9th PAMCA Annual Conference and Exhibition: Day 2
MESA Correspondents bring cutting-edge coverage from the 9th PAMCA Annual Conference and Exhibition “Reorienting surveillance and management in the context of emerging threats of disease vectors”.
Day 2 : Tuesday, 19th September 2023
Plenary Talk 3 - Special District Model - Reimagining Malaria Control in Africa by Focusing on Local Mosquito Control
Wakoli Wekesa (East Side Mosquito Abatement District, United States) began by sharing a reflection on Africa experiencing a larger portion of the malaria burden even though its vector was discovered more than a century ago. Using historical evidence, Wekesa nailed the sensitive role of mosquito control in the elimination of malaria and other vector-borne diseases (VBD), providing an example of the eradication of yellow fever in Cuba and Panama as well as the eradication of An. gambiae in Brazil. He added that African countries should put more effort into vector control than in managing pathogens. He also proposed that African countries should adopt a special district model for effective vector control, such as that employed in the USA. Finally, he issued a wake-up call to African professionals to convert their knowledge to practical efforts for mosquito control, insisting on the adoption of integrated vector management (IVM), changing building codes for housing, and eliminating mosquito breeding habitats.
Plenary Talk 4 - Women Leading the Charge: Breaking the Gender Barrier in Malaria & Vector-Borne Disease Response
Corine Karema (Roll Back Malaria - RBM) gave a talk on “Women Leading The Charge: Breaking the Gender Barrier in Malaria and Vector-Borne Disease Response.” She began by emphasizing the importance of support from family and mentors in the development of a female scientist. Karema also stated that whether as patients or caregivers, women bear a disproportionate share of the health, societal, and economic burden of malaria and VBDs. She urged more women to participate in malaria strategy and policy development, recognizing the progress made in terms of women holding such positions over the years. Karema emphasized the importance of recognizing women's achievements in the field, highlighting an award that was created to honor Mwele Malecela's legacy by mentoring female leaders in NTDs. She encouraged PAMCA to transition from gender-unequal programs to gender-transforming programs and advised women in vector control to take action in order to expand their role and advance their involvement in positions of leadership.
Parallel Scientific Session 7 - Vector surveillance: surveillance systems, community-based surveillance, epidemiology, disease control programs and global health
Session Chair: Mercy Opiyo; Co-chair: Mauro Pazmino
Steven Gowelo (University of California San Francisco, United States) proposed a replacement of a paper-based Entomological Surveillance Planning Tool (ESPT) with a digital entomological surveillance planning tool (eSPT) for better surveillance outcomes. Despite the crucial role entomological surveillance plays, implementation is always arbitrary, hence exhibiting the need for a digital platform for effective entomological surveillance. Therefore, a digital version of the surveillance tool was developed, tested with stakeholders, and piloted in Ethiopia, Malawi, and Mozambique. The study remarkably increased the acquisition of participants’ knowledge and gained confidence in developing entomological surveillance plans, an essential component of entomological surveillance.
Abdoulaye Niang (Research Institute of Health Sciences - IRSS, Burkina Faso) presented the need to engage local communities to achieve better surveillance of malaria vectors in Burkina Faso. They conducted a study, where government stakeholders, researchers, university members, and the NMCP gathered along and decided to train new entomologists within the Ministry of Health for effective entomological surveillance at the country level. Participants were trained in larvae and adult mosquito collection methods in the field, assessment of resistance profiles, morphological identification of mosquitoes, sample conditioning, and others. A pre- and post-test were conducted to evaluate the training; participants lacking in some ways were re-trained while others were deployed in districts for entomological surveillance.
Mauro Pazmino (University of Glasgow, United Kingdom) in his presentation emphasized that vector’s age is a crucial component for entomological surveillance as it determines malaria transmission. However, the available working models involving complex and time-consuming dissections are not efficient and are unsuitable for field samples exposed to different temperatures. To address this gap, he proposes an improvement in the infrared spectroscopy-based surveillance generalization model for better age grading, blood meal, and species identification of wild mosquito populations irrespective of their setting. Upon comparison of the age predicted by infrared spectroscopy algorithms against the predictions using the current methods, they were able to demonstrate that infrared spectroscopy with machine models predicted better biological ages. This is a step forward in transforming malaria surveillance without limitations.
Gift Mwaanga (Macha Research Trust, Zambia), reported on the bio-efficacy of Attractive Targeted Sugar Bait (ATSB) in Western province Zambia. During the Phase III epidemiological trial, ATSBs were placed for seven months on the outside wall of households in twelve selected clusters. Once collected, labeled and conditioned in a pre–designed wooden box for further experiments, new ATSBs were installed. Among collected ATSBs, the non-damaged were used to evaluate the product bio-efficacy. For 48 hours, Anopheles gambiae s.s (Kisumu) were left in cages where the removed ATSB was mounted. Compared to the new ATSB, the results showed that the field-deployed ATSB retained bio-efficacy mortality above 80% even after being deployed for seven months.
Parallel Scientific Session 8 - Precision public health and innovations for VBD elimination: artificial intelligence, entomological databases, genomic surveillance, new and re-emerging disease vectors, climate change, One health
Session Chair: Josephine Malinga; Co-chair: Nick Golding
Gilles Yemien (Research Institute of Health Sciences - IRSS, Burkina Faso) presented his study on the identification of yellow-g in Anopheles gambiae, the gene involved in eggshell formation in Drosophila melanogaster, and the design of molecular strategy to study its function in view of genetically controlled malaria vectors. Using the Basic Local Alignment Search Tool (BLAST), CD-Search, and gene expression databases, AGAP005958 was found to be a yellow-g ortholog in An. gambiae. He added that AGAP005958 may be involved in An. gambiae fertility. However, in vivo studies are required to determine its function in An. gambiae, and its suitability as a genetic control target.
Odette Nabasnogo Zongo (Research Institute of Health Sciences - IRSS, Burkina Faso) presented her research, which aimed at designing an in-silico model to study the beta tubulin2 gene in Anopheles gambiae related to male infertility. Sheused the FlyBase database to identify and design a guide RNA to serve as CRISPR-Cas9 guide to the target site. Three orthologs for beta tubulin2 in An. gambiae (AGAP008622, AGAP010929 and AGAP008623) were identified. The final design may be injected into the mosquito for in vivo testing to evaluate Drosophila AGAP008622 function in An. gambiae in order to create genetic control techniques against malaria vectors.
Prashanth Selvaraj (Bill and Melinda Gates Foundation - BMGF, United States) presented his study entitled, “Microsporidia MB: Evaluating the impact of symbiont-based malaria vector control via EMOD, an agent-based model of vector genetics and malaria transmission”. Drivers of microsporidia prevalence in vector populations were investigated with conclusive outputs, regarding seasonality, horizontal and vertical transmission, and fitness costs. The model suggested that microsporidia MB can be a valuable tool in the fight against malaria transmission in sub-Saharan Africa even with limited deployment. Future studies should look at refining the model and cost-effectiveness of microsporidia MB deployment.
Josephine Malinga (Swiss Tropical and Public Health Institute, Switzerland) discussed the value and application of modeling to provide evidence that combines data, models, and simulations to answer stakeholders' questions and accelerate product development. She cited projects that used modeling to develop oral chemoprevention drugs, pre-erythrocytic monoclonal antibodies, and also investigated the public health impact of malaria vaccines. Notably, a simulation model in humans is driven by parasite dynamics and immunity and is linked to a model in mosquitoes. Malingaalso presented the outcomes of ongoing projects and emphasized the importance of intervention layering in disease prevention and progress toward malaria elimination.
Nick Golding (Telethon Kids Institute, Australia) presented on mapping the current and potential future distribution of Anopheles stephensi in Africa. The spatial model was developed while considering micro-climate suitability, larval habitat preferences, spatial spread, and variable probability of detection. Analysis suggests that Central Africa would be suitable for vector persistence due to its microclimatic conditions, however, the probability of detection is estimated to be minimal across most of the continent. Golding added that maps can be routinely updated as information grows on An. stephensi distribution and surveillance efforts and are disseminated to mosquito control experts through the Vector Atlas.
Dominic P. Dee (Imperial College London, United Kingdom) provided an update on the Malaria INtervention Tool (MINT), an online tool used to determine the most cost-effective interventions used in a region. The update includes new pyrethroid-pyrrole nets and features that allow for multi-region strategies. His methodology included the use of experimental hut trials to characterize the efficacy of modeled ITNs, as well as a suppository simulation to create the interface. He concluded that when combined with real-world data, the MINT tool can assist in selecting the best vector control tool combinations in various settings.
Parallel Scientific Session 9 - Vector bionomics: vector biology, ecology, taxonomy, and population genetics
Session Chair: Lindelwe Mabika; Co-chair: Sanjay Curtis Nagi
Lindelwe Mabika (KwaZulu-Natal Department of Health, South Africa) and team in a bid to understand the outdoor biting and host seeking behavior of mosquitoes in the Anopheles gambiae complex, collected mosquitoes in two sites from September 2022 to June 2023 hourly using mouth aspirator from 5pm to 12am. These mosquitoes were collected in animal shelters, identified first morphologically and then using species specific PCRs. Mabika results unexpectedly revealed that the primary malaria vector was Anopheles arabiensis with a peak biting time between 7pm and 10pm in both districts.
David Audu (Federal University of Agriculture, Nigeria) presented his work aimed at evaluating the effect of supplementing sugar meals with either herbal or synthetic antimalarials on the microbiota of Anopheles mosquitoes given their role in either preventing or promoting the transmission of malaria. Mosquitoes were collected from Odeda Local Government in Nigeria and once in the insectary, 250 females were split into five groups and exposed to Morinda lucida, artemether-lumefantrine (AL), Morinda lucida + artemether-lumefantrine, amoxicillin and distilled water for 1 hour in different groups. Gut enzymatic activity and microbial composition will be analyzed 24, 48, and 72 hours after exposure in order to see if differences occur between groups.
Thomas O Onchuru (International Centre of Insect Physiology and Ecology - ICIPE, Kenya) gave a presentation on a symbiont-based approach for malaria control, emphasizing the interaction between Anopheles arabiensis and Microsporidia MB. Microsporidia MB has been shown to block the development of Plasmodium falciparum to its infective stage, the sporozoite. He highlighted features of this fungi that makes it suitable for vector control such as: horizontal and vertical transmission, avirulent but stable infection of male gonads and the possibility of using both male and female mosquitoes for dissemination. He concluded his talk by providing insights relevant for timing to release Microsporidia MB-infected mosquitoes as a novel strategy for fighting malaria.
Henrique Silveira (Global Health and Tropical Medicine, Portugal) highlighted that bloodless diet is a promising alternative to blood for rearing Anopheles mosquitoes. Traditionally, blood from different sources was used for rearing mosquitoes, however, it is either expensive or has ethical issues. He discussed findings that a bloodless diet had yielded mosquitoes with comparable fecundity, longevity, and infection permissiveness. He presented the preliminary results of an ongoing research that maintained Anopheles stephensi colony for 3 years without blood. Silveira indicated that bloodless diet mimics blood, produces viable offspring, sustains long term production of Anopheles species and is a breakthrough in Anopheles rearing.
Sanjay C. Nagi (Liverpool School of Tropical Medicine, United Kingdom) came up with a novel locus that confers resistance to pirimiphos-methyl (PM) in Anopheles gambiae s.l. Whole-genome sequencing of mosquitoes from eight African countries helped to identify two carboxylesterase novel loci (COEAE1F and COEAE2F) for PM insecticide resistance. This gene is overexpressed in resistant An. gambiae s.l populations. Orthologs gene from Culex Pipiens was found to confer organophosphate resistance and is spread worldwide. Haplotype clustering indicates the occurrence of multiple and distinct selective sweeps on this locus. However, the mechanisms are often convergent across species and complex, so that many different haplotypes are under selection, and it is unclear what they all do.
This report is brought to you by the MESA Correspondents Akua Obenewaa Danquah Yirenkyi, Ashu Fred Ayukarah, Augustino Mmbaga, Helga D.M. Saizonou, Julius Ichodo Odero, Ndey Bassin Jobe and Temesgen Ashine, with the support of a former correspondent Leslie Diane Nkahe. Senior editorial support has been facilitated by Zawadi Mboma & Billy Tene.