Dengue surveillance among French military in Africa.
|Article Type:||Letter to the editor|
Dengue (Risk factors)
de Laval, Franck
|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|
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)
(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: email@example.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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