BACKGROUND: In areas of seasonal malaria transmission, long-term asymptomatic carriage of Plasmodium falciparum throughout the dry season has been primarily studied in terms of the parasites, and the clinical consequences of persistent parasite carriage are unknown. METHODS: A prospective study was conducted in Senegal, from 2001 through 2003 among 1356 children living in areas where malaria is endemic, with seasonal transmission occurring from August through December. Cross-sectional parasitological measurements and detection of active malaria attacks were performed. A malaria attack was defined as an axillary temperature > or =37.5 degrees C, associated with a parasite density >2500 trophozoites/microL. Children harboring P. falciparum in June who did not have clinical signs were defined as asymptomatic carriers. The association of asymptomatic carriage with parasite densities and with the occurrence of malaria attacks during the rainy season were analyzed separately for the years 2002 and 2003, taking into account potential confounding covariates and use of antimalarial drugs. RESULTS: The prevalence of asymptomatic carriage was 32% (332 of 1025 persons) in June 2002 and 23% (208 of 912 persons) in June 2003. Asymptomatic P. falciparum carriers had a significantly higher mean parasite density and a significantly lower probability of developing a malaria attack during the subsequent rainy season than did noncarriers (adjusted odds ratio in 2002, 0.56; P = .01; adjusted odds ratio in 2003, 0.50; P = .01). CONCLUSIONS: These results suggest that in areas of seasonal transmission, asymptomatic carriage of P. falciparum may protect against clinical malaria. Further studies are needed to understand the immune effectors and host susceptibility that could be involved in this phenomenon.
BACKGROUND: In areas of seasonal malaria transmission, long-term asymptomatic carriage of Plasmodium falciparum throughout the dry season has been primarily studied in terms of the parasites, and the clinical consequences of persistent parasite carriage are unknown. METHODS: A prospective study was conducted in Senegal, from 2001 through 2003 among 1356 children living in areas where malaria is endemic, with seasonal transmission occurring from August through December. Cross-sectional parasitological measurements and detection of active malaria attacks were performed. A malaria attack was defined as an axillary temperature > or =37.5 degrees C, associated with a parasite density >2500 trophozoites/microL. Children harboring P. falciparum in June who did not have clinical signs were defined as asymptomatic carriers. The association of asymptomatic carriage with parasite densities and with the occurrence of malaria attacks during the rainy season were analyzed separately for the years 2002 and 2003, taking into account potential confounding covariates and use of antimalarial drugs. RESULTS: The prevalence of asymptomatic carriage was 32% (332 of 1025 persons) in June 2002 and 23% (208 of 912 persons) in June 2003. Asymptomatic P. falciparum carriers had a significantly higher mean parasite density and a significantly lower probability of developing a malaria attack during the subsequent rainy season than did noncarriers (adjusted odds ratio in 2002, 0.56; P = .01; adjusted odds ratio in 2003, 0.50; P = .01). CONCLUSIONS: These results suggest that in areas of seasonal transmission, asymptomatic carriage of P. falciparum may protect against clinical malaria. Further studies are needed to understand the immune effectors and host susceptibility that could be involved in this phenomenon.
Authors: Kathryn E Tiedje; Abraham R Oduro; Godfred Agongo; Thomas Anyorigiya; Daniel Azongo; Timothy Awine; Anita Ghansah; Mercedes Pascual; Kwadwo A Koram; Karen P Day Journal: Am J Trop Med Hyg Date: 2017-07 Impact factor: 2.345
Authors: Mônica da Silva-Nunes; Marta Moreno; Jan E Conn; Dionicia Gamboa; Shira Abeles; Joseph M Vinetz; Marcelo U Ferreira Journal: Acta Trop Date: 2011-10-12 Impact factor: 3.112
Authors: Silvia Portugal; Tuan M Tran; Aissata Ongoiba; Aboudramane Bathily; Shanping Li; Safiatou Doumbo; Jeff Skinner; Didier Doumtabe; Younoussou Kone; Jules Sangala; Aarti Jain; D Huw Davies; Christopher Hung; Li Liang; Stacy Ricklefs; Manijeh Vafa Homann; Philip L Felgner; Stephen F Porcella; Anna Färnert; Ogobara K Doumbo; Kassoum Kayentao; Brian M Greenwood; Boubacar Traore; Peter D Crompton Journal: Clin Infect Dis Date: 2017-03-01 Impact factor: 9.079
Authors: Bernhards Ogutu; Alfred B Tiono; Michael Makanga; Zulfiqarali Premji; Adama Dodji Gbadoé; David Ubben; Anne Claire Marrast; Oumar Gaye Journal: Malar J Date: 2010-01-22 Impact factor: 2.979