Dengue surveillance among French military in Africa.
Article Type: Letter to the editor
Subject: Soldiers (Health aspects)
Dengue (Risk factors)
Dengue (Diagnosis)
Dengue (Research)
Authors: de Laval, Franck
Plumet, Sebastien
Simon, Fabrice
Deparis, Xavier
Leparc-Goffart, Isabelle
Pub Date: 02/01/2012
Publication: Name: Emerging Infectious Diseases Publisher: U.S. National Center for Infectious Diseases Audience: Academic; Professional Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2012 U.S. National Center for Infectious Diseases ISSN: 1080-6040
Issue: Date: Feb, 2012 Source Volume: 18 Source Issue: 2
Topic: Event Code: 310 Science & research
Geographic: Geographic Scope: France; Africa Geographic Code: 4EUFR France; 60AFR Africa
Accession Number: 281175424
Full Text: To the Editor: In their recent article, Amarasinghe et al. (1) describe dengue virus distribution in Africa. Their data were based on published reports of dengue cases among local populations and travelers returning from Africa. To complement the description by Amarasinghe and colleagues of dengue serotypes found in Africa, we report results from dengue virologic testing during 19982010. The tests were performed at the Arbovirus National Reference Center (Tropical Medicine Institute of the Military Health Service, Marseille, France).

Each year, [approximately equal to] 14,000 French soldiers are stationed in dengue-endemic areas of Africa (mainly Cameroon, Central African Republic, Chad, Djibouti, Gabon, Cote d'Ivoire, Senegal, and Mayotte and Reunion islands), from which they travel throughout Africa. The population of soldiers is under constant epidemiologic surveillance. If symptoms of dengue fever develop in a soldier, a blood sample and a dengue-specific questionnaire from the patient are sent to the Tropical Medicine Institute of the Military Health Service. Virus culture and reverse transcription PCR, or both, were performed on early samples; otherwise, serologic testing was performed by using in-house assays (IgM antibody capture ELISA and direct IgG ELISA).

During the 12 years of surveillance, the laboratory received 2,423 samples from patients with suspected dengue within the French Armed Forces in Africa. Of these, 224 were probable acute dengue infections: 202 had positive IgM serologic results for dengue, and 22 were confirmed as dengue cases by RT-PCR or culture (Table). Serologic data may be confusing because of potential cross-reactions with other flavivirus antibodies (in particular in Chad with West Nile virus).

Because of probable underreporting from the field, our reported number of confirmed dengue cases likely underestimates the actual number of cases among French troops stationed in Africa. Nonetheless, our data complement those reported by Amarasinghe et al. by demonstrating additional locations for circulation of serotype 1 (Cameroon, Djibouti, Gabon, Mayotte) and serotype 3 (Comoros). Military epidemiologic surveillance systems can detect dengue circulation where soldiers stay. Thus, these systems could serve to evaluate the risk for dengue infection in countries without local epidemiologic surveillance systems, thereby improving knowledge about dengue circulation in African countries.

Franck de Laval, Sebastien Plumet, Fabrice Simon, Xavier Deparis, and Isabelle Leparc-Goffart

Author affiliations: Epidemiologic and Public Health Military Center, Marseille, France (F. de Laval, X. Deparis); French Army Forces Biomedical Institute, Marseille (S. Plumet, I. Leparc-Goffart); and Laveran Military Hospital, Marseille (F. Simon)

DOI: http://dx.doi.org/10.3201/eid1802.111333

Reference

(1.) Amarasinghe A, Kuritsky JN, Letson GW, Margolis HS. Dengue virus infection in Africa. Emerg Infect Dis. 2011;17:1349 54.

Address for correspondence: Isabelle Leparc-Goffart, IRBA Marseille, Parc du Pharo, BP60109, 13262 Marseille Cedex 07, France; email: isabelle.leparcgoffart@gmail.com
Table. Countries in Africa with evidence of dengue virus
transmission among French Armed Forces, 1998-2010

                                                                Dengue
                                 No.     Testing     Infection   virus
Country and year                cases     method      status    serotype

Cameroon, 2010                    1        PCR       Confirmed     1
Cape Verde, 2010                  5      Culture     Confirmed     3
Central African Republic, 1995    1      Serology    Probable   Unknown
Chad, 1998-2001, 2003, 2006,     28      Serology    Probable   Unknown
  2009-2010
Comoros
  2010                            1    PCR, culture  Confirmed     1
  2010                            2        PCR       Confirmed     3
Cote d'lvoire
  1999                            1      Culture     Confirmed     1
  2000, 2004-2007                11      Serology    Probable   Unknown
  2010                            1        PCR       Confirmed     3
Djibouti
  1998                            4      Culture     Confirmed     1
  1998                           24      Serology    Probable   Unknown
  2000                            2      Culture     Confirmed     1
  2000                            4      Serology    Probable   Unknown
  2001-2005                      123     Serology    Probable   Unknown
  2005                            1        PCR       Confirmed    ND
  2006                            4      Serology    Probable   Unknown
  2008                            2      Serology    Probable   Unknown
Gabon
  1998, 2006-2008                22      Serology    Probable   Unknown
  2010                            1        PCR       Confirmed     1
Mayotte, 2009                     1      Culture     Confirmed     1
Senegal, 2009                     1        PCR       confirmed     3
Somalia, 1999                     1      culture     confirmed     2
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