BackgroundBotswana is one of eight SADC countries targeting malaria elimination by 2018. Through spirited upscaling of control activities and passive surveillance, significant reductions in case incidence of Plasmodium falciparum (0.96 – 0.01) was achieved between 2008 and 2012. As part of the elimination campaign, active detection of asymptomatic Plasmodium species by a highly sensitive method was deemed necessary. This study was carried out to determine asymptomatic Plasmodium species carriage by nested PCR in the country, in 2012.MethodA cross-sectional study involving 3924 apparently healthy participants were screened for Plasmodium species in 14 districts (5 endemic: Okavango, Ngami, Tutume, Boteti and Bobirwa; and 9 epidemic: North East, Francistown, Serowe-Palapye, Ghanzi, Kweneng West, Kweneng East, Kgatleng, South East, and Good Hope). Venous blood was taken from each participant for a nested PCR detection of Plasmodium species.ResultsThe parasite rates of asymptomatic Plasmodium species detected were as follows: Plasmodium falciparum, 0.16 %; Plasmodium vivax, 4.66 %; Plasmodium malariae, (Pm) 0.16 %; Plasmodium ovale, 0 %, mixed infections (P. falciparum and P. vivax), 0.055 %; and (P. vivax and P. malariae), 0.027 %, (total: 5.062 %). The high proportion of asymptomatic reservoir of P. vivax was clustered in the East, South Eastern and Central districts of the country. There appeared to be a correlation between the occurrence of P. malariae infection with P. vivax infection, with the former only occurring in districts that had substantial P. vivax circulation. The median age among 2–12 year olds for P. vivax infection was 5 years (Mean 5.13 years, interquartile range 3–7 years). The odds of being infected with P. vivax decreased by 7 % for each year increase in age (OR 0.93, 95 % CI 0.87–1.00, p = 0.056).ConclusionWe have confirmed low parasite rate of asymptomatic Plasmodium species in Botswana, with the exception of P.vivax which was unexpectedly high. This has implication for the elimination campaign so a follow up study is warranted to inform decisions on new strategies that take this evidence into account in the elimination campaign.

BackgroundBotswana has made substantial progress towards malaria elimination across the country. This work assessed interventions and epidemiological characteristics of malaria in Botswana, during a period of decreasing transmission intensity.MethodsNational passive malaria surveillance data for five years (2008–2012) were analysed. A district-level, random effects model with Poisson regression was used to explore the association between malaria cases and coverage with long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS). Malaria cases were mapped to visualize spatio-temporal variation in malaria for each year.ResultsWithin five years, a reduction in malaria prevalence (approximately 98%) and number of deaths (12 to three) was observed. Between 2008 and 2012, 237,050 LLINs were distributed and 596,979 rooms were sprayed with insecticides. Coverage with LLINs and IRS was not uniformly distributed over the study period and only targeted the northern districts with a high malaria burden. The coverage of IRS was associated with a reduction in malaria cases.ConclusionsBotswana has made significant strides towards its goal of country-wide elimination of malaria. A major challenge in the future will be prevention and management of imported malaria infections from neighbouring countries. In order to accurately monitor progress towards the elimination goal, the malaria control programme (NMP) should strengthen the reporting and capturing of data at household and individual level. Systematic, periodic operational research to feedback the NMP will help to guide and achieve elimination.

Malaria elimination requires infection detection using quality assured diagnostics and appropriate treatment regimens. Although Botswana is moving towards malaria elimination, reports of unconfirmed cases may jeopardise this effort. This study aimed to determine the proportion of cases treated for malaria that were confirmed by rapid diagnostic testing (RDT) and/or microscopy. This was a retrospective descriptive study using routine national data from the integrated disease surveillance and case-based surveillance systems from 2008 to 2014. The data were categorised into clinical and confirmed cases each year. An analysis of the data on cases registered in three districts that reported approximately 70% of all malaria cases was performed, stratified by year, type of reporting health facilities and diagnostic method. During 2008-2014, 50 487 cases of malaria were reported in Botswana, and the proportion of RDT and/or blood microscopy confirmed cases improved from 6% in 2008 to 89% in 2013. The total number of malaria cases decreased by 97% in the same period, then increased by 41% in 2013. This study shows that malaria diagnostic tests dramatically improved malaria diagnosis and consequently reduced the malaria burden in Botswana. The study identified a need to build capacity on microscopy for species identification, parasite quantification and guiding treatment choices.

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