Brian Greenwood is Professor of Clinical Tropical Medicine at the London School of Hygiene and Tropical Medicine in the UK. From 2001 -2009 he directed the Gates Malaria Partnership which supported a programme of research and capacity development in many countries in Africa directed at improving treatment and prevention of malaria. In 2008, he became director of a new capacity development initiative supported by the Wellcome Trust and the Bill and Melinda Gates Foundation, the Malaria Capacity Development Consortium (MCDC), which operates a post-graduate malaria training programme in five countries in sub-Saharan Africa, and he also directs a new consortium (MenAfriCar) established with support from the Wellcome Trust and the Bill and Melinda Gates Foundation to study meningococcal carriage in Africa.
Q: In the recently published Malaria Elimination series in the Lancet, a paper which you co-authored states that 32 countries may be able to eliminate malaria in the next decade. Many prerequisites for achieving this are described, but if you would have to select two issues that are vital for success, what would these be?
A: Elimination of malaria (interruption of local transmission in a defined geographical area) is not going to be easy for any country, or areas within a country, that attempts to do this and a very careful assessment of whether elimination is feasible and cost effective is essential before this is attempted, as set out in the recent publications by the Malaria Elimination Group (MEG). In most circumstances, the two key features that are likely to determine success are (a) the susceptibility of the main vector or vectors to the current malaria control tools and (b) the functionality of the health system. Final interruption of transmission through vector control will be difficult when the primary vectors are exophilic and/or day biters as the primary vector control tools currently used (insecticide treated bednets and indoor residual spraying) are directed at indoor biting and indoor resting mosquitoes. Control may be further compromised if there is any insecticide resistance. A functional health service will be essential for the delivery in a precise way of the control tools that are needed to interrupt the final pockets of transmission, to detect the last few indigenous cases and to pick up any reintroductions. Plasmodium falciparum will be easier to eliminate than P. vivax because of the existence of hypnozoites in the latter.
Q: Global investments in research and control/elimination efforts have reached unprecedented levels but the risk exists that getting closer to the Millenium Development Goals will result in reduced donor interest. What can and should, in your opinion, be done to sustain high levels of funding?
A: Sustaining investment for malaria control, either from internal or external resources, is going to be difficult once the number of cases in a particular country has been brought down to a low level. Once elimination has been achieved, and widely acclaimed as a national success, securing funds to maintain a malaria free status may be even more difficult. However, there are precedents which suggest that sustaining funding for malaria control at the appropriate level may not be an impossible task. The international community still supports universal immunisation of infants against diptheria and tetanus although the risk from these diseases is now very low in nearly all parts of the world. Unfortunately, sustaining malaria control is likely to be more expensive than sustaining control of other common diseases of childhood through vaccination. Education at all levels, from the public to the most senior policy makers, of what malaria control and elimination mean, with reminders of what happened when control programmes were stopped too early during the previous malaria eradication campaign, will be key to ensuring that, this time round, control programmes are not wound up too early. Education will need to start as soon as the goal of elimination is embraced and to involve all media outlets.
Q: A Chinese-led mass drug administration programme on the island of Moheli (Comores) led to the elimination of malaria there. It is likely that increased presence of China in Africa will lead to a 'trade' involving funding or even the execution of malaria elimination programmes in return for natural resources. How do you view this development?
A: China is playing an increasing role in sub-Saharan Africa in many areas including health and therefore it is logical that Chinese scientists should be involved in malaria elimination activities in Africa. Malaria transmission continues in some parts of China and discussions are in progress as to whether the Chinese Government should make a major effort to eliminate malaria from the remaining areas of China where transmission continues. Lessons learnt from how best to eliminate malaria in China, for example on how to deploy mass drug administration most effectively, could be helpful to countries in Africa as they approach the end stage of their elimination programmes. Involvement of Chinese scientists in working towards the ultimate goal of eliminating malaria from Africa is to be welcomed but it would be helpful if these efforts are integrated into an overall continental plan rather than being conducted as independent programmes.
Q: As countries proceed with scaling up of existing interventions like LLINs and IRS, what do you consider the next most valuable add-on strategy against vectors?
A: I don't think that any one intervention can be identified as the most valauble tool to add to LLINs and IRS. It is likely that in many situations IRS and LLINs alone will not be sufficient to completely interrupt transmission and that some additional measure will be needed to do this. However, what this measure might be will be situation specific. For example larviciding against Anopheles gambiae sl might be the best additional tool to use in urban areas but not in rural parts of Africa. The same caveats apply to the use of repellents. There is already some evidence to show that these are especially effective in areas where the main vectors are early biters and repellents would be a logical additional line of attack in such areas. Larvivorous fish are also highly effective in some specific situations. I do not see any additional tool that could be used in all situations that is on the near horizon. In the future, new technologies that interfere with mosquito behaviour and genetically modified mosquitoes may become available that are widely applicable but these are still some way away.
Q: Your brilliant career spans decades of research in developing countries and the UK. If you compare the starting point of your career with 2010, what are the main differences you observe? What is the most forgotten lesson from the past that we should remember today?
A: I would not agree with the first sentence but I have been fortunate in my career. I started my research on malaria at a time when interest in the subject was very low following the collapse of the malaria eradication campaign. This had disadvantages in that funding for malaria research was difficult to come by and that, with a few exceptions, few people were interested in one's research findings. However, the counter advantage was that the field was wide open with little scientific competition and it was possible for a small research team to cover the many disciplines necessary for malaria control including laboratory, clinical and social sciences -it was then still possible to be malariologist. However, now that there is much more support for malaria research, a situation to be welcomed, young scientists interested in malaria cannot be expected to develop a career that covers the whole field and they need to focus on a defined area, whether in the lab or in the field but there are dangers in this. For example, there are malaria epidemiologists who have never read a blood film and experienced laboratory researchers who have never seen a case of malaria. A need for specialisation is an inevitable consequence of the advacement of science but I think that it is important to try and ensure that all those working on malaria have some idea of subject as a whole and not just detailed knowledge of their own particular field. At the London School we try to encourage this multidisciplinary approach through the Malaria Centre (http://malaria.lshtm.ac.uk) which brings together scientists from across many disiplines who have an interest in malaria.
Tropical medicine has a rich history and many of its past practitioners were outstanding scientists whose contributions went far beyond the particular field that they were studying. For example, it is widely accepted that Ross was one of the first to recognise the potential of mathematical approaches to the study of infectious diseases. Most of the key biological questions that we fret about today, such as the immunological implications of removing exposure to malaria, have been thought about by previous generations of malariologists. We now have new tools to investigate these problems but I think that there are still many helpful ideas that could initiate productive new areas of research to be found in the publications of the earlier generations of malariologists.