diseases Department, Infectious Diseases Directorate, Naval Medical Research Institute, Silver Spring,
Maryland, U.S.A.Kenneth F. Wagner
Infectious Diseases and Tropical Medicine, Islamorada, Florida, U.S.A.INTRODUCTION
It is a familiar and captivating scenario: an exotic infection acquired abroad developing within
a returning traveler. Sometimes symptoms begin as early as on the plane ride home, sometimes
not until weeks later. In either case, the patient becomes progressively ill, critically so, all the
while unknowingly infecting others. The disease spreads, chaos is loosed, and only the timely
insight of an awkwardly introverted yet surprisingly attractive physician stands between
armageddon and the return of normalcy. In reality, travel medicine is rarely so dramatic.
Nonetheless, the likelihood of today’s critical care physician having to manage patients with a
tropical infection is increasing, as international travel has increased from an estimated
25 million border crossings in 1950 to over 806 million crossings in 2005 (1).
To better prepare travelers prior to their trips abroad, the discipline of travel medicine
has been refined over the past 25 years, with an increasing reliance upon evidence-based data
and the recent publication of practice guidelines (2). This information assists the physician in
determining not only what vaccines or prophylactic regimens may help prevent infection in
the traveler, but also stresses the importance of safety awareness and environmental risk
avoidance. Unfortunately, the International Society of Travel Medicine (ISTM) suggests that of
all travelers, only 8% will seek pretravel medical advice, and recommendations received may
be incomplete or inaccurate (3). It is no surprise, then, that each year four million travelers
returning from developing countries become ill enough that medical intervention is required
either en route or upon return home (4). That is not to say there are four million cases of Ebola
or African trypanosomiasis every year, but how can the clinician know what illnesses are being
seen, and more importantly, which to consider more likely in their patients? Best available data
comes from the GeoSentinel global surveillance network of the ISTM and the Centers for
Disease Control (CDC) (5). Established in 1995, it now comprises 41 travel or tropical medicine
clinics (16 in the United States, 25 in other countries representing all continents) that not only
report what diagnoses are seen in their facilities, but additional invaluable data such as time to
presentation of illness, geographic exposures, adherence to prophylactic measures, etc.
With now more than a decade of surveillance information available, it has been shown
that febrile illness, dermatologic disorders (especially insect bites), and acute/chronic diarrheal
illnesses comprise almost 70% of all travel-related illness (4). An analysis of 6957 travelers with
fever revealed that malaria (21%), acute diarrheal disease (15%), respiratory illness (14%), and
dengue (6%) were the most commonly identified etiologies (6). In a notable 22% of cases, no
etiology was identified. While most patients present within one month of travel, 10% suffer
The views expressed in this chapter are those of the authors and do not reflect the official policy of the Department of Army,
Navy, Department of Defense, or US government.