Response of cowpea genotypes to Alectra vogelii parasitism in Kenya

Cowpea is popular in Eastern Kenya where it is attractive to farmers because of its high economic value and the belief that it does not require many external inputs. Farmers are however discouraged to grow the crop in this region due to massive attack by a parasitic weed Alectra vogelii (Benth). Yield losses due to A. vogelii have being estimated to range from 50 to 100% in Mbeere, Kitui and Makueni districts. No single method however is available to farmers in these regions in control of the parasitic weed. Combining several control methods, as in the management of Striga spp in Western Kenya should be a sustainable option. Field studies were conducted in 2010 and 2011 at Kenya Agricultural Research Institute (KARI), Kiboko farm to determine the response of 143 cowpea genotypes to Alectra infestation. The aim for the study was to identify resistant genotypes that could be used in breeding programme. Significant differences were observed amongst cowpea genotypes in days to first Alectra emergence, number of Alectra shoots emerged at 6, 8, 10 and 12 week after planting and grain yield. Cowpea genotypes Kir/Nya-005 and Mbe/Mach-022 showed complete resistance to  Alectra while Ken-Kunde, M66 and K80 (all commercial varieties) supported the highest number of Alectra shoots. Grain yield loss in the three susceptible varieties was 80, 79 and 50% respectively. On the other hand, Sia/Cia-004, Mbe/Mach-014 and Kib-006 had high grain yields despite the high number of Alectra shoots present. There was a strong correlation (r = -0.57) between grain yield and number of Alectra shoots emerged at 12 weeks after planting. A significant negative (r = -0.37) correlation was also obtained between pod number per plant and number of emerged Alectra shoots at 12 weeks after planting. This negative correlation proves the high accumulation dry matter in the cowpea roots at the expense of the pods thus decreasing grain yield. This information showed that there is sufficient genetic variability in the cowpea genotypes studied, which can be exploited in breeding improved cowpea varieties for resistance to A. vogelii in Kenya. A great progress towards developing improved cowpea variety that meets farmer’s preferences with durable resistance to A. vogelii can be achieved if the genes from the resistant and tolerant local cowpea cultivars identified in this study could be introgressed into the adapted susceptible improved varieties. This will increase the potential impact of adoption of resistant cowpea varieties in the zones.Key words: Cowpea, Alectra vogelii, Resistance/tolerance and grain yield

The influence of host and pathogen genotypes on symptom severity in banana streak disease

Banana is the fourth most important food crop worldwide. However, its production has been threatened by banana streak disease, caused by banana streak virus (BSV). Despite this situation, little is known about the inter-relationships between symptom severity and cultivar/virus genotypes. Symptom severity assessment for sixty five symptomatic samples was carefully done. The rolling circle amplification technique was used to identify the virus species (isolate) infecting each sample. The Mysore virus isolates (BSMysV) and the banana cultivars containing the balbisiana (B) component were associated with the most severe banana streak disease symptoms.Key words: Banana streak disease, symptom severity, banana streak virus (BSV) isolate, rolling circle amplification

Prevalence and Types of Coinfections in Sleeping Sickness Patients in Kenya (2000/2009)

The occurrence of coinfections in human African trypanosomiasis (HAT) patients was investigated using a retrospective data of hospital records at the National Sleeping Sickness Referral Hospital in Alupe, Kenya. A total of 31 patients, 19 males and 12 females, were diagnosed with HAT between the years 2000 and 2009. The observed co-infections included malaria (100%), helminthosis (64.5%), typhoid (22.5%), urinary tract infections (16.1%), HIV (12.9%), and tuberculosis (3.2%). The species of helminthes observed included Ancylostoma duodenale (38.7%), Ascaris lumbricoides (45.7%), Strongyloides stercoralis (9.7%), and Taenia spp. (3.2%). The patients were also infected with Entamoeba spp. (32.3%) and Trichomonas hominis (22.6%) protozoan parasites. The main clinical signs observed at the point of admission included headache (74.2%), fever (48.4%), sleep disorders (45.2%), and general body pain (41.9%). The HAT patients were treated with suramin (early stage, 9/31) and melarsoprol (late stage, 22/31). In conclusion, the study has shown that HAT patients have multiple co-infections which may influence the disease pathogenesis and complicate management of HAT

Use of the nested polymerase chain reaction for detection of Toxoplasma gondii in slaughterhouse workers in Thika District, Kenya

Background. The widely used methods of diagnosis of Toxoplasma gondii are serological. Current reports indicate a high seroprevalence of T. gondii in humans in Kenya. There is a need for more sensitive diagnostic tests, especially when the specific antibody titres are below detectable threshold levels. Use of the polymerase chain reaction (PCR) targeting the repetitive 529 base pair loci has been reported to be sensitive and specific.Objective. To detect T. gondii in a high-risk group of public health workers in Thika District, Kenya.Methods. In total, 87 human blood samples were collected from male slaughterhouse workers between 1 March 2013 and 25 June 2013. The DNA extracted was amplified by the nested PCR.Results. T. gondii was detected in 39.1% (34/87) of the workers. In the cow-sheep-goat slaughterhouses the prevalence ranged between 20% and 60%, while all the chicken slaughterhouse workers (6/6, 100%) tested positive. The difference in T. gondii positivity between the workers in the chicken slaughterhouse and those in the cattle-sheep-goat slaughterhouses was statistically significant (p=0.003).Conclusion. This study shows the presence of T. gondii in an asymptomatic high-risk group in Thika District, indicating the need for enhancement of public health awareness

Factors influencing smallholder farmers’ inputs use in major bean production corridors in Kenya

This study analysed socio-economic determinants for inputs use in major bean corridors in Kenya. It comprised 417 respondents sampled from four major bean corridors. A structured questionnaire was used in data collection. Probit model was used to assess determinants of input use among the bean-farming households. From the results, 74% of respondents were male with a mean age of 48.6 years. The probability of using agricultural inputs increased with education level and income from crop sales. Fertilizer was mainly used in Bomet (73%) and Narok (74%) counties. Eighty-five percent planted recycled seeds. Education level and Income from crops positively influenced inputs use. It was concluded that education level, incomes from sale of crops, livestock and livestock products, and farm income influenced use of inputs. As a recommendation, Capacity building on merits of input use and promotion of public-private partnerships to strengthen input supply system would enhance increased input use by smallholder farmers.Keywords: Bean, inputs, determinants, Keny

Prognostic factors influencing HIV-free survival among infants enrolled for HIV early infant diagnosis services in selected hospitals in Nairobi County, Kenya

YesDespite being a preventable disease, pediatric HIV infection continues to be a public health concern due to the morbidity and mortality associated with the disease. Vertical transmission of HIV occurs when a mother living with HIV passes the virus to her baby during pregnancy, childbirth, or breastfeeding. Globally, the vertical transmission rate of HIV is 9% with sub-Saharan Africa accounting for 90% of these infections. In Kenya, the national vertical transmission rates of HIV stood at 11.5% by the end of 2018, with a target to reduce vertical transmission rates to below 5% and 2% in breastfeeding and non-breastfeeding infants respectively, by the end of 2021. To determine the prognostic factors influencing HIV-free survival among infants enrolled for HIV early infant diagnosis (EID) services in selected hospitals in Nairobi County, Kenya. A prospective cohort study design was adopted. HIV exposed infants were recruited at six weeks to determine HIV-free survival over 12 months follow up. Simple random sampling was used to select 166 infants and data were collected from the mothers using semi-structured interviewer-administered questionnaires. Log-rank tests were used to test for associations at the bi-variable level while Cox-proportional regression was used to analyze data at the multi-variable level, with the aid of STATA 14 software. Ethical approval was obtained from Kenya Medical Research Institute, Scientific Ethics Review Unit. The overall infant HIV incidence rate over one-year follow-up was 9 cases per 100 person-years (95% CI: 5.465-16.290). The failure event was defined as an infant with a positive PCR test during the study period with total failures being 13 (9.41%) over 12 months. Prognostic factors associated with poor infant HIV-free survival were young maternal age (18-24 years) and mothers with a recent HIV diagnosis of ≤ 2 years since a positive HIV diagnosis (HR 5.97 CI: 1.20, 29.58) and (HR 6.97 CI: 1.96, 24.76), respectively. Maternal prognostic factors associated with poor infant HIV-free survival were young maternal age (18-24 years) and recent maternal HIV diagnosis of ≤ 2 years since positive HIV diagnosis. The study recommended the development of an intervention package with more rigorous adherence counseling and close monitoring for young mothers, and mothers with recent HIV diagnoses

Ambient synthesis of nanomaterials by in situ heterogeneous metal/ligand reactions

Coordination polymers are ideal synthons in creating high aspect ratio nanostructures, however, conventional synthetic methods are often restricted to batch-wise and costly processes. Herein, we demonstrate a non-traditional, frugal approach to synthesize 1D coordination polymers by in situ etching of zerovalent metal particle precursors. This procedure is denoted as the heterogeneous metal/ligand reaction and was demonstrated on Group 13 metals as a proof of concept. Simple carboxylic acids supply the etchant protons and ligands for metal ions (conjugate base) in a 1 : 1 ratio. This scalable reaction produces a 1D polymer that assembles into high-aspect ratio 'nanobeams'. We demonstrate control over crystal structure and morphology by tuning the: (i) metal center, (ii) stoichiometry and (iii) structure of the ligands. This work presents a general scalable method for continuous, heat free and water-based coordination polymer synthesis

Use of the nested polymerase chain reaction for detection of Toxoplasma gondii in slaughterhouse workers in Thika District, Kenya

Background. The widely used methods of diagnosis of Toxoplasma gondii are serological. Current reports indicate a high seroprevalence of T. gondii in humans in Kenya. There is a need for more sensitive diagnostic tests, especially when the specific antibody titres are below detectable threshold levels. Use of the polymerase chain reaction (PCR) targeting the repetitive 529 base pair loci has been reported to be sensitive and specific.Objective. To detect T. gondii in a high-risk group of public health workers in Thika District, Kenya.Methods. In total, 87 human blood samples were collected from male slaughterhouse workers between  1 March 2013 and  25 June 2013. The DNA extracted was amplified by the nested PCR.Results. T. gondii was detected in 39.1% (34/87) of the workers. In the cow-sheep-goat slaughterhouses the prevalence ranged between 20% and 60%, while all the chicken slaughterhouse workers (6/6, 100%) tested positive. The difference in T. gondii positivity between the workers in the chicken slaughterhouse and those in the cattle-sheep-goat slaughterhouses was statistically significant (p=0.003).Conclusion. This study shows the presence of T. gondiiin an asymptomatic high-risk group in Thika District, indicating the need for enhancement of public health awareness.

Post-harvest evaluation of selected hybrids to maize weevil Sitophilus zeamais resistance

Sitophilus zeamais has been identified as one of the most destructive pests of maize stored in tropical regions. While most maize hybrids are being developed, it is necessary to evaluate their resistance to this pest. This study determined the resistance of selected maize hybrids to infestation by S. zeamais. Twenty two hybrids with varying resistance to weevil infestation and two checks DUMA 41-suceptible and MTP0701-resistant were used in a randomized complete block design experiment. Assessment was done at 10, 60 and 120 days of maize storage. Data was collected on percent weevil damage, grain weight loss and number of live and dead weevils. Heritability and correlation of factors were also estimated. Analysis of variance showed significant differences (P ≤ 0.05) on weight loss. The selection of the resistant genotypes was based on percent weight loss after 60 days. KH631Q and PH4 were selected as the most resistant and moderately resistant hybrids, respectively. The resistant check MTPO701 was also found to maintain resistance to weevil attack. There was a strong positive correlation between weight loss, number of live weevils and percent damage. Moderate heritability estimates of hybrids at 60 days of storage indicated the possibility of their parents to transfer the desirable traits to subsequent generations. Therefore, parents of the resistant hybrids could be utilized in breeding programs for maize weevil resistance and be deployed to farmers for use, respectively

Discovery and Validation of Biomarkers to Guide Clinical Management of Pneumonia in African Children

Background Pneumonia is the leading cause of death in children globally. Clinical algorithms remain suboptimal for distinguishing severe pneumonia from other causes of respiratory distress such as malaria or distinguishing bacterial pneumonia and pneumonia from others causes, such as viruses. Molecular tools could improve diagnosis and management. Methods We conducted a mass spectrometry–based proteomic study to identify and validate markers of severity in 390 Gambian children with pneumonia (n = 204) and age-, sex-, and neighborhood-matched controls (n = 186). Independent validation was conducted in 293 Kenyan children with respiratory distress (238 with pneumonia, 41 with Plasmodium falciparum malaria, and 14 with both). Predictive value was estimated by the area under the receiver operating characteristic curve (AUC). Results Lipocalin 2 (Lpc-2) was the best protein biomarker of severe pneumonia (AUC, 0.71 [95% confidence interval, .64–.79]) and highly predictive of bacteremia (78% [64%–92%]), pneumococcal bacteremia (84% [71%–98%]), and “probable bacterial etiology” (91% [84%–98%]). These results were validated in Kenyan children with severe malaria and respiratory distress who also met the World Health Organization definition of pneumonia. The combination of Lpc-2 and haptoglobin distinguished bacterial versus malaria origin of respiratory distress with high sensitivity and specificity in Gambian children (AUC, 99% [95% confidence interval, 99%–100%]) and Kenyan children (82% [74%–91%]). Conclusions Lpc-2 and haptoglobin can help discriminate the etiology of clinically defined pneumonia and could be used to improve clinical management. These biomarkers should be further evaluated in prospective clinical studies