STORIES

Fighting Malaria in Africa, a CRID perspective

Mosquittoes in Africa: expert research and recommendations to National Malaria Control Programmes – Dr. NDO Cyrille, Vector Biologist, Head of Parasitology and Microbiology Department at CRID

Mosquittoes in Africa: expert research and recommendations to National Malaria Control Programmes – Dr. NDO Cyrille, Vector Biologist, Head of Parasitology and Microbiology Department at CRID

Africa has over 10 indigenous Anopheles species with ability to transmit Plasmodium parasites that cause malaria [2, 3]. Therefore, control of these vector species is the pillar of prevention strategies. Vector control relies extensively on the use of pyrethroid-based insecticide-treated bed nets or indoor residual spraying. Mosquitoes have however developed resistance against the insecticides actually in use. More so, in some settings, it has been noticed that instead of biting indoor (as people are protected by bed net), some mosquito populations have developed a new tendency of biting outdoor in the early hours of the day when people are not protected by the bed net. This high insecticide resistance profile (and associated change in biting behaviour) is a major challenge to the efforts of National Malaria Control Programmes in fighting the killer disease [4, 5].

The Centre for Research in Infectious Diseases (CRID) has over the years sort to understand the challenges in the fight against malaria vectors, and to find ways to improve the efficacy of current vector control tools. Drawing from studies conducted in Central, West and  East Africa, cases of high resistance levels to insecticides in major malaria vectors leading to loss of efficacy of Long Lasting Insecticidal Nets (LLINs) have been reported [6-13].

 In order to improve malaria control and a possible disease elimination which is backed in the agenda [14], there is an urgent need to first preserve the optimal efficacy of existing vector control tools. We advise National Malaria Control Programmes to conduct routine entomological surveillance for determination of insecticide resistance profile and mechanisms in vector populations, using standard WHO bioassays protocols, but also molecular techniques that can allow early detection of target site [15, 16] and metabolic-mediated resistance [6, 11, 17]. Availability of these data will help to better design resistance management strategies, and to implement evidence-based and integrated vector control.

Meanwhile researchers at the CRID are working, in collaboration with the broad malaria research community,  in  indentifying new insecticides with different mode of action and/or in developing alternative vector control tools such as the sterile insect technique [18, 19].

References

1.   WHO: World Malaria Report 2019. WHO Global Malaria Programme. World Health Organiszation https://wwwwhoint/publications-detail/world-malaria-report-2019.

2.   Fontenille D, Cohuet A, Awono-Ambene PH, Antonio-Nkondjio C, Wondji C, Kengne P, Dia I, Boccolini D, Duchemin JB, Rajaonarivelo V et al: [Systematics and biology of Anopheles vectors of Plasmodium in Africa, recent data]. Med Trop (Mars) 2003, 63(3):247-253.

3.   Antonio-Nkondjio C, Kerah CH, Simard F, Awono-Ambene P, Chouaibou M, Tchuinkam T, Fontenille D: Complexity of the malaria vectorial system in Cameroon: contribution of secondary vectors to malaria transmission. J Med Entomol 2006, 43(6):1215-1221.

4.   Benelli G, Beier JC: Current vector control challenges in the fight against malaria. Acta Trop 2017, 174:91-96.

5.   Sougoufara S, Doucoure S, Backe Sembene PM, Harry M, Sokhna C: Challenges for malaria vector control in sub-Saharan Africa: Resistance and behavioral adaptations in Anopheles populations. J Vector Borne Dis 2017, 54(1):4-15.

6.   Weedall GD, Mugenzi LMJ, Menze BD, Tchouakui M, Ibrahim SS, Amvongo-Adjia N, Irving H, Wondji MJ, Tchoupo M, Djouaka R et al: A cytochrome P450 allele confers pyrethroid resistance on a major African malaria vector, reducing insecticide-treated bednet efficacy. Sci Transl Med 2019, 11(484).

7.   Tchigossou G, Djouaka R, Akoton R, Riveron JM, Irving H, Atoyebi S, Moutairou K, Yessoufou A, Wondji CS: Molecular basis of permethrin and DDT resistance in an Anopheles funestus population from Benin. Parasit Vectors 2018, 11(1):602.

8.  Kamgang B, Tchapga W, Ngoagouni C, Sangbakembi-Ngounou C, Wondji M, Riveron JM, Wondji CS: Exploring insecticide resistance mechanisms in three major malaria vectors from Bangui in Central African Republic. Pathog Glob Health 2018, 112(7):349-359.

9.   Riveron JM, Watsenga F, Irving H, Irish SR, Wondji CS: High Plasmodium Infection Rate and Reduced Bed Net Efficacy in Multiple Insecticide-Resistant Malaria Vectors in Kinshasa, Democratic Republic of Congo. J Infect Dis 2018, 217(2):320-328.

10. Ibrahim SS, Fadel AN, Tchouakui M, Terence E, Wondji MJ, Tchoupo M, Kerah-Hinzoumbe C, Wanji S, Wondji CS: High insecticide resistance in the major malaria vector Anopheles coluzzii in Chad Republic. Infect Dis Poverty 2019, 8(1):100.

11. Mugenzi LMJ, Menze BD, Tchouakui M, Wondji MJ, Irving H, Tchoupo M, Hearn J, Weedall GD, Riveron JM, Wondji CS: Cis-regulatory CYP6P9b P450 variants associated with loss of insecticide-treated bed net efficacy against Anopheles funestus. Nat Commun 2019, 10(1):4652.

12. Ibrahim SS, Mukhtar MM, Irving H, Labbo R, Kusimo MO, Mahamadou I, Wondji CS: High Plasmodium infection and multiple insecticide resistance in a major malaria vector Anopheles coluzzii from Sahel of Niger Republic. Malar J 2019, 18(1):181.

13. Riveron JM, Huijben S, Tchapga W, Tchouakui M, Wondji MJ, Tchoupo M, Irving H, Cuamba N, Maquina M, Paaijmans K et al: Escalation of Pyrethroid Resistance in the Malaria Vector Anopheles funestus Induces a Loss of Efficacy of Piperonyl Butoxide-Based Insecticide-Treated Nets in Mozambique. J Infect Dis 2019, 220(3):467-475.

14. Rabinovich RN, Drakeley C, Djimde AA, Hall BF, Hay SI, Hemingway J, Kaslow DC, Noor A, Okumu F, Steketee R et al: malERA: An updated research agenda for malaria elimination and eradication. PLoS Med 2017, 14(11):e1002456.

15. Nwane P, Etang J, Chouasmall yi UM, Toto JC, Mimpfoundi R, Simard F: Kdr-based insecticide resistance in Anopheles gambiae s.s populations in. BMC Res Notes 2011, 4:463.

16. Djogbenou L, Weill M, Hougard JM, Raymond M, Akogbeto M, Chandre F: Characterization of insensitive acetylcholinesterase (ace-1R) in Anopheles gambiae (Diptera: Culicidae): resistance levels and dominance. J Med Entomol 2007, 44(5):805-810.

17. Riveron JM, Yunta C, Ibrahim SS, Djouaka R, Irving H, Menze BD, Ismail HM, Hemingway J, Ranson H, Albert A et al: A single mutation in the GSTe2 gene allows tracking of metabolically based insecticide resistance in a major malaria vector. Genome Biol 2014, 15(2):R27.

18. Lobo NF, Achee NL, Greico J, Collins FH: Modern Vector Control. Cold Spring Harb Perspect Med 2018, 8(1).

19. Ndo C, Poumachu Y, Metitsi D, Awono-Ambene HP, Tchuinkam T, Gilles JLR, Bourtzis K: Isolation and characterization of a temperature-sensitive lethal strain of Anopheles arabiensis for SIT-based application. Parasit Vectors 2018, 11(Suppl 2):659.

STORIES

Prof Charles Wondji in conversation with MESA Alliance

The Executive Director of CRID and Professor of Genetics at the Liverpool School of Tropical Medicine Prof Charles Wondji, on May 26, was in conversation with the MESA Alliance, a living database which captures research projects and institutions’ portfolios in malaria elimination and eradication.

The conversation with Professor Charles Wondji focused on Genetic and genomic tools to fight vector-borne diseases where he reveals in depth the importance of genetic epidemiology research in malaria surveillance and control, how genetic epidemiology can facilitate the management of insecticide resistance in Africa, how it can improve the operational decisions made by National Malaria Control Programmes, challenges researchers are faced with and the necessary steps that the malaria community could take in order to advance towards malaria elimination.

Find and read complete interview here http://www.mesamalaria.org/updates/genetic-and-genomic-tools-fight-vector-borne-diseases-conversation-prof-charles-wondji

STORIES

Vector Control and the Emergence of Resistance, Charles S. Wondji – ASTMH 2019

Malaria infection is still one of the major causes of deaths in populations of the African continent. The global tally of malaria deaths lingers around 400,000-500,000 deaths annually. Since 2000, the incidence of malaria has reduced by 17% and mortality rates by 26%, giving hopes for a possible control towards elimination. Although malaria case incidence has fallen globally since 2010, the rate of decline has stalled and even reversed in some regions. Mortality rates have followed a similar pattern. National Malaria Programs and researchers still battle a plethora of challenges ranging from case management, transmission dynamics, insecticide and drug resistance, requiring innovative approaches. Presumptive treatment is still syndromic in most health establishments

Treatment is frequently interrupted by drug stock outs and systemic dysfunctions of the health sector. With the known 450 anopheles species, of which 60 can potentially transmit malaria, resistance to insecticides has become a worrisome undertaking for malaria control programs in the face of other control program difficulties of effective interventions and environmental hygiene. Besides there is great genetic diversity and a changing epidemiology of resistant parasite populations. The malaria control programs manage these bottle necks amid weak heath systems and are still faced with malaria case management inadequacies and poor mass drug administration. Combination options such as with drugs and vaccines or the identification of the anopheline metabolic resistance biomarker in Cameroon, may provide new insights into control efforts.

These innovations, in addition to other solutions to overcome programmatic challenges, is being debated as an Africa-led leadership approach towards malaria elimination. The goal of this symposium is to provide African research leaders’ perspectives on challenges and ways to circumvent programmatic challenges for malaria elimination. The specific objectives are: i) to demonstrate the importance of a holistic approach to malaria elimination in Africa; ii) to outline the challenges encountered by National Malaria Control Programs in Africa in vector control, parasite resistance amid mass drug administration, and programmatic related issues; and iii) to propose solutions and directions for further consideration in interventions towards malaria elimination.

Listen to and download Prof Charles’ presentation at the 68th ASTMH annual meeting in Maryland, November 2019 http://www.mesamalaria.org/resource-hub/astmh-2019-charles-s-wondji-vector-control-and-emergence-resistance

STORIES

Road to high insecticide resistance management in Uganda

Uganda presents one of three sites (Mozambique and Cameroon inclusive) with high insecticide resistance profile as research carried out by scientists at the Centre for Research in Infectious Diseases (CRID) reveal.

Under Prof Charles Wondji’s Wellcome Trust Senior Fellowship project, a team of researchers from CRID have kick-started the journey of temporal monitoring of insecticide resistance escalation in Uganda. The first step was principally the collection of indoor resting mosquitoes.

Every morning for fourteen (14) days, indoor resting mosquitoes were collected using electric aspirators.  Researchers were assisted by volunteer field workers who were previously trained on this collection technique and on how to handle the mosquitoes collected.

CRID Researcher with volunteer field workers
CRID Researcher with volunteer field workers

Mosquitoes were collected in two districts in Eastern Uganda, Busia and Mayuge which were identified as sites with high density of mosquitoes.

Found in Eastern Uganda, the population of Busia and Mayuge use impregnated bed net as the major vector control tool – standard and PBO-based nets from the mass campaign of 2016-2017 were found in use in these villages.

Collected mosquitoes were made to lay eggs and were brought to the insectary for the rearing of F1 generation to be used for bioassays.

Collection of indoor resting mosquitoes
Collection of indoor resting mosquitoes

Researchers reveal that, by the end of March 2020, the first results on the resistance profiling will be known and evidence generated from this research will serve as springboard to Uganda’s National Malaria Control Programme.

“The completion of this Research will have practical implications for decisions on resistance management taken by the National Malaria Control Programme in this country and help to ensure the continues effectiveness of existing and novel insecticide-based control interventions” says Medical Entomologist on the field Magellan TCHOUAKUI.

STORIES

Fighting tsetse Flies in Campo, Cameroon

Following several years of research in Campo, coupled with screening and treatment campaigns which diagnosed many positive sleeping sickness cases, the prevention phase to control the vector which transmits this disease has officially been launched in Campo. The official ceremony took place on January 14, 2020 at Campo Beach.

Under the project Partnership for Increasing the Impact of Vector Control (PIIVeC)-, one of CRID’s Principal Investigators, Dr. Melachio, undertook some work onThe Impact of Insecticide Impregnated Screens on tsetse density and sleeping sickness transmission in Campo“. He used as preliminary data all the research results gathered by the team since 2009 in Campo, intended to assimilate the behaviour of the tsetse vector, identify and adopt the right vector control tool to control these flies

According to reports, about eight new cases of sleeping sickness are reported in Campo each year. Though some patients notice the signs early enough and seek treatment, others die and some of these deaths are attributed to witchcraft.

To kick-start the prevention phase of tsetse flies in Campo, a vector control tool named “Tiny Target” has been adopted. The Tiny Targets are insecticide impregnated blue-black screens planted as traps in areas suitable for tsetse development, meant to attract and kill every tsetse fly which comes in contact with them.

Our people have suffered a lot in the hands of these tsetse flies. It is a great concern as it affects the productivity of the people, lives have been lost too; but we are enthusiastic about this tiny target which has been introduced to kill these flies, we are hopeful for a positive change” says the chief of Mabiogo Village HRH NANYABO NGUIONG Martin.

The project will run for two years and each impregnated screen will be separated from the other by 50 metres and will be replaced every six months.

After 2 years, we will use results obtained from controlling the tsetse vector with these insecticide impregnated screens as leverage to engage Cameroon’s Ministry of Public Health, Sleeping Sickness Control Programmes, decision makers and other stakeholders to invest in and intensify the fight against tsetse flies which transmits sleeping sickness in so as to save lives in Campo” Dr. Melachio says

Dr. Tresor empowering village youth to plant tiny targets
Dr. Tresor empowering village youth to plant tiny targets

Locked in the Equatorial forest of the Ocean Division, South Region of Cameroon with a population of about five thousand (5000) people – majority engaged in fishing, farming, and hunting, Campo hosts a high concentration of tsetse flies which transmit the Human African Trypanosomiasis otherwise known as Sleeping Sickness.