Novel Vectors of Malaria Parasite in the Western Highlands of Kenya

The primary malaria control techniques, indoor application of residual insecticides and insecticide-treated bed nets, are used on the basis of previously assumed key characteristics of behaviors of vectors of malaria parasites, i.e., resting and feeding indoors. Any deviation from the typical activities of a species related to exophagy (feeding outdoors) and exophily (living and resting outdoors) or to population replacement, followed by increased outdoor biting or resting, may undermine malaria control efforts. Identification of mosquitoes that transmit malaria parasites has, for the most part, relied on the use of outdated morphologic keys and, more recently, species-diagnostic PCR. Cryptic species or subpopulations that exhibit divergent behaviors may be responsible for maintaining malaria parasite transmission, and without adequate discriminatory techniques, these vectors may be misidentified and their key behavioral differences overlooked.Emerging Infectious Diseases is published by the Centers for Disease Control and Prevention, a U.S. Government agency. Therefore, materials published in Emerging Infectious Diseases, including text, figures, tables, and photographs are in the public domain and can be reprinted or used without permission with proper citation. This is an open access article, available to all readers online, published under a creative commons licensing (https://creativecommons.org/licenses/by/4.0/). The attached file is the published version of the article

The incidence, aetiology and outcome of acute seizures in children admitted to a rural Kenyan district hospital

<p>Abstract</p> <p>Background</p> <p>Acute seizures are a common cause of paediatric admissions to hospitals in resource poor countries and a risk factor for neurological and cognitive impairment and epilepsy. We determined the incidence, aetiological factors and the immediate outcome of seizures in a rural malaria endemic area in coastal Kenya.</p> <p>Methods</p> <p>We recruited all children with and without seizures, aged 0–13 years and admitted to Kilifi District hospital over 2 years from 1^stDecember 2004 to 30^thNovember 2006. Only incident admissions from a defined area were included. Patients with epilepsy were excluded. The population denominator, the number of children in the community on 30^thNovember 2005 (study midpoint), was modelled from a census data.</p> <p>Results</p> <p>Seizures were reported in 900/4,921(18.3%) incident admissions and at least 98 had status epilepticus. The incidence of acute seizures in children 0–13 years was 425 (95%CI 386, 466) per 100,000/year and was 879 (95%CI 795, 968) per 100,000/year in children <5 years. This incidence data may however be an underestimate of the true incidence in the community. Over 80% of the seizures were associated with infections. Neonatal infections (28/43 [65.1%]) and falciparum malaria (476/821 [58.0%]) were the main diseases associated with seizures in neonates and in children six months or older respectively. Falciparum malaria was also the main illness (56/98 [57.1%]) associated with status epilepticus. Other illnesses associated with seizures included pyogenic meningitis, respiratory tract infections and gastroenteritis. Twenty-eight children (3.1%) with seizures died and 11 surviving children (1.3%) had gross neurological deficits on discharge. Status epilepticus, focal seizures, coma, metabolic acidosis, bacteraemia, and pyogenic meningitis were independently associated with mortality; while status epilepticus, hypoxic ischaemic encephalopathy and pyogenic meningitis were independently associated with neurological deficits on discharge.</p> <p>Conclusion</p> <p>There is a high incidence of acute seizures in children living in this malaria endemic area of Kenya. The most important causes are diseases that are preventable with available public health programs.</p

Anopheles larval abundance and diversity in three rice agro-village complexes Mwea irrigation scheme, central Kenya

<p>Abstract</p> <p>Background</p> <p>The diversity and abundance of <it>Anopheles </it>larvae has significant influence on the resulting adult mosquito population and hence the dynamics of malaria transmission. Studies were conducted to examine larval habitat dynamics and ecological factors affecting survivorship of aquatic stages of malaria vectors in three agro-ecological settings in Mwea, Kenya.</p> <p>Methods</p> <p>Three villages were selected based on rice husbandry and water management practices. Aquatic habitats in the 3 villages representing planned rice cultivation (Mbui Njeru), unplanned rice cultivation (Kiamachiri) and non-irrigated (Murinduko) agro-ecosystems were sampled every 2 weeks to generate stage-specific estimates of mosquito larval densities, relative abundance and diversity. Records of distance to the nearest homestead, vegetation coverage, surface debris, turbidity, habitat stability, habitat type, rice growth stage, number of rice tillers and percent <it>Azolla </it>cover were taken for each habitat.</p> <p>Results</p> <p>Captures of early, late instars and pupae accounted for 78.2%, 10.9% and 10.8% of the total <it>Anopheles </it>immatures sampled (n = 29,252), respectively. There were significant differences in larval abundance between 3 agro-ecosystems. The village with 'planned' rice cultivation had relatively lower <it>Anopheles </it>larval densities compared to the villages where 'unplanned' or non-irrigated. Similarly, species composition and richness was higher in the two villages with either 'unplanned' or limited rice cultivation, an indication of the importance of land use patterns on diversity of larval habitat types. Rice fields and associated canals were the most productive habitat types while water pools and puddles were important for short periods during the rainy season. Multiple logistic regression analysis showed that presence of other invertebrates, percentage <it>Azolla </it>cover, distance to nearest homestead, depth and water turbidity were the best predictors for <it>Anopheles </it>mosquito larval abundance.</p> <p>Conclusion</p> <p>These results suggest that agricultural practices have significant influence on mosquito species diversity and abundance and that certain habitat characteristics favor production of malaria vectors. These factors should be considered when implementing larval control strategies which should be targeted based on habitat productivity and water management.</p

Shifts in malaria vector species composition and transmission dynamics along the Kenyan coast over the past 20 years

BACKGROUND: Over the past 20 years, numerous studies have investigated the ecology and behaviour of malaria vectors and Plasmodium falciparum malaria transmission on the coast of Kenya. Substantial progress has been made to control vector populations and reduce high malaria prevalence and severe disease. The goal of this paper was to examine trends over the past 20 years in Anopheles species composition, density, blood-feeding behaviour, and P. falciparum sporozoite transmission along the coast of Kenya. METHODS: Using data collected from 1990 to 2010, vector density, species composition, blood-feeding patterns, and malaria transmission intensity was examined along the Kenyan coast. Mosquitoes were identified to species, based on morphological characteristics and DNA extracted from Anopheles gambiae for amplification. Using negative binomial generalized estimating equations, mosquito abundance over the period were modelled while adjusting for season. A multiple logistic regression model was used to analyse the sporozoite rates. RESULTS: Results show that in some areas along the Kenyan coast, Anopheles arabiensis and Anopheles merus have replaced An. gambiae sensu stricto (s.s.) and Anopheles funestus as the major mosquito species. Further, there has been a shift from human to animal feeding for both An. gambiae sensu lato (s.l.) (99% to 16%) and An. funestus (100% to 3%), and P. falciparum sporozoite rates have significantly declined over the last 20 years, with the lowest sporozoite rates being observed in 2007 (0.19%) and 2008 (0.34%). There has been, on average, a significant reduction in the abundance of An. gambiae s.l. over the years (IRR = 0.94, 95% CI 0.90–0.98), with the density standing at low levels of an average 0.006 mosquitoes/house in the year 2010. CONCLUSION: Reductions in the densities of the major malaria vectors and a shift from human to animal feeding have contributed to the decreased burden of malaria along the Kenyan coast. Vector species composition remains heterogeneous but in many areas An. arabiensis has replaced An. gambiae as the major malaria vector. This has important implications for malaria epidemiology and control given that this vector predominately rests and feeds on humans outdoors. Strategies for vector control need to continue focusing on tools for protecting residents inside houses but additionally employ outdoor control tools because these are essential for further reducing the levels of malaria transmission

Abundance and growth characteristics of Leguminosae nodulating bacteria in Embu and Taita benchmark sites of Kenya

The populations of Leguminosae nodulating bacteria (LNB) were assessed under glasshouse conditions in soils collected from various land use systems in Embu and Taita benchmark sites. The populations were estimated by the most-probable-number (MPN) plant infection technique using Macroptilium atropurpureum (DC.) Urban (siratro) as the trap host species. The LNB populations in Embu and Taita sampling points varied from <2.5 to 2.3 × 10 2 and <5.1 to 6.1 × 10 6 cells g -1 of soil, respectively. There was apparent land use effect on abundance of LNB in both sites with maize-bean cropping system most frequently giving high population estimates. LNB were isolated from root nodules of nodulated siratro inoculated with dilution series of the soils. Over 643 pure isolates were isolated from root nodules of siratro MPN plants. The isolates were characterized on yeast extract mannitol mineral salts agar (YEMA) media containing bromothymol blue. Abundance and growth characteristics of Leguminosae nodulating bacteria in Embu and Taita benchmark sites of Kenya (PDF Download Available). Available from: http://www.researchgate.net/publication/228510315_Abundance_and_growth_characteristics_of_Leguminosae_nodulating_bacteria_in_Embu_and_Taita_benchmark_sites_of_Kenya [accessed Sep 25, 2015]

Establishing exclusive breastfeeding among in-patient malnourished infants in a rural Kenyan hospital: mothers' experiences of a peer supporter intervention

Background: The 2013 WHO guidelines for nutritional rehabilitation of hospitalized and non-hospitalized malnourished infants under six months (u6m) recommend the re-establishment of exclusive breastfeeding. However, in most low-income settings these recommendations are not consistently applied. A recently concluded pilot study on the effects of implementing these guidelines among hospitalized malnourished infants u6m of age in Kilifi, Kenya introduced breastfeeding peer supporters (BFPS) to the inpatient setting to support guideline implementation. Here we report a sub-study investigating mothers’ experiences and perceptions of the process of re-establishing exclusive breastfeeding during their infant’s admission to hospital. Methods: Interviews were conducted with mothers just prior to their infant’s discharge to explore their experiences and perceptions of the breastfeeding support process. A trained social science researcher conducted the interviews in Kiswahili language using a structured interview guide with open questions. Interviews were tape recorded, transcribed and translated into English for analysis. Data were managed and organized using NVIVO version 10 and analyzed using a framework approach. Results: Twenty mothers were interviewed. While some mothers found re-establishing breastfeeding challenging, they all reported improved knowledge on the relationships between maternal nutrition, stress management, hygiene practices and breastmilk production. They also reported gaining skills in breast care, breastfeeding techniques, hand expression and handling of expressed breastmilk. The breastfeeding peer supporters were said to have provided technical, social and emotional support which facilitated the process of re-establishing exclusive breastfeeding. The mothers identified the key characteristics of an effective and trustworthy BFPS as well as gaps in support. Conclusion: BFPS are able share knowledge and skills in a way that is understood and appreciated by the mothers of inpatient malnourished infants u6m of age, enhancing the reestablishment of exclusive breastfeeding. Central to the success of BFPS is their ability to develop close and supportive relationships with the mothers based on shared social and cultural backgrounds. Future studies should focus on evaluating the long-term impact of inpatient breastfeeding support strategies on the quality of breastfeeding and growth, as well as on understanding where, when and how BFPS might be incorporated into routine hospital settings.</br

Mothers' experiences of exclusive breastfeeding in a postdischarge home setting

Re-establishment and maintenance of exclusive breastfeeding (EBF) is recommended by the World Health Organization for the nutritional rehabilitation of malnourished infants under 6 months; however, there is no explicit guidance on how this should be achieved. The IBAMI study-a pilot study conducted in Kilifi, Kenya-implemented these recommendations using an intervention for hospitalized infants and their mothers that included ward-based breastfeeding peer supporters. This paper explores how the challenges of maintaining EBF are recontextualized after infant hospitalization for malnutrition. Four weeks after discharge, semistructured interviews on experiences of trying to maintain EBF in a postdischarge home setting were conducted with a total of 20 mothers. Although most stated the aspiration of maintaining EBF for 6 months, a range of challenges were reported and not all had successfully maintained EBF post discharge. Reported challenges include the stress of household chores, food insecurity, technical difficulties and social stigma of expressing breast milk, pressure from neighbours and family members to introduce mixed feeding, and needing more community-based awareness and support. Most of these challenges were specific to the home setting and were not easily surmountable, despite the breastfeeding practices mothers had learned in the ward. Indeed, in some cases, challenges were exacerbated by the overmedicalized nature of the breastfeeding practices taught in the ward. In order to aid the transition from ward to home, there may be a need to further translate ward-based education and promotional messaging for EBF into a community setting, targeting other caregivers as well

Screening of Local Bacillus thuringiensis Isolates for Toxicity to Chilo partellus, Sesamia calamistis and Busseola fusca in Kenya

Stem borers are a major source of pre-harvest maize crop losses in Kenya and many Sub- Saharan African countries. This menace needs to be addressed if food security is to be realized in this region. Seven local isolates of Bacillus thuringiensis (Bt) strains were isolated from soils collected from Kakamega and Machakos districts in Kenya. They were screened for toxicity against 1st and 2nd instar larvae of Chilo partellus, Sesamia calamistis and Busseola fusca through laboratory bioassays on artificial and natural diets. On farm Bt toxin potency trials were carried out only in Machakos using isolate 1M which was isolated from the area. The various isolates showed differences in their toxicity to the three stem borers. Isolates 1M and VM-10 (from Machakos district) were found to be the most potent against C. partellus with larval mortalities of 100 % within 72 h. Their LD50 values were 0.004 mg/ml and 0.04 mg/ml respectively. The most toxic isolates against S. calamistis were, 44M, VM-10 and 1M, with larval mortalities of 73%, 64% and 62% respectively after 72h at a concentration of 8.6 mg/ml through artificial diet bioassays on 1st instar larvae. Isolates 44M and K10-2 showed high toxicity against B. fusca with larval mortalities of 20% by artificial diet bioassays and 44% by maize leaf bioassays respectively. Leaf disk bioassays with all the insect species showed higher larval mortalities than those done with the artificial diet bioassays indicating the larval preference of natural diet. However leaf disk bioassays with B. fusca recorded higher larval mortalities with sorghum than maize leaves. Field trial results obtained from Machakos district using a biopesticide made from isolate 1M indicated that it was highly effective in stem borer control. Keywords: Bacillus thuringiensis; bioassays; B. fusca; C. partellus; S. calamistis; insect larvae; mortality; toxicity. J. Trop. Microbiol. Biotechnol. Vol. 3 (2) 2007: pp. 27-3