In-vitro Evaluation of Fungicide Sensitivity of Tomato Leaf Blight Pathogens

Tomato early and late blight diseases caused by Alternaria solani and Phytophthora infestans respectively, are constraints to tomato production globally. Conventional use of commercial synthetic fungicides in management of tomato blight disease has become a key input for tomato production among farmers in Tharaka Nithi County, Kenya. Indiscriminate use and application of sub-lethal doses of fungicides negate disease management efforts, and may lead to gradual fungicide resistance.  Yet, local tomato farmers have continued to use the fungicides without periodic evaluation of their effectiveness. This study was carried out in-vitro to evaluate the efficacy of six synthetic commercial fungicides used by farmers around River Ruguti, against two tomato leaf blight pathogens; Alternaria solani and Phytophthora infestans. The poison food method was used to evaluate fungicides known by trade names and application levels;  Mancozeb (640 g kg-1) + Metalaxyl (40 g kg-1), Mancozeb 640 g/kg + Metalaxyl 80 g/kg, Mancozeb, Propineb700 g/kg + Cymoxanil 60 g/kg, Carbendazim and Triticonazole at different concentration (25%, 50% and 75%). The in-vitro plate experiment was laid out in a Complete Randomized Design with 3 replicates, and data on mycelia growth inhibition analyzed through General Linear Model (α=.05) and significant means separated using Least significant difference (LSD) using Scientific Analysis System version 9.4. All the tested fungicides significantly (p≤ 0.05) inhibited mycelial growth of tested pathogen.  Percentage inhibition for early blight pathogen (Alternaria solani) was 80.42% compared to late blight pathogen Phytophthora infestans at 69.51%. Mancozeb   (640 g kg-1) + Metalaxyl (40 g kg-1) and Propineb700 g/kg + Cymoxanil 60 g/kg recorded higher per cent inhibition of mycelia growth of 92.4% and 89.71% respectively. Carbendazim recorded lower per cent inhibition of 39.15%.  Mycelia growth inhibition increased with an increase in fungicide concentration. Lower inhibition of 71.78% was observed at 25% concentration as compared to 50% and 75% with 76.77% and 76.36% respectively. Fungicides screened varied in mycelia inhibition against P. infestans and A. solani isolates with Mancozeb   (640 g kg-1) + Metalaxyl (40 g kg-1) and Propineb700g/kg +Cymoxanil 60g/kg giving significantly (p≤ 0.05) better inhibition while Carbendazim had the lowest inhibition effect. Increased fungicide concentration effectively inhibited mycelia growth. Thus higher concentration of fungicide application is recommended in cases where there is low efficacy of fungicides

Prevalence of gestational diabetes mellitus based on various screening strategies in western Kenya : a prospective comparison of point of care diagnostic methods.

Background: Early diagnosis of gestational diabetes mellitus (GDM) is crucial to prevent short term delivery risks and long term effects such as cardiovascular and metabolic diseases in the mother and infant. Diagnosing GDM in Sub-Saharan Africa (SSA) however, remains sub-optimal due to associated logistical and cost barriers for resource-constrained populations. A cost-effective strategy to screen for GDM in such settings are therefore urgently required. We conducted this study to determine the prevalence of gestational diabetes mellitus (GDM) and assess utility of various GDM point of care (POC) screening strategies in a resource-constrained setting. Methods: Eligible women aged ≥18 years, and between 24 and 32 weeks of a singleton pregnancy, prospectively underwent testing over two days. On day 1, a POC 1-h 50 g glucose challenge test (GCT) and a POC glycated hemoglobin (HbA1c) was assessed. On day 2, fasting blood glucose, 1-h and 2-h 75 g oral glucose tolerance test (OGTT) were determined using both venous and POC tests, along with a venous HbA1c. The International Association of Diabetes in Pregnancy Study Group (IADPSG) criteria was used to diagnose GDM. GDM prevalence was reported with 95% confidence interval (CI). Specificity, sensitivity, positive predictive value, and negative predictive value of the various POC testing strategies were determined using IADPSG testing as the standard reference. Results: Six hundred-sixteen eligible women completed testing procedures. GDM was diagnosed in 18 women, a prevalence of 2.9% (95% CI, 1.57% - 4.23%). Compared to IADPSG testing, POC IADPSG had a sensitivity and specificity of 55.6% and 90.6% respectively while that of POC 1-h 50 g GCT (using a diagnostic cut-off of ≥7.2 mmol/L [129.6 mg/dL]) was 55.6% and 63.9%. All other POC tests assessed showed poor sensitivity. Conclusions: POC screening strategies though feasible, showed poor sensitivity for GDM detection in our resource-constrained population of low GDM prevalence. Studies to identify sensitive and specific POC GDM screening strategies using adverse pregnancy outcomes as end points are required

Comparison of least absolute shrinkage and selection operator and maximum likelihood estimators to establish determinants of immunization in Trans - Nzoia County

The client factors that influence under-five child guardian compliance to the immunization schedule are interlinked based on household characteristics, socioeconomic status, and maternal health practices. An incentive to motivate the mothers to prioritize their child’s health practices especially on vaccination, works perfectly towards the achievement of full immunization coverage. A randomly sampled study carried out within Weonia Location–Trans Nzoia County in March 2014 with target population of under-five children showed the vital role an incentive innovation plays towards immunization coverage. Multinomial logistic regression model was used to analyze the determinant of partial or none-immunized and the parameters estimated using the maximum likelihood estimator (MLE) and the shrinkage estimator-Least Absolute Shrinkage and Selection Operator (LASSO). The shrinkage estimator method gave a sparse model that was easy to interpret and increased the estimated predictability accuracy. Maternal health practices and access to a motivating intervention are significant factors that ensure a guardian’s compliance to their child immunization

Associations of Sociodemographic and Clinical Factors with Late Presentation for Early Infant HIV Diagnosis (EID) Services in Kenya

Background: Understanding the missed opportunities in early infant HIV testing within the PMTCT program is essential to address any gaps. The study set out to describe the clinical and sociodemographic characteristics of the infants presenting late for early infant diagnosis in Kenya. Methods: We abstracted routinely collected clinical and sociodemographic characteristics, in a cross-sectional study, on all HIV-infected infants with a positive polymerase chain reaction (PCR) test from 1,346 President’s Emergency Plan for AIDS Relief (PEPFAR) supported health facilities for the period October 2016 to September 2018. We used multivariate logistic regression to examine the association of sociodemographic and clinical characteristics with late (>2 months after birth) presentation for infant HIV testing. Results: Of the 4,011 HIV-infected infants identified, the median infant age at HIV diagnosis was 3 months [interquartile range (IQR), 1-16 months], and two-thirds [2,669 (66.5%)] presented late for infant HIV testing. Factors that were associated with late presentation for infant testing were: maternal ANC non-attendance, adjusted odds ratio (aOR) 1.41 (95% confidence interval (CI) 1.18 -1.69); new maternal HIV diagnosis, aOR 1.45, (95%CI 1.24 -1.7); and lack of maternal antiretroviral therapy(ART), aOR 1.94, (95% CI 1.64 - 2.30). There was a high likelihood of identifying HIV-infected infants among infants who presented for medical services in the outpatient setting (aOR 18.9; 95% CI 10.2 - 34.9) and inpatient setting (aOR 12.2; 95% CI 6.23-23.9) compared to the infants who presented late in maternity. Conclusion and Global Health Implications: Gaps in early infant HIV testing suggest the need to increase maternal pre-pregnancy HIV diagnosis, timely antenatal care, early infant diagnosis services, early identification of mothers who seroconvert during pregnancy or breastfeeding and improved HIV screening in outpatient and inpatient settings. Early referral from the community and access to health facilities should be strengthened by the implementation of national PMTCT guidelines.publishedVersio

The negative and positive impacts of Prosopis juliflora on the Kenyan and Ethiopian ecosystems: A review study

Invasive alien species pose a serious threat to the world’s ecosystems and livelihoods. This review aimed to investigate the negative and positive impacts of Prosopis juliflora (Sw.) DC on ecosystems in Kenya and Ethiopia. The bibliographic analysis highlighted that Prosopis juliflora was introduced to Kenya and Ethiopia to tackle desertification, ensure the self-sufficiency of wood products, and conserve water and soil in semi-arid areas. Years later, this species has turned invasive; although the communities in infested areas have realized some benefits from this tree such as obtaining timber, charcoal, firewood, shelter, and livestock feed from its pods; the negative impacts of this tree have far outweighed the positives. Notably, this invasive plant has significantly impacted agricultural and livestock productivity by invading pasturelands and farmlands. For instance, the negative health implications for livestock significantly reduce their productivity. Similarly, this plant has reduced the diversity of the native trees, herbaceous, and grasses because of its ability to outcompete them. Control methods such as biological, mechanical, chemical, and control by utilization have been tried but none have so far been effective in controlling this invasive plant. Our results showed that Prosopis juliflora is a serious invader that has a huge potential to invade the arid and semi-arid lands of Kenya and Ethiopia. Therefore, stakeholders at all levels need to implement integrated management strategies to reduce the spread and the negative impacts of this species

Application Of The Hough Transform For Seed Row Localisation Using Machine Vision

This paper compares two methods based on machine vision to provide driver assistance in seed drill guidance in order to improve spacing accuracy during contiguous passages. The first case consisted of following the furrow created at the preceding passage by a special marker disc attached to the seed drill. A camera was located on the tractor and detected this furrow. In the second case, the seed rows themselves were detected by the camera without making use of the marker disc. In both cases, several video sequences were acquired in various situations, including different soil textures and various illumination conditions (375 sequences were acquired during three years). A pre-treatment of these sequences was performed and included a background subtraction in order to remove shadows and other wide unevenness. In the first case, the best results were obtained by using an image treatment based on the Hough transform coupled to a recursive filter. The search of the maximum of the Hough transform was performed using a mean shift algorithm. In the second case, where several parallel rows were simultaneously present on the images, an adapted Hough transform was proposed which took into account the a priori knowledge of the rows spacing. The trueness and precision in row detection were superior in the second case. The results are compatible with the application, since the trueness was smaller than 30 mm. This suggested that it can be possible to assist the manual guidance of a seed drill by an automatic system consisting in a camera detecting the seed rows

Performance assessment of hybrid recuperative heat exchanger for diesel engine generated exhaust gas

In this study, the use of supplemental heat energy from exhaust gas of a stationary diesel engine was assessed to explore a new method of drying black nightshade seeds in a solar-exhaust gas greenhouse dryer. The energy recovery potential of a hybrid recuperative heat exchanger (HRHE) was demonstrated with the objective of utilizing the recovered energy from an engine on milling operations to heat a fluid stream of drying air. The results show that 4.45 kW of thermal energy was available in exhaust gas of a diesel engine operated at 2500 rpm when mass flow rate was 45.07 kg/h at a temperature of 357.36 °C. The rate of heat utilized for solar-exhaust gas mode ranged from 40.49 to 685.94 J/m2.s and from 21.69 to 668.11 J/m2.s in exhaust gas mode of drying. The heat exchanger raised the dryer temperature by an average of 11.78 °C when temperature differences between inside and outside were compared in solar-exhaust gas mode of drying. The average hourly rise in temperature inside the dryer was 8.04 °C with a minimum rise of 3.7 °C and a maximum of 9.41 °C when exhaust gas was utilized to provide heat energy. The performance of the solar-exhaust gas greenhouse dryer improved when thermal energy was used as a supplement in drying and as a result the drying time for black nightshade seeds was significantly reduced from 11 h in solar mode to 10 h in solar-exhaust gas mode of drying. Moreover, the seeds were dried for 14 h when exhaust gas mode of drying was performed without utilizing solar energy. The percent internal uncertainty for experimental measurements of relative humidity (γ) was 4.1% and 17.5% for temperature (T) observations. The three proposed thermal models for temperatures and moisture evaporation performed better with low RMSEs in exhaust gas mode compared to the other modes of drying

Spatial Variations in Aquatic Insect Community Structure in the Winam Gulf of Lake Victoria, Kenya

Background. Aquatic insect community structure is dynamic due to threats by anthropogenic activities coupled with changing climatic conditions. The insect’s survival is dependent on the substrate, water quality, and environmental effects. The changes in water quality influence their distribution and abundance and are reflected in spatial and temporal trends. This study sought to document the effects of spatial variation on aquatic insects in Winam Gulf of Lake Victoria, Kenya. Materials and Methods. Systematic random design was used in sampling, and water quality parameters were assessed. Insects were sampled by profundal lake procedure, pooled, sorted, and identified based on the morphological approach and diversity indices analyzed. The relationship between insects and water quality was established. Results. Statistical homogeneity in water quality parameters was documented with the exception of nitrates, nitrites, soluble reactive phosphorus, ammonium, and silicates, which displayed significant variation at p<0.05. A total of 383 individual insects representing 19 species, 19 genera, 16 families, and six orders were obtained from Winam Gulf. Hemiptera, Ephemeroptera, and Diptera were the most predominant orders, respectively. Chironomus spp. and Ablebesmyia spp. were representatives of the Chironomidae family. Species distribution and water quality were determined using cluster analysis (CA) and conical correspondence analysis (CCA). Conclusion. The findings of this study demonstrated that spatial variations were associated with change in water quality and had a corresponding influence on insect community structure

Epidemiological patterns of Rift Valley Fever from diverse habitats during an extreme unprecedented flooding of Lake Baringo basin, Kenya, 2012-2013

Mosquitoes’ ecology and associated arboviruses are heavily influenced by precipitation and retention of water in the environment. In 2011 and 2014, unprecedented floods occurred in Lake Baringo basin inundating approximate 88 km2 of the shoreline land. This caused abrupt environmental changes raising fears of an outbreak of Rift Valley Fever (RVF) disease. This study was carried out to determine the situation of RVF disease in livestock from diverse habitats during the extreme unprecedented flooding phenomenon that occurred in Lake Baringo basin, in 2012-2013. Blood was drawn from ear vein of livestock selected randomly from the three study areas (lakeshore land, swamp marshy and dry rangeland habitats). Mosquitoes were trapped using CDC light traps and identified morphologically. From a total of 77 blood samples, eight were positive for RVF virus (RVFV) representing an overall infection of 12%. RVF prevalence from livestock resident in flooded lakeshore land habitat was 2.6% (N=77) compared to the swamp marshy habitat at 7.8% (N=77). No infections were recorded from dry rangeland (0%). Mosquitoes of genus Mansonia dominated the catches in flooded lakeshore (98%). Highest individual catches of mosquitoes of genus Aedes was from swamp marshy area whose abundance was 96.8% and below 2% in other habitats. The Simpson’s Diversity Index for mosquitoes from swamp marshy habitat was 0.56, dry rangeland 0.57 and lakeshore land 0.13. The flooded lakeshore land was the most affected by the unprecedented floods resulting in uneven mosquito diversity and subsequently low prevalence of RVF in this habitat. This could be attributed to prolonged disruption of biotic and abiotic factors creating unfavourable breeding sites of multiple species of primary vectors of RVF in flooded lakeshore land unlike in other habitats

Mosquitoes composition, abundance and distribution in swampy and flooded shoreline habitats of Lake Baringo, Kenya, during a period of extreme flooding (2012-2013)

Mosquito ecology is influenced by wetness in the environment. In 2011-2014, a rise in waters of Lake Baringo resulted in unprecedented flooding that inundated over 88km2 of the shoreline. A longitudinal study carried out from October 2012-October 2013 assessed mosquito abundance and diversity in two habitats. A total of 386,624 mosquitoes were captured, 89% from flooded shoreline and 11% from swampy habitat. Family Culicinae constituted 10 genera. Mansonia dominated the catches with 98% from flooded shoreline and swampy habitat 2%. Genetic sequences of Aedes albopictus species was identified and reported for the first time in the basin. Diversity index was higher in swampy habitat (Simpson Diversity Index=0.56), compared to flooded shoreline (Simpson diversity index =0.13). Future recurring floods will result in drastic changes of the ecology and could lead to emergence and reemergence of more species