Abstract & Commentary

Dengue in Pediatric Travelers

This article originally appeared in the April 2012 issue of Travel Medicine Alert.

By Philip R. Fischer, MD, DTM&H, Professor of Pediatrics, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester MN.

Dr. Fischer reports no financial relationships to this field of study.

Synopsis: Dengue fever occurs in children traveling to visit friends and relatives in a pattern similar to what is seen in children living in endemic areas. Careful attention to pre-travel counsel about insect bite prevention is warranted.

Source: Krishnan N, et al. Severe dengue infection in pediatric travelers visiting friends and relatives after travel to the Caribbean. Am J Trop Med Hyg 2012;86:474-476.

A retrospective review of pediatric cases of dengue fever was undertaken at a single health center in the Bronx area of New York. Over a 3 ½ year period, eight children with dengue infection were identified. Each child had traveled to the Caribbean (seven to the Dominican Republic, one to Puerto Rico), and the duration of their trips ranged from ten days to four years. Care was sought within 11 days of returning to New York. Each affected child presented with fever, and most indicated both gastrointestinal complaints and myalgia. Leukopenia and thrombocytopenia were common, and half showed ascites that was visible on abdominal ultrasonography. Three (38%) of the children had complicated courses, two with dengue hemorrhagic fever and one with dengue shock syndrome. With treatment, each child recovered fully.

Many of these children, including both of those with dengue hemorrhagic fever, had serologic evidence of having also had a previous dengue infection. However, a child with dengue shock syndrome was eight months old and experiencing a primary dengue infection.

Commentary

Even as malaria is receding from some areas of the world, dengue infections are spreading geographically and becoming increasingly common.1 Imported dengue is increasingly identified both in North America1 and Europe.2

Dengue is transmitted by the bites of Aedes mosquitoes that are well-adapted to urban environments.3 These mosquitoes will bite humans who are either indoors or outdoors, and they often feed during daylight hours. These vectors are "nervous" feeders that can interrupt blood meals and then restart another meal on a nearby individual, thus resulting in multiple infections in the same household at the same time.3,4

Four distinct serotypes of dengue virus cause human infection.4 Typically, severe disease occurs in individuals who have also had previous dengue infection with a different dengue serotype. It is thought that antibody enhancement of the second infection superimposed on existing sero-specific immunity triggers an exaggerated cytokine response with capillary leak and severe illness.4,5 Interestingly, as seen in this new report from the Bronx and in pediatric populations in dengue-endemic areas, the dengue shock syndrome form of illness is often seen in infants during the second half of the first year of life. Perhaps this is due to interactions between the child's primary dengue infection and waning maternal antibodies that had been acquired transplacentally. Another recent report, however, revealed that adult travelers could have significant ultrasonic evidence of capillary leakage even with primary dengue infection that presented without severe illness.6

This report from the Bronx highlights the importance of providing pre-travel guidance to individuals and families who make repeated visits to dengue-endemic areas. Mosquito avoidance measures must be emphasized.

References

  1. Streit JA, et al. Upward trend in dengue incidence among hospitalized patients, United States. Emerg Infect Dis online 2011, DOI: 10.3201/eid1705.101023
  2. Odolini S, et al. Travel-related imported infections in Europe, EuroTravNet 2009. Clin Micro Infect online 2011, DOI:10.1111/j.1469-0691.2011.03596.x
  3. Chen LH, et al. Dengue and chikungunya infections in travelers. Current Opinion in Infectious Diseases 2010;23:438-444.
  4. Wilder-Smith A, et al. Dengue in travelers. N Engl J Med 2005;353:924-932.
  5. Wahala WMPB, et al. The human antibody response to dengue virus infection. Viruses 2011;3:2374-2395.
  6. Meltzer E, et al. Capillary leakage in travelers with dengue infection: implications for pathogenesis. Am J Trop Med Hyg 2012;86:536-539.