Strengthening surveillance systems for vector-borne disease elimination in Africa
Day 1: Monday 23 September 2019
Dr Antonio-Nkondjio Christophe (Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale, OCEAC) chair of the local organizing committee, opened the stage of this 6th Pan-African Mosquito Control Association (PAMCA) Annual Conference organized for the first time in Yaoundé, city of 7 mountains, Cameroon, Central Africa. Dr Christophe emphasized the need to break down the deadly cycles of vector-borne diseases (VBDs) as one of the prerequisites to achieve economic prosperity in Africa. This conference provides a platform to enable the exchange of knowledge, capacities, and actions and face the challenges to foster the elimination of VBDs in Africa.
PAMCA president Prof Charles Mbogo (Kenya Medical Research Institute, KEMRI and University of Nairobi, Kenya) expressed a very warm welcome to all conference participants and took the opportunity to recapture the PAMCA vision of an "Africa free of vector-borne diseases". With about 350 participating delegates, this 3-day event follows two pre-conference workshops: the Gene Drive Technology Training Course and the Women in Vector Control Workshop. These workshops served to equip young African scientists, especially women, with effective tools to enable them to play their rightful role in the control of VBDs in Africa. Prof Mbogo concluded that
"one of the key drivers of PAMCA is to comprehensively develop a vector surveillance in one voice, in one action to combat vector-borne diseases - we do not want to continue working in isolation, but in unison".
James Newell spoke on behalf of Dr Prosper Chaki, PAMCA Executive Director, and reminded the audience of the necessity to build entomological capacities, strong systems and to use appropriate management systems that enable the African continent to respond effectively to VBDs.
Dr Phanuel Habimana (WHO Cameroon Representative) emphasized the tremendous cost caused by VBDs in Africa with malaria causing the highest burden.
Finally, Dr Manuel-Nso Obiang (OCEAC Executive Director) presented OCEAC’s facilities and its technical platform. These assist central African countries in their fight against infectious and vector-borne diseases through health policy development, research and training, and health emergency management and responses.
After being treated to a taste of the Cameroonian cultural dance by the University of Yaounde musical group, Prof Joseph Lebel Tamesse, the representative of the Minister of State Higher Education, presided over an award ceremony to recognize 15 outstanding scientist/researchers. This was followed by a group photo, a stunning musical performance and an official opening address by Prof Tamesse.
Prof Charles S. Wondji (Executive Director of Centre for Research in Infectious Diseases, CRID, Cameroon and Wellcome Trust Senior Research Fellow in Biomedical Sciences) highlighted the current challenge of genomic evolution of insecticide resistance facing pyrethroid-based interventions of malaria vectors. He cited reliance of a single class of insecticides, the pyrethroids as a major cause of resistance that necessitates the diversification of control strategies. He further described the need for molecular markers for the detection of insecticide resistance in malaria vectors (An. gambiae and An. funestus). Additionally, the operation of resistance management strategies early enough will help to control the spread of insecticide resistance. New approaches are also needed beyond IRS and LLNs to reduce malaria transmission e.g. genetic approaches such as CRISPRcas9 and gene drives; and capacity development through training of the next generation of African researchers on mosquito-borne diseases control.
The function was graced by the presence of Rodger Miler, PAMCA goodwill ambassador. Mr Miler is a former Cameroonian footballer and his passion for malaria stems from personal experience.
Plenary session 1.
Prof Yeya Touré (Retired from WHO/TDR and Malaria Research & Training Centre (MRTC), Mali) mentioned the lack of progress in malaria control in recent years in general and the vector control challenges with respect to achieving malaria elimination, in particular: to achieve high ITN and IRS coverage, and to address insecticide resistance that is spreading across Africa. Prof Touré explained that, in 2016, the WHO identified 21 countries with the potential to eliminate malaria by 2020, the E 2020 goal. Currently 11 of these countries are on track to achieve elimination but 10 countries are off track. The WHO adopted the new “high burden to high impact” approach that complements the E 2020 goal. Finally, he highlighted the need to optimize current vector control strategies, strengthen integrated vector surveillance and enhance multi-sectoral collaboration to move closer towards malaria elimination.
Dr Didier Fontenille (Institut de recherche pour le développement, IRD, France) took the participants through mosquito biology, ecology and control. Particularly, he focused on dengue fever viruses and Plasmodium species; these species are transmitted by vectors that have different biotypes. Hence, it is difficult to use one control strategy to target all the vectors. Effective mosquito vector control should therefore take into consideration different ecological settings, evolution and public health risk. He challenged participants to think globally and act locally.
The presentation by Prof Hillary Ranson (Liverpool School of Tropical Medicine, UK) provided an overview of current malaria status in Burkina Faso. This country has high malaria cases despite high coverage and use of bed nets. A longitudinal study in Bukina Faso reveals presence of pyrethroid resistance and poor health seeking behavior of adults. The highlight of the talk perhaps, is the need for multidisciplinary approach in malaria control.
Parallel session 1: Harnessing research capacity in Africa to empower national programs
Agapitus Kato (Ministry of Health Uganda, Uganda Virus Research Institute) demonstrated how the design of cost-effective and scalable implementation systems for larviciding policies can reduce malaria transmission in Uganda, especially in large populations. Jessy Marlene Goupeyou-Youmsi (University of Malawi) talked about the susceptibility of Anopheles mosquitoes to Plasmodium falciparum and Plasmodium vivax infections in Madagascar. Her work demonstrated the need to monitor P. vivax infections in clinics and mentioned the potential for vector control to prevent both P. falciparum and P. vivax infections. Elodie Vajda (University of California San Francisco) discussed a novel Entomological Surveillance Planning Tool (ESPT) to improve vector-control decision-making. This tool provides national malaria programs with a decision framework for entomological surveillance planning, analysis of entomological data, and for measuring human behavior associated to vector behaviour. Mutale Chisanga (Macha Research Trust, Zambia) showed how a reference laboratory that offers entomological services to other research institutes enabled Zambia to successfully support programmatic operations in the area of entomological surveillance. Aurelie Prisca Yougang (University of Yaoundé 1, Cameroon). Presented a study about the susceptibility profile and mechanisms involved in insecticide resistance in populations of Aedes albopictus in Cameroon. Finally, Efundem Agboraw (Liverpool School of Tropical Medicine) discussed a systematic review of the cost and cost-effectiveness of malaria control strategies and related health outcomes.
Parallel session 2: Mosquito genomics: progress and challenges
Nsa Dada (CDC, USA, KEMRI, Kenya) ) talked about microbiota-mediated insecticide resistance. Dada’s study demonstrated significant differences in the bacterial composition and putative enzymes of resistant vs. susceptible mosquitoes. Flore M. M. Kouamo described a study outlining the role of GST genes in conferring resistance to pyrethroids/DDT. Tony Nolan (Liverpool School of Tropical Medical, UK) described a study detailing an improvement to the CRISPR-Cas 9 gene drive system, a mosquito genetic control that is being explored to suppress mosquito populations. Thabo Mashatola (National Institute for Communicable Diseases of the National Health Laboratory Service, South Africa) talked about a review of the progress of sex-separation techniques for sterile insect technique (STI) application against Anopheles arabiensis. Alistair Miles’ (The An. gambiae 1000 genome consortium) presentation focused on the An. gambiae genome, specifically looking at single nucleotide polymorphisms (SNPs) and copy number variations (CNVs). Interestingly, Cytochrome P450 gene cluster is a CNV hot spot. Also, he explained how these genes can be exploited for surveillance/insecticide resistance management. David Weetman (LSTM, UK) then talked about gene duplication and selection and how these processes can drive the spread of organophosphate resistance in African An. gambiae. Keith R. Hayes (The Commonwealth Scientific and Industrial Research Organisation, CSIRO, Australia) provided insights on risk assessment (e.g. effect on target organism, spread and persistence, horizontal gene transfer) with respect to genetic control methods for malaria vectors.
Symposium 1: Guidance on stakeholder engagement principles to inform the development of area-wide vector control methods
New vector control approaches have led to renewed focus on stakeholder engagement and consent. Area-wide interventions require a community-based approach and Delphine Thizy (Imperial college London, UK) discussed the importance of responsible and thorough stakeholder engagement during the R&D process. The need for alternative and supplementary strategies was discussed by Lina Finda (Ifakara Health Institute, Tanzania) and Damaris Matoke-Muhia (KEMRI, Kenya). At the end, Lea Pare Toé (Institut de Recherches en Sciences de la Santé, IRSS-Burkina Faso) explained the seven years community engagement with a release project of sterile male mosquitoes in Burkina Faso through step-by step engagement, inclusive engagement and transparency in the research.
Parallel session 3: Vector biology and control
Caroline W. Kiuru (Max plank Institute for Infection Biology, Germany) talked about the role of bacteria in mosquito growth and development. Using different E. coli mutants she highlighted two different pathways that influence mosquito larvae development. Etienne Fondjo (Abt Associates, Cameroon) described how he used different approaches to assess insecticide resistance intensity in An. Gambiae. His work focused on four sentinel sites in Cameroon and selection of these sites was based on malaria transmission levels. A similar talk by Delenasaw Yewhalaw (Jimma University, Ethiopia) focused on pyrethroid resistance in malaria vector populations in Ethiopia. From his findings, he suggests that Pyrethroid-PBO nets should be incorporated in areas with pyrethroid resistant mosquito populations. Kenyssony Valera (Abt Associates, Mozambique) presented a study conducted in Mopeia, Mozambique evaluating the impact of a third generation IRS. The use of this product resulted in a reduction of Anopheles funestus, both outdoor and indoor. Theresia Nkya (ICIPE, Kenya) presented the experimental design of a project that assesed the feasibility and impact of community-based winter larviciding on malaria transmission in Namibia, Botswana and Swaziland.
This report is brought to you by MESA Correspondents Nathalie Amvongo Adija (Institute of Medical Research and Medicinal Plants Studies, Cameroon), Joanna Furnival-Adams (Liverpool School of Tropical Medicine, UK), Trizah Koyi (International Centre of Insect Physiology and Ecology, Kenya) and Teresia Njoroge (University of Illinois at Urbana-Champaign, USA) with mentoring and editorial support from MESA and MalariaWorld. Senior editorial support has been facilitated by Elijah Juma & Silas Majambere from PAMCA. This report is cross-posted on the MESA Website and on MalariaWorld.