The growth and development of Anopheles gambiae Giles larvae were studied in artificial habitats in western Kenya. Larvae responded to increasing densities by extending their development time and by emerging as smaller adults, although survival was not significantly affected. Addition of nutrients in the form of cow dung collected near the study site had no impact on larval growth and development. Regression analysis showed that female development time increased by 0.020 d and female dry mass decreased by 0.74 microg with each additional larva. By fitting the data to the pupation window model, the estimated minimum dry mass to achieve pupation was 0.130 mg and the estimated minimum time to pupation was 5 d. The most likely food source for An. gambiae larvae was algal growth, which was significantly reduced by the presence of larvae. Bacterial densities were not significantly affected by the presence of larvae although total bacteria counts were lower at the higher densities indicating they may provide a secondary food source when algal resources are depleted. Similarly, the levels of nitrogen and phosphorus in the habitats were not significantly affected by the presence of larvae although there was evidence of decreasing nitrogen levels occurring with increasing larval densities suggesting that nitrogen may be a limiting resource in the larval environment. The data indicate that competition within the larval environment may indirectly regulate An. gambiae populations by reducing adult body size, which may in turn reduce adult survivorship and fecundity. The potential impact of density-dependent interactions among An. gambiae larvae on the transmission of Plasmodium falciparum is discussed.

Background Noninfectious comorbid diseases (NCDs) contribute to morbidity and mortality in human immunodeficiency virus (HIV)–infected populations in resource-rich countries. With antiretroviral therapy (ART) scale-up in Africa, understanding burden NCD informs public health strategy. Methods At enrollment, participants at 11 HIV clinics in Kenya, Uganda, Tanzania, and Nigeria underwent medical history, physical, laboratory, and neuropsychological assessments to identify elevated blood pressure, hypercholesterolemia, dysglycemia, renal insufficiency, and cognitive impairment. Poisson regression models estimated adjusted relative risks (ARRs) and 95% confidence intervals (CIs) for the number of NCDs associated with factors of interest. Logistic regression was used to evaluate each NCD separately among HIV-infected participants. Results Among 2720 participants with complete NCD data, 2159 (79.4%) were HIV-infected. Of those, 1426 (66.0%) were taking ART and 813 (37.7%) had at least 1 NCD. HIV infection was associated with more NCDs, especially with ART (ARR, 1.42; 95% CI, 1.22–1.66). In addition to age, body mass index, and program site, ART usage was associated with more NCDs (ARR, 1.50; 95% CI, 1.27–1.78 for virologically suppressed and ARR, 1.38; 95% CI, 1.13–1.68 for viremic) among HIV-infected participants. In participants taking ART, CD4 nadir below 200 cells/mm3 was associated with more NCDs (ARR, 1.43; 95% CI, 1.06–1.93). ART use was independently associated with hypercholesterolemia and dysglycemia. Program site was significantly associated with all comorbidities except renal insufficiency. Conclusions HIV infection was a risk for NCDs, which were common in HIV-infected participants, geographically variable, and largely consistent with metabolic complications of first-line ART.

Background Insecticide resistance poses a growing challenge to malaria vector control in Kenya and around the world. Following evidence of associations between the mosquito microbiota and insecticide resistance, the microbiota of Anopheles gambiae sensu stricto (s.s.) from Tulukuyi village, Bungoma, Kenya, with differing permethrin resistance profiles were comparatively characterized. Methods Using the CDC bottle bioassay, 133 2–3 day-old, virgin, non-blood fed female F1 progeny of field-caught An. gambiae s.s. were exposed to five times (107.5 µg/ml) the discriminating dose of permethrin. Post bioassay, 50 resistant and 50 susceptible mosquitoes were subsequently screened for kdr East and West mutations, and individually processed for microbial analysis using high throughput sequencing targeting the universal bacterial and archaeal 16S rRNA gene. Results 47 % of the samples tested (n = 133) were resistant, and of the 100 selected for further processing, 99 % were positive for kdr East and 1 % for kdr West. Overall, 84 bacterial taxa were detected across all mosquito samples, with 36 of these shared between resistant and susceptible mosquitoes. A total of 20 bacterial taxa were unique to the resistant mosquitoes and 28 were unique to the susceptible mosquitoes. There were significant differences in bacterial composition between resistant and susceptible individuals (PERMANOVA, pseudo-F = 2.33, P = 0.001), with presence of Sphingobacterium, Lysinibacillus and Streptococcus (all known pyrethroid-degrading taxa), and the radiotolerant Rubrobacter, being significantly associated with resistant mosquitoes. On the other hand, the presence of Myxococcus, was significantly associated with susceptible mosquitoes. Conclusions This is the first report of distinct microbiota in An. gambiae s.s. associated with intense pyrethroid resistance. The findings highlight differentially abundant bacterial taxa between resistant and susceptible mosquitoes, and further suggest a microbe-mediated mechanism of insecticide resistance in mosquitoes. These results also indicate fixation of the kdr East mutation in this mosquito population, precluding further analysis of its associations with the mosquito microbiota, but presenting the hypothesis that any microbe-mediated mechanism of insecticide resistance would be likely of a metabolic nature. Overall, this study lays initial groundwork for understanding microbe-mediated mechanisms of insecticide resistance in African mosquito vectors of malaria, and potentially identifying novel microbial markers of insecticide resistance that could supplement existing vector surveillance tools.

Background Plasmodium falciparum prevalence (PfPR) is a widely used metric for assessing malaria transmission intensity. This study was carried out concurrently with the RTS,S/AS01 candidate malaria vaccine Phase III trial and estimated PfPR over ≤ 4 standardized cross-sectional surveys.MethodsThis epidemiology study (NCT01190202) was conducted in 8 sites from 6 countries (Burkina Faso, Gabon, Ghana, Kenya, Malawi, and Tanzania), between March 2011 and December 2013. Participants were enrolled in a 2:1:1 ratio according to age category: 6 months–4 years, 5–19 years, and ≥ 20 years, respectively, per year and per centre. All sites carried out surveys 1–3 while survey 4 was conducted only in 3 sites. Surveys were usually performed during the peak malaria parasite transmission season, in one home visit, when medical history and malaria risk factors/prevention measures were collected, and a blood sample taken for rapid diagnostic test, microscopy, and haemoglobin measurement. PfPR was estimated by site and age category.ResultsOverall, 6401 (survey 1), 6411 (survey 2), 6400 (survey 3), and 2399 (survey 4) individuals were included in the analyses. In the 6 months–4 years age group, the lowest prevalence (assessed using microscopy) was observed in 2 Tanzanian centres (4.6% for Korogwe and 9.95% for Bagamoyo) and Lambaréné, Gabon (6.0%), while the highest PfPR was recorded for Nanoro, Burkina Faso (52.5%). PfPR significantly decreased over the 3 years in Agogo (Ghana), Kombewa (Kenya), Lilongwe (Malawi), and Bagamoyo (Tanzania), and a trend for increased PfPR was observed over the 4 surveys for Kintampo, Ghana. Over the 4 surveys, for all sites, PfPR was predominantly higher in the 5–19 years group than in the other age categories. Occurrence of fever and anaemia was associated with high P. falciparum parasitaemia. Univariate analyses showed a significant association of anti-malarial treatment in 4 surveys (odds ratios [ORs]: 0.52, 0.52, 0.68, 0.41) and bed net use in 2 surveys (ORs: 0.63, 0.68, 1.03, 1.78) with lower risk of malaria infection.ConclusionLocal PfPR differed substantially between sites and age groups. In children 6 months–4 years old, a significant decrease in prevalence over the 3 years was observed in 4 out of the 8 study sites. Trial registration Clinical Trials.gov identifier: NCT01190202:NCT. GSK Study ID numbers: 114001Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-017-2078-3) contains supplementary material, which is available to authorized users.

The coronavirus disease 2019 (COVID-19) pandemic and associated public health responses have disrupted daily living activities with economic and health consequences globally. We observed transient decreases in human immunodeficiency virus (HIV) clinic visit adherence and food security among persons living with HIV early in the pandemic, and an increase in viral suppression later in the pandemic.