Ambient air pollution in urban cities in sub-Saharan Africa (SSA) is an important public health problem with models and limited monitoring data indicating high concentrations of pollutants such as fine particulate matter (PM_2.5). On most global air quality index maps, however, information about ambient pollution from SSA is scarce. We evaluated the feasibility and practicality of longitudinal measurements of ambient PM_2.5 using low-cost air quality sensors (Purple Air-II-SD) across thirteen locations in seven countries in SSA. Devices were used to gather data over a 30-day period with the aim of assessing the efficiency of its data recovery rate and identifying challenges experienced by users in each location. The median data recovery rate was 94% (range: 72% to 100%). The mean 24 h concentration measured across all sites was 38 µg/m³ with the highest PM_2.5 period average concentration of 91 µg/m³ measured in Kampala, Uganda and lowest concentrations of 15 µg/m³ measured in Faraja, The Gambia. Kampala in Uganda and Nnewi in Nigeria recorded the longest periods with concentrations >250 µg/m³. Power outages, SD memory card issues, internet connectivity problems and device safety concerns were important challenges experienced when using Purple Air-II-SD sensors. Despite some operational challenges, this study demonstrated that it is reasonably practicable and feasible to establish a network of low-cost devices to provide data on local PM_2.5 concentrations in SSA countries. Such data are crucially needed to raise public, societal and policymaker awareness about air pollution across SSA.

Resistance to artemisinin derivatives, the most potent antimalarial drugs currently used, has emerged in Southeast Asia and threatens to spread to Africa. We report a case of malaria in a man who returned to Vietnam after 3 years in Angola that did not respond to intravenous artesunate and clindamycin or an oral artemisinin-based combination.

Molecular epidemiological data on Group A Streptococcus (GAS) infection in Africa is scarce. We characterized the emm-types and emm-clusters of 433 stored clinical GAS isolates from The Gambia collected between 2004 and 2018. To reduce the potential for strain mistyping, we used a newly published primer for emm-typing. There was considerable strain diversity, highlighting the need for vaccine development offering broad strain protection.

In The Gambia, the scale-up of malaria control interventions in the past decades resulted in a substantial decrease of the malaria burden. However, low levels of malaria transmission persist. We conducted an observational cohort study in eastern Gambia to better understand the relative contribution of symptomatic and asymptomatic malaria infections to the infectious reservoir. Parasite and gametocyte carriage were determined by molecular methods. Infectiousness to mosquitoes was assessed by mosquito membrane feeding assays on a subset of symptomatic and asymptomatic individuals identified by passive case detection and community surveys. Incidence of clinical malaria was 1.46 episodes/100 person-months. Prevalence of malaria infection as determined by PCR in community surveys was 10.5%. Among asymptomatic malaria-infected individuals, total parasite density was positively associated with gametocyte density (β = 0.40; P < .0001). Mosquito infection rates in membrane feeding experiments were positively associated with gametocyte density (β = 2.81; P < 0.0001). More than 84% of mosquito infections occurred in asymptomatic individuals with patent infections, with the highest contribution from older children (40.3%), and adolescents and adults (45.5%). Clinical malaria cases identified by passive case detection were responsible for only 1% of mosquito infections; if the definition of clinical malaria included infected individuals identified by community surveys with a history of fever in the preceding week, the contribution of clinical cases to mosquito infections increased to 16%. In eastern Gambia, malaria transmission is maintained by asymptomatic malaria-infected individuals, mostly adults, adolescents and school-age children, while clinical cases are comparatively less important for transmission.

In Vietnam, the importance of vivax malaria relative to falciparum during the past decade has steadily increased to 50%. This, together with the spread of multidrug-resistant Plasmodium falciparum, is a major challenge for malaria elimination. A 2-year prospective cohort study to assess P. vivax morbidity after radical cure treatment and related risk factors was conducted in Central Vietnam. The study was implemented between April 2009 and December 2011 in four neighboring villages in a remote forested area of Quang Nam province. P. vivax-infected patients were treated radically with chloroquine (CQ; 25 mg/kg over 3 days) and primaquine (PQ; 0.5 mg/kg/day for 10 days) and visited monthly (malaria symptoms and blood sampling) for up to 2 years. Time to first vivax recurrence was estimated by Kaplan–Meier survival analysis, and risk factors for first and recurrent infections were identified by Cox regression models. Among the 260 P. vivax patients (61% males [159/260]; age range 3–60) recruited, 240 completed the 10-day treatment, 223 entered the second month of follow-up, and 219 were followed for at least 12 months. Most individuals (76.78%, 171/223) had recurrent vivax infections identified by molecular methods (polymerase chain reaction [PCR]); in about half of them (55.61%, 124/223), infection was detected by microscopy, and 84 individuals (37.67%) had symptomatic recurrences. Median time to first recurrence by PCR was 118 days (IQR 59–208). The estimated probability of remaining free of recurrence by month 24 was 20.40% (95% CI [14.42; 27.13]) by PCR, 42.52% (95% CI [35.41; 49.44]) by microscopy, and 60.69% (95% CI [53.51; 67.11]) for symptomatic recurrences. The main risk factor for recurrence (first or recurrent) was prior P. falciparum infection. The main limitations of this study are the age of the results and the absence of a comparator arm, which does not allow estimating the proportion of vivax relapses among recurrent infections. A substantial number of P. vivax recurrences, mainly submicroscopic (SM) and asymptomatic, were observed after high-dose PQ treatment (5.0 mg/kg). Prior P. falciparum infection was an important risk factor for all types of vivax recurrences. Malaria elimination efforts need to address this largely undetected P. vivax transmission by simultaneously tackling the reservoir of P. falciparum and P. vivax infections.