Abstract
Introduction
Effective control of malaria remains challenging in many parts of sub-Saharan Africa. Currently, there is interest in using attractive toxic sugar baits (ATSBs) as novel vector control tools. ATSBs control mosquitoes by attracting them to feed on a sweet solution with mosquitocidal properties. ATSBs have already shown efficacy in killing sandflies, as well as mosquitoes from various genera including Anopheles, Aedes and Culex, in indoor and outdoor settings. We aimed to assess the possible impact of ATSBs on the population of malaria vectors (principally Anopheles funestus s.l. and A. gambiae s.l.) in the lush equatorial environment of South Kivu in the Democratic Republic of Congo (DRC).
Methods
In 2018, we carried out a pilot study in the town of Tchonka, Lulingu, DRC, using ATSB’s made from locally available materials and using a sugary ivermectin solution. We identified two sets of 23 households with similar densities of anopheline mosquitoes, used as experimental and control clusters. ATSBs were then placed in the experimental cluster, and continuous capture with CDC light traps was carried out in both clusters every three or four days for the 12 weeks of the study.
Ethics
This study was approved by the MSF Ethics Review Board and by the National Ethical Committee of the Ministry of Health in DRC.
Results
During the study period, the reduction in A. gambiae s.l. incidence rate ratio (IRR) for control households from baseline was 46% (IRR=0.54, 95%CI 0.36-0.77), whilst in experimental (ATSB) households this reduction was 64% (IRR=0.36, 95%CI 0.20-0.73). We did not observe an effect on the density of the A. funestus s.l. population. Acceptance of ATSB was extremely high, with all households (control and experimental), willing to obtain one ATSB.
Conclusion
Our data suggest that ATSBs might help to reduce the population of A. gambiae s.l. within the household. ATSBs can be made from locally available materials, and use is compatible with bednets, however a challenge for implementation relates to the need to renew the ivermectin solution. Further data is needed to evaluate the use of ATSBs in different contexts, to assess and increase the impact on other species of malaria vector, and to assess potential impact on malaria incidence. Limitations of this study include the non-randomised nature of the comparison, as well as being unable to assess whether impact is sustained beyond 12 weeks.
Conflicts of interest
None declared.
Maite Guardiola-Claramonte
Maite Guardiola is the Water and Sanitation Technical Advisor, MSF Spain. She is a hydrologist and geologist by training, and supports field teams in their water, sanitation and vector control activities, assists in planning emergency responses, provides MSF training, and represents MSF in Nairobi within the east African humanitarian community, where she is based. She has been leading vector control activities within MSF Spain, including the research pilot being presented here. She is a strong advocate for environmental health, comprising the framework for her work.
