9th PAMCA Annual Conference and Exhibition – 2023: Day 1

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”.

9th PAMCA Annual Conference and Exhibition

The #PAMCA2023 Annual Conference & Exhibition is being held at the Ethiopian Skylight Hotel, Addis Ababa, Ethiopia, from 17th to 21st September 2023. This year’s event marks the 9th annual edition and it is themed “Reorienting surveillance and management in the context of emerging threats of disease vectors”.

Opening Ceremony

The opening ceremony of the 9^th Pan-African Mosquito Control Association (PAMCA) Annual Conference and Exhibition was held on September 17, 2023, and was attended by PAMCA delegates from many countries around the world, and from diverse sectors including mosquito and mosquito-borne disease researchers, representatives of National Malaria Control Programs (NMCPs), policy makers and several partners (both national and international). The opening remarks were delivered by Delenasaw Yewhalaw (PAMCA Country Chapter Chairperson for Ethiopia), Emma Orefuwa (PAMCA Ag. Executive Director) accompanied by Prosper Chaki (PAMCA Executive Director) and finally Charles Mbogo, the PAMCA president. They all commended this year’s turnout, extended a warm welcome to all participants, and encouraged them to embrace this year’s annual meeting proceedings in the beautiful setting of Ethiopia’s Skylight Hotel. They also highlighted the need to search for and implement innovative solutions to eradicate vector borne diseases (VBDs) such as malaria in the African continent. This was done in a friendly atmosphere accompanied by light refreshments.

Keynote Speech

The Keynote address was delivered by Beyene Petros (Policy Study Institute, Ethiopia). Petros’ address delved into the conference theme of “Re-orienting surveillance and management in the context of emerging threats of disease vectors”. He commended the PAMCA secretariat for bringing together different stakeholders whose main work is centered around the eradication of VBDs in Africa. Petros discussed the current threats VBDs pose, from emergence to re-emergence and resurgence. He highlighted the challenges in vector control such as the development of insecticide resistance and the invasion of new species like Anopheles stephensi, and further recommended that PAMCA remain steadfast in addressing these challenges. He further noted that PAMCA has reinforced its capacity to support African countries in their efforts to eliminate malaria and other VBDs. He then concluded by encouraging everyone to continue to promote the one health approach in the control of VBDs, taking climate change, integrated VBDs surveillance, and capacity development of African scientists in data analysis and interpretation into account.

Day 1: Monday, 18th September 2023

Plenary Talk – Living with mosquitoes: Inevitable reality or an African fallacy? A call to action

Manuel F. Lluberas (Mosquito Den LLC, Puerto Rico) in his plenary talk urged the audience to explore thinking out-of-the-box while seeking solutions against mosquito species. He highlighted that the eradication of malaria in the South American Region was achieved in the mid-1950s. However, the elimination gains were not sustained due to policy failure to control disease-carrying insects. On the other hand, Africa was not included in the malaria eradication arrangement. Malaria causes a serious disease burden in Africa, while the dengue burden in America still far exceeds other viral diseases. He emphasized on finding a way to eliminate vectors that transmit diseases regardless of the species and combine strategies not only within countries but also across borders, perhaps globally. He urged entomologists to continue to work together as first responders in order to be able to deal with any emergencies. He concluded by encouraging National Malaria Control Programs (NMCPs) to rebrand their programs and set up advisory boards involving multi sectoral representation to draw on resources beyond health for comprehensive vector management.

Parallel Scientific Sessions

Parallel Scientific Session 1 – LLINS, IRS, and insecticide resistance management

Session Chair: Basiliana Emidi; Co-chair: Magellan Tchouakui

Magellan Tchouakui (Centre for Research in Infectious Diseases, Cameroon) presented their research work on new nets designed to mitigate pyrethroid resistance. The main objective of their study was to evaluate the performance of new generation nets (NGN) against pyrethroid resistant malaria vectors compared to pyrethroid-piperonyl butoxide (PBO) based and pyrethroid only nets. To do this, they conducted both cone/tunnel tests and experimental hut trials. The study results showed that the InterceptorⓇ G2 net, a type of NGN, was the most efficient net against An. funestus in the region of Elende, Cameroon. He concluded by calling for an urgent need to implement a suitable resistance management plan to preserve the efficacy of the InterceptorⓇ G2 net.

Joseph D. Challenger (Imperial College London, United Kingdom) argued that experimental hut trials are key in assessing mosquito control interventions and are increasingly used to inform policy and product development. For better outcomes of experimental hut trials, there is a need to assess the level of variability. Using simulation-based methods, they were able to explore and establish variations in the number of mosquitoes entering the huts among others. Due to this finding, plans are underway to develop tools to improve the outcomes of experimental huts trials.

Ole Skovmand (MCC47, France) presented on improved test methods for Long Lasting Insecticidal Nets (LLINs) in laboratory evaluations. It was highlighted that the current methods used to evaluate Insecticide Treated Nets (ITNs) for prequalification do not support the improvements in the quality of ITNs. Net sampling should reflect production methods to ensure that the before and after tests yield accurate results. He recommended three alternative methods which are (i) chemical analysis, (ii) using bioassay median knockdown time only for insecticides with knockdown effect, and (iii) using a sufficiently resistant strain where mortality does not reach 100%.  He concluded that the wash interval of bed nets must follow the chemical regeneration.

Olukayode Ganiu Odufuwa (Ifakara Health Institute, Tanzania; London School of Hygiene and Tropical Medicine, United Kingdom; and Swiss Tropical and Public Health Institute, Switzerland) presented on the use of house modification tools (i.e., insecticide-treated eave nets (ITENs) and insecticide-treated window screens (ITWs)) for malaria control. Although the majority of malaria vectors bite indoors, house design influences the exposure of humans to mosquito bites. They used a 4×4 latin square design to assess the efficacy of unaged ITENs and ITWs, aged ITENs and ITWs and aged Olyset Plus ITNs by measuring the feeding inhibition of mosquitoes (An. arabiensis, An. funestus, Culex quinquefasciatus and Aedes aegypti). The results of their study showed that unaged ITENs and ITWs performed better than aged Olyset Plus ITNs. He concluded that ITENs and ITWs are efficient tools for additional protection against vectors of malaria and dengue.

Parallel Scientific Session 2 – Vector bionomics: vector biology, ecology, taxonomy and population genetics 

Session Chair: Diego Ayala; Co-chair: David P. Tchouassi 

Diego Ayala (Institut Pasteur, Madagascar) presented on the importance of human settlements on the adaptation of malaria vectors. Human settlement was found to create a suitable environment that facilitated the adaptation of malaria vectors. Although stable populations of An. gambiae and An. coluzzii are still found in areas far from human settlement, still outstanding phenotypic and genetic plasticity of An. coluzzii was observed across gradients of sylvatic and domestic settings. More importantly, malaria vectors adapt to new areas, while they remain stable in their host preference. In addition, natural areas can act as refugees for malaria mosquitoes escaping vector control measures and representing an epidemiological risk for zoonotic vector borne diseases.

Etienne Fondjo (PMI VectorLink, Cameroon) presented his team’s research aimed at assessing the biting and resting behavior of malaria vectors in Cameroon. Entomological sampling was made bimonthly in five sites that represented different geographical areas. Human landing and pyrethrum spray catches were used as collection methods. The result indicated that malaria vectors were observed biting both indoors and outdoors during the night, with indoor biting continuing during the morning. The malaria vectors, An. gambiae s.l. exhibited endophagic behavior in two of the study sites. These findings can help assist Cameroon’s NMCP in selecting appropriate and targeted vector control tools to reduce malaria burden.

Parallel Scientific Session 3 – Vector surveillance: surveillance systems, community-based surveillance, epidemiology, disease control programs and global health

Session Chair: Neil Lobo; Co-chair: Givemore Munhenga 

Karine Mouline (Research Institute for Development – IRD, France) presented her study which aimed at addressing the issue of low mosquitocidal plasma concentration of ivermectin in hosts, causing a reduction in efficacy and necessitating repeated dosing of this systemic insecticide. To achieve this, she tested a long-acting injectable ivermectin formulation (LAIF) which delivered the drug with a controlled kinetics. Calves were exposed to An. dirus and An. minimus after a single dose of LAIF. The study revealed that this single dose was able to kill mosquitoes that blood-fed on treated calves compared to untreated calves during a period of three months.

Mgeni M Tambwe (Ifakara Health Institute – IHI, Tanzania) assessed the reliability and performance of various malaria diagnostic tools i.e., malaria rapid diagnostic tests (RDT), light microscopy (LM) and quantitative polymerase chain reaction (qPCR) in detecting asymptomatic Plasmodium falciparum in school children (6-14 years) capable of infecting mosquitoes. Blood from P. falciparum positive children was fed via direct membrane feeding assays (DMFAs) to female mosquitoes. The results showed that positive asymptomatic P. falciparum children were able to infect mosquitoes and mRDTs detected 95% infected mosquitoes comparatively to LM (84%). Tambwe’s investigation reveals that asymptomatic infections with low gametocyte densities that can infect mosquitoes and maintain malaria transmission, can be accurately detected by RDTs.

Betwel John Msugupakulya (Ifakara Health Institute – IHI, Tanzania), conducted a systematic review to assess the contribution of different vectors in malaria transmission in eastern and southern Africa years after the implementation of ITN and IRS. Studies published between 2000 and 2022 were selected from three online databases. The proportional contribution of each species to malaria transmission was calculated using data extracted from these studies i.e., biting rates, sporozoites infections, and entomological inoculation rate (EIR). The results suggested that Anopheles gambiae was the major vector before 2010, beyond which, Anopheles funestus took the lead. These same trends were equally observed with the entomological inoculation rate. The review also showed that the vector composition in eastern and southern Africa has changed after the implementation of vector control tools.

Parallel Scientific Session 4 – Larval source management and integrated vector management, New and re-emerging vectors

SessionChair: ManuelFLluberas; Co-chair: PatriciaL.V. Belisse 

Patricia Lucie Vanessa Doumbe Belisse (OCEAC, Cameroon) presented on the impact of larviciding in malaria transmission and vector dynamics in the city of Yaoundé, Cameroon. To do so, a two-arm cluster randomized trial study was conducted with a total of 26 clusters, 13 clusters each for both control and treatment. During the intervention period, they achieved over 70% mosquito density reduction, an impact that was observed during both wet and dry seasons. Findings also indicated a decrease in malaria prevalence from 24% to 13.16%. She concluded that larviciding is a potential tool for sustaining the strides made in malaria control.

Ace North (University of Oxford, United Kingdom) modeled the impact of gene drive releases on the burden of malaria in West Africa. The study was carried out in 15 representative Central and West African countries using a combined entomological-epidemiological model to estimate the impact of gene drive on the reduction of the mosquito population density. Results showed a great and sustained vector population suppression in the most populated sites. This suppression contributed to a decrease in the disease prevalence. In addition, modeling the association between RTS-vaccine/gene drive implementation and the shift from pyrethroids to novel PBO-nets was found to be beneficial for high-risk settings.

Dereje DA Alemayehu (Alameda County Mosquito Abatement District, United States) presented on Mosquito Abatement Through Empowerment (MATE), a program developed to use a donated tractor for community farming. MATE aims to eliminate stagnant water that might serve as potential breeding habitats for mosquitoes. In the long run, funds obtained from community farming will be used to support vector control interventions such as buying nets, housing improvement, and assisting in capacity building in mosquito biology and surveillance. Alemayehu concluded his presentation by insisting that community empowerment extends beyond bed nets to achieve malaria control and elimination.

Stephen O. Okeyo (Kenya Medical Research Institute – KEMRI, Kenya) spoke on a new spatial repellent transfluthrin base intervention which used transcriptomic data to identify potential markers of transfluthrin insensitivity in Anopheles gambiae ss. The authors used a high throughput screening system on Kisumu, susceptible; and a local resistant strain to determine the spatial activity index of transfluthrin-treated surfaces. The main results showed varying responses from one strain to another. The comparison of metabolic expression of monooxygenase genes between non responder and responder mosquitos revealed an over-expression of CYP12F2, suggesting a possible transformation of transfluthrin by cytochrome-P450 resulting in an absence of olfactory responses.

Cynthia CAO Odhiambo (Kenya Medical Research Institute – KEMRI, Kenya) presented a study that aimed to identify insecticide resistance markers in Anopheles arabiensis and Anopheles gambiae. The Weighted Gene Co-Expression Network Analysis (WGCNA) algorithm was used to identify genes showing similar expression patterns and identify genes that can be used as markers for insecticide resistance surveillance. Phenotypic resistance to permethrin, alphacypermethrin, and deltamethrin insecticides was assessed for both species. Overall, in both mosquito species, four resistance markers were identified: serine protease, E3 ubiquitin-protein ligase, cuticular protein RR2, and leucine-rich immune protein. However, Odhiambo suggested that the functional validation of these findings is required.

Helen Nnenaya Nwanosike (MESA, Spain) commenced her presentation with an introduction to MESA Track, MESA’s open knowledge platform for global malaria projects, catering to researchers, NMCPs, funders, and policymakers. MESA Track enhances project visibility and facilitates comprehensive landscaping reviews on selected subjects. She then introduced MESA’s “Landscaping Review on Anopheles stephensi“, which analyzes research on An. stephensi since its 2012 invasion into Africa. This review encompasses examination questions, participating countries, institutions, and principal investigators. Helen concluded by emphasizing identified research and funding gaps, including the necessity for impact studies examining the correlation between An. stephensi invasion and malaria burden, evaluating the effectiveness of current surveillance methods and control strategies like gene modification and larviciding, and investigating the influence of climate change on An. stephensi distribution.

Parallel Symposium Session 1 – A new tool to enable more efficient delivery of indoor residual spraying. 

Organizer: Inigo Garmendia, PhD

Iñigo Garmendia (Goizper S. Coop, Spain) presented the IK Smart Light, a new tool to enhance the use of indoor residual spraying (IRS) in national malaria control programmes. The IK Smart Light addresses issues of over- and/or under-dosing, a lack of training equipment, variations in working conditions, a lack of supervisory employees, time and resource constraints to train teams. Its design prioritizes simplicity, speed, and cost-efficiency, guiding spray operators on the correct spraying distance and speed, while facilitating spray quality and quantity evaluation by supervisors. The IK Smart Light comprises three tools: 1) an electronic device (incorporating a beeper, laser, and three-color LED), 2) a smart phone app and 3) a cloud-based digital platform. The beeper determines spraying speed, the laser measures spraying distance, and the LED lights signal whether operators are under or overdosing. The electronic device (tool one) assists operators, while supervisors can assign and rate workers via the smartphone app along with gathering information and evaluating quality of daily output. The third tool visualizes global statistics for malaria control programmes. This invention promises significant improvements in IRS program training, supervision, data gathering and analysis, and overall effectiveness during implementation.

Parallel Symposium Session 3 – Larval Source Management, a Tale of Two Continents: Integrated Vector Management in North America and Africa

Organizer: Ary Faraji, PhD

Ary Faraji (Salt Lake City Mosquito Abatement District, United States) shared his experience in integrated vector management in a mosquito abatement district in Salt Lake City, that covers an area of 13,000 hectares of wetland habitats. With an $8 million budget, 13 full time staff and 40 seasonal staff (entomologist, biologists, ecologist, virologist & molecular biologist), state-of-the-art laboratories and equipment. They have become experts at mosquito control in predictable flood water habitats, salt marshes, and bogs. Their integrated vector management integrates research, training and operations, public education, control, and surveillance. He concluded by stating that their efforts have ended the need for the population to use ITNs or IRS. Further, he also asserted that if larval source management (LSM) was doable with 13,000 hectares of wetland in Salt Lake City, it can be implemented in Africa too.

Mark Breidenbaugh (Northwest Mosquito and Vector Control District, United States) presented his work on LSM in Southern California. This independent agency was formed in 1959 with the goal of eliminating vectors over an area of 350 sq. miles with a population of approximately 900,000. Their team comprises 20 full-time and 10 seasonal employees for 8 zones and each assigned with 1 full-time technician. The work is performed in 7 communities and a dedicated wetlands zone for larval sampling, identification, and treatments. Treatment decisions are made by the technicians often on-the-spot which consist of dumping/draining, application of larvicides (oil, liquid, granules, sachets, etc.), and biological control (fish).  The principle behind their work is to manage mosquito larvae in the early stage in order to prevent adult mosquitoes from impacting public health.

Marc Clifton (North Shore Mosquito Abatement District, United States) presented their LSM work at the North Shore Mosquito Abatement District established in 1927 to control Culex restuans (Theobald) and Culex pipiens (Linnaeus). It covers 70 sq. miles and serves 14 communities totaling 300,000 people. The team comprises 7 full-time staff and 14 seasonal staff who undertake larval control treatment of 61,865 stormwater catch basins, 4,538 mosquito breeding sites and 723 acres of floodwater multiple times per year. The control materials they use are VectoLex, VectoBac, BVA 2 larvicide oil and Sumilarv 0.2 g which are highly specific to mosquitoes with human and environment safety profiles. To address logistical challenges involved, they have developed a digital geographic information system (GIS) infrastructure for field surveillance of larval habitat. In addition, residents also report information by mobile technology of potential habitats in their areas. This has been key for mosquito control in this setting.

Mark Smith (Metropolitan Mosquito Control District, United States) walked the audience through their integrated vector management program which focuses on surveillance and species identification, snow melt/floodwater mosquito control (Aedes), cattail mosquito control (Cq. perturbans), vector control and surveillance (Culex), public education and outreach, tick surveillance, and black fly (biting gnat) control. It is a local government program with a budget of $19 million and covers 7 counties, 182 communities and townships serving 3 million people. They have adopted their integrated pest management to accommodate for each species of concern and regional larval control programs, surveillance-based larvicide operations using mobile technology, and efficient control operations by use of helicopters and drones. In conclusion, surveillance of larval habitats can be effectively coordinated with efficient operations. They work on the principle of organization and consider it the key to success.

Dennis Wallette (Tangipahoa Mosquito Abatement District, United States) walked the audience through the larviciding equipment and techniques used in Louisiana in rice fields, cypress swamps, coastal marshlands and roadside drainage ditches which are the main breeding areas for Culex quinquefasciatus, a primary vector of West Nile virus in the Southeast U.S. Methoprene mineral oil and granules are used to treat drainage ditches. They use Wide-Area Larviciding (WALS) technique, spray equipment such dynafog LV-8, A1 mist sprayer and the Buffalo Turbine. They also use drones and aircrafts to facilitate larviciding. They acknowledge having the right equipment is key for LSM.

Mohamed Traore (University of Bamako, Mali) presented a first of its kind pilot study on integrated vector control management in Mali. This was a collaboration between two mosquito control districts of the USA and Africa. He highlighted the performance challenges of core intervention strategies (ITNs and IRS) and proposed integrated vector management as a solution to achieve eradication. Collaboratively, the USA and Africa partners received training on surveillance, products support and larviciding operations. The results were impressive which demonstrated the added advantage of integrating LSM in their national malaria programs despite the challenges around funding, limited capacity and equipment, and vector resistance. He concluded with a thought-provoking question for the global partners on huge spendings on the core malaria interventions (ITNs and IRS), when greater public health gains can be achieved by redirecting the same efforts towards LSM.

Christian Atta-Obeng (National Malaria Elimination Program, Ghana) presented their experience with LSM managed by a private sector entity, Zoomlion Ghana Ltd, and supervised by the government. He highlighted the serious challenges faced by the core vector control strategies (ITNs and IRS) that shifted their approach towards integrated vector management (IVM). The IVM approach integrates vector control, entomological surveillance, novel new tools, and multisectoral collaboration to control malaria. They also engaged stakeholders at all levels, trained workers, performed mapping of water bodies and larviciding, recruited spray operatives, and trained people from implementing communities. The use of mobile applications for data capture was key in the success of the program. Delays in receiving payment from the Government for the recruited spray operatives, and in procurement and shipment of larvicide presented a major challenge. However, debt financing from commercial banks and early initiation of procurement helped to overcome these challenges.

Emmanuel Hakizimana (Rwanda Biomedical Centre, Rwanda) centered his presentation around the reasoning for the co-deployment of LSM with the ITNs. The presenter highlighted that Rwanda experienced a 20-fold increase in malaria cases between 2011 – 2016 hence the need for LSM which was deployed on 93, then 336 and finally on 946 hectares of rice field, intercrop drains, mining pits and water paddles.  The deployment of LSM complemented ITNs, harnessed community support and attracted government and local partners. On the other hand, non-targeted peri-domestic breeding sites sustaining mosquito density (Culex spp) and limited resources for scale up for managing community expectations posed some challenges. Future plans to scale-up LSM in Rwanda include combination of drones and hands-based application of larvicides and community engagement to control peri-domestic breeding sites.

Parallel Symposium Session 4 – Scaling up malaria elimination: Public-private partnership and evidence-based programming to boost and accelerate progress in north-western Zambia.

Organizer: Buumba P Bubala. PhD

Buumba P Bubala (Ministry of Health, Zambia) started the symposium by briefing the situation on malaria prevalence in Solwezi. A district located in North-Western Zambia. She added that, despite the robust strategic plan for malaria elimination in place, inadequate funding, and little capacity building contributed to derailing its implementation. This necessitates the need to seek a different sustainable way to control the transmission. The public-private partnership (PPP), with First Quantum Minerals Limited (FQML), identified among potential stakeholders has been seen as a potential solution. Since 2021, a drastic decrease in malaria cases has been observed as the result of a PPP established. Bubala pinpointed major factors that contributed to their success, these include community participation, skilled human resources, the presence of the regional malaria end councils, as well as partnership and funding from FQML. He concluded by stating, PPP is the key to supporting and strengthening malaria elimination.

Mumba Temple (First Quantum Minerals Limited, Zambia) discussed their partnership with the Ministry of Health that was launched in 2020. In order to create this site-based malaria control, various parameters were assessed including malaria risk, a review of vector control strategies employed, case management, and funding. The main audit revealed that malaria accounted for the highest cause of sick offs, the support from the District Health Office (DHO) comprised mainly monetary and material assistance, parasitological and entomological surveillance were not localized, larval source management were not implemented and there was no standardized case management at health facilities.

Godwill Mlambo (First Quantum Minerals Limited, Zambia) presented actions taken by FQML from 2021 to address gaps identified by Mumba Temple. These actions include increasing budget allocation, capacity building, improving data management systems, implementing LSM and the creation of a local malaria control center (MoH/FQM) for sample processing. The progress of each of these actions have been monitored according to specific indicators. Consequently, annual entomological surveillance has been conducted, which includes recording species composition/distribution and assessing insecticide susceptibility. Mlambo concluded, emphasizing that entomological data should guide the selection of the most effective vector control method or insecticides and help monitor the impact of vector control interventions.

Herbert Tato Nyirenda (Copperbelt University, Zambia) presented a study titled “Malaria parasite prevalence survey in school children in Solwezi District”. A quasi-experimental study design was used, where a simple random sampling was done to enroll pupils aged 5 – 14 years for both FQML-supported catchment (intervention) and non-FQML-supported catchment (control). Lab-RDT and thick blood smear for microscopy analysis were done for each participant to determine malaria infection status. Findings suggest that malaria prevalence was nearly double in the intervention group compared to control. Furthermore, no significant difference was observed in malaria prevalence in the control between initial and subsequent assessments. Tato concluded his talk by pointing out that malaria is still a burden, emphasizing the need for increased efforts to curb asymptomatic malaria and highlighting the important role of the private sector in malaria control.

Parallel Symposium Session 5 – Vector genomics surveillance program in Africa: opportunities, progress, and future outlook

Organizer: Elijah Juma, PhD; Co-organizer: Alistair Miles, PhD

Elijah Juma (PAMCA), introduced in a broad manner the need for genomic surveillance to control malaria vectors. With the potential emergence of new resistant variants and species, it is an important task for African scientists to better equip themselves to respond to any challenges arising from anomalies they may encounter reviewing phenotypic data. As such, PAMCA, in collaboration with MalariaGen and other groups dealing with genomic data analysis such as G-AVENIR have implemented a big data analysis platform where genotype data are stored and are ready for analysis by anyone with a keen knowledge on genomic data analysis. A training course is available at: ‘https://anopheles-genomic-surveillance.github.io/home.html’. He emphasized that understanding phenotypes on a genomic level can inform decision making by competent authorities, leverage communication and advocacy between countries, and enhance the importance of implementing genomic data surveillance in routine entomological surveillance. Future prospects in this aspect include capacity building to enable young scientists to be more knowledgeable on data analysis, securing funding to support both sequencing and storage platforms in Africa, and fostering partnerships between genomic epidemiology and genomics for synergy.

Kwi Pilate Nkineh (Pan-African Malaria Genetic Epidemiology Network – PAMGEN, Cameroon) presented findings on the diversity, transmission dynamics and resistance of malaria vectors around the slopes of Mount Cameroon. The results showed that An. gambiae complex and An. funestus are the predominant Anopheles species. Additionally, An. cinctus was identified for the first time as a possible secondary vector for malaria. Biting patterns of Anopheles species were similar both indoors and outdoors, with the exception of An. nili.

Edward Lukyamuzi (PAMCA) demonstrated the importance of including genomic surveillance in routine surveillance. Using mosquitoes collected from Kwi Pilate’s study, DNA was extracted, and sequencing conducted. The genomic data analysis revealed that Anopheles coluzzii in the country formed two clusters, differentiating mosquitoes from the north and the south regions. Furthermore, within mosquitoes from the south two clusters were identified, with different levels of resistance confirmed by the presence of alleles conferring resistance to one population. This shows that within the same region, the same control methods cannot effectively manage all vectors present. This highlights how important including genomic surveillance could enhance both vector surveillance and vector monitoring.

Parallel Symposium Session 6 – Field Trials of Malaria Vectors Engineered with Gene-Drive: If Not Now, When?

Organizer: Ana Kormos, PhD

Ana Kormos (University of California Malaria Initiative – UCMI, United States) emphasized the need to reassess traditional vector control methods like IRS and ITNs due to various challenges such as vector and parasite resistance, financial investment limitations, distribution issues and environmental changes. She introduced the potential of genetically engineered mosquitoes and discussed the University of California Malaria Initiative (UCMI). One UCMI objective is to contribute to malaria eradication through mosquito population modification. As this progress is slow, the symposium aimed to emphasize the importance of fieldwork to advance this technology further.

Adionilde Aguiar (Ministry of Health, Sao Tome and Principe) provided an overview of malaria epidemiology in Africa, particularly in Sao Tome and Principe (STP). Recognizing insecticide resistance as a significant challenge. STP is considering trials of genetically engineered mosquitoes (GEM) as a safe and sustainable approach to eliminate and prevent malaria resurgence. Success in STP could encourage other African countries to adopt this tool as they strive to achieve the malaria free goal.

Greg Lanzaro (Vector Genetics Laboratory, United States) gave a brief outline of the framework guidance for testing genetically engineered mosquitoes (GEM). Phase 1 of the testing pathway has been ongoing since 2004. He stressed the ongoing burden of malaria and the importance of seizing the opportunity for eradication to prevent fatigue among investors, scientists, and communities. Lanzaro called for government stakeholder commitment to conduct GEM trials, assess efficacy in natural environments, evaluate risks if they do occur, and allow room for improvement.

Joao Pinto (University of California Malaria Initiative – UCMI, United States;Portuguese Institute of Hygiene and Tropical Medicine – IHMT, Portugal) reported on the use of Mark-Release-Recapture method used to estimate population size and characterize the population structure of Anopheles coluzzii as well as other non-target living organism within the mosquito breeding sites. Their aim was to evaluate the potential environmental impact of GEM in Sao Tome and Principe, to evaluate the first site of potential release and finally evaluate whether the GEM mosquitoes will be resistant to insecticide. They found Sao Tome and Principe to be the most appropriate for a first release and noted that the released GEM would likely have resistance due to local mosquito populations’ high insecticide resistance.

Lodney Nazare (University of California Malaria Initiative – UCMI, United States), introduced the Relationship-based Model (RBM) as an engagement framework strategy developed for gaining community acceptance of genetically engineered mosquitoes (GEM) trials in Sao Tome and Principe. In that settlement, RBM messages are specifically addressed at the community level to get their perception regarding the GEM implementation. They are delivered to schools to inform students and to the stakeholders for engagement. The preference of the community to get information is then assessed, scientific workshops and booklets are shared in schools, regular meetings with stakeholders take place, and the national media reports on the UCMI plan contributing to the goal of malaria eradication.

Parallel Symposium Session 7 – Pan African Vivax and Ovale network (pavon): scoping the burden and transmission of P. vivax and P. ovale in Africa.

Organizer: Isaac Quaye, PhD

Bruna Djeunang (Pan African Vivax and Ovale Network – PAVON, Cameroon) on behalf of Isaac Quaye (PAVON) gave a brief introduction on PAVON, a consortium of 14 African countries, aiming at sustaining surveillance, standardizing procedures, and training in Plasmodium vivax and Plasmodium ovale research in Africa. She added that the absence of tests to detect cryptic and hypnozoite infections, the lack of a strategy for testing and treating asymptomatic infections, and the invasion of Anopheles stephensi in Africa, an efficient vector of P. vivax, needs to be addressed as part of the goals to achieve malaria elimination. She concluded by stressing the need for sustained research, looking for new strategies and innovation for surveillance and improvement of countries’ infrastructural capabilities to better understand the biology of P. vivax transmission.

Laurent Dembele (University Of Science Of Technical And Technology De Bamako, Mali) discussed tackling the relapsing Plasmodium species along with Plasmodium falciparum to enable malaria elimination. He highlighted that P. vivax and P. ovale can undergo dormant liver stage “hypnozoites’’ that escape treatment and cause relapsing infections. Although studies to understand the biology of these species and their susceptibility to reference and novel antimalarial drugs are ongoing, the discovery of Plasmodium Liver-Specific Protein 2 (LISP2), an early marker for liver stage development, brings hope for radical cure drug discovery against P. vivax. However, new antimalarial drugs have shown promising results against P. ovale. Dembele concluded the talk by emphasizing the need for innovative diagnostic tools and treatment against P. vivax and P. ovale hypnozoites for the effective control of P. vivax and eventual elimination.

Bruna Djeunang (PAVON, Cameroon) presented a literature review on the profile of vectors involved in the transmission of P. vivax and P. ovale in Africa. She pointed out that while the transmission process of P. ovale in Africa is well known, the epidemiology of P. vivax remains unclear. Additionally, the predominant vector of P. vivax in Africa remains unknown. Local African malaria vectors, An. arabiensis, An. pharoensis, An. gambiae s.s, An. coluzzii and An. funestus were found to be infected with P. vivax. Meanwhile, Africa is facing a new threat, the invasion of a new and efficient malaria vector An. stephensi in recent years. She added that studies showed non anopheline mosquitoes might also be involved in the transmission of P. vivax. Strengthening research and collaboration, as well as creating a database that will facilitate decision-making for vector control in Africa was highlighted as a gap that remains to be addressed.

Parallel Symposia Session 8 – From research to impact: steps in the development, registration and deployment of a new insecticide chemistry to help tackle the growing threat of insecticide resistance in malaria vectors in sub-Saharan Africa.

Organizer: Ayumi Kawase

Ayumi Kawase (Mitsui Chemicals Crop & Life Solutions, Inc, Japan) presented on the development and use of an Indoor Residual Spraying (IRS) product called VECTRON T500, containing a TENEBENAL insecticide. TENEBENAL affects a newly discovered site on the GABA_A receptor of the insect nerve. By stopping the nerve signal, the insecticide causes the death of the mosquito upon contact. The product has long residuality, meaning it stays long on sprayed surfaces.  It has also been evaluated to have long-term efficacy on various surfaces such as mud, concrete, painted cement, tile, and dung. Additionally, it is an odourless and non-toxic ingredient which is important for community adherence. She concluded by sharing that VECTRON T500 met WHO prequalification on March 11, 2023. As of September 2023, 18 countries in Africa have registered to possibly use the product.

Renaud Govoetchan (London School of Hygiene and Tropical Medicine – LSHTM, United Kingdom) followed up with a presentation on the community evaluation of VECTRON T500 for malaria control in central Benin. The study was conducted through a two arm non-inferiority cluster randomized trial by comparing VECTRON T500 (also referred to as Arm A) with FLUDORA Fusion (also referred to as Arm B) in 15 villages. The results of their study showed that VECTRON T500 was non-inferior to FLUDORA Fusion in its impact on malaria vector density when applied for IRS at a community level. However, VECTRON T500 remained efficacious in WHO cone bioassays 24 months post-application. It was concluded that this prolonged efficacy means that VECTRON T500 can be applied every two years and may help reduce the operational costs of IRS.

Delenasaw Yewhalaw (Jimma University, Ethiopia) presented their study on the residual efficacy of VECTRON T500 in Ethiopia. They determined the effect of different wall substrate types on the persistence of VECTRON T500, as well as the susceptibility of local mosquito populations to the product. The results of their study showed that the residual efficacy of VECTRON T500 extends up to nine (9) months.  The product also performed well across all wall surface types throughout the duration of the study. Furthermore, CDC bottle bioassays showed that An. gambiae s.l., An. arabiensis susceptible strain, and An. stephensi were found to be susceptible to a range of doses of TENEBENAL.

Mbanga Muleba (Tropical Diseases Research Centre, Zambia) presented research findings from a small-scale community household evaluation of VECTRON T500 as a control tool against malaria vectors in Zambia. Both insectary reared and wild mosquitoes were used for this study. The results showed that VECTRON T500 had 10 months of residual efficacy against susceptible An. gambiae s.s. Kisumu strains mosquitoes. Also, VECTRON T500 showed at least 6 months of residual efficacy against resistant wildtype An. funestus s.I. mosquitoes. He concluded that since there is widespread resistance of malaria mosquitoes to pyrethroids, new mode of action insecticides such as VECTRON T500 are required to implement insecticide resistance management strategies.

Sydney Abilba (Ghana Health Services, Ghana) presented on the challenge of insecticide resistance in Ghana and the decision-making process to include vector control tools containing insecticides with novel modes of action (e.g., VECTRON T500). Indoor residual Spraying (IRS) and Long-Lasting Insecticidal Nets (LLINs) remain at the frontlines of malaria vector control. However, with the current challenges associated with insecticide usage such as the rapid development of resistance, there is a need to expand our insecticide arsenal. According to him, Ghana is able to review data and incorporate new insecticides such as VECTRON T500 into its current malaria control interventions.

Parallel Symposia Session 9 – Technical updates about the preparedness, gaps, and response to Anopheles stephensi in Africa

Organizer: Ayman Ahmed, PhD

Ayman Ahmed (University of Khartoum, Sudan), who delivered the opening presentation highlighted technical challenges with An. stephensi such as the ability to transmit both Plasmodium falciparum and P. vivax, the resistance to all common classes of insecticides, the diversity in larval habitats, and the presence in urban, peri-urban and rural settings as the principal technical issues for the control of this vector. Ahmed also pointed out a shortage of trained personnel, and operational and laboratory resources as the major resource gaps. Adding that current vector control policies are out of date, he came to the conclusion that action should be taken to address these challenges and fill the gaps.

Nathan Rose (Oxitec Ltd, United Kingdom) discussed the Djibouti friendly mosquito program, a current project that will be used in the future to manage the invasive species An. stephensi. This program consists of using gene drive technology, i.e., to insert two elements into male mosquitoes: a self-limiting gene and a tracking gene. When released, these male mosquitoes’ mate with wild female mosquitoes and the female dies, hence reducing mosquito density in the community. The tracking gene will be used to assess the distribution of these modified mosquitoes.

Fitsum Girma Tadesse (Armauer Hansen Research Institute, Ethiopia) presented several factors associated with An. stephensi that are daunting. He emphasized that An. stephensi is a bigger concern because of the vector’s year-round persistence due to its preference for breeding in artificial and natural aquatic reservoirs, its ability to evade standard malaria control measures, its resistance to the insecticides currently used for IRS and LLINS, its ability to switch between human and animal hosts, and indoor and outdoor biting and his vector capacity to transmit both P. falciparum and vivax.

Seth Irish (Swiss Tropical and Public Health Institute, Switzerland) began with an update on the WHO initiative to stop the spread of Anopheles stephensi in Africa. Its five key goals are to promote collaboration, strengthen surveillance, exchange information, develop guidelines, and prioritize research. He gave a brief overview of the WHO Malaria Threats Map which has a section for surveillance of the vector’s spread and encouraged researchers to report negative as well as positive detection of An. stephensi. He then delved into a deep dive being carried out in India, Sri Lanka and Iran to understand surveillance and control of An. stephensi via discussion with researchers and policy makers. Findings indicate IRS was the main control strategy used, with lTNs and larviciding using fish taking a secondary role. He also noted that political situations in a country can hinder surveillance efforts.

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.