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CDC Activities in Kenya

The CDC Research Station in Kenya was established in 1979 by the Division of Parasitic Diseases (DPD), working in collaboration with the Kenya Medical Research Institute (KEMRI). KEMRI is a parastatal organization of the Kenyan Ministry of Health and is responsible for conducting research into the major public health problems of the country. Over the past 27 years, CDC's investment in the Research Station has resulted in a well-trained staff of Kenyan scientists, clinicians, laboratory technicians, and field workers.

The Research Station is located in an area in western Kenya where P. falciparum malaria and HIV are major public health problems. It is estimated that globally, approximately 300-500 million persons suffer from malaria each year, resulting in approximately one million deaths. The burden of disease is located largely in sub-Saharan Africa. Western Kenya, where the Research Station is located, has intense malaria transmission; on average, each inhabitant in this area receives 150-300 infective mosquito bites per year. HIV has also had a devastating impact on Kenya. The overall HIV infection prevalence is estimated at approximately 10%, and in some groups such as pregnant women attending antenatal clinics, rates as high as 25-30% have been observed. Diarrheal and respiratory pathogens are also major causes of infectious disease morbidity and mortality in western Kenya.

Kenya Institute of Medical Research (KEMRI), Centre for Vector Biology and Control Research (CVBCR), located outside Kisumu, Kenya. (Courtesy KEMRI)

Major Areas of Research

Since 2000, in response to these national, regional, and global health challenges, the Research Station has expanded its mission and staff. Before this time, most activities focused on the major public health problem of malaria. Although malaria remains a priority, HIV research supported by CDC’s Division of HIV/AIDS Prevention, National Center for HIV/AIDS, STD, and TB Prevention (NCHSTP) and HIV prevention and care program activities supported by the Global AIDS Program are now also a primary focus. The U.S. President’s Emergency Plan for AIDS Relief (PEPFAR) supports many of the HIV programmatic activities.

Another focal area is the International Emerging Infectious Diseases Program (IEIP). IEIP has one person directly hired by CDC at the field station in Kisumu and three people in Nairobi, along with close to 100 Kenyan staff members in both sites. Activities focus on surveillance for emerging infections, outbreak response, applied public health research, and training of Kenya Ministry of Health doctors and laboratory technologists. Currently, there are eight employees directly hired by CDC at the Research Station (six scientists and two public health advisors); additional staff includes Kenyan and expatriate scientists, including PhD candidates and master’s students, dozens of core facility workers, and several hundred Kenyan field workers as well as data personnel.

Laboratory and Communications Capabilities

The KEMRI/CDC Research Station has well-developed malaria and HIV laboratories that perform a range of standard diagnostic procedures (serology, hematology, microscopy).

• The malaria laboratory has the capability to perform sophisticated research assays such as polymerase chain reaction [PCR], gene sequencing and microsatellite work, lymphocyte subtyping, and cytokine measurement and is actively engaged in research on parasite diversity and the immunology of malaria in children under five years and pregnant women.
• The HIV laboratory conducts a range of HIV diagnostic tests, including rapid tests, enzyme-linked immunosorbent assay (ELISA), Western blot, BED HIV incidence testing, viral load and infant DNA PCR, CD4 immunology; a variety of chemistry and hematology assays; and diagnostic tests for sexually transmitted infections (chlamydia, gonorrhea, syphilis, HSV-2, Trichomonas vaginalis) and, using both rapid diagnostic tests and ELISA, hepatitis B and C. The HIV research laboratory also has the capacity to perform HIV drug resistance testing and HIV subtyping.
• The microbiology laboratory performs primary isolation and identification of enteric organisms (Vibrio cholerae, Shigella) and respiratory organisms (Streptococcus pneumoniae) as well as antimicrobial susceptibility testing for these pathogens. Research on the immunology of schistosomiasis is also conducted.
• A computer network and geographic information system/geographic positioning system capabilities have been established, and a VSAT satellite link has improved Internet linkage and communication capability.

A health worker interviewing a member of the community during a malaria bed net study, Asembo Bay, Kenya. (Courtesy KEMRI)

1. Current projects: Data collection underway

Entomologic evaluation of long-lasting insecticide-treated nets

This project initially compared four types of commercial long-lasting insecticide-treated nets and one conventional net made more wash-durable (long-lasting) using a retreatment process developed by CDC. Researchers compared the ability of commercially treated versus field-treated nets to retain effective doses of insecticide. This study has been extended and is now looking only at PermaNets, as they were found to be the most reliable of the long-lasting nets tested.

Demographic and health surveillance (DSS)

The populations of Asembo and Gem (135,000) in western Kenya have been visited 3 times per year since 2001 to record changes in the status of all residents and to register new immigrants. Linked to this demographic data are all pediatric out-patient visits to peripheral clinics in the study area and in-patient admissions at two district hospitals. Verbal autopsies are performed on all deaths. Entomologic surveillance to measure correlates of malaria transmission is conducted. Similar data are available going back to 1996. The DSS serves as a platform on which impact of interventions can be measured and clinical trials can be performed. It is an integral part of the field station’s activities and is a resource to researchers within and outside CDC.

Efficacy and safety of intermittent preventive treatment for infants (IPTi) with antimalarial drugs in decreasing anemia and malaria morbidity in Rarieda Division, western Kenya

Specific objectives are:

• Compare the efficacy of iron supplementation and intermittent preventive treatment for infants (IPTi) with sulfadoxine-pyrimethamine and three doses of artesunate (SP/AS) given at routine Expanded Programme on Immunization (EPI) visits with iron supplementation and IPTi using one of two alternative antimalarial drug regimens: Lapdap (chlorproguanil-dapsone), or amodiaquine + three doses of AS (AQ/AS); or iron supplementation alone, on the prevention of clinical malaria, moderate anemia, and severe anemia in the first two years of life;
• Assess the impact of IPTi on response to routine childhood immunizations; and
• Assess the impact of IPTi with the aforementioned regimens (particularly SP/AS) on the nasal carriage rates of Haemophilus influenzae type b and the immune response to Haemophilus influenzae type b (Hib) vaccine.

Enrollment was completed in March 2006, and follow-up will continue for 2 years. Additional research questions to be explored in the upcoming months include drug efficacy of the study drug combinations, an IPTi acceptability study, and a cost analysis of the intervention.

The 2-year-old child shown here is enrolled the IPTi study, but did not show up for her 24 month visit. The study staff went to her home and found her very sick, with a hemoglobin count of 3.8. The staff then paid for her transfer from her rural home, where she surely would have died, to the provincial hospital, where she was able to receive a blood transfusion. On the day Dr. Mary Hamel, Malaria Branch Chief of the CDC/KEMRI Research Station, visited her in the hospital, the child was smiling and eating bread and getting ready to go home. As Dr. Hamel says, “We are here to do research, but frequently we find our projects have results beyond what we present in papers – like this – a child who is alive because she was enrolled in our study and benefited from the transport and hospital fees paid for by the study.” (Courtesy KEMRI)

Demographic and health surveillance

The populations of Asembo and Gem (135,000) in western Kenya are visited 3 times per year to record changes in the status of all residents and to register new immigrants. Linked to this demographic data are all pediatric out-patient visits to peripheral clinics in the study area and in-patient admissions at two district hospitals. Verbal autopsies are performed on all deaths. Entomologic surveillance to measure correlates of malaria transmission is conducted.

Larval ecology

The objectives of this research are to evaluate, map, and record the characteristics of productive larval habitats. New information learned at CDC/KEMRI indicates that long-held beliefs that larval control efforts would not be effective as a malaria control tool in Africa may not be correct. Based on recent findings, efforts are underway to develop and initiate a trial to determine the added benefit of larval control in an area with high use of insecticide-treated nets. Related studies on the oviposition behavior of Anopheles gambiae have identified soil moisture as the main determinant of where female mosquitoes lay their eggs. Additional studies are being conducted to identify other attractants for gravid females. The ultimate aim of these studies is to develop oviposition traps for surveillance and control of mosquito populations.

Insecticide resistance

A major concern for any insecticide-based control strategy—including insecticide-treated nets (ITN)—is the development and spread of insecticide resistance in the mosquito population. We are currently monitoring for insecticide resistance using both bioassays to detect phenotypic resistance as well as molecular and biochemical assays to detect markers associated with resistance. In the DSS study area, where ITN use is >80%, we have observed an increase in the frequency of the knock down resistance gene, although our standard bioassays have yet to demonstrate a clear increase in phenotypic resistance. We are also monitoring for behavioral changes in Anopheles gambiae, such as earlier biting or outdoor biting, which would limit mosquito exposure to ITNs. Lastly, we are developing strategies to slow the development and spread of insecticide resistance and to prolong the effectiveness of insecticide-based interventions.

Parasite diversity

The genetic  complexity of  the parasite causing  malaria infection is thought to be one determinant of drug resistance. Use of insecticide-treated bednets (ITNs) may actually  reduce antimalarial drug resistance development by reducing the genetic  complexity of infection among those who sleep under ITNs.

The objective of this study is to assess the change in complexity of infection and drug-resistant molecular markers from blood  specimens collected from patients  before and after widespread ITN introduction, using molecular methods. Findings will help us to understand whether ITNs not only prevent malaria among those who sleep under them, but also reduce the development of drug resistance. If we demonstrate that ITNs help restore drug susceptibility genes, we may be able to use inexpensive antimalarial drugs to which the parasite had become resistant.

Evaluation of the introduction of Coartem on clinical and entomologic measure

The objectives of the study are to measure the change in malaria morbidity, all-cause and malaria-specific mortality, and community parasitemia and anemia prevalence before and after the introduction of guidelines promoting artemether-lumefantrine (Coartem) as first-line treatment for uncomplicated malaria. This antimalarial drug has gametocidal properties, and potentially could result in decreased malaria transmission once the drug is in widespread use. If this is shown to be the case, the findings could be used to provide clinical and cost-effectiveness evidence supporting the Kenyan Ministry of Health’s decision to choose this highly effective but relatively expensive drug for first-line treatment of malaria.

Evaluating barriers to treatment of ITNs in an area of intense malaria transmission in western Kenya

The goal of this project is to understand the reasons for the low percentage of bed nets being brought for redipping at central village locations in the CDC/KEMRI study area of Asembo. The information gathered by these activities will help to improve the delivery of insecticide to the communities in our study area.

2. Studies now being analyzed

Evaluation of the World Health Organization (WHO) color scale in measuring hemoglobin levels in young children

A comparison was done of the WHO color scale in measuring hemoglobin with the Hemocue machine in 800 children aged 2 months to 2 years in 3 clinics in Asembo and Gem.

Survey to determine use of malaria control methods and frequency of antenatal care in pregnant women, western Kenya

The objective of this survey is to assess among women who have recently completed a pregnancy their perceptions of the problem of malaria in pregnancy, document use of malaria prevention measures used during pregnancy, evaluate use of and access to antenatal clinics in the area, measure participation in intermittent preventive treatment (IPTp), and identify factors important for decisions to deliver at home or at a health unit. The survey was conducted in three divisions in western Kenya (Rarieda, Wagai, and Yala) where insecticide-treated nets have been distributed among women who have delivered in the last 6 months.

Evaluation of early warning surveillance systems for highland malaria epidemics in Kenya

The aims of this project were: 1) to determine if rainfall, temperature or Anopheles mosquito density correlate with the incidence of clinical P. falciparum malaria in highland Kenya; 2) to evaluate the accuracy of a sequential sampling scheme for Anopheles mosquito density in the prediction of malaria epidemics in highland Kenya; 3) to evaluate the accuracy of climate-based algorithms in the prediction of malaria epidemics in highland Kenya. Data have been collected and are being analyzed.

3. Studies planned to begin between June and December 2006

Rapid diagnostic test (RDT) evaluation

The objectives are to evaluate how best to incorporate RDTs for malaria into the current health care system. RDTs are to accompany the introduction of artemether-lumefantrine (Coartem) as first-line treatment for malaria in Kenya.

Malarial anemia study

The objective of this study is to assess whether the gene polymorphisms in patients’ Interleukin 12 [IL-12] and Migration Inhibitory Factor [MIF] influence the production and balance of IL-12 and MIF in severe malarial anemia in Kenyan children. If polymorphism in these two genes is a risk factor in severe malarial anemia, it may be possible to predict severe malarial anemia using IL-12 and/or MIF related genetic markers.

The efficacy of cotrimoxazole in preventing malaria among HIV-infected pregnant women and HIV-exposed children

The objective of this study is to measure the efficacy of daily cotrimoxazole, which is prescribed for the prevention of opportunistic infections, in preventing malaria parasitemia.

Insecticide-treated bed nets (ITNs) are used to reduce malaria transmission. These two health workers in Asembo Bay, western Kenya, are retreating an ITN by dipping it in an insecticide preparation.

Contact Details

Mary J. Hamel, M.D.
Malaria Branch Chief
CDC/KEMRI Research Station
PO Box 1578
Kisumu, Kenya
Office tel: 254-(0)57-20-22902/59/83
FAX: 254-(0)57-20-22981