Background Plasmodium falciparum malaria dominates throughout sub-Saharan Africa, but the prevalence of P. malariae, P. ovale spp., and P. vivax increasingly contribute to infection in countries which control malaria using P. falciparum-specific diagnostic and treatment strategies. Methods We performed qPCR on 2,987 dried blood spots from the 2015-2016 Malawi Demographic and Health Survey to identify the presence and distribution of non-falciparum infection. Bivariate models were used to determine species-specific associations with demographic and environmental risk factors. Results Non-falciparum infections had a broad spatial distribution. Weighted prevalence was 0.025 (SE: 0.004) for P. malariae, 0.097 (SE: 0.008) for P. ovale spp., and 0.001 (SE: 0.0005) for P. vivax. Most infections (85.6%) had low-density parasitemias ≤10 parasites/µL, and 66.7% of P. malariae, 34.6% of P. ovale spp., and 40.0% of P. vivax infections were co-infected with P. falciparum. Risk factors for P. malariae were like those known for P. falciparum, however, there were few risk factors recognized for P. ovale spp. and P. vivax, perhaps due to the potential for relapsing episodes. Conclusions The prevalence of any non-falciparum infection was 11.7%, with infections distributed across Malawi. Continued monitoring of Plasmodium spp. becomes critical as non-falciparum infections become important sources of ongoing transmission.

Malaria remains a significant cause of morbidity and mortality in Malawi, with an estimated 18–19% prevalence of Plasmodium falciparum in children 2–10 years in 2015–2016. While children report the highest rates of clinical disease, adults are thought to be an important reservoir to sustained transmission due to persistent asymptomatic infection. The 2015–2016 Malawi Demographic and Health Survey was a nationally representative household survey which collected dried blood spots from 15,125 asymptomatic individuals ages 15–54 between October 2015 and February 2016. We performed quantitative polymerase chain reaction on 7,393 samples, detecting an overall P. falciparum prevalence of 31.1% (SE = 1.1). Most infections (55.6%) had parasitemias ≤ 10 parasites/µL. While 66.2% of individuals lived in a household that owned a bed net, only 36.6% reported sleeping under a long-lasting insecticide-treated net (LLIN) the previous night. Protective factors included urbanicity, greater wealth, higher education, and lower environmental temperatures. Living in a household with a bed net (prevalence difference 0.02, 95% CI − 0.02 to 0.05) and sleeping under an LLIN (0.01; − 0.02 to 0.04) were not protective against infection. Our findings demonstrate a higher parasite prevalence in adults than published estimates among children. Understanding the prevalence and distribution of asymptomatic infection is essential for targeted interventions.

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Background Although WHO recommends that all blood donations be screened for transfusion transmissible infections, these data are currently not incorporated into national surveillance. We set out to use routinely collected data from blood donors in Blantyre district, Malawi to explore HIV and syphilis prevalence and identify seroconversions among repeat donors. Methods We conducted a retrospective cohort analysis of blood donation data collected by the Malawi Blood Transfusion Service (MBTS) from October, 2015 to May, 2021. All blood donations were routinely screened for HIV and syphilis. We characterized donor demographics as well as screening outcomes, including identifying seroconversions among repeat donors who previously tested negative on their last donation. Log binomial regression was used to model the impact of individual level covariates on HIV and syphilis prevalence and risk of seroconversion. Results A total of 23,280 donations from 5,051 donors were recorded, with a median frequency of donations of 3 (IQR:2–6). At the time of their first donation, most donors were male (4,294; 85%) and students (3262; 64.6%). Of those screened for HIV and syphilis at first donation, 1.0%, (52/5,051) and 1.6% (80/5,051) tested positive, respectively. Among repeat donors who previously tested negative, 52 HIV seroconversions and 126 syphilis seroconversions were identified, indicating an incidence rate per 1,000 person-years of 5.9 (95% CI: 4.7, 7.4) and 13.3 (95% CI:11.4, 15.4) respectively. Prevalence of HIV (Prevalence ratio (PR) = 0.31: 95% CI: 0.15, 0.65) and syphilis (PR = 0.54: 95% CI:0.30, 0.94) were lower and risk of syphilis seroconversion (Risk ratio = 0.47: 95% CI:0.31, 0.70) was higher among students compared to other donors. Conclusions While blood donors are generally considered a low-risk population for HIV and syphilis, we were able to identify that there remain relatively high rates of undiagnosed HIV and syphilis infections among donors. The routinely collected data from national blood donation services may be used to better understand the epidemiology of HIV and syphilis in specific locations, with the potential to enhance existing population-level disease surveillance systems. In addition, these findings may be used to identify priority prevention areas and populations in Blantyre district that can inform targeted interventions for improved disease prevention, testing and treatment.