Mwingira, Felista Walafried. Molecular community surveillance of Plasmodium falciparum in 6 sites of different malaria endemicity in Tanzania. 2014, PhD Thesis, University of Basel, Faculty of Science.
Official URL: http://edoc.unibas.ch/diss/DissB_11085
For the above aims we conducted community surveys at 6 sites in Tanzania between 2011 and 2013. These sites were classified as low (Iringa), low urban (Dar-Es Salaam), moderate (coastal Tanga and Lugoba) and high (Rufiji and Morogoro) endemic sites according to district prevalence data recorded by the Tanzania HIV and Malaria indicator surveys of 2008 (THMIS 2009): A total of 2046 volunteers of all ages with signed consent forms were recruited. Finger prick blood was drawn from all individuals for parasite detection by LM, RDT and 18S rRNA qPCR. Gametocytes were detected by both LM and qRT-PCR targeting transcripts of the gametocyte specific expressed marker pfs25.
Generally, high P. falciparum Prevalence rates of 20% (416/2046; 95% CI 18-22%) by 18S rRNA qPCR, 17% (349/2046; 95% CI 15.4-18.7%) by RDT and 11% (229/2046; 95% CI 9.8-12%) by LM were recorded in Tanzania. A substantial variation in molecular prevalence rates from geographically different sites was observed varying from 50% in the high endemic site, Rufiji, to 0.6% in the low endemic site, Iringa. These observed differences highlight the heterogeneity of transmission patterns in Tanzania attributed to geographical differences. Molecular parasite diagnostics unveiled that more than a half, 60% (249/416) of P. falciparum positive samples carried submicroscopic infections. Submicroscopic carriage was prevalent in all endemic settings. However, very few positive samples from areas of low and moderate endemicity impede a firm conclusion on the association of endemicity and submicroscopic carriage to be drawn from our samples. Molecularly determined Gametocyte prevalence was 15.3% (312/2046; 95% CI 13.6-16.8%) when data from all sites were combined. On the other hand, LM detected only 0.88% (18/2046; 95% CI 0.47-1.2%) of all samples implying only about 5% of the total gametocytes detected by molecular assay.
In conclusion molecular parasite detection revealed high parasite prevalence in Tanzania, such precise point prevalence molecular data obtained from community sampling may provide a more reliable basis of planning new tools of interventions or monitoring and evaluating the performance of existing tools in the country. Furthermore, high submicroscopic carriage of >50% in Tanzania, particularly in adults is key indicator of transmission potential of asymptomatic infections in Tanzania community and thus it is relevant for control strategies to focus on identifying submicroscopic carriers in order to successfully interrupt transmission.
|Committee Members:||Felger, Ingrid and Borrmann, Steffen|
|Faculties and Departments:||09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH) > Department of Epidemiology and Public Health (EPH) > Health Interventions > Malaria Vaccines (Tanner)|
|Bibsysno:||Link to catalogue|
|Number of Pages:||127 S.|
|Last Modified:||30 Jun 2016 10:56|
|Deposited On:||13 Jan 2015 14:30|
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