Bed net research in western Kenya

Notes from Ned:

I wanted to post some information here about my research on insecticide treated bed nets in Kenya, and to show how the research is related to the Michigan State Nothing but Nets Team. Interestingly, none of the research described below has a direct relationship to the Nothing but Nets program. The donations are not used for my research. I am not even sure that any of the nets obtained through the program will even end up in Kenya, vs. another country or setting, but that is fine. I asked the Nothing but Nets administrators if there was a way to steer the funds to western Kenya to identified villages as a philanthropic activity, but that is not the way the program operates and they were not able to support this idea. Rather, Nothing but Nets at the programmatic level interacts with the United Nations, the World Health Organization, the Global Fund, the Gates Foundation, and other groups to ensure that the bed nets purchased by donations arrive into users' hands in needy areas of a wide variety of countries. The distribution system, interestingly, is tied to measles vaccination programs in ante-natal medical clinics, so that pregnant women and women with newborns can learn about bed nets and have access to the bed nets when they come in for care and for vaccinations for their children.

The main thing is that we know that use of bed nets really helps to push malaria infection down wherever they are used in SubSaharan Africa, and that is a worthy philanthropic goal and participating in a program like this one is very unifying. It brings people together who otherwise would never interact with each other. My motivation is to think with my head and my heart as my technical studies of bed nets in Kenya go forward. Just doing the science alone, without trying to apply the results of the research to achieve a noble end such as alleviating the malaria problem, is not enough for me.

RESEARCH VENUE AND PARTNERSHIPS
My research engages two partner organizations: the Kenya Medical Research Institute and the US Centers for Disease Control. These two groups have themselves formed a partnership to conduct research on infectious diseases in western Kenya, including malaria. The governments of Kenya and the United States signed a cooperative agreement to work together in this way. They have constructed a laboratory complex in a village called Kisian, which is about 10 km west of the city of Kisumu. The research station is called the Centre for Global Health Research. Kisumu is the third largest city in Kenya, and is located on the shores of Lake Victoria. University researchers such as myself can bring forward projects to this research station, particularly if external funding is available (which we do have) and if the Kenyan and US staff scientists based at the station agree to collaborate (which they have). My main collaborators in Kenya are Dr. Nabie Bayoh, Dr. John Vulule, Dr. John Ayisi, Dr. Luna Kamau, Dr. Simon Kariuki, and Ms. Damaris Matoke. Two key staff members are Mr. George Olang and Mr. Maurice Ombok. On the US CDC side, my main collaborators are Dr. Mary Hamel, Dr. Kayla Laserson, Dr. Ya-Ping Shi, and Dr. John Gimnig. The other MSU scientist involved is Dr. Joe Messina. So you can see that this is really a team effort which I feel privileged to lead.

RESEARCH ACTIVITIES
Anopheles mosquitoes
The research itself builds upon several recent studies at this same site, including some of my own work, on how community-based implementation of insecticide treated bed nets affects the mosquito populations and the intensity of malaria transmission. We already know, based upon a set of randomized field trials conducted in this setting and in 4 other locations in SubSaharan Africa, that when most people in a community use bed nets nightly for an extended period, malaria transmission goes way down and the burden of malaria infection in children and pregnant women also goes down. What we don't know is how sustainable this kind of program is, and what the potential long term consequences are. My particular interest has to do with what we call the "population structure" of the mosquitoes and the malaria parasites. For the mosquito populations, we think that the widespread use of the bed nets causes a shift from a mostly human feeding form of Anopheles to a mostly cattle feeding form, with an overall reduction in density of the mosquitoes too. Those are both highly desirable outcomes. We will test this idea over a 5 year period, to see if such a desirable shift occurs and sustains itself. Secondly, we are concerned about the emergence of insecticide resistance in the mosquito populations, so we are establishing some long term studies on the kind of insecticide resistance (either "target site" resistance or "metabolic" resistance) and are putting into place some methods and procedures to analyze the frequency of these traits genetically in the mosquito populations. Thirdly, we are interested in the interactions of lowered mosquito density and the rate at which genes conferring insecticide resistance "flow" or move through populations, which obviously will affect its spread.

Malaria parasites
Our research on malaria parasites parallels that of the mosquito research described above. As transmission drops with increased bed net use in western Kenya, we will study the "population structure" of the malaria parasites using molecular methods to study genetic factors in the parasite populations. It is important because malaria has always been very resilient to control; history has shown that it is a difficult disease system to manipulate for purposes of controlling it. The malaria parasites are tough. They easily evolve resistance to drugs, and they have virulent forms. One thing that sometimes happens in disease control programs generally is that the control results in emergence of more virulent forms of pathogens. We would like to know if that happens in the malaria parasite populations during the course of a long term bed net implementation program. So we are studying some of their "virulence factors" using genetic methods. Secondly, we are studying the frequency and form of antibiotic resistance in the malaria parasites. Just as with the insecticide resistance issue mentioned above, we would like to find out if the use of bed nets (which we know already causes a drop in malaria transmission) also concomitantly results in reduced frequency of antibiotic resistance in the parasite populations, and reduced gene flow of the genetic factors underlying this resistance. Wouldn't it be wonderful if use of bed nets turned out to be a way to manage drug resistance in malaria parasite populations? So we are having a look at that possibility.

People
Lastly, we are studying people. There are two aspects to our studies of the rural residents of western Kenya where our bed net studies are taking place. First, we would like to know how well these people adopt the use of bed nets into their homes and their lifestyles. We have a situation underway where one population of people has already been engaged in a long term bed net study and so have been educated about their use and are very familiar with them. The other population of people has had no such experience but now has the opportunity to obtain bed nets through a Kenyan national bed net campaign voluntarily, but one that does not include an educational component. Will this latter group assimilate use of bed nets to a high enough coverage rate in their villages to have an effect? What is their knowledge of bed nets, and their opinion about them? We will ask them about these things, including economic and other barriers to use. It may be that we will find out that education is a crucial component of the national program, but as of yet we have not started that part of the study. You can see that this part of our research is oriented toward social sciences rather than biological sciences.

The second aspect of our study with people is more medical and epidemiological. We are enrolling groups of people (babies, children, and adults) into a program where we will obtain a small blood sample from them and analyze the blood for presence, type, and number of malaria parasites. We will also test the people for anemia, and we will use the malaria parasites we find for the studies outlined above. When we find malaria-infected people, we will treat them for the infection. This part of the study will engage people in the two study populations described above, i.e., the group that has had a long term experience with bed net use and the group that has not had this experience. We will do these studies over a 5 year period, with the goal being to find out if bed net use programs sustainably reduce malaria infection over the long term.