Common Epidemiology of Rickettsia felis Infection and Malaria, Africa

Oleg Mediannikov¹, Cristina Socolovschi¹, Sophie Edouard, Florence Fenollar, Nadjet Mouffok, Hubert Bassene, Georges Diatta, Adama Tall, Hamidou Niangaly, Ogobara Doumbo, Jean Bernard Lekana-Douki, Abir Znazen, M’hammed Sarih, Pavel Ratmanov, Herve Richet, Mamadou O. Ndiath, Cheikh Sokhna, Philippe Parola, and Didier Raoult

Author affiliations: 1These authors contributed equally to this article.; Aix Marseille Université, Marseille, Faculté de Médecine, Marseille, France (O. Mediannikov, C. Socolovschi, S. Edouard, F. Fenollar, Patmanov P., H. Richet, P. Parola, D. Raoult); Institut de Recherche pour le Développement, Dakar, Senegal (O. Mediannikov, F. Fenollar, H. Bassene, G. Diatta, M.O. Ndiath, C. Sokhna, D. Raoult); Centre Hospitalo-Universitaire d'Oran, Oran, Algeria (N. Mouffok); Institut Pasteur de Dakar, Dakar (A. Tall); University of Sciences, Techniques and Technology, Bamako, Mali (H. Niangaly, O. Doumbo); Unité de Parasitologie Médicale Centre International de Recherche Médicale de Franceville, Franceville, Gabon (J.B. Lekana-Douki); Université des Sciences de la santé de Libreville, Libreville, Gabon (J.B. Lekana-Douki); Habib Bourguiba University Hospital, Sfax, Tunisia (A. Znazen); Institut Pasteur du Maroc, Casablanca, Morocco (M. Sarih); Far Eastern State Medical University, Khabarovsk, Russia (P. Ratmanov)

Abstract

This study aimed to compare the epidemiology of Rickettsia felis infection and malaria in France, North Africa, and sub-Saharan Africa and to identify a common vector. Blood specimens from 3,122 febrile patients and from 500 nonfebrile persons were analyzed for R. felis and Plasmodium spp. We observed a significant linear trend (p< 0.0001) of increasing risk for R. felis infection. The risks were lowest in France, Tunisia, and Algeria (1%), and highest in rural Senegal (15%). Co-infections with R. felis and Plasmodium spp. and occurrences of R. felis relapses or reinfections were identified. This study demonstrates a correlation between malaria and R. felis infection regarding geographic distribution, seasonality, asymptomatic infections, and a potential vector. R. felis infection should be suspected in these geographical areas where malaria is endemic. Doxycycline chemoprophylaxis against malaria in travelers to sub-Saharan Africa also protects against rickettsioses; thus, empirical treatment strategies for febrile illness for travelers and residents in sub-Saharan Africa may require reevaluation.

Investigations examining the etiologic spectrum of fever of unknown origin in Africa rapidly progressed during 2008–2011 (1–3), providing increased knowledge about bacterial infections. Bacterial agents that have been most frequently identified in North and sub-Saharan Africa by culture are non-typhoidal Salmonella, Streptococcus pneumoniae, Staphylococcus aureus, Escherichia coli, and Mycobacterium tuberculosis (2). Several studies have assessed the effect of fastidious bacterial infections in systemic febrile illness, including Rickettsia felis (4–6), Coxiella burnetii (7), Tropheryma whipplei (3), and Borrelia spp. (1,8). Tourism, immigration, international business travel, international aid work, and the deployment of troops overseas were documented as contributors to a tremendous increase in international travel during 1996–2004 (9). International tourist arrivals reached 940 million worldwide during 2010, an increase of 6.6% over 2009, and the current total number of international migrants has increased to an estimated 214 million persons in 2012 (10). Consequently, physicians in the Western hemisphere increasingly encounter febrile patients returning from international travel who were exposed to tropical infections that the physicians are unfamiliar with (9,10). Among international travelers, malaria, dengue, and rickettsiosis are among the most identified etiologies of febrile illness, and exposure to mosquitoes is reported as the most common source of fever (11).