A population genetic perspective on the origin, spread and adaptation of the human malaria agents Plasmodium falciparum and Plasmodium vivax

A systematic review on malaria and dengue vaccines for the effective management of these mosquito borne diseases: Improving public health

Insect vector-borne diseases (VBDs) pose significant global health challenges, particularly in tropical and subtropical regions. The WHO has launched the "Global Vector Control Response (GVCR) 2017-2030" to address these diseases, emphasizing a comprehensive approach to vector control. This systematic review investigates the potential of malaria and dengue vaccines in controlling mosquito-borne VBDs, aiming to alleviate disease burdens and enhance public health. Following PRISMA 2020 guidelines, the review incorporated 39 new studies out of 934 identified records. It encompasses various studies assessing malaria and dengue vaccines, emphasizing the significance of vaccination as a preventive measure. The findings indicate variations in vaccine efficacy, duration of protection, and safety considerations for each disease, influencing public health strategies. The review underscores the urgent need for vaccines to combat the increasing burden of VBDs like malaria and dengue, advocating for ongoing research and investment in vaccine development.

Epidemiology of malaria in Gabon: A systematic review and meta-analysis from 1980 to 2023

The objective of this were conducted to elucidate spatiotemporal variations in malaria epidemiology in Gabon since 1980. For that, five databases, were used to collect and identify all studies published between 1980 and 2023 on malaria prevalence, antimalarial drug resistance, markers of antimalarial drug resistance and insecticide resistance marker. The findings suggest that Gabon continues to face malaria as an urgent public health problem, with persistently high prevalence rates. Markers of resistance to CQ persist despite its withdrawal, and markers of resistance to SP have emerged with a high frequency, reaching 100 %, while ACTs remain effective. Also, recent studies have identified markers of resistance to the insecticides Kdr-w and Kdr-e at frequencies ranging from 25 % to 100 %. Ace1R mutation was reported with a frequency of 0.4 %. In conclusion, the efficacy of ACTs remains above the threshold recommended by the WHO. Organo-phosphates and carbamates could provide an alternative for vector control.

Current Status of Malaria Control and Elimination in Africa: Epidemiology, Diagnosis, Treatment, Progress and Challenges

The African continent carries the greatest malaria burden in the world. Falciparum malaria especially has long been the leading cause of death in Africa. Climate, economic factors, geographical location, human intervention and unstable security are factors influencing malaria transmission. Due to repeated infections and early interventions, the proportion of clinically atypical malaria or asymptomatic plasmodium carriers has increased significantly, which easily lead to misdiagnosis and missed diagnosis. African countries have made certain progress in malaria control and elimination, including rapid diagnosis of malaria, promotion of mosquito nets and insecticides, intermittent prophylactic treatment in high-risk groups, artemisinin based combination therapies, and the development of vaccines. Between 2000 and 2022, there has been a 40% decrease in malaria incidence and a 60% reduction in mortality rate in the WHO African Region. However, many challenges are emerging in the fight against malaria in Africa, such as climate change, poverty, substandard health services and coverage, increased outdoor transmission and the emergence of new vectors, and the growing threat of resistance to antimalarial drugs and insecticides. Joint prevention and treatment, identifying molecular determinants of resistance, new drug development, expanding seasonal malaria chemo-prevention intervention population, and promoting the vaccination of RTS, S/AS01 and R21/Matrix-M may help to solve the dilemma. China's experience in eliminating malaria is conducive to Africa's malaria prevention and control, and China-Africa cooperation needs to be constantly deepened and advanced. Our review aims to help the global public develop a comprehensive understanding of malaria in Africa, thereby contributing to malaria control and elimination.

Patterns of genetic differentiation imply distinct phylogeographic history of the mosquito species Anopheles messeae and Anopheles daciae in Eurasia

Detailed knowledge of phylogeography is important for control of mosquito species involved in the transmission of human infectious diseases. Anopheles messeae is a geographically widespread and genetically diverse dominant vector of malaria in Eurasia. A closely related species, An. daciae, was originally distinguished from An. messeae based on five nucleotide substitutions in its ribosomal DNA (rDNA). However, the patterns of phylogeographic history of these species in Eurasia remain poorly understood. Here, using internal transcribed spacer 2 (ITS2) of rDNA and karyotyping for the species identification we determined the composition of five Anopheles species in 28 locations in Eurasia. Based on the frequencies of 11 polymorphic chromosomal inversions used as genetic markers, a large-scale population genetics analysis was performed of 1932 mosquitoes identified as An. messeae, An. daciae and their hybrids. The largest genetic differences between the species were detected in the X sex chromosome suggesting a potential involvement of this chromosome in speciation. The frequencies of autosomal inversions in the same locations differed by 13%-45% between the species demonstrating a restricted gene flow between the species. Overall, An. messeae was identified as a diverse species with a more complex population structure than An. daciae. The clinal gradients in frequencies of chromosomal inversions were determined in both species implicating their possible involvement in climate adaptations. The frequencies of hybrids were low ~1% in northern Europe but high up to 50% in south-eastern populations. Thus, our study revealed critical differences in patterns of phylogeographic history between An. messeae and An. daciae in Eurasia. This knowledge will help to predict the potential of the malaria transmission in the northern territories of the continent.

Malaria and environmental, socioeconomics and public health conditions in the municipality of São Félix do Xingu, Pará, Eastern Amazon, Brazil: An ecological and cross-sectional study

BACKGROUND

Malaria is a parasitosis conditioned by several factors. This study sought to analyze the spatial distribution of malaria considering environmental, socioeconomic, and political variables in São Félix do Xingu, Pará, Brazil, from 2014 to 2020.

METHODS

Epidemiological, cartographic, and environmental data were obtained from the Ministry of Health, Brazilian Geographical and Statistical Institute, and National Space Research Institute. Statistical and spatial distribution analyses were performed using chi-squared tests of expected equal proportions and the kernel and bivariate global Moran's techniques with Bioestat 5.0 and ArcGIS 10.5.1.

RESULTS

The highest percentage of cases occurred in adult males with brown skin color, mainly placer miners, with a primary education level, living in rural areas, who were infected with Plasmodium vivax and with parasitemia of two or three crosses as diagnosed by the thick drop/smear test. The disease had a non-homogeneous distribution, with distinct annual parasite indices associated with administrative districts and clusters of cases in locations with deforestation, mining, and pastures close to Conservation Units and Indigenous Lands. Thus, a direct relationship between areas with cases and environmental degradation associated with land use was demonstrated, along with the precarious availability of health services. Pressure on protected areas and epidemiological silence in Indigenous Lands were also noted.

CONCLUSIONS

Environmental and socioeconomic circuits were identified for development of diseases associated with precarious health services in the municipality. These findings highlight the need to intensify malaria surveillance and contribute to the systematic knowledge of malaria's epidemiology by considering the complexity of its conditioning factors.

Systematic Review on Diversity and Distribution of Anopheles Species in Gabon: A Fresh Look at the Potential Malaria Vectors and Perspectives

Gabon is located in the malaria hyper-endemic zone, where data concerning malaria vector distribution remains fragmentary, making it difficult to implement an effective vector control strategy. Thus, it becomes crucial and urgent to undertake entomological surveys that will allow a better mapping of the Anopheles species present in Gabon. In this review, we examined different articles dealing with Anopheles in Gabon from ProQuest, Web of Science, PubMed, and Google scholar databases. After applying the eligibility criteria to 7543 articles collected from four databases, 42 studies were included that covered a 91-year period of study. The review revealed a wide diversity of Anopheles species in Gabon with a heterogeneous distribution. Indeed, our review revealed the presence of 41 Anopheles species, of which the most abundant were members of the Gambiae and Nili complexes and those of the Funestus and Moucheti groups. However, our review also revealed that the major and minor vectors of malaria in Gabon are present in both sylvatic, rural, and urban environments. The observation of human malaria vectors in sylvatic environments raises the question of the role that the sylvatic environment may play in maintaining malaria transmission in rural and urban areas. Ultimately, it appears that knowledge of biodiversity and spatial distribution of Anopheles mosquitoes is fragmentary in Gabon, suggesting that additional studies are necessary to complete and update these entomological data, which are useful for the implementation of vector control strategies.

Evolutionary history of Plasmodium vivax and Plasmodium simium in the Americas

Malaria is a vector-borne disease caused by protozoan parasites of the genus Plasmodium. Plasmodium vivax is the most prevalent human-infecting species in the Americas. However, the origins of this parasite in this continent are still debated. Similarly, it is now accepted that the existence of Plasmodium simium is explained by a P. vivax transfer from humans to monkey in America. However, many uncertainties still exist concerning the origin of the transfer and whether several transfers occurred. In this review, the most recent studies that addressed these questions using genetic and genomic approaches are presented.