Malaria incidence and prevalence on Pemba Island before the onset of the successful control intervention on the Zanzibar Archipelago

Malaria Journal

Research

Sunil Sazawal¹  James Tielsch¹  Thomas Jaenisch²  David J Sullivan³  Roger Gaczkowski⁴  Arup Dutta⁵  Saikat Deb⁵  Mashavu K Othman⁵  Mahdi Ramsan⁶ 

[1] Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, USA;Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, USA;Institute of Public Health, Heidelberg University Hospital, Heidelberg, Germany;Department of Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, USA;Institute of Public Health, Heidelberg University Hospital, Heidelberg, Germany;Public Health Laboratory - IdC, Pemba, Zanzibar, Tanzania;Public Health Laboratory - IdC, Pemba, Zanzibar, Tanzania;Zanzibar Malaria Control Programme, Zanzibar, Tanzania;

关键词: Malaria;    Rapid Diagnostic Test;    Indoor Residual Spray;    Malaria Incidence;    Parasite Prevalence;   

DOI  :  10.1186/1475-2875-9-32

 received in 2009-08-26, accepted in 2010-01-25,  发布年份 2010

来源: Springer

【 摘 要 】

BackgroundMalaria incidence has been reported to decrease substantially in parts of sub-Saharan Africa, including the Zanzibar Archipelago in East Africa. A cohort study with an intensive follow-up on Pemba Island just before the onset of the highly successful malaria control intervention was conducted. The reported estimates of parasite prevalence and incidence can serve as a robust baseline to evaluate the effect size of the successful interventions and the potential contribution of quality controls and other factors associated with research studies in the decreased estimate of transmission.MethodsIn a rural clinic, two successive cohorts of 537 children total aged 2-23 months were followed for six months each with an intensive visitation schedule of bi-weekly follow-up. Robust estimates of incidence and prevalence according to four different malaria definitions were obtained.ResultsMalaria incidence and prevalence placed Pemba Island in a hyperendemic rather than holoendemic setting for the years 2003-2005. Overall parasite prevalence was estimated to be 39% - with monthly estimates varying between 30% and 50%. Incidence of malaria varied between 2.3 and 3.8 malaria episodes per year based on a diagnosis of fever and various microscopy-based parasite thresholds and between 4.8 and 5.7 based on a diagnosis of fever and 100 parasites/microliter analogous to detection by rapid diagnostic tests. Both parasite densities and malaria incidence increased with age and rainy season. Malaria incidence also varied substantially between the individual villages within the study area.ConclusionsPemba Island was previously considered holo-endemic for Malaria. The data suggest that the transmission situation on Pemba Island was significantly lower in 2003-2005 suggesting a hyper-endemic or meso-endemic transmission environment. The figures were obtained just before the onset of the highly successful malaria control intervention by impregnated bed nets and IRS on the Zanzibar Archipelago and provide robust estimates of the malaria transmission situation prior to the control programme. Together with other published data, the results suggest that malaria transmission had started to decrease before the onset of the control programme. The local heterogeneity in malaria incidence highlights the importance of a micro-epidemiological approach in the context of malaria control and elimination.

【 授权许可】

Unknown   
© Jaenisch et al; licensee BioMed Central Ltd. 2010. 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.