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BackgroundIdentifying asymptomatic reservoirs of malaria parasites using index cases as entry points into the community is potentially a cost-effective way towards achieving malaria elimination.MethodsWithin 1 year, 1430 confirmed malaria cases were identified in Marani hospital, western Kenya. Fifty cases were followed up, and 108 index case household members and 612 neighbours within a 100 m radius were screened. As controls, samples were collected from 510 individuals matched with index cases and located at a distance of ≥ 500 m from them. Infections were diagnosed by microscopy and PCR while simultaneously collecting malaria vectors indoor using pyrethrum spray catches.ResultsIn the index case and neighbour households, the prevalence of infection was approximately twice as high as in control households (by PCR: index cases households: 28.9%, neighbours: 25.3%, matched controls: 12.9%). In index case households, the indoor vector density (Anopheles gambiae and Anopheles funestus) was higher (0.46 female/house/night) than in neighbouring (0.31 f/h/n) and control houses (0.29 f/h/n).ConclusionsScreening index case households and neighbours approximately doubles the chance to detect asymptomatic infections compared to randomly selected households. However, even if all cases were followed up, only a small proportion (˂ 10%) of the asymptomatic reservoir in the population would have been identified. Control programmes need to weigh the increased chance to find cases around index cases vs. the logistical challenges to target this subgroup within the population.

Background Prompt diagnosis and effective malaria treatment is a key strategy in malaria control. However, the recommended diagnostic methods, microscopy and rapid diagnostic tests (RDTs), are not supported by robust quality assurance systems in endemic areas. This study compared the performance of routine RDTs and smear microscopy with a simple molecular-based colorimetric loop-mediated isothermal amplification (LAMP) at two different levels of the health care system in a malaria-endemic area of western Kenya. Methods Patients presenting with clinical symptoms of malaria at Rota Dispensary (level 2) and Siaya County Referral Hospital (level 4) were enrolled into the study after obtaining written informed consent. Capillary blood was collected to test for malaria by RDT and microscopy at the dispensary and county hospital, and for preparation of blood smears and dried blood spots (DBS) for expert microscopy and real-time polymerase chain reaction (RT-PCR). Results of the routine diagnostic tests were compared with those of malachite green loop-mediated isothermal amplification (MG-LAMP) performed at the two facilities. Results A total of 264 participants were enrolled into the study. At the dispensary level, the positivity rate by RDT, expert microscopy, MG-LAMP and RT-PCR was 37%, 30%, 44% and 42%, respectively, and 42%, 43%, 57% and 43% at the county hospital. Using RT-PCR as the reference test, the sensitivity of RDT and MG-LAMP was 78.1% (CI 67.5–86.4) and 82.9% (CI 73.0–90.3) at Rota dispensary. At Siaya hospital the sensitivity of routine microscopy and MG-LAMP was 83.3% (CI 65.3–94.4) and 93.3% (CI 77.9–99.2), respectively. Compared to MG-LAMP, there were 14 false positives and 29 false negatives by RDT at Rota dispensary and 3 false positives and 13 false negatives by routine microscopy at Siaya Hospital. Conclusion MG-LAMP is more sensitive than RDTs and microscopy in the detection of malaria parasites at public health facilities and might be a useful quality control tool in resource-limited settings.

Background: Anti-malarial drug resistance remains a major threat to global malaria control efforts. In Africa, Plasmodium falciparum remains susceptible to artemisinin-based combination therapy (ACT), but the emergence of resistant parasites in multiple countries in Southeast Asia and concerns over emergence and/or spread of resistant parasites in Africa warrants continuous monitoring. The World Health Organization recommends that surveillance for molecular markers of resistance be included within therapeutic efficacy studies (TES). The current study assessed molecular markers associated with resistance to Artemether−lumefantrine (AL) and Dihydroartemisinin−piperaquine (DP) from samples collected from children aged 6-59 months enrolled in a TES conducted in Siaya County, western Kenya from 2016 to 2017. Methods: Three hundred and twenty-three samples collected pre-treatment (day-0) and 110 samples collected at the day of recurrent parasitaemia (up to day 42) were tested for the presence of drug resistance markers in the Pfk13 propeller domain, and the Pfmdr1 and Pfcrt genes by Sanger sequencing. Additionally, the Pfpm2 gene copy number was assessed by real-time polymerase chain reaction. Results: No mutations previously associated with artemisinin resistance were detected in the Pfk13 propeller region. However, other non-synonymous mutations in the Pfk13 propeller region were detected. The most common mutation found on day-0 and at day of recurrence in the Pfmdr1 multidrug resistance marker was at codon 184F. Very few mutations were found in the Pfcrt marker (< 5%). Within the DP arm, all recrudescent cases (8 sample pairs) that were tested for Pfpm2 gene copy number had a single gene copy. None of the associations between observed mutations and treatment outcomes were statistically significant. Conclusion: The results indicate absence of Pfk13 mutations associated with parasite resistance to artemisinin in this area and a very high proportion of wild-type parasites for Pfcrt. Although the frequency of Pfmdr1 184F mutations was high in these samples, the association with treatment failure did not reach statistical significance. As the spread of