© The International Society for Neglected Tropical Diseases 2014
In your opinion what are the top three priority areas of research needed to reduce the gap between adaptive vector control strategies and changing disease transmission dynamics?
Firstly, vector ecology and behaviour: vector borne diseases (VBDs) can have multiple vectors, different in their ecology and behaviour. Control strategies exploit ‘typical’ behavioural traits but these may not always be the most suitable method in sites where the predominant vectors may exhibit different patterns of feeding, resting...
Vector competence: our understanding of the efficiency of vectors in transmitting VBDs and how this might be influenced by environmental factors or physiological status of the vector, is woefully inadequate. Local control programmes need more in-depth knowledge of the major vectors in particular settings so that they can be adapted accordingly.
Finally, the impact of insecticide resistance: the rapid spread of resistance to pyrethroids in malaria vectors across Africa is well documented yet we know very little about the impact on current vector control tools. Given that it will be many years before insecticides with new modes of action are available for use in public health, it is vital that we understand the extent of the problem caused by current and projected levels of resistance.
What would you say are the hottest emergent technologies and new tools for malaria vector control?
One of the major challenges facing malaria control, in the era of mass distribution of bednets and increasing coverage with IRS, is how to target mosquitoes that feed and rest outside the domestic environment. Several approaches are being investigated and some very promising initial results are emerging from trials on spatial repellents and sugar baited traps, for example.
We at the ISNTD often hear about the lack of sustainability in terms of existing interventions such as LLINs and IRS - what more needs to be done to get back onto this sustainability curve?
New insecticides that are suitable for use on nets or for IRS are urgently needed to control insecticide resistant populations of malaria vectors. Pyrethroid resistance is now widespread in Anopheles gambiae and Anopheles funestus and populations of Anopheles gambiae mosquitoes that are resistant to all available classes of insecticide available for IRS have been detected in West Africa. Available data indicates that this resistance is already having a negative impact on the efficacy of LLINs and IRS and the situation will only deteriorate as mosquito exposure to these insecticides increases.
How can the LITE facility assist in the above areas? What would you say are the greatest strengths?
Firstly, LITE is the only widely accessible facility able to test new insecticide products against a range of fully characterised insecticide susceptible and resistant strains. This essential service enables agrochemical companies to incorporate screening against known resistance mechanisms, circulating in field populations of mosquitoes, in their product development pipeline.
The link between LITE, a testing facility operating to industrial/GLP standards and the medical entomologists in the LSTM's Department of Vector Biology provides excellent synergies and ensures that the services and materials offered by LITE reflect new research findings in insecticide resistance management.
In addition to bioassays, LITE is developing new in vitro tests to screen insecticides against a panel of mosquito enzymes known to metabolise insecticides – again this new resource will be valuable in accelerating the insecticide development pipeline.
What new technologies would LITE be looking to invest into to strengthen its capacity and depth?
In addition to continually updating the range of biological material available for testing, we hope to expand our range of chemical analysis to enable us to offer a full range of services to detect active ingredients on insecticide treated surfaces.
Pr. Hilary Ranson is Professor in Medical Entomology at the Liverpool School of Tropical Medicine
My research activities encompass various aspects related to the control of mosquito vectors of human disease. I have a particular interest in the causes and consequences of insecticide resistance and my group have been using a variety of molecular approaches to study the mechanisms of insecticide resistance in Anopheles and Aedes mosquitoes. Field studies are exploring the impact of this resistance on malaria and dengue control programmes. I was coordinator of the TDR network on study insecticide resistance in African malaria vectors from 2008-2011. This network consisted of LSTM and partners in six African countries and developed a set of standardised protocols for vector population monitoring and for determining the levels of insecticide susceptibility in sentinel sites in each country, in addition to conducting more detailed research into resistance mechanisms.