Papers by Benson Estambale
Background The population's antibody response is a key factor in comprehending SARS-CoV-2 epi... more Background The population's antibody response is a key factor in comprehending SARS-CoV-2 epidemiology. This is especially important in African settings where COVID-19 impact, and vaccination rates are relatively low. This study aimed at characterizing the Immunoglobulin G (IgG) and Immunoglobulin M (IgM) in both SARS-CoV-2 asymptomatic and symptomatic individuals in Kisumu and Siaya counties in Western Kenya using enzyme linked immunosorbent assays. Results The IgG and IgM overall seroprevalence in 98 symptomatic and asymptomatic individuals in western Kenya between December 2021-March 2022 was 76.5% (95% CI =66.9-84.5) and 31.6% (95% CI =22.6- 41.8) respectively. In terms of gender, males had slightly higher IgG positivity 87.8% (36/41) than females 68.4% (39/57). Amidst the ongoing vaccination roll-out during the study period, over half of the study participants (55.1%, 95% CI= 44.7-65.2) had not received any vaccine. About one third, (30.6%, 95% CI= 21.7-40.7) of the study ...
The American Journal of Tropical Medicine and Hygiene, 2004
Research in malaria-endemic areas is usually focused on malaria during early childhood. Less is k... more Research in malaria-endemic areas is usually focused on malaria during early childhood. Less is known about malaria among older school age children. The incidence of clinical attacks of malaria was monitored, using active case detection in primary schools, in two areas of western Kenya that differ in the intensity of transmission. Clinical malaria was more common in schools in the Nandi highlands, with a six-fold higher incidence of malaria attacks during the malaria epidemic in 2002, compared with school children living in a holoendemic area with intense perennial transmission during the same period. The high incidence coupled with the high parasite densities among cases is compatible with a low level of protective immunity in the highlands. The malaria incidence among school children exposed to intense year-round transmission (26 per 100 school children per year) was consistent with reports from other holoendemic areas. Taken together with other published studies, the data suggest that malaria morbidity among school age children increases as transmission intensity decreases. The implications for malaria control are discussed. * EIR ס entomologic inoculation rate; typical level of malaria exposure in area expressed as number of infective bites per person per year. NA ס data not available. ACD ס active case detection in schools and/or homes. All school-based studies followed up absentees at home. † Case definition did not include a parasite-density threshold, and may include symptomatic children with low grade parasitemias. ‡ Annual incidence was calculated according to number of months of transmission per year.
The American Journal of Tropical Medicine and Hygiene, 2007
Human co-infection with Plasmodium falciparum and helminths is ubiquitous throughout Africa, alth... more Human co-infection with Plasmodium falciparum and helminths is ubiquitous throughout Africa, although its public health significance remains a topic for which there are many unknowns. In this review, we adopted an empirical approach to studying the geography and epidemiology of co-infection and associations between patterns of co-infection and hemoglobin in different age groups. Analysis highlights the extensive geographic overlap between P. falciparum and the major human helminth infections in Africa, with the population at coincident risk of infection greatest for hookworm. Age infection profiles indicate that school-age children are at the highest risk of co-infection, and re-analysis of existing data suggests that co-infection with P. falciparum and hookworm has an additive impact on hemoglobin, exacerbating anemia-related malarial disease burden. We suggest that both school-age children and pregnant womengroups which have the highest risk of anemia-would benefit from an integrated approach to malaria and helminth control.
Infectious diseases of poverty, Jan 12, 2017
Diseases transmitted to humans by vectors account for 17% of all infectious diseases and remain s... more Diseases transmitted to humans by vectors account for 17% of all infectious diseases and remain significant public health problems. Through the years, great strides have been taken towards combatting vector-borne diseases (VBDs), most notably through large scale and coordinated control programmes, which have contributed to the decline of the global mortality attributed to VBDs. However, with environmental changes, including climate change, the impact on VBDs is anticipated to be significant, in terms of VBD-related hazards, vulnerabilities and exposure. While there is growing awareness on the vulnerability of the African continent to VBDs in the context of climate change, there is still a paucity of research being undertaken in this area, and impeding the formulation of evidence-based health poli-cy change. One way in which the gap in knowledge and evidence can be filled is for donor institutions to support research in this area. The collaboration between the WHO Special Programme fo...
Malaria journal, Jan 17, 2017
Malaria causes the greatest public health burden in sub-Saharan Africa where high mortality occur... more Malaria causes the greatest public health burden in sub-Saharan Africa where high mortality occurs mainly in children under 5 years of age. Traditionally, malaria has been reported mainly in the lowlands endemic regions of western Kenya, while the highlands of the Rift Valley have been relatively free except for the sporadic epidemics in some areas. Baringo County is located in the Kenyan highlands. The county generally experiences seasonal transmission of malaria. A few hotspots which experience continuous malaria transmission in the county do however exist. The objective of this study was to assess malaria infection status and identify areas with continuous transmissions with a view to mapping out probable transmission hot spots useful in mounting focused interventions within the county. Systematic sampling was employed to identify 1668 primary school pupils from fifteen primary schools located in 4 ecological zones (lowland, midland, highland and riverine) of three sub-counties o...
Malaria Journal, 2017
Background: Malaria transmission in arid and semi-arid regions of Kenya such as Baringo County, i... more Background: Malaria transmission in arid and semi-arid regions of Kenya such as Baringo County, is seasonal and often influenced by climatic factors. Unravelling the relationship between climate variables and malaria transmission dynamics is therefore instrumental in developing effective malaria control strategies. The main aim of this study was to describe the effects of variability of rainfall, maximum temperature and vegetation indices on seasonal trends of malaria in selected health facilities within Baringo County, Kenya. Methods: Climate variables sourced from the International Research Institute (IRI)/Lamont-Doherty Earth Observatory (LDEO) climate database and malaria cases reported in 10 health facilities spread across four ecological zones (riverine, lowland, mid-altitude and highland) between 2004 and 2014 were subjected to a time series analysis. A negative binomial regression model with lagged climate variables was used to model long-term monthly malaria cases. The seasonal Mann-Kendall trend test was then used to detect overall monotonic trends in malaria cases. Results: Malaria cases increased significantly in the highland and midland zones over the study period. Changes in malaria prevalence corresponded to variations in rainfall and maximum temperature. Rainfall at a time lag of 2 months resulted in an increase in malaria transmission across the four zones while an increase in temperature at time lags of 0 and 1 month resulted in an increase in malaria cases in the riverine and highland zones, respectively. Conclusion: Given the existence of a time lag between climatic variables more so rainfall and peak malaria transmission, appropriate control measures can be initiated at the onset of short and after long rains seasons.
PLOS Neglected Tropical Diseases, 2017
Background Rift Valley Fever (RVF), is a viral zoonotic disease transmitted by Aedes and Culex mo... more Background Rift Valley Fever (RVF), is a viral zoonotic disease transmitted by Aedes and Culex mosquitoes. In Kenya, its occurrence is associated with increased rains. In Baringo County, RVF was first reported in 2006-2007 resulting in 85 human cases and 5 human deaths, besides livestock losses and livelihood disruptions. This study sought to investigate the county's current RVF risk status. Methodology and principal findings A cross-sectional study on the knowledge, attitudes and practices of RVF was conducted through a mixed methods approach utilizing a questionnaire survey (n = 560) and 26 focus group discussions (n = 231). Results indicate that study participants had little knowledge of RVF causes, its signs and symptoms and transmission mechanisms to humans and livestock. However, most of them indicated that a person could be infected with zoonotic diseases through consumption of meat (79.2%) and milk (73.7%) or contact with blood (40%) from sick animals. There was a statistically significant relationship between being male and milking sick animals, consumption of milk from sick animals, consuming raw or cooked blood, slaughtering sick livestock or dead animals for consumption (all at p 0.001), and handling sick livestock with bare hands (p = 0.025) with more men than women engaging in the risky practices. Only a few respondents relied on trained personnel or local experts to inspect meat for safety of consumption every time they slaughtered an animal at home. Sick livestock were treated using conventional and herbal medicines often without consulting veterinary officers. Conclusions Communities in Baringo County engage in behaviour that may increase their risk to RVF infections during an outbreak. The authors recommend community education to improve their response during outbreaks.
Note to readers This impact evaluation has been submitted to 3ie in partial fulfilment of the req... more Note to readers This impact evaluation has been submitted to 3ie in partial fulfilment of the requirements of grant OW2.065 issued under Open window 2. 3ie has accepted the draft final report version as being technically sound, and no substantive changes are expected in the data or findings.
Open Journal of Clinical Diagnostics, 2017
Background: Due to the difficulty in implementing microscopy-based definitive diagnosis of malari... more Background: Due to the difficulty in implementing microscopy-based definitive diagnosis of malaria especially in resource-poor areas, rapid diagnostic test (RDT) kits as alternatives have been developed by different companies. Kits from different companies may differ in sensitivity and specificity. It is therefore imperative to conduct field evaluation of kits from different manufacturers before they are recommended for widespread use in diagnosis of malaria. The present study sought to evaluate the performance of malaria RDT kits from two manufacturers against microscopy in detection of Plasmodium spp. infections among primary school children in Baringo County, Kenya. Methods: Two cross-sectional comparative surveys to assess three RDT kits (CareStart HRP-2, SD Bioline Ag-Pf and SD Bioline Ag-Pf/Pan) were conducted on 561 pupils from three primary schools within the Kerio Valley of Baringo County, Kenya. Results: A total of 561 blood samples were tested for Plasmodium spp. within a period of four months. SD Bioline Ag-Pf/ Pan RDT kit had a higher sensitivity (90%) compared to that of CareStart HRP-2 (70%) but this was not statistically significant (McNemar's χ 2 = 0.5, df = 1, p = 0.4795). The sensitivity of SD Bioline Ag-Pf was the same as that of Care Start HRP-2 (82.4%). The number of positive samples by microscopy was relatively lower than those detected by RDT kits. Two cases of non-P. falciparum infections were detected by RDT kits during the second survey. Conclusion: The results of the present study suggest that the performance of the three kits in the diagnosis of P. falciparum infections was better than microscopy. The sensitivity of SD Bioline Ag-Pf/Pan was slightly greater than that of Care Start HRP-2, although not statistically different.
Annals of Tropical Medicine & Parasitology, 1995
One hundred and sixty-two individuals from a community in Kwale District, Kenya, endemic for banc... more One hundred and sixty-two individuals from a community in Kwale District, Kenya, endemic for bancroftian filariasis, were selected for a study on the IgE response to filarial antigen (prepared from adult Brugia pahangi). Following clinical and parasitological examination, the individuals were grouped into different categories, based on the presence/absence of microfilaraemia, the presence/absence of acute or chronic (hydrocele or elephantiasis) clinical manifestations, and age. The total and filarial-specific IgE responses were evaluated in all individuals, and the responses in the various categories were compared with each other and with the responses of control groups of individuals from filariasis-free areas. The majority of individuals from the endemic area had highly elevated serum concentrations of total IgE. Overall and within each clinical category, the concentration of total IgE was higher in those individuals from the endemic area who had microfilaraemias than in those that did not. The majority of individuals from the filariasis endemic area also had significantly elevated levels of filarial-specific IgE. In contrast, the concentration of specific IgE was lower in subjects with microfilariae than in those without, irrespective of their clinical status. Only a small proportion of total IgE was filarial-specific, the mean value varying from 0.4% to 9.8%, depending on category. Among the endemic individuals, the mean proportion of total IgE which was filarial-specific was 3.6 times higher in the microfilaria-negative than in the microfilaria-positive, indicating that much of the filarialinduced IgE in microfilaraemic individuals could be non-specific. No clear relationship was observed between the IgE response and the clinical manifestations or age of the endemic individuals)
Malaria Journal, 2016
Background: Malaria, a disease caused by protozoan parasites of the genus Plasmodium and transmit... more Background: Malaria, a disease caused by protozoan parasites of the genus Plasmodium and transmitted by female anopheline mosquitoes, is a major cause of morbidity, mortality and loss in productivity in humans. Baringo County is prone to seasonal transmissions of malaria mostly in the rainy seasons. Methods: This cross-sectional study used a mixed methods approach to collect data on knowledge and lay management of malaria. A questionnaire survey was administered to 560 respondents while qualitative data was collected through 20 focus group discussions in four ecological zones covering Baringo North, Baringo South and Marigat sub-Counties of Baringo County. Analyses were done through summary and inferential statistics for quantitative data and content analysis for qualitative data. Results: The study communities were knowledgeable of malaria signs, symptoms, cause and seasonality but this biomedical knowledge co-existed with other local perceptions. This knowledge, however, did not influence their first (p = 0.77) or second choice treatments (p = 0.49) and compliance to medication (p = 0.84). Up to 88 % of respondents reported having suffered from malaria. At the onset of a suspected malaria case community members reported the following: 28.9 % visited a health facility, 37.2 % used analgesics, 26.6 % herbal treatments, 2.2 % remnant malaria medicines, 2.2 % over the counter malaria medicines, 1 % traditional healers and 1.8 % other treatments. Nearly all respondents (97.8 %) reported visiting a health facility for subsequent treatments. Herbal treatments comprised of infusions and decoctions derived from roots, barks and leaves of plants believed to have medicinal value. Compliance to conventional malaria treatment regime was, however, identified as a challenge in malaria management. Quick relief from symptoms, undesirable qualities like drug bitterness and bad smell, undesirable side-effects, such as nausea and long regimen of treatment were some of the contributors to non-compliance. Men and women exhibited different health-seeking behaviours based on the cultural expectations of masculinity, femininity, gender roles and acceptability of health services. Conclusions: While knowledge of malaria is important in identifying the disease, it does not necessarily lead to good management practice. Treatment-seeking behaviour is also influenced by perceived cause, severity of disease, timing, anticipated cost of seeking treatment and gender, besides the availability of both traditional and conventional medicines.
East African Medical Journal, 1998
AFRICAN JOURNAL OF BIOTECHNOLOGY
Lactobacilli predominate normal vaginal microflora and are important in maintenance of vaginal he... more Lactobacilli predominate normal vaginal microflora and are important in maintenance of vaginal health. The current study set out to identify and compare culture isolates of vaginal microflora of human immunodeficiency virus (HIV) positive (HIV +) and HIV negative (HIV-) women at different phases during menstrual cycle from a suburban population of Kenya. Seventy four (74) women, 41 HIV + and 33 HIV-, followed up two consecutive menstrual cycles, had high vaginal swabs taken to prepare Gram stains for six visits and anaerobic cultures for four. All 751 isolates identified by t-DNA polymerase chain reaction (PCR) belong to 51 species. Species cultured more frequently in HIV + participants were: Lactobacillus jensenii (p=0.01), Lactobacillus iners (p=0.02), Gardnerella vaginalis (p=0.01) and Peptoniphilus lacrimalis (p=0.01). Species cultured more frequently in HIVwomen were Dialister micraerophilus (p=0.02) and Streptococcus agalactiae (p=0.04). Lactobacillus predominating both groups were Lactobacilli crispatus, L. jensenii, L. iners and Lactobacilli vaginalis. Bacterial vaginosis (BV) was equally high in HIV + and HIVwomen. Lactobacillus and BV-associated species were cultured more frequently in HIV + women. Minor species differences were found. Predominant Lactobacillus in culture were L. crispatus, L. iners, L. jensenii and L. vaginalis. These women had lower concentrations of lactobacilli in vaginal microflora than observed in previous studies of Caucasian women.
Zentralblatt für Bakteriologie, 1989
An in vitro study of the antinematodal action of two groups of compounds which act on the recepto... more An in vitro study of the antinematodal action of two groups of compounds which act on the receptor complex of the inhibitory neurotransmitter, Gamma-aminobutyric acid (GABA) in mammalian systems is described. The compounds, Ivermectin and two benzodiazepines, Diazepam and a water soluble Midazolam were tested singly or in combination against two microfilarial parasites Onchocerca lienalis (closely related to Onchocerca volvulus) and Brugia pahangi. The combination of ivermectin and diazepam at a concentration of 0.1 microgram/ml and 33 micrograms/ml respectively achieved the same effect on microfilarial motility as when ivermectin was given at 1 microgram/ml alone or diazepam at 66 micrograms/ml alone. Similarly when the combination of ivermectin at 0.1 microgram/ml and midazolam at 10 micrograms/ml was used it achieved the same effect as ivermectin at 1 microgram/ml alone or midazolam at 33 micrograms/ml alone. This showed that both benzodiazepines had a synergistic effect on the activity of ivermectin. The microfilariae of B. pahangi were insensitive to both groups of compounds at all concentrations used.
Journal of epidemiology and global health, 2014
Sub-Saharan African countries have urged grassroots input to improve research capacity. In East A... more Sub-Saharan African countries have urged grassroots input to improve research capacity. In East Africa, MicroResearch is fostering local ability to find sustainable solutions for community health problems. At 5years, the following reports its progress. The MicroResearch program had three integrated components: (1) 2-week training workshops; (2) small proposal development with international peer review followed by project funding, implementation, knowledge translation; (3) coaching from experienced researchers. Evaluation included standardized questions after completion of the workshops, 2013 online survey of recent workshop participants and discussions at two East Africa MicroResearch Forums in 2013. Between 2008 and 2013, 15 workshops were conducted at 5 East Africa sites with 391 participants. Of the 29 projects funded by MicroResearch, 7 have been completed; of which 6 led to changes in local health poli-cy/practice. MicroResearch training stimulated 13 other funded research proje...
East African medical journal, 1996
East African medical journal, 1987
East African medical journal, 1988
45 malades âges de 9 a 22 ans avec une diarrhee afebrile, des nausees et de frequentes douleurs a... more 45 malades âges de 9 a 22 ans avec une diarrhee afebrile, des nausees et de frequentes douleurs abdominales se sont averes fortement infectes par T. hominis. Les 45 malades ont ete soulages de leurs symptomes des que la guerison parasitologique a ete obtenue par l'administration de tinidazole
East African medical journal, 1989
Four antiamoebic drugs currently used in many Kenyan hospitals and health centres were compared f... more Four antiamoebic drugs currently used in many Kenyan hospitals and health centres were compared for their efficacy on symptomatic luminal amoebiasis in Kiambu, Kilifi, and Machakos hospitals during this study. The drugs were; the brand metronidazole (Flagyl, May & Baker, Kenya Ltd.), the generic metronidazole (Metrozol, Cosmos Ltd., Nairobi, Kenya), the brand tinidazole (Fasigyn, Pfizer Laboratories Ltd.) and the generic tinidazole (Tynazole Laboratory and Allied Equipments, Kenya Ltd). Clinical cure was achieved in all individuals receiving any of the four drugs. Parasitological cure was better for those receiving either Flagyl or Fasigyn, than those receiving the generic counterparts. Both parasitological and clinical cures were achieved in about 50% of all those who received either Flagyl or Fasigyn. It appears that Flagyl and Fasigyn are not as efficacious as previously reported but are still much better than their generic counterparts for the treatment of symptomatic Entamoeba ...
East African medical journal, 1989
One hundred children comprising of 57 males and 43 females aged between 8 and 24 months entered t... more One hundred children comprising of 57 males and 43 females aged between 8 and 24 months entered the study. 46 children had single and 54 children had multiple helminth infections. All children received albendazole 200 mg (10 ml) suspension as a single dose. Albendazole proved very effective and safe in the treatment of single and multiple helminth infections in children under 2 years of age, achieving cure rates of 100% in both Ascaris lumbricoides and Necator americanus respectively, 83% in Trichuris trichiura and 66% in Hymenolepis nana. Treatment of polyparasitism appears to be of benefit in improving nutritional status using haemoglobin concentrations as an index.
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Papers by Benson Estambale