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Serious Infections in Travelers

July 1, 2013
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“You got to be careful if you don’t know where you’re going because you might not get there.” — Yogi Berra

By Stan Deresinski, MD, FACP, FIDSA, Clinical Professor of Medicine, Stanford University, Hospital Epidemiologist, Sequoia Hospital, Redwood City, CA, Editor of Infectious Disease Alert.

Synopsis: More than three-fourths of these serious infections were due to Plasmodium falciparum, followed at some distance by typhoid and paratyphoid fever, and by leptospirosis and a variety of other infections.

Source: Jensenius M, et al. GeoSentinel Surveillance Network. Acute and potentially life-threatening tropical diseases in western travelers—a GeoSentinel multicenter study, 1996-2011. Am J Trop Med Hyg 2013; 88:397-404.

GeoSentinel is a worldwide network of 57 travel and tropical medicine clinics in 26 countries on 6 continents. Jensenius and colleagues analyzed the GeoSentinel database for cases of acute and potentially life-threatening tropical diseases occurring during or after travel to Central America, South America, Africa, Oceania, or tropical and subtropical regions of Asia. The evaluation was limited to 82,825 travelers who resided in North America, Europe, Israel, Japan, Australia or New Zealand who were evaluated at GeoSentinel sites from 1965 to 2011.

A total of 3666 acute or potentially life-threatening infections was identified in 3655 travelers with a median age of 35 years; 65% were male. Falciparum malaria was by far the most common, making up 76.9% of the total. This was followed by typhoid fever (11.7%), paratyphoid fever 6.4%, and leptospirosis (2.4%). The remaining 2.6% included 29 cases of spotted fever rickettsial infection (infections from Africa were not included because of their usually mild nature), 18 of dengue hemorrhagic fever or shock syndrome (DHF/ DSS), 16 of murine typhus, 13 scrub typhus, 7 relapsing fever, 6 each of meliodosis and African trypanosomiasis, and one each of Plasmodium knowlesi and Japanese encephalitis virus infection. Infection was fatal in 0.4% of patients.

One-third of cases of DHF/DSS were acquired in Thailand. Two-thirds of cases of typhoid fever were acquired in South Central Asia, the majority in India, while 79% of paratyphoid infections were also acquired in that region. Southeast Asia was the source of most cases of leptospirosis, as well as of murine and scrub typhus. Five of 7 with relapsing fever had traveled to sub-Saharan Africa. West Africa was the source of 54% of the 2827 cases of falciparum malaria; 10 patients died, Trypanosoma brucei rhodesiense infection was acquired in Tanzania (2), Zambia (2), Kenya (1), and Zimbabwe (1); all survived. The authors note that there were no hemorrhagic fever virus infections — including no cases of yellow fever. There were also no cases of Japanese encephalitis.

Commentary

The single most frequent infection was due to Plasmodium falciparum, an entirely preventable disease. The large number of cases of typhoid and paratyphoid fever, especially in south central Asia is a reflection of the poor hygienic and public health conditions in those areas. While modestly effective vaccines exist for prevention of typhoid fever, there is currently no vaccine specifically for paratyphoid.

There were only 6 cases of infection with Burkholderia pseudomallei, and two were fatal. This is consistent with the knowledge that meliodosis, which is acquired by contact with soil and surface water in tropical Asia, northern Australia, and Latin America, may be associated with a rapidly deteriorating course. A study of this sort has general value in assisting the clinician in directing their diagnostic and empiric efforts toward those infections that have the potential to kill and are amenable to therapeutic intervention.