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A comparison of parametric methods of modeling mosquito survival using temperature and age-dependent mosquito survival data
Full text linkIt is estimated that malaria affects over 200 million people every year, and accounts for about 750,000 deaths during the same period. The disease control measures often include interventions aimed at reducing the survival of the adult female Anopheles mosquitoes. Whereas research effort has been paid to evaluate the effects on the vector survival, little research has been done on how temperature and time affect the vector adult life-history parameters. This paper sought to compare the performance of four parametric models, namely; Gompertz, gamma, Weibull, and exponential models to determine the best model for analyzing the survival of the female Anopheles mosquito. Using data from a mosquito survival experiment, the paper compared the performance of the models in fitting mosquito mortality. The results showed that temperature and age are significant predictors of vector mortality. In addition, the Gompertz model fitted the data on the adult A. gambiae and A. stephensi better than the Weibull, Gamma, and the Exponential models. The findings of the current paper are useful in parameterizing reliable mathematical models that examine the potential impact of temperature as well as global warming on the transmission of malaria
Advancing understanding and modeling of climate processes for provision of deterministic climate information for sustainable development in Kenya and Eastern Africa
Full text linkThe implications of climate variability and emerging climate change make East Africa particularly vulnerable region due to dependence of most socio-economic activities on highly variable climatic variables like rainfall which has relatively low predictability. Dynamical climate modelling for both operational climate information services like seasonal outlooks, and long-term projections has made notable improvements since 1990s. Models are the only tools for projecting the long-term future climate alongside provision of short-term information for planning and management of climate sensitive socio-economic activities like rain-fed agriculture and water resources. Using rainfall and moist circulation evaluation results, this study illustrates the “UM HadGEM-GC2” model give good indications of processes which quantify climate extremes namely floods and droughts over East Africa. Among the most important processes revealed in this study, vertically integrated moisture flux, which embraces both horizontal moisture transport into or out of East Africa with sufficient moist-air depth or dry atmospheric column are crucial mechanisms for occurrence of floods and droughts in Kenya and East Africa. Knowledge products like these can translate into mitigation and adaptation decisions in water resources, agriculture and food security. To model developers, processed based model evaluation outcomes like these reveals what physics and dynamics attributes to focus on in the formulation of next generation models and development of evaluation metrics
Anti-inflammatory activity of selected plants used by the Ilkisonko Maasai, Kenya
Full text linkBackground: The Ilkisonko Maasai are a Kenyan pastoralist community that uses indigenous plants for the management of pain and inflammatory conditions such as arthritis. Objectives: The purpose of this study was to validate the use of plants for medicinal purposes by the Ilkisonko Maasai through testing for anti-inflammatory activity using the carrageenan-induced rat paw oedema assay. Methodology: The methanol extracts (400 mg/kg body weight) of Rhus natalensis (bark), Acacia drepanolobium (bark), Acacia nilotica (bark), Acacia reficiens (bark), Acacia robusta (bark), Grewia villosa (bark), Ximenia americana (bark and leaves) and Rhus vulgaris (leaves) were evaluated for in vivo anti-inflammatory efficacy using the carrageenan-induced rat paw oedema assay. Diclofenac (20 mg/kg body weight) was used as the positive control and paw volume was measured by a plethysmometer. Results: The maximum percentage inhibition (PI) of the extracts was observed as Grewia villosa (58.6% at 24 h), Rhus vulgaris (57.8% at 24 h), Acacia nilotica (55.5% at 1 h), Ximenia americana (54.5% at 1 h), Acacia drepanolobium (50.9% at 24 h), Acacia reficiens (47.6% at 1 h), Rhus natalensis (43.8% at 24 h) and Acacia robusta (37.4% at 24 h) (p < 0.05 for all PI). Diclofenac (20 mg/kg) showed a steady increase in PI from 1 h to 4 h with a maximum PI of 66.2% (p < 0.05) at 4 h and the lowest PI of 14.3% at 24 h. Conclusion: All extracts of the plants assessed exhibited anti-inflammatory activity at early phase of inflammation. Additionally, extracts of five plants, namely Rhus natalensis, Acacia drepanolobium, Acacia robusta, Grewia villosa and Rhus vulgaris showed anti-inflammatory activity at both early and late phases of inflammation. There is need for further studies to identify phytochemicals with active anti-inflammatory activity. Key words- Ilkisonko Maasai, carrageenan, inflammation, Rhus, Acacia, Grewia and Ximeni
THE JOINT EFFECT OF ORGANIZATIONAL STRATEGY, ORGANIZATIONAL CULTURE AND EXTERNAL ENVIRONMENT ON ORGANIZATIONAL PERFORMANCE OF LARGE PRIVATE HEALTH FACILITIES IN KENYA
Full text linkThe goal of this study was to determine the joint effect of organizationalstrategy, organizational culture and external environment on organizationalperformance, using data from Sixty-one large private health facilities inKenya. A descriptive cross-sectional design grounded on positivism researchphilosophy was used. Multiple linear regression analyses were employed toanalyze the data. Generally, the results revealed that the joint effect oforganizational strategy, culture and external environment on performancedimensions, which include efficiency, effectiveness, relevance and financialviability was statistically significant. Consequently, it was concluded thatorganizational culture and strategy are not separated from the externalenvironment in which they are embedded. It was recommended that in orderto maximize on performance, the private health facilities must establish anoptimal balance among the three factors
Understanding the Risks Factors of Under-Five Child Mortality in Kenya: Random Survival Forest and Accelerated Failure Time Shared Frailty Models
Full text linkUnder-five mortality rates is one of the health indicators of great importance to any country. Kenya is among the countries in the Sub-Saharan Africa with high Under-Five Child Mortality (U5CM) rates. It is therefore important to apply best statistical approaches to establish which factors influence child mortality. This will go a long way to inform the optimal design of health intervention strategies within the country and globally. In this study, Random Survival Forest (RSF) and Accelerated Failure Time Shared Frailty Models have been used to analyze U5CM based on the Kenya Demographic Health Survey (KDHS, 2014) dataset. Akaike Information Criterion (AIC) statistics was used to select the model of best fit. Results obtained from fitting the AFT-shared frailty model, showed that there was presence of unobserved heterogeneity at community level. However, there was no evidence to conclude the existence of unobserved heterogeneity at the household level. Among the variants of the AFT Shared Frailty models analysed, the Log-logistic AFT- model showed that “the sons who have died,” “daughters who have died,” “duration of breastfeeding,” and “months of breastfeeding” had significant influence on the U5CM (p <0.05). The Log-logistic AFT model with Gaussian frailty emerged to be the best model for the U5CM since it had the least Akaike Information Criterion (AIC) statistic. On the other hand, the results from Random Survival Forest, “sons who have died,” “daughters who have died,” “living children plus current pregnancy,” “sex of child,” “duration of breastfeeding,” “number of living children,” and “months of breastfeeding” were ranked as important factors that have influence on the under-five mortality. Furthermore, this study also found out that there was presence of unobserved heterogeneity at community level of clustering. At the household level however, there was no unobserved heterogeneity, hence there was no need for household frailty term
Pattern of distribution of AIDS-related Kaposi’s sarcoma lesions in HIV patients in a referral hospital in Kenya
Full text linkBackground: Kaposi’s sarcoma (KS) is an angioproliferative malignancy caused by infection with human herpes virus -8 (HHV-8). The tumour has four subtypes including Classic KS, African- endemic, Iatrogenic and Acquired immunodeficiency syndrome (AIDS)-related KS. AIDS- related KS is the most common malignancy in patients with human immunodeficiency virus (HIV) infection and has variable clinical presentation with diverse distribution of lesions. Objective: To assess the pattern of distribution of KS lesions in patients with AIDS-related KS at Kenyatta National Hospital. Methods: We carried out a descriptive study on patients with HIV infection with histological diagnosis of KS. The study commenced upon approval by KNH-University of Nairobi Ethics and Research Committee. Following consent, clinical and demographic data was obtained from participants through verbal interviews and from medical records using a data capture form. Follow up was until 10 weeks. Management of patients was at the discretion of the attending clinician. Data was analyzed by a statistician using Instat Biostatistics program. Results Seventy-four participants aged between 13 to 55 years were enrolled into the study. Males were 42 (56.7%) and females 32 (43.2%). Mean age was 36.8 years. The distribution of KS lesions was variable. We demonstrate high predilection of lesions for skin and lymph nodes at 62.6%. Other sites were involved were the oral cavity 14.9%. Twenty-eight (38%) of the participants had multifocal lesions with a male predominance in skin and viscera with male to female ratio of skin 1.8:1 and viscera 7:1 respectively. Conclusion: We demonstrate reduced male: female ratio and multifocal distribution of AIDS-related KS lesions with predominance in skin and lymph nodes and male predominance in visceral lesions. Future studies should aim to determine what favours increase in, KS in women and visceral lesions in males among patients with HIV infection. Keywords: Kaposi’s Sarcoma, human immunodeficiency virus (HIV), Acquired Immunodeficiency Syndrome (AIDS
Anti-nociceptive and anti-inflammatory activities of methanol root extract of Andropogon gayanus Kunth (Poaceae) in rodents
Full text linkBackground: Andropogon gayanus is widely used in traditional medicine for various ailments such as postpartum pain, bronchitis and oedema. Objective: This study evaluated the anti-nociceptive and anti-inflammatory activities of methanol root extract of A. gayanus in experimental rodents. Methods: Phytochemical screening tests and acute toxicity studies were carried out. Analgesic activity using acetic acid-induced writhing response and hot plate test in mice, formalin-induced pain and carrageenan-induced paw oedema in rats were evaluated at doses of 250, 500 and 1000 mg/kg of the extract. Results: Oral median lethal dose was >5000 mg/kg in both mice and rats. The extract significantly (p<0.01) decreased the number of writhing movements at all tested doses. It also significantly (p<0.05) increased the mean reaction times. A significant (p<0.05) decrease in mean pain scores was also observed in both phases of the formalin test at 1000 mg/kg. The extract at 1000 mg/kg significantly (p<0.05) reduced the oedema at the 1st hour, while at the 5th hour, all doses tested significantly reduced the oedema. Conclusion: The methanol root extract of Andropogon gayanus possesses antinociceptive and anti-inflammatory activities. Keywords: Andropogon gayanus, Analgesic, Anti-inflammatory, Pai
Origin of Carbon dioxide in Selected Mofette Springs in the Eastern Mt. Kenya Region and Associated Characteristics
Full text linkThe Eastern Mt. Kenya region has a significant number of mofette springs containing high content of dissolved carbon dioxide. They include Gikumene, Kathathantu, Kiambogo, Mbwinjeru, Mulathankari, Nthungu, Rwarera-A, Rwarera-B, Tharu and Ukuu. The origin of carbon dioxide and their geochemistry has not been understood. This work was aimed at establishing the origin of carbon dioxide and thereof the chemistry of the mofette springs as a significant contributor of carbon dioxide in the environment. The source of carbon dioxide was determined by measuring the δ13C for dissolved inorganic carbon using cavity ring-down spectroscopy. The δ13C which ranged from -3.394 to +0.283 ‰ Vienna Pee Dee Belemnite was above the mantle signatures of -6 ± 2.5 ‰. This indicated that the CO2 was mantle or deep crust derived probably due to post volcanic degassing with a minor contribution from carbonate minerals. The springs had low temperatures between 21.9-29.7 oC and slightly acidic pH of 5.83-6.57. Dissolved inorganic carbon ranged between 39,184-89,013 μmol/kg, total alkalinity 14,925-61,810 μmol/L and electrical conductivity 1,375-5,195 μS/cm. The predominant cation in the waters was Na+ at 5,261-55,348 μmol/L which was largely counterbalanced by HCO3-. Other ions found in lesser amounts included Mg2+, Ca2+, K+, Cl- and SO42-. The apparent carbon dioxide degassing phenomenon would be of interest in terms of understanding the geoscience of this region, climate change monitoring and harnessing the potential socio-economic benefit
Organochlorine pesticides in rain, rivers and groundwater in the Lake Naivasha basin and implications for their management
Full text linkOrganochlorines (OCs) have a high persistence in the environment and toxicity to humans and wildlife. Despite their ban in several countries, they are still found in agricultural areas. Their presence in drinking water resources (rivers, rain and groundwater) in Lake Naivasha area, which has had a booming horticultural industry in the last three decades was investigated. Twenty-two water samples from the rift floor around Lake Naivasha were collected in June 2017 and analysed for organochlorines. Findings show that all the water samples are contaminated with various organochlorine pesticides and metabolites. The abundance of OCs in water resources can be ranked as follows, rain> river >groundwater in which 18 compounds were identified; alpha, beta, gamma and delta HCH, endrin, aldrin, heptachlor, chlordane, b-endosulfan, methoxychlor, p,p′-DDE, p,p′-DDD, endrin aldehyde, endosulphan sulphate, p,p′-DD and endrin ketone. Their concentrations range from 0.1 to1 μg/L. The OCs with high concentrations are aldrin, endrin aldehyde and endosulphan sulphate. Twelve banned compounds were found present, several decades after their ban (1986 - 2014) shows either occasional usage in the region or the residues drift from use elsewhere. Despite the low concentrations, many of these pollutants can exceed acceptable daily intake (ADI) for humans. Thus, the National Environment Management Authority, Kenya needs to set OCs guidelines on drinking water quality and concerted efforts with agriculture, water and health ministries is needed to ensure public health safety
Understanding and explaining observed variability in microwave amplification by stimulated emission of radiation (maser) sources in NGC 6334 I
Full text linkAn active star forming region NGC 6334I has continued to undergo variations in the velocity and flux intensity of the 1665 MHz OH maser transition. We report the findings of the periodic variation observed in the velocity of the 1665 MHz OH maser for observations that started in October 2011 to December 2016 using the 26 m Hartebeeshoek Observatory radio telescope. Two velocity channels -10.6 kms-1 and -10.2 kms-1 in the Left Circular Polarization showed evidence of periodic variation. The period of variation was found to be equal to 366.01 ± 3.33 and 365.89 ± 1.28 days, respectively. The cause of the periodic variation was the uncorrected velocity local standard of rest for maser sources which are far away from NGC 6334I