Early Introduction and Delayed Dissemination of Pandemic Influenza, Gabon

Sonia Etenna Lekana-Douki, Augustin Mouinga-Ondémé, Dieudonné Nkoghe, Christian Drosten, Jan Felix Drexler, Mirdad Kazanji, and Eric M. Leroy

Author affiliations: Centre International de Recherches Médicales de Franceville, Franceville, Gabon (S.E. Lekana-Douki, A. Mouinga-Ondémé, D. Nkoghe, E.M. Leroy); Ministère de la Santé Publique, Libreville, Gabon (D. Nkoghe); Bonn Medical Centre Institute of Virology, Bonn, Germany (C. Drosten, J.F. Drexler); Institut Pasteur de Bangui, Bangui, Central African Republic (M. Kazanji); Institut de Recherche pour le Développement, Montpellier, France (E.M. Leroy)

Abstract

Active surveillance in health care centers in Gabon during 2009–2011 detected 72 clinical cases of pandemic (H1N1) 2009 (pH1N1). We found that pH1N1 virus was introduced in mid-2009 but spread throughout the country in 2010. Thus, Gabon was also affected by pH1N1.

In April 2009, a pandemic strain of influenza A (H1N1) (pH1N1) virus emerged in Mexico and the United States; the World Health Organization declared a pandemic alert on June 11, 2009 (1,2). This virus was responsible for a large outbreak with thousands of cases in the Reunion Islands and in several French tropical Pacific islands during July–October 2009 (3). The circulation and public health effects of pH1N1 virus are largely unknown in Africa, with the exception of South Africa and Kenya, which were heavily affected by disease outbreaks during 2009 and 2010 (4–6). Other pH1N1 cases were reported in several countries of North, West, and East Africa and in Madagascar (7,8).
In the humid tropical forest of Central Africa, a study demonstrated the circulation of influenza virus in Cameroon during 2007–2008 (9); another reported cases of pH1N1 in Cameroon in 2009 (10). A sentinel surveillance program for influenza in Kinshasa, Democratic Republic of the Congo, during 2009–2011 reported several cases of pH1N1 (11).
Gabon is a typical humid, tropical, forested country in Central Africa, with 1,517,685 inhabitants and a surface area of 270,000 km². The country has a short dry season during January–February, a long rainy season during March–May, a long dry season during June–September, and a short rainy season during October–December. We report the results of a large surveillance study for pH1N1 in Gabon during a 2-year period, July 2009–June 2011.