7th PAMCA (and 1st Virtual) Conference and Exhibition – 2021: Day 1

MESA Correspondents bring you cutting-edge coverage from the 1st Virtual and 7th PAMCA Conference & Exhibition 2021

Day 1: Monday, 20th September 2021 

Opening Ceremony and Keynote Address:  

The opening ceremony of the 1st Virtual and 7th Pan-African Mosquito Control Association (PAMCA) Conference was moderated by Silas Majambere (Director of Scientific Operations, PAMCA). He welcomed all attendees and highlighted the theme of the conference – “Empowering local institutions to set the agenda for the elimination of vector-borne diseases”. Majambere then invited Charles Mbogo (President of PAMCA), Samuel Dadzie (Chairman, PAMCA Local Organizing Committee – LOC, Ghana) and Prosper Chaki (Executive Director, PAMCA) to share with the audience their opening remarks. They thanked the sponsors and all attendees, giving the reason for the virtual conference – COVID-19. They also highlighted the need for a coordinated multisectoral approach in fighting vector-borne diseases, in the face of multiple outbreaks of mosquito-borne diseases.

The keynote talk on “Empowering local institutions to set the agenda for the elimination of vector-borne diseases” was given by Florence Larbi (Zoomlion Ghana Limited, Ghana), who stood in for Joseph Siaw Agyepong (Jospong Group of Companies, Ghana). She started by highlighting the burden of vector-borne diseases (VBDs) in Africa and globally, with a staggering 17% of all infectious diseases and one million deaths annually. The emergence and re-emergence and drivers of VBDs, particularly dengue in Africa was also discussed. Larbi pointed out the positives in increased coverage and use of vector control tools, as was observed in the decline of malaria between the years 2000 and 2015. She, however, emphasized that VBDs are multifaceted, hence requiring intersectoral and multisectoral approaches to control them. She outlined ways by which local institutions can be empowered for VBDs elimination. Larbi concluded that VBDs can be eliminated by coordinated and well-tailored efforts involving all stakeholders in vector control.

Plenary Session 1: Strengthening National Malaria Control Programs capacity for vector surveillance for malaria elimination

Keziah Malm (National malaria Control Program – NMCP, Ghana) presented vector control as a core intervention in the fight against malaria especially in high-burden countries Africa-wide which has mainly involved insecticide treated nets (ITNs) and indoor residual spraying (IRS). She recommended that malaria surveillance be implemented as a core intervention including the identification of vectors, species diversity, habitats and monitoring the impact of implemented control measures. She mentioned that according to Russel et al., 2020, 80% of countries use vector data for decision making, the remaining 20% don’t, mostly due to inadequate finances and human resources. Ghana has already launched entomological surveillance in 30 insecticide resistance monitoring sites amongst which 20 sentinel sites are also used for entomological surveillance. A wide range of entomological indicators were monitored such as vector diversity, abundance, among others. Malm mentioned the example of the National Insecticide Resistance Monitoring Partnership (NIRMOP) as a case study conducted in the Obuasi-Ashanti region in Ghana. NIRMOP brings together researchers and partners in malaria vector control to plan, conduct, and evaluate results of insecticide resistance testing at sentinel sites throughout the country.  The project has produced some preliminary findings highlighting gaps in the entomological surveillance involving limited funding, lack of capacity in entomology amongst others that need to be filled. To end the presentation, she made a call to action to donors, WHO, Africa CDC, NMCP, PAMCA, RBM, governments and other stakeholders to collaborate and develop a strategic plan and also build capacity in vector control that could lead to informed decision-making for better vector control management strategies.

Symposium Session 1:

Parallel symposium 1 – Strengthening entomological surveillance capacity towards malaria elimination in sub-Saharan Africa

This symposium looked at Pan-African Mosquito Control Association (PAMCA) efforts in strengthening entomological surveillance capacity. Three countries participated in this program at different levels and each country represented their progress. Silas Majambere (PAMCA, Kenya) and Samson Kiware (PAMCA, Kenya) talked about PAMCA’s plans in ensuring an Africa that is vector-borne disease-free. Majambere and Kiware presented PAMCA’s activities which centered on capacity building and knowledge management. PAMCA aims to train entomologists at National Malaria Control Program (NMCP) and district level while also fostering better collaborations between research institutions and NMCP. PAMCA is also working towards the goal of localizing decision making and data management so that they are not outside driven but are generated to respond to local needs. Activities in Burkina Faso was represented by Abdoulaye Diabate (Institute for Research in Health Sciences – IRSS, Burkina Faso), Cameroon was represented by Charles Wondji (Centre for Research in Infectious Diseases – CRID, Cameroon) and lastly, Tanzania was represented by Fredros Okumu (Ifakara Health Institute – IHI, Tanzania). Ghislaine Aquedeogo-Ametchie (PAMCA, Kenya) from Ivory Coast talked about the people involved in vector surveillance in the three countries. The three countries partaking in the program lacked entomologists at NMCP level, district level and facility level. The research institutions (CRID, IRSS and IHI) with support from PAMCA conducted training of vector surveillance specialists with the collaboration of the Ministry of Health at the district level. Aquedeogo-Ametchie reported that less than half of the people involved in vector surveillance in the three countries were trained entomologists with a third being women. Most of the entomologists had PhD acquired from their countries and the vast majority worked in research institutions and universities. There was a collaboration between the Ministry of Health, which was the implementing body and research institutions with support from funders who provided the interventions. Data was stored using archaic data servers with the exception of Tanzania which had better databases. The general conclusion was that all three countries had insufficient human resources.

Parallel symposium 2 – Vector surveillance during the New Nets Project pilot evaluations: Estimating the entomological impact of next-generation insecticide-treated nets in high-transmission malaria endemic countries

The session was moderated by Okefu Okoko (National Malaria Elimination Programme – NMEP, Nigeria), who gave a brief background of the New Nets Project (NNP). The NNP uses 4 surveillance indicators to evaluate the impact of next-generation insecticide-treated bed nets (ITNs) distributed under the project: epidemiological, anthropological, durability monitoring of ITNs and entomological indicators. The NNP was designed to accelerate the scale-up of next-generation, dual active ingredient ITNs and provide evidence of their efficacy, effectiveness as well as cost-effectiveness. The goal of this symposium was to share the progress of the pilot NNP in 4 participating countries: Burkina Faso, Rwanda, Mozambique and  Nigeria, represented by Wamdaogo Guelbeogo, (National Center for Research and Training on Malaria – CNRFP, Burkina Faso),  Emmanuel Hakizimana (Rwanda Biomedical Center, Rwanda), Dalcisaria Marrenjo (National Malaria Control Programme – NMCP, Mozambique) and Adedapo Adeogun (Nigeria Institute for Medical Research – NIMR, Nigeria). They distributed Interceptor G2 (IG2), Piperonyl Butoxide (PBO), Royal Guard (RG) and standard ITNs, as well as combined standard ITNs plus indoor residual spraying (IRS). Similar tests and methods including susceptibility tests, human landing catches, CDC light traps are used across all the study areas. Baseline reports indicated that the most abundant anopheline in the four study countries is Anopheles gambiae s.l, followed by Anopheles funestus and then, other Anopheles species. Indoor and outdoor biting ratios are similar in most of the pilot areas, skewed towards outdoor biting but seem not to be significantly different. Nightly biting patterns also differed between areas, from the early night (19:00 to 20:00) to early morning (2:00 to 6:00), although there were some common trends in the biting timings observed. However, pyrethroid resistance profile is moderate to high across the study areas, depending on insecticide exposure, with the exception of Rwanda where pyrethroid resistance was very low. All four countries reported variations in ITNs coverage to households after the net distribution campaigns. However, the ‘use given access’ proportion is encouraging across the study countries.

Scientific Sessions:

Parallel session 1: Vector surveillance, entomological capacity and National Malaria Program support

Jessica Amegee Quach (Liverpool School of Tropical Medicine – LSTM, UK) began her talk by introducing the Partnership for Increasing the Impact of Vector Control (PIIVeC) as a multinational programme aimed at developing and training postdoctoral fellows to build reliable evidence for informed vector control strategies. Her research aimed at assessing the effectiveness of the programme in accelerating the development of the fellows’ expertise in addition to evaluating the factors that have hindered or enhanced their contribution towards the programme’s success. The four-year study used a mixed methods approach to collect data. From her study, Amegee Quach found that four overlapping factors contributed to the fellows’ expertise development. These included the mentoring structure and attributes of the programme, the flexibility and high diversity of support, professional and personal development opportunities, the individual personalities and intrinsic motivation and the quality of the fellow-advisors relationship and institutional working environment. She concluded the talk by stating that there is an increase in the use of research consortia models that aimed at developing leadership and expertise among scientists. Furthermore, multifaceted interventions formed a vital support approach for postdoctoral fellows for them to develop varying critical capacities and transferable skill sets. In the end, Amegee Quach emphasised the importance of having diverse professionals supporting postdoctoral fellows in order to provide them with a holistic approach in regards to training and perspective in order to hone an array of skills that would position the fellows’ research outputs in national, regional and international contexts.

Alex K Musiime’s (Infectious Disease Research Collaborations, Uganda)  presentation was about a  study conducted in the historically high malaria transmission district of Tororo, Uganda, where intensive vector control measures were implemented starting with LLIN distribution in October 2013/2017 followed by sustained IRS (bendiocarb and actellic) in December 2014 – 2019. IRS intervention led to a decline in microscopic parasitaemia from 34.9% before intervention to 1.8% in the 5th year of implementation. Also, acute respiratory infection, gastrointestinal illness and housing improvements and their potential impact on malaria transmission were assessed 5 years after IRS implementation. There was a marked reduction in entomological metrics after IRS, for example from 218 to 0.42 infective bites/person/year. Two cohort studies from September 2017 to October 2019 with approximately 100 households per cohort, as well as the longitudinal participant follow-up and entomological monitoring, was conducted involving CDC light traps every two weeks and routine participant/sick visits every 28 days. Mean daily human biting rate was correlated to the degree of rainfall/month during IRS implementation with pirimiphos‐methyl (Actellic) showing peaks of biting rate in the months of May and June. The association between house type, the incidence of malaria and diarrhoeal disease revealed that modern houses were associated with 53% reduction in human biting rate and 24% reduction in gastrointestinal illness compared to traditional houses. Musiime’s work was funded by the NIH and conducted by the PRISM study and the Infectious Disease Research Collaboration (IDRC) teams.

Parallel session 2: Vector surveillance, entomological capacity and National Malaria Program support 

Emily Dantzer (University of California San Francisco – UCSF, USA) presented “Key findings of a global landscape analysis on entomological surveillance best practices” which highlighted five main themes that could be summarized from outcomes of Key Informant Interview of 30 individuals. These themes included: 1. Need for inherent and internal advocacy for malaria. 2. Good funding meant good entomological surveillance as countries prioritized best practices. 3. There was a difference in priorities between donors and the country. The main difference between donors and countries was the thought about what were the key important tools required for best practices in vector surveillance.  4. Human resources – all agreed on training with the main concern being the impact of the age gap between retiring entomologists and the early career researchers. 5. Need for collaborations with clearly defined roles of responsibilities and priorities. The problem arose in funding these collaborations as each party had their own expectations. The donor had the last say in most important matters.

Rosemary Susan Lees (Liverpool School of Tropical Medicine – LSTM, UK) talked on “Validating entomological methods for evaluation of vector control tools” which captures the essence of developing a process of validating bioassays, methods and standard operating procedures (SOPs) used for the evaluation of vector control tools (VCTs). She discussed four main stages of method validation, which include: defining design outcomes and refining the methods; quantifying inherent error in the methods; evaluating the ability of the methods to accurately characterize VC products; and affirming results by two external laboratories. The goal of this work is to help in developing a “consensus SOP” of methods for the monitoring of next-gen ITNs.

Parallel session 3: LLINS, IRS and Insecticide Resistance Management

Chris Clarkson (Anopheles gambiae 1000 genomes consortium – Ag1000G Consortium) started his talk on “Insecticide resistance in the Anopheles gambiae complex – analysis of whole genome sequence data from 19 countries and three mosquito species” by explaining the Ag1000G project. This dataset consists of 2784 wild-caught samples, and Illumina whole-genome deep sequencing from 19 countries and 26 partner’s studies. This data set is open and can be analysed in the cloud for free. Clarkson explained the results of the analysis of different insecticide resistance mechanisms. First was target-site resistance to pyrethroids. They discovered previously unknown mutations of the Vgsc genes. However, these unknown mutations were present in mosquitoes already with kdr mutations. These double and triple mutants can show much stronger pyrethroid resistance. They found 7 double mutants with high frequency in West and Central Africa. Another type of resistance they investigated was metabolic. They identified metabolic resistance using gene copy number variants as markers. They found geographical heterogeneity prevalence of pyrethroid resistance between West, Central and East Africa. Most samples had kdr mutations and P450 amplifications in the West and East but in Central Africa, kdr was more prevalent.  Organophosphate resistance was present in the form of Ace1 in the West and Gste in the East. Finally, using genome-wide scans, they detected 3 novel genome loci possibly linked to insecticide resistance. One of them, Keap1, activates multiple metabolic insecticide resistant genes.

Iddrisu Alidu (Vestergaard – NMIMR Vector Labs Accra, Ghana) started his presentation on “Maintaining Anopheles gambiae s.l mosquitoes using an artificial membrane feeding technique at Vetergaard-NMIMR Vector Labs, Ghana” by mentioning the importance of blood-feeding in mosquito mass-rearing. Females mosquitoes require animal access to blood-feeding but animal access, especially live ones, can be challenging to handle. Therefore, artificial membrane feeders are an option to provide blood meals to female mosquitoes. They used a Hemotek feeding machine with parafilm to hold sheep blood. Then, the feeder was set to 33 ℃ before putting it in the cage. After that, they compared feeding rate and hatch rate between membrane feeding and direct feeding during 5 months (October – February). They found no difference in feeding rate or hatching rate between direct and membrane feeding. Direct feeding showed slightly higher percentages across the five months except in November and February. These results show no apparent negative effects from membrane feeding in Anopheles gambiae strains. Moreover, this technique is easier to manipulate, has fewer risks associated and improves the quality of research.

Francesco Baldini (University of Glasgow) began his talk “Transgenerational effects in life history traits and malaria susceptibility induced by insecticide sub-lethal exposure in the mosquito Anopheles gambiae” addressing the impact of insecticide resistance on vector control effectiveness. The aim of the study was to understand the fitness cost of exposure to insecticide in susceptible Anopheles mosquitoes. They designed an experiment where mosquitoes were blood-fed and one group was exposed to a sublethal dose of permethrin (0.3%) with the other being the control group.  Both groups layed eggs and their offspring were reared until adulthood. The offspring were blood-fed with infected blood and exposed to insecticide. Adult survival and fecundity, larval survival and development time, adult body size and malaria prevalence, and specifically intensity of infection, were then measured. Results showed that insecticide exposure affected survival by reducing it, although larger mosquitoes tended to have higher survival. Moreover, the number of eggs produced also reduced. Larvae survival was reduced from mothers exposed to insecticide but larvae developed into pupae in a shorter time compared to the control. Finally, there was no difference in larvae size between the two groups. Generally, maternal exposure to the insecticide did not affect the survival of their offspring.  Another interesting observation was that at day 12, maternal exposure made offspring tolerate the insecticide better than in the control but they layed fewer eggs. In terms of malaria infection, there was no difference between the two groups in malaria prevalence but the intensity of infection was lower in mosquitoes exposed to insecticide. However, this effect was not seen when the mothers were exposed to insecticide. These results showed the impact of maternal exposure to insecticide and how it affects the offspring’s life history traits.

Priscille Barreaux (Liverpool School of Tropical Medicine – LSTM, UK) started her talk on “Exposure to pyrethroid nets reduces blood feeding efficiency and longevity in resistant mosquitoes” explaining how insecticides affect the mosquito’s life. Insecticides prevent the mosquito from entering the house, decreases biting, and kills mosquitoes before or after blood meal. However, resistant mosquitoes do not die and they can finish the gonotrophic cycle and transmit the malaria parasite. The aim of the project was to explore if insecticide treated nets (ITNs) alter mosquito’s host searching and blood feeding behaviour,  the amount of blood ingested and its longevity. They tested blood feeding and mosquito survival by exposing resistant mosquitoes to permanet 2.0  and 3.0. Results showed that ITN reduced feeding success by reducing the time spent feeding with a feeding success of 9% when exposed to ITN + PBO. Longevity was also reduced by ITN with 20 days for fed females and 12 days for unfed females. They also tested blood seeking efficiency with ITN with Olyset, Permanet 2 and untreated using a baited box method. Mosquitoes spent more time flying avoiding the ITN compared to the control. Also, mosquitoes had a higher number of landings in the net and finally the proportion of mosquitoes flying away was higher with ITN.  Moreover, there was a reduced proportion of blood fed mosquitoes and  the blood volume also was reduced. This trend was also found in blood feeding duration, defecation time and proportion of defecating mosquitoes, suggesting that ITN decreased blood meal quality. Overall, ITN decreases blood feeding success, longevity and blood meal sizes in resistant mosquitoes.

This report is brought to you by the MESA Correspondents Stella Riunguh, Amelie Wamba, Eggrey Aisha Kambewa, Mauro Pazmino Betancourth, Udoka Nwangwu, Thoan Ho Dac, Faith Hungwe and Jackson Nyarko. Senior editorial support has been facilitated by Charles Quaye (Noguchi Memorial Institute for Medical Research, Ghana). It is cross-posted on the MESA website and on MalariaWorld.