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The Anopheles stephensi mosquito is an invasive malaria vector recently reported in Djibouti, Ethiopia, Sudan, Somalia, Nigeria, and Ghana. The World Health Organization has called on countries in Africa to increase surveillance efforts to detect and report this vector and institute appropriate and effective control mechanisms. In Kenya, the Division of National Malaria Program conducted entomological surveillance in counties at risk for An. stephensi mosquito invasion. In addition, the Kenya Medical Research Institute conducted molecular surveillance of all sampled Anopheles mosquitoes from other studies to identify An. stephensi mosquitoes. We report the detection and confirmation of An. stephensi mosquitoes in Marsabit and Turkana Counties by using endpoint PCR and morphological and sequence identification. We demonstrate the urgent need for intensified entomological surveillance in all areas at risk for An. stephensi mosquito invasion, to clarify its occurrence and distribution and develop tailored approaches to prevent further spread.

When taking a blood meal on a person infected with malaria, female Anopheles gambiae mosquitoes, the major vector of human malaria, acquire nutrients that will activate egg development (oogenesis) in their ovaries. Simultaneously, they infect themselves with the malaria parasite. On traversing the mosquito midgut epithelium, invading Plasmodium ookinetes are met with a potent innate immune response predominantly controlled by mosquito blood cells. Whether the concomitant processes of mosquito reproduction and immunity affect each other remains controversial. Here, we show that proteins that deliver nutrients to maturing mosquito oocytes interfere with the antiparasitic response. Lipophorin (Lp) and vitellogenin (Vg), two nutrient transport proteins, reduce the parasite-killing efficiency of the antiparasitic factor TEP1. In the absence of either nutrient transport protein, TEP1 binding to the ookinete surface becomes more efficient. We also show that Lp is required for the normal expression of Vg, and for later Plasmodium development at the oocyst stage. Furthermore, our results uncover an inhibitory role of the Cactus/REL1/REL2 signaling cassette in the expression of Vg, but not of Lp. We reveal molecular links that connect reproduction and immunity at several levels and provide a molecular basis for a long-suspected trade-off between these two processes.

Malaria transmission persists despite the scale-up of interventions such as long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS). Understanding the entomological drivers of transmission is key for the design of effective and sustainable tools to address the challenge. Recent research findings indicate a shift in vector populations from the notorious Anopheles gambiae ( s.s. ) as a dominant vector to other species as one of the factors contributing to the persistence of malaria transmission. However, there are gaps in the literature regarding the minor vector species which are increasingly taking a lead role in malaria transmission. Currently, minor malaria vectors have behavioural plasticity, which allows their evasion of vector control tools currently in use. To address this, we have reviewed the role of Anopheles merus , a saltwater mosquito species that is becoming an important vector of malaria transmission along the East and Southern African coast. We performed a literature review from PubMed and Google Scholar and reviewed over 50 publications relating to An. merus 's bionomics, taxonomy, spatial-temporal distribution and role in malaria transmission. We found that An. merus is an important vector of malaria and that it contributes to residual malaria transmission because of its exophilic tendencies, insecticide resistance and densities that peak during the dry seasons as the freshwater mosquitoes decline. Spatial and temporal studies have also shown that this species has increased its geographical range, densities and vectorial capacity over time. In this review, we highlight the resting behaviour and breeding habitats of this mosquito, which could be targeted for surveillance studies and control interventions. Graphical Abstract

The use of MALDI-TOF MS for mosquito identification and surveillance is routinely used in developed countries as an affordable alternative to molecular methods. However, in low- and middle-income countries (LMIC) where mosquito-borne diseases carry the greatest burden, the method is not commonly employed. Using the Kenyan national malaria program (NMCP) as a case study, we compared the costs of current methods used for malaria vector surveillance to those that would be incurred if MALDI-TOF MS were used instead. A deterministic decision tree analytic model was developed to systematically calculate the costs associated with materials and labour, and time-to-results for two workflows, i.e., current molecular methods versus MALDI-TOF MS. The analysis assumed an annual sample size of 15,000 mosquitoes (representing the average number of mosquitoes analysed annually by the Kenyan NMCP) processed at a local laboratory in Kenya. We estimate that if the Kenyan national entomological surveillance program shifted sample processing completely to MALDI-TOF MS, it would result in 74.48% net time saving, up to 84% on material costs and 77% on labour costs, resulting in an overall direct cost savings of 83%. Adoption of MALDI-TOF MS for malaria vector surveillance can result in substantial time and cost savings. The ease of performance, the rapid turn-around time, and the modest cost per sample may bring a paradigm shift in routine entomological surveillance in Africa.

Tsetse fly exhibit species-specific olfactory uniqueness potentially underpinned by differences in their chemosensory protein repertoire. We assessed 1) expansions of chemosensory protein orthologs in Glossina morsitans morsitans, Glossina pallidipes, Glossina austeni, Glossina palpalis gambiensis, Glossina fuscipes fuscipes and Glossina brevipalpis tsetse fly species using Café analysis (to identify species-specific expansions) and 2) differential expressions of the orthologs and associated proteins in male G. m. morsitans antennae and head tissues using RNA-Seq approaches (to establish associated functional molecular pathways). We established accelerated and significant (P<0.05, λ = 2.60452e-7) expansions of gene families in G. m. morsitans Odorant receptor (Or)71a, Or46a, Ir75a,d, Ionotropic receptor (Ir) 31a, Ir84a, Ir64a and Odorant binding protein (Obp) 83a-b), G. pallidipes Or67a,c, Or49a, Or92a, Or85b-c,f and Obp73a, G. f. fuscipes Ir21a, Gustatory receptor (Gr) 21a and Gr63a), G. p. gambiensis clumsy, Ir25a and Ir8a, and G. brevipalpis Ir68a and missing orthologs in each tsetse fly species. Most abundantly expressed transcripts in male G. m. morsitans included specific Or (Orco, Or56a, 65a-c, Or47b, Or67b, GMOY012254, GMOY009475, and GMOY006265), Gr (Gr21a, Gr63a, GMOY013297 and GMOY013298), Ir (Ir8a, Ir25a and Ir41a) and Obp (Obp19a, lush, Obp28a, Obp83a-b Obp44a, GMOY012275 and GMOY013254) orthologs. Most enriched biological processes in the head were associated with vision, muscle activity and neuropeptide regulations, amino acid/nucleotide metabolism and circulatory system processes. Antennal enrichments (>90% of chemosensory transcripts) included cilium-associated mechanoreceptors, chemo-sensation, neuronal controlled growth/differentiation and regeneration/responses to stress. The expanded and tsetse fly species specific orthologs includes those associated with known tsetse fly responsive ligands (4-methyl phenol, 4-propyl phenol, acetic acid, butanol and carbon dioxide) and potential tsetse fly species-specific responsive ligands (2-oxopentanoic acid, phenylacetaldehyde, hydroxycinnamic acid, 2-heptanone, caffeine, geosmin, DEET and (cVA) pheromone). Some of the orthologs can potentially modulate several tsetse fly species-specific behavioral (male-male courtship, hunger/host seeking, cool avoidance, hygrosensory and feeding) phenotypes. The putative tsetse fly specific chemosensory gene orthologs and their respective ligands provide candidate gene targets and kairomones for respective downstream functional genomic and field evaluations that can effectively expand toolbox of species-specific tsetse fly attractants, repellents and other tsetse fly behavioral modulators.

Matrix-assisted laser desorption-ionisation time of flight mass spectrometry (MALDI-TOF MS) is a powerful analytical method that has been used extensively to identify sample ions of complex mixtures, and biological samples such as proteins, tissues and microorganisms. MALDI-TOF MS has revolutionised clinical microbiology with accurate, rapid, and inexpensive species-level identification of microbes. MALDI-TOF MS technology generates spectral signatures and matches them to a library of similar organisms using bioinformatics pattern matching. The use of MALDI-TOF MS for entomological samples has been explored by multiple groups with proven efficacy at differentiating between closely related species, as well as detecting pathogens in different vectors. The low cost per sample processing, rapid turnaround and robustness are attractive for surveillance of vector control programs. Libraries are built in-house for institutional usage, although a multi-user platform with sharing of spectra and data would be attractive. Only a few studies have strived to make their libraries publicly available. Here, we outline a stepwise approach for creating an in-house MALDI-TOF MS library and subsequent query, using malaria vector species identification as a case study for entomological samples. A protocol and video of the methodology are also shared. Moreover, the libraries related to this publication have been deposited in public repository ( https://doi.org/10.7910/DVN/VYQFNO37 ) for anyone with MALDI-TOF MS equipment to adapt.

Plasmodium falciparum secretes extracellular vesicles ( Pf EVs) that contain parasite-derived RNA. However, the significance of the secreted RNA remains unexplored. Here, we compare secreted and intracellular RNA from asexual cultures of six P. falciparum lines. We find that secretion of RNA via extracellular vesicles is not only periodic throughout the asexual intraerythrocytic developmental cycle but is also highly conserved across P. falciparum isolates. We further demonstrate that the phases of RNA secreted via extracellular vesicles are discernibly shifted compared to those of the intracellular RNA within the secreting whole parasite. Finally, transcripts of genes with no known function during the asexual intraerythrocytic developmental cycle are enriched in Pf EVs compared to the whole parasite. We conclude that the secretion of extracellular vesicles could be a putative posttranscriptional RNA regulation mechanism that is part of or synergise the classic RNA decay processes to maintain intracellular RNA levels in P. falciparum . Here, Kioko et al. describe a putative posttranscriptional RNA regulation mechanism involving secreted extracellular vesicles to maintain the intracellular steady-state RNA levels during the asexual blood stage of malaria parasites.

Background Malaria is transmitted when infected Anopheles mosquitoes take a blood meal. During this process, the mosquitoes inject a cocktail of bioactive proteins that elicit antibody responses in humans and could be used as biomarkers of exposure to mosquito bites. This study evaluated the utility of IgG responses to members of the Anopheles gambiae D7 protein family as serological markers of human–vector contact. Methods The D7L2, D7r1, D7r2, D7r3, D7r4 and SG6 salivary proteins from An. gambiae were expressed as recombinant antigens in Escherichia coli . Antibody responses to the salivary proteins were compared in Europeans with no prior exposure to malaria and lifelong residents of Junju in Kenya and Kitgum in Uganda where the intensity of malaria transmission is moderate and high, respectively. In addition, to evaluate the feasibility of using anti-D7 IgG responses as a tool to evaluate the impact of vector control interventions, we compared responses between individuals using insecticide-treated bednets to those who did not in Junju, Kenya where bednet data were available. Results We show that both the long and short forms of the D7 salivary gland antigens elicit a strong antibody response in humans. IgG responses against the D7 antigens reflected the transmission intensities of the three study areas, with the highest to lowest responses observed in Kitgum (northern Uganda), Junju (Kenya) and malaria-naïve Europeans, respectively. Specifically, the long form D7L2 induced an IgG antibody response that increased with age and that was lower in individuals who slept under a bednet, indicating its potential as a serological tool for estimating human–vector contact and monitoring the effectiveness of vector control interventions. Conclusions This study reveals that D7L2 salivary antigen has great potential as a biomarker of exposure to mosquito bites and as a tool for assessing the efficacy of vector control strategies such as bednet use. Graphical abstract

Treatments for soil-transmitted helminthiases face challenges, especially in addressing Trichuris trichiura. Combination regimens, particularly of ivermectin and albendazole, are promising. We aimed to assess the safety, efficacy, and palatability of a combination tablet for the treatment of T trichiura, hookworm, and Strongyloides stercoralis infections among school-aged children in Ethiopia, Kenya, and Mozambique. We conducted an adaptive phase 2/3, randomised, parallel-group, active-controlled, superiority trial in 15 schools in Ethiopia, Kenya, and Mozambique. Eligible participants for both phases were aged 5–18 years, weighed at least 15 kg, and were infected with T trichiura, hookworms, or S stercoralis. Participants were randomly assigned via a computer-generated sequence to either a single dose of a fixed-dose combination (FDC×1) of albendazole (400 mg) plus ivermectin (9 mg or 18 mg), three consecutive daily doses of an FDC (FDC×3) of albendazole (400 mg) plus ivermectin (9 mg or 18 mg), or a single dose of albendazole alone (400 mg) via block randomisation, stratified by soil-transmitted helminth species. Participants and those administering the treatments were not masked to treatment assignment, but those assessing the outcomes were masked. The primary outcome of phase 2 (conducted in Kenya only) was safety during the first 3 h after the intervention and for 7 days, and the primary outcome of phase 3 was efficacy (ie, the proportion of individuals cured at day 21 out of the total number infected at baseline) for T trichiura; both primary outcomes were analysed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT05124691, and is terminated. Between Jan 20, 2022, and March 24, 2023, 1001 participants were recruited (465 [46%] were female and 536 [54%] were male). 636 (64%) were infected with T trichiura, 360 (36%) with hookworm, and 104 (10%) with S stercoralis; 94 (9%) of 1001 participants had co-infections and were included in the analysis of each infecting species. A total of 243 participants were allocated to the albendazole group, 381 to the FDC×1 group, and 377 to the FDC×3 group. In both phase 2 and 3, gastrointestinal symptoms were the most common mild-to-moderate adverse events in the FDC groups, but resolved within 48 h without intervention. At least one treatment-related adverse event occurred in 34 (14%) of 243 participants in the albendazole group, 75 (20%) of 381 participants in the FDC×1 group, and 88 (23%) of 377 participants in the FDC×3 group. No serious adverse events occurred. For T trichiura, both FDC groups had a higher cure rate (97·2% [95% CI 95·2– 99·3] for FDC×3 and 82·9% [78·2–87·5] for FDC×1) than albendazole (35·9% [27·7–44·1]), with absolute differences of 61·3% (98% CI 50·2–71·2) and 47·0% (34·7–58·1), respectively. For hookworms, FDC×3 had a higher cure rate (95·0% [95% CI 91·1–98·9]) than albendazole (65·1% [56·0–74·2]), with absolute differences of 29·9% (98% CI 17·2–42·4), whereas FDC×1 had a similar cure rate (79·8% [72·8–86·9]) to albendazole. The sample size for efficacy evaluation of S stercoralis was not met. An FDC of albendazole plus ivermectin has a similar safety profile but superior efficacy to albendazole alone against T trichiura infection and hookworms. These findings open opportunities for control of all soil-transmitted helminth species of interest, including potentially S stercoralis. Evaluation of safety in larger populations and implementation scenarios are the next steps for this innovation to promote its incorporation into programmatic activities. European and Developing Countries Clinical Trials Partnership. For the Portuguese translation of the abstract see Supplementary Materials section.

Background Gene copy number variants (CNVs), which consist of deletions and amplifications of single or sets of contiguous genes, contribute to the great diversity in the Plasmodium falciparum genome. In vitro studies in the laboratory have revealed their important role in parasite fitness phenotypes such as red cell invasion, transmissibility and cytoadherence. Studies of natural parasite populations indicate that CNVs are also common in the field and thus may facilitate adaptation of the parasite to its local environment. Results In a survey of 183 fresh field isolates from three populations in Eastern Africa with different malaria transmission intensities, we identified 94 CNV loci using microarrays. All CNVs had low population frequencies (minor allele frequency < 5%) but each parasite isolate carried an average of 8 CNVs. Nine CNVs showed high levels of population differentiation (F ST  > 0.3) and nine exhibited significant clines in population frequency across a gradient in transmission intensity. The clearest example of this was a large deletion on chromosome 9 previously reported only in laboratory-adapted isolates. This deletion was present in 33% of isolates from a population with low and highly seasonal malaria transmission, and in < 9% of isolates from populations with higher transmission. Subsets of CNVs were strongly correlated in their population frequencies, implying co-selection. Conclusions These results support the hypothesis that CNVs are the target of selection in natural populations of P. falciparum . Their environment-specific patterns observed here imply an important role for them in conferring adaptability to the parasite thus enabling it to persist in its highly diverse ecological environment.