Biology subjects

Manguin, S.

Publications and source records attributed to Manguin, S..

6 recordsLinked to original sources

bioRxiv2026

Understanding malaria transmission in Angola: first detection of Plasmodium malariae in Anopheles spp. and the role of secondary vectors in the Balombo region, Benguela Province

Background: Angola is one of the most affected countries in sub-Saharan Africa and was off-track to meet the WHO Global Technical Strategy targeting of a 75% reduction in malaria incidence and mortality by 2025. Recent studies highlighted major knowledge gaps regarding malaria vectors in Angola, particularly secondary vectors. A malaria control project initiated in 2007 in Balombo (Benguela Province, central Angola) has monitored malaria dynamics for 18 years, revealing increased Plasmodium prevalence and more frequent detection of non-falciparum species, mainly Plasmodium malariae (in co-infection with P. falciparum) in villagers of the Balombo region. This study aimed to characterize Anopheles populations in this region by assessing species composition, behavioural patterns, and infection rate. And to a less extent, to compare the performance of two indoor and outdoor mosquito trapping methods. Methods: Surveys were conducted during the rainy (December 2023 and 2024) and dry seasons (July 2024) in villages around the town of Balombo. Adult mosquitoes were collected indoors and outdoors using CDC Light Traps and BG-Pro traps in randomly selected houses. Female Anopheles were morphologically and molecularly identified. Primary and secondary vectors were screened for Plasmodium spp. using qPCR-high resolution melting, and positive samples were sequenced. Results: A strong seasonal effect was observed in Anopheles populations, with higher abundance, diversity, and Plasmodium- infection rates during the rainy season. An. funestus remained the main vector, but Plasmodium spp. was also detected in five other species: An. arabiensis, An. gambiae, An. marshallii, An. rufipes, and An. maculipalpis. This is the first report of P. malariae in Anopheles mosquitoes and the first mention of the role of secondary vectors in malaria transmission in Benguela Province. Conclusion: This study provides a thorough and updated inventory of Anopheles species in the Balombo region. Molecular biology confirmed the presence of P. falciparum and P. malariae in several species of Anopheles underscoring the existence of a complex transmission system in villages of Balombo. Infected exophagic and exophilic Anopheles species, exhibiting opportunistic behaviour, likely contribute, as secondary vectors, to the increase of Plasmodiumspp. transmission in the study sites. Therefore, confirming the need to implement complementary interventions targeting outdoor malaria transmission.

microbiology↗

bioRxiv2026

Genetic Variability and Population Structure within the Anopheles tessellatus complex (Theobald, 1901) in Indonesia using ITS2 nuclear and COI, COII mitochondrial sequences

Some Anopheles species that act as malaria vectors are members of species complexes, a concept whereby sibling species cannot be differentiated solely on the basis of morphological characters. Therefore, species complexes represent a major problem in malaria vector control, because within an Anopheles complex, vectors cannot be differentiated from non-vector species, unless molecular techniques are used to identify them. The Anopheles tessellatus species complex is an important potential vector in South, East, and Southeast Asia, including certain regions of Indonesia. However, no in-depth studies have been conducted on this species complex in that country. Therefore, this study investigated the taxonomic status of An. tessellatus from diverse populations across five Indonesian islands (Sumatra, Java, West Nusa Tenggara, East Nusa Tenggara, and Sulawesi) and identified interpopulation genetic variation based on molecular data of the ITS2, COI, and COII genes. Phylogenetic relationships were constructed using the Maximum Likelihood method. Haplotype and network analysis were also conducted. The results indicate that An. tessellatus constitutes a monophyletic group comprising three well-defined lineages that exhibit clear intraspecific genetic differentiation. Cluster 1 corresponds to the population of Sumatra, Cluster 2 represents population from Sulawesi, and Cluster 3 encompasses populations from Java, West Nusa Tenggara, and East Nusa Tenggara. These findings demonstrate high haplotype diversity and low nucleotide diversity within the species. Populations from West Sumatra, Manado, Tojo Una - Una, and North Morowali (Sulawesi) have the potential for speciation with a genetic distance of 0.61 - 0.94% for COI, between 0.81 - 0.95% for ITS2, and between 0.62 - 0.71% for COII. These findings underscore the need for further integrative studies to obtain a more comprehensive understanding of the An. tessellatus complex in Indonesia and its role in malaria transmission.

molecular biology↗

bioRxiv2025

Anopheles barbirostris in Indonesia: A more complex metapopulation than expected.

Anopheles barbirostris, a member of the Barbirostris Subgroup in the Anopheles genus, comprises a complex of species in South and Southeast Asia. This An. barbirostris complex includes eight species such as An. barbirostris sensu stricto (s.s.), An. campestris, An. dissidens, An. donaldi, An. saeungae, An. sarpangensis, An. vanderwulpi, and An. wejchoochotei. This study employed molecular markers, including ITS2 and COI genes, to investigate the phylogenetic relationships within An. barbirostris sensu lato (s.l.) populations from various locations in Indonesia. The analysis reveals the presence of nine distinct populations within this complex, including the first report of An. wejchoochotei in North Sulawesi and an unique Barbirostris population in Magelang, Central Java. This makes it a more complex metapopulation than previously thought. These findings provide critical insights into the diversity of malaria and lymphatic filariasis vectors in Indonesia. Understanding the complex structure of the An. barbirostris populations and their genetic diversity will be useful for effective vector control and disease elimination strategies.

molecular biology↗

bioRxiv2025

Immunological surveillance using gSG6-P1 biomarker reveals spatio-temporal dynamics of Anopheles exposure and gaps in malaria risk assessment

Malaria risk assessment often relies on the entomological inoculation rate (EIR), which quantifies infectious bites per person over time. However, this approach does not account for human behavioral variability, limiting its effectiveness in accurately reflecting malaria risk at the population level. Recent studies have attempted to estimate mosquito-bite risk through the measurement of antibody responses to Anopheles salivary peptides. However, this approach has yet to be applied to evaluate malaria transmission risks along the Thailand-Cambodia border. This study aims to employ an immune biomarker for Anopheles salivary peptide (anti-gSG6-P1) to identify key risk factors associated with exposure to Anopheles mosquitoes in Sisaket Province, a region bordering Thailand and Cambodia. Blood samples from the same set of 184 participants were collected via finger prick during each season: rainy (August 2022), cool-dry (December 2022), and hot-dry (April 2023). Anti-gSG6-P1 antibody levels were quantified using enzyme-linked immunosorbent assay (ELISA). Factor Analysis of Mixed Data (FAMD) revealed that seasonality exerts the strongest influence on antibody levels. This pattern was likely driven by human activities, particularly the frequency of rubber tapping activity in the rubber plantation area where Anopheles species, especially Anopheles dirus, are present. While this study successfully identifies seasonality and human factors as critical influences on antibody responses, it also highlights gaps in understanding the kinetics of anti-salivary peptide responses to Anopheles bites, particularly in species with low salivary peptides sequence similarity to that of Anopheles gambiae. These findings emphasize the need for the development of new serological tools tailored to malaria vectors in the Greater Mekong Subregion to enhance malaria risk assessment and improve vector control strategies.

immunology↗

bioRxiv2023

Dirus Complex Species Identification PCR (DiCSIP) improves identification of Anopheles dirus complex from Greater Mekong Subregion

BackgroundThe Anopheles dirus complex plays a significant role as malaria vectors in the Greater Mekong Subregion (GMS), with varying degrees of vector competence among species. Accurate identification of sibling species in this complex is essential for understanding malaria transmission dynamics and deployment of effective vector control measures. This becomes increasingly crucial as the GMS advances towards malaria elimination while facing with the emergence of zoonotic simian malaria transmission. However, the original molecular identification assay, Dirus Allele Specific PCR (AS-PCR) targeting the ITS2 region have pronounced non-specific amplifications leading to ambiguous results and misidentification of the sibling species. This study investigates the underlying causes of these inconsistencies and develops new primers for accurate identification of species within the Anopheles dirus complex. Methodology/Principal findingsDespite several optimizations by reducing primer concentration, decreasing thermal cycling time, and increasing annealing temperature, the Dirus AS-PCR continued to produce inaccurate identifications, particularly for Anopheles dirus, Anopheles scanloni, and Anopheles nemophilous. Subsequently, in silico analyses pinpointed problematic primers with high GC content and multiple off-target binding sites. Through a series of in silico analyses and laboratory validation, a new set of primers for Dirus Complex Species Identification PCR (DiCSIP) has been developed. DiCSIP primers improve specificity, operational range, and sensitivity for accurate identification of five complex member species found in the GMS. Validation with laboratory and field An. dirus complex specimens demonstrated that DiCSIP could correctly identify all samples while the original Dirus AS-PCR misidentify An. dirus as other species when used with different thermocyclers. Conclusion/SignificanceThe DiCSIP assay offers a significant improvement in An. dirus complex identification, addressing challenges in specificity and efficiency of the previous ITS2-based assay. This new primer set provides a valuable tool for accurate entomological surveys, supporting effective vector control strategies to reduce transmission, and prevent the re-introduction of malaria in the GMS. Author SummarySeveral species of Anopheles mosquitoes belong to species complexes due to their indistinguishable morphology from closely related sibling species. However, members of the same species complex may exhibit varied vectorial capability, i.e. the ability to spread human pathogens, in this case malaria parasites, ranging from dominant vector to non-vector. The Dirus AS-PCR molecular assay to identify species within the An. dirus complex, a significant malaria vector species in the GMS, can produce inconsistent PCR results leading to misidentification. Furthermore, our analysis of An. dirus ITS2 sequences in the NCBI database indicated misidentification between these sibling species suggesting the need for a new set of primers to improve reproducibility and sensitivity in identifying members of the An. dirus complex. This study presents thorough analyses of the existing primers that cause difficulties in correct amplification and a development of a new set of primers for Dirus Complex Species Identification PCR (DiCSIP) assay. The DiCSIP assay offers several advantages over the original Dirus AS-PCR. It provides a higher specificity, sensitivity and wider operational range allowing for the use of the DNAzol direct reagent to process mosquito samples without the need for DNA extraction, saving both time and cost in sample processing. Our study provides a valuable molecular tool for entomological surveys, which is crucial for effective vector control measures in the GMS.

molecular biology↗

bioRxiv2020

Evaluation of Fecal Immunoassays for Canine Echinococcus Infection in China

Human echinococcosis is present worldwide but it is in China that prevalence is the highest. Western China and in particular the Tibetan plateau is the region where the burden of echinococcosis is the most important. Dogs are a major carrier of echinococcosis and monitoring the presence of Echinococcus worms in dogs is therefore essential for efficiently controlling the disease. Detection kits based on three different technologies, i.e. sandwich ELISA, ELISA and gold immunodiffusion are currently marketed and used in China. The objective of this work was to assess the efficacy of these kits, in particular with respect to sensitivity and specificity. Four fecal antigen detection kits for canine echinococcosis covering the three technologies were obtained from companies and tested in parallel on 220 fecal samples. The results indicate that the performance is lower than expected, in particular in terms of sensitivity. The best results were obtained with the sandwich ELISA technology. The gold immunofiltration yielded the poorest results. In all cases, further development is needed to improve the performance of these kits, which represent a key element for the control of echinococcosis. Author summaryAlthough present worldwide, human echinococcosis is at its highest prevalence in Western China and particularly on the Tibetan plateau. Controlling echinococcosis is a national priority and routine monitoring must be established. Dogs are the main carriers of echinococcosis and surveying Echinococcus worms in dogs is therefore a key issue. Commercial detection kits are currently in use in China for monitoring the presence of Echinococcosis in dogs. These kits are based on three different technologies, i.e. sandwich ELISA with two monoclonal antibodies, ELISA, and gold immunodiffusion. National survey programs are essential for the control of echinococcosis and it is thus very important to assess the efficacy of these kits, planned to be used for the national survey programs. The work was thus undertaken to assess this efficacy, in particular with respect to sensitivity and specificity. Four fecal antigen detection kits for canine echinococcosis covering the three technologies were obtained from companies and tested in parallel on 220 fecal samples. The performance was lower than expected, in particular for their sensitivity, which ranged from 51.5% to 83.9% with only two samples displaying a worm burden lower than 100. Three out of four kits showed non-specific cross-reactions with other parasites. The best results were obtained with the sandwich ELISA technology, whereas gold immunofiltration yielded the poorest results. However, in all cases, further development is strongly needed to improve the performance of these kits, which represent a key element for the control of echinococcosis.

zoology↗