Artemisinin-based combination therapy does not measurably reduce human infectiousness to vectors in a setting of intense malaria transmission

Malaria Journal

Research

Adriana Tami¹  Salim MK Abdulla²  Aniset Kihonda²  Japhet Kihonda²  Heather M Ferguson³  Gerard F Killeen⁴  S Patrick Kachur⁵  Bernadette J Huho⁶  J Derek Charlwood⁷  Christian Lengeler⁸  Thomas A Smith⁸ 

[1] Department of Medical Microbiology, University Medical Center Groningen, Groningen, The Netherlands;Royal Tropical Institute, Biomedical Research, Amsterdam, The Netherlands;Ifakara Health Institute, Dar-es-Salaam, Tanzania;Ifakara Health Institute, Dar-es-Salaam, Tanzania;Division of Infection and Immunity, University of Glasgow, G12 8TA, Glasgow, UK;Ifakara Health Institute, Dar-es-Salaam, Tanzania;Liverpool School of Tropical Medicine, Liverpool, UK;Ifakara Health Institute, Dar-es-Salaam, Tanzania;Malaria Branch, US Centers for Disease Control and Prevention, Atlanta, USA;Ifakara Health Institute, Dar-es-Salaam, Tanzania;Swiss Tropical and Public Health Institute, Basel, Switzerland;University of Basel, Petersplatz 1, CH-4003, Basel, Switzerland;Liverpool School of Tropical Medicine, Liverpool, UK;Swiss Tropical and Public Health Institute, Basel, Switzerland;University of Basel, Petersplatz 1, CH-4003, Basel, Switzerland;

关键词: Malaria;    Artemisinin-based combination therapy;    Transmission reduction;    Malaria;   

DOI  :  10.1186/1475-2875-11-118

 received in 2011-12-27, accepted in 2012-04-18,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundArtemisinin-based combination therapy (ACT) for treating malaria has activity against immature gametocytes. In theory, this property may complement the effect of terminating otherwise lengthy malaria infections and reducing the parasite reservoir in the human population that can infect vector mosquitoes. However, this has never been verified at a population level in a setting with intense transmission, where chronically infectious asymptomatic carriers are common and cured patients are rapidly and repeatedly re-infected.MethodsFrom 2001 to 2004, malaria vector densities were monitored using light traps in three Tanzanian districts. Mosquitoes were dissected to determine parous and oocyst rates. Plasmodium falciparum sporozoite rates were determined by ELISA. Sulphadoxine-pyrimethamine (SP) monotherapy was used for treatment of uncomplicated malaria in the contiguous districts of Kilombero and Ulanga throughout this period. In Rufiji district, the standard drug was changed to artesunate co-administered with SP (AS + SP) in March 2003. The effects of this change in case management on malaria parasite infection in the vectors were analysed.ResultsPlasmodium falciparum entomological inoculation rates exceeded 300 infective bites per person per year at both sites over the whole period. The introduction of AS + SP in Rufiji was associated with increased oocyst prevalence (OR [95%CI] = 3.9 [2.9-5.3], p < 0.001), but had no consistent effect on sporozoite prevalence (OR [95%CI] = 0.9 [0.7-1.2], p = 0.5). The estimated infectiousness of the human population in Rufiji was very low prior to the change in drug policy. Emergence rates and parous rates of the vectors varied substantially throughout the study period, which affected estimates of infectiousness. The latter consequently cannot be explained by the change in drug policy.ConclusionsIn high perennial transmission settings, only a small proportion of infections in humans are symptomatic or treated, so case management with ACT may have little impact on overall infectiousness of the human population. Variations in infection levels in vectors largely depend on the age distribution of the mosquito population. Benefits of ACT in suppressing transmission are more likely to be evident where transmission is already low or effective vector control is widely implemented.

【 授权许可】

Unknown   
© Huho et al; licensee BioMed Central Ltd. 2012. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.