KISUMU
DSS - PROJECTS
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1.
Prevalence of schistosomiasls and soil-transmitted helminths in
school-aged children |
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Funded by : CDC |
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Collaborators : |
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Period : 2002 |
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Results (Background, Objectives,Summary) |
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A survey of school-aged children (10-12 years) in Asembo was undertaken in 2002. Thirty-two schools participated and a minimum of 30 children in each school were tested for Schistosoma mansoni, S. haematobium and soil-transmitted helminths (Ascaris lumbricoides, Trichuris trichuria, hookworms and Strongyloides stercoralis. Nearly 70% of children were infected with one or more parasites. Prevalence of schistosomiasis varied between 0 and 80% with a mean of 16.5%. Schistosome infections were inversely correlated with distance to Lake Victoria with an r value of –0.91 (P<0.001). Schools that were 4 km or closer to the lake had a mean prevalence of 36% and those that were within 2 km had a mean prevalence of 54%. Nearly two-thirds of the children were infected with one or more helminth.
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2. Enteric surveillance |
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Funded by :CDC |
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Collaborators: |
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Period :1998-2004 |
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Results (Background, Objectives, Summary) |
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Diarrhea
is a major cause of morbidity and mortality in sub-Saharan Africa.
Surveillance data on the causes, relative importance, and
antimicrobial susceptibility patterns of specific diarrheal pathogens in
western Kenya can establish the magnitude of the problem, trends in
incidence, provide guidance on effective therapy, and help to direct
studies to identify prevention strategies. With funding provided through
Global Emerging Infectious Diseases Program, the Foodborne and Diarrheal
Diseases Branch (FDDB), DBMD and the Kenya Medical Research Institute
KEMRI/CDC field station in Kisumu, western Kenya have collaborated to
establish surveillance for bacterial enteric pathogens. The objectives of the study are: 1.To isolate, identify, and determine the antimicrobial susceptibility of Shigella (including S. dysenteriae typ1), Salmonella, Vibrio, Campylobacter, and diarrheagenic E. coli. 2. To collect information on the incidence and associated morbidity and mortality due to bloody and non-bloody diarrhea in the population 3. To determine risk factors for transmission of important diarrheal pathogens in the study area and identify potential prevention strategies. Sentinel
rural surveillance is currently being conducted at 4 clinics in the
Asembo study area. Information
collected at each visit includes demographics, reason for visit,
symptoms, previous health care sought, health care provider diagnosis,
and treatment given. Up to
five stool specimens are collected each day at each clinic (20 total
specimens possible) from persons of all ages presenting with diarrhea
(>3 loose stools in 24 hours). Specimens
are kept refrigerated and shipped to the CDC/KEMRI Enterics Laboratory
with 24 hours of collection. An
average of 5 total specimens is processed daily from these 4 sites.
Surveillance is also conducted at the Provincial General Hospital’s
Pediatric Diarrhea Clinic. Up
to 5 specimens per day are collected from randomly chosen children <5
years old presenting with diarrhea.
These specimens are processed within 8 hours of collection.
All testing is conducted in Kenya, with two exceptions that
require resources not locally available: 1) determination of Campylobacter species and their antimicrobial susceptibilities,
and 2) evaluation for the presence of diarrhoeagenic E. coli. |
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3. Turbid water treatment health outcome study |
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Funded by :Procter and Gamble |
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Collaborators : |
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Period :2003 |
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Results (Background, Objectives, Summary) |
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WHO estimates that 1.1 billion persons do not have access to improved water supplies. Drinking contaminated water contributes substantially to the estimated 1.8 million deaths from diarrhoea that occur annually. The least expensive method of home water treatment in these settings involves adding dilute household bleach (Sodium Hypochlorite) to the water. However, unimproved water supplies are commonly surface water heavily contaminated with organic matter and microorganisms. When chlorine bleach is added to such water the chlorine in bleach binds to the organic matter, and so is unavailable to kill pathogens. If water is not too heavily contaminated with organic matter, higher dosages of bleach can make it microbiologically safe, but such high levels of chlorine adversely affects the taste of the water and so people’s willingness to treat the water. It also creates high concentrations of chlorinated aromatic compounds, which are carcinogenic. The
Procter & Gamble company has developed a new home water treatment
technology, which combines precipitation, coagulation, flocculation and
chlorination. The product
physically pulls dirt, other organic matter, and heavy metals out of
solution. It then releases
hypochlorite so the resulting water is clear and microbiologically safe.
The objective of this study is to introduce a home water treatment technology which combines precipitation, coagulation, flocculation and chlorination into a community with turbid drinking water and frequent diarrhoea and evaluate if:
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4. Efficacy and safety of paediatric immunization-linked preventive intermittent treatment (PIPIT) with antimalarials in decreasing anaemia and malaria morbidity in rural western Kenya |
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Funded by : CDC and Gates Foundation |
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Collaborators : |
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Period : 2003-2006 |
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Results (Background, Objectives, Summary) |
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Approximately three quarters of preschool children in eastern Africa suffer from anaemia, defined as a haemoglobin (Hb) concentration below 11 g/dL. For children < 5 years of age, the overall incidence of severe malarial anaemia (Hb < 5 g/dl) is estimated at 15-60 cases per 1,000 children per year. Other studies have confirmed that the burden of malaria-related anaemia falls primarily on infants and young children. Recently, Schellenberg and colleagues, working in an area of Tanzania with a low to moderate level of Plasmodium falciparum transmission and a low level of sulfadoxine-pyrimethamine (SP) resistance, demonstrated that by linking intermittent prophylaxis to routine immunization visits through the national Expanded Program on Immunization (EPI), SP could be administered to children at 2,3, and 9 months of age, resulting in a 59% reduction in rates of clinical malaria and a 50% reduction in the rate of severe anaemia (Hb<8 g/dl) compared to those receiving placebo. We propose to conduct randomized double blind placebo-controlled trial to estimate the efficacy of Paediatric Immunization-Linked Preventive Intermittent Treatment (PIPIT) with SP + three doses of artesunate (AS) (SP/AS3) given in combination with iron supplementation from 2-6 months of age at routine EPI visits on the prevention of clinical malaria, moderate anaemia, and severe anaemia in the first 18 months of life in an area with intense malaria transmission and near universal ownership of insecticide treated nets (ITNs). Specific objectives are: 1) Compare the efficacy of iron supplementation and PIPIT with SP/AS3 given at routine EPI visits with iron supplementation and PIPIT using one of two alternative antimalarial drug regimens: Lapdap (chlorproguanil-dapsone), or AQ + three doses of AS (AQ/AS3); or iron supplementation alone, on the prevention of clinical malaria, moderate anemia, and severe anemia in the first 18 months of life; 2) Assess the impact of PIPIT with the aforementioned regimens on seroconversion to EPI vaccines (Polio, Diphtheria, Tetanus, Pertussus, Hepatitis B, Hemophilus Influenzae type B, and Measles; 3) Assess the impact of PIPIT with the aforementioned regimens (particularly SP/AS3) on the nasal carriage rates of Streptococcus pneumoniae and Haemophilus influenza type b; and 4) Estimate the effect of different PIPIT regimens on gametocyte carriage rates at 9 months of age. Enrolled children will be followed with regularly scheduled clinical visits, haemoglobin determinations, and malaria blood films until 18 months of age. This trial will generate important public health information on the efficacy of PIPIT in preventing anaemia and clinical malaria among infants in an area with intense malaria transmission and ongoing prevention efforts through the use of insecticide treated nets. |
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5. Evaluation of the WHO Haemoglobin Colour Scale in children <2 years old |
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Funded by :CDC |
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Collaborators : |
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Period :2003 |
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Results (Background, Objectives, Summary) |
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Cases
of mild to moderate anaemia are frequently unrecognized in peripheral
health units lacking laboratory facilities.
Use of pallor signs to diagnose anaemia by health care workers
has not proven to be dependable. The
WHO Haemoglobin Colour Scale (HCS) has been developed to be a simple,
reliable and cost-effective tool to screen for anaemia in the absence of
laboratory-based haemoglobinometry.
Requiring no chemical agents, the HCS compares the colour of a
single blood drop with a set of standards ranging from 4-14 g/dl.
While preliminary results indicate that the sensitivity and
specificity of the method compare favorably with other rapid techniques
such as the HemoCue machine (HemoCue AB, Angelholm, Sweden), the HCS has
not yet been extensively evaluated in children < 2 years old.
We propose to evaluate this tool in the population most likely to
experience high rates of anaemia, that is children < 2 years of age.
The study will take place in the KEMRI/CDC study area of Gem in
western Kenya. The nurses
in charge of 3 peripheral health units will be trained in use of the HCS
in a 2-day workshop. After
training, hemoglobin measurements made using the HCS will be compared
with those of the HemoCue machine on 820 children aged 0-2 years old.
The sensitivity, specificity, positive and negative predictive
values of the HCS in comparison with the HemoCue machine will be
calculated. It is
anticipated that the results will assist in determining whether HCS can
be used at the level of the peripheral health unit to improve
recognition of anaemia in young children. |
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6.
Studies of larval ecology of malaria mosquitoes in Kenya in preparation
for source reduction for malaria control |
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Funded by :NIH |
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Collaborators :Michigan State University |
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Period :2002-2006 |
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Results (Background, Objectives, Summary) |
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The predominant theme of the research we propose here is that microorganisms that occur in larval habitats of Anopheles gambiae have crucial, dual roles in the Resource Ecology of these mosquitoes. First, there is strong evidence that microorganisms form the basis for production of adult Anopheles gambiae from larval habitats, Second, microorganisms emit volatile chemicals that guide and arrest females to oviposition sites, and stimulate oviposition. Thus, microorganisms mediate how females find appropriate habitats to place their eggs, and how larval habitats produce mature, fit adults. Because food limitation due to density-dependent processes due to food limitation likely occurs in larval habitats, yield adult females of variable size and nutrient reserves, therefore nutrient and microbial production in larval habitats ultimately affects population dynamics and vectorial capacity of this important mosquito species. 1. Delineate the density, form, and productivity of larval habitats of Anopheles gambiae in areas defined by low and high An. gambiae densities in the Asembo Bay research area. We hypothesize that productive larval habitats of Anopheles gambiae s.s (i.e., small, confined, soil lined puddles formed by human and animal activity) are not randomly distributed, as is often assumed, but rather are located in particular features among rural villages in malaria-endemic settings, due to human and domestic animal activity. We will study production of habitats on a spatial scale in an area of western Kenya (70 sq km area) that has been the focus of intensive, long term malaria transmission analyses, and where key features have been mapped in detail. Rigorous studies of larval habitat abundance, distribution, and productivity are lacking there. We hypothesize that (a) productive habitats will be just a subset of all potential water-holding bodies; (b) the number of productive habitats can be estimated on an area-wide basis through rigorous sampling; and (c) their stability (capacity to hold water for a sufficient amount of time to produce larval cohorts and adults) can be measured, their rate of turnover determined, and their productivity quantified. 2.
Investigate
the role that microorganisms play in mediating oviposition site
selection by female Anopheles gambiae.
We hypothesize that microbial metabolic activity in larval
habitats produces chemical cues in the form of volatile organic
compounds (VOCs) that attract and arrest gravid females at oviposition
sites, and stimulate oviposition. Thus, gravid females will be most
likely to lay eggs selectively in habitats where microbial production is
evident, because these volatiles are indicative of productive and
therefore suitable habitat. Natural
selection would not favor oviposition into nonproductive habitats. We
will quantify VOCs generated from microbial metabolism especially of
nitrogenous (indol and its derivatives) and humic acid substances (phenolic
derivatives), as recent studies indicate their importance.
We will identify and quantify VOCs emitted from habitats, trace
these to their microbial sources through rigorous microbiologic
characterizations of larval habitats, and will study behavioral and
electroantennogram responses of gravid females to specific compounds
using oviposition choice experiments, GC/MS-electroantennogram
detection, and wind tunnel response and arrestment assays. 3. Quantify the dynamics of nutrient flow and microbial community structure in relation to production of Anopheles gambiae from larval habitats. We hypothesize that microorganisms form the basis for production of adults from habitats, by transforming inorganic nutrients through autotrophic and heterotrophic processes into assimilable forms, by providing food items and by satisfying the bulk and specific larval nutritional demands. To accomplish this aim, we will quantify nutrient dynamics relative to microbial production, and relate them both to larval growth and adult mosquito production, using larval cohort studies in lab, simulated field habitat experiments, and natural habitat manipulations and measurements. Because density-dependent competition for food in the larval stage yields adults of variable body size and varied nutrient reserves at emergence, it will affect parameters of population dynamics (survivorship and fecundity of females) and vectorial capacity (survivorship and infection rate of females). Thus we will describe size-frequency distributions of emerged and field-caught females, will measure their nutrient reserves, and will quantify size-dependent frequency of sporozoite infection rates size-dependent survivorship relationships in field populations. |
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7. Survey to determine use of malaria control methods and frequency of antenatal care in pregnant women in Rarieda Division, Western Kenya |
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Funded by :CDC |
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Collaborators: |
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Period :2003 |
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Results (Background, Objectives, Summary) |
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In malaria endemic areas in sub-Saharan Africa, pregnant women, especially primi - and secundigravidae, are more likely to have placental and peripheral parasitemia with Plasmodium falciparum than non-pregnant women. Adverse consequences of malaria in pregnancy include maternal anaemia, and low birth weight of the new born. Low birth weight is known to be the most important risk factor for infant mortality. Intermittent preventive treatment (IPT) with sulfadoxine-pyrimethamine (SP) in pregnancy has been shown to be effective in decreasing low birth weight and anaemia, presumably by decreasing placental malaria, which cannot always be detected by the presence of maternal parasitemia (Shulman et al, 1999; Rogerson et al, 2000). Recently the beneficial effects of insecticide treated bed nets (ITN) on birth weight and maternal haemoglobin level were reported in an area with high transmission of malaria (ter Kuile, personal communication). We propose a survey in three divisions in western Kenya (Rarieda, Wagai and Yala, areas where ITNs have been distributed) among women who have delivered in the last 6 months, to assess their perceptions of the problem of malaria in pregnancy and any malaria prevention measures they have used during pregnancy, use of and access to antenatal clinics in the area, participation in IPT and factors important for decisions to deliver at home or at a health unit. Data from this study will be useful to assist the MOH in the implementation of IPT, and to improve access to antenatal clinics and health centers in a rural area. |
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8.
Cross-sectional assessment of HIV/STI prevalence and HIV risk behaviour
in rural Western Kenya |
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Funded by :CDC |
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Collaborators:Institute of Tropical Medicine, Antwerp |
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Period :2003 |
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Results (Background, Objectives, Summary) |
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The HIV/AIDS epidemic continues with force in sub-Saharan Africa, making it the most adversely affected region in the world. An estimated 28.5 million adults and children in sub-Saharan Africa are living with HIV/AIDS with 3.5 million incident infections in 2001. Youth, especially teenage girls, are at high risk for HIV infection. An HIV vaccine may be the most effective weapon in controlling the epidemic in the world’s most resource-limited countries, where access to antiretrovirals is expected to remain limited in the near future. Several potential HIV vaccine candidates may be ready for testing in phase II and III clinical trials in the next 5-10 years. However, a paucity of epidemiologically well-characterized populations and cohorts have been developed to test such vaccine candidates. Additionally, effective HIV-prevention interventions specifically targeting young people are urgently needed to protect this high-risk population. The objectives of this study are: 1) To gather data on the prevalence of HIV, sexually transmitted infections (STIs) and refusal rates in a well-defined rural population with assumed high-risk behaviour, in order to guide the sampling for a prospective incidence cohort in preparation for an HIV vaccine clinical trial. 2) To provide a baseline for evaluating the effect of youth-focused interventions on the prevalence of HIV and other STIs, sexual behaviour, and teenage pregnancy. The study will be a cross-sectional population-based survey in the rural community of Asembo in western Kenya. A random sample of 3,125 residents of Asembo aged 13-34 years will be selected from all those in the area, using our existing demographic surveillance system. This will ensure a sample size of 2,500, allowing for refusals. Consenting participants will be interviewed about potential HIV risk behaviours and counselled and tested for HIV and STIs. Participants will be further screened for signs of STIs and symptoms of active tuberculosis. For a sub-sample of 716 persons, a malaria smear will be made to assess prevalence of malaria by HIV status. . Participants diagnosed with tuberculosis, treatable STIs, or malaria will be treated. Partners and close contacts will receive the same care. HIV-infected participants will be referred to an HIV-care clinic for treatment of opportunistic infections and follow up. The prevalence and refusal data will guide the sampling and feasibility for a prospective HIV-incidence cohort to be established later in the same community in preparation for a vaccine clinical trial. The prevalence data for 13-20 year olds along with the behavioural data will be used as a baseline against which to evaluate the effect of a package of youth-targeted interventions to be set up in the same area. The survey will be repeated in this targeted sub-population of 13-20 year olds 3 years after the intervention is in place. |
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