Health risk analysis of cryptosporidiosis and other hazards in urban smallholder dairy production
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Item Cryptosporidium species detected in calves and cattle in Dagoretti, Nairobi, Kenya(Journal Article, 2012-09) Kang'ethe, Erastus K.; Mulinge, E.K.; Skilton, Robert A.; Njahira, Moses N.; Monda, J.G.; Nyongesa, C.; Mbae, C.K.; Kamwati, S.K.A total of 1,734 cattle faecal samples from 296 dairy-keeping households were collected from urban settings in Nairobi, Kenya. Modified Ziehl–Neelsen staining method and an immunofluorescence assay were used to identify those samples with Cryptosporidium oocyst infection. Oocysts from positive faecal samples were isolated by Sheather's sucrose flotation method and picked from the concentrate using cover slips. Genomic DNA was extracted from 124 of the faecal samples that were positive for Cryptosporidium and was used as template for nested PCR of the 18S rRNA gene. Twenty-five samples (20 %) were PCR-positive for Cryptosporidium, and 24 of the PCR products were successfully cloned and sequenced. Sequence and phylogenetic analysis identified 17 samples (68 %) as Cryptosporidium parvum-like, four samples (16 %) as Cryptosporidium ryanae, three samples (12 %) as Cryptosporidium andersoni and one sample (4 %) as Cryptosporidium hominis. To the best of our knowledge, this is the first genotyping study to report C. parvum-like, C. andersoni and C. hominis in cattle from Kenya. The results of this study show Cryptosporidium infections in calves and cattle may be potential zoonotic reservoirs of the parasite that infects humans.Item Social and gender determinants of risk of cryptosporidiosis, an emerging zoonosis, in Dagoretti, Nairobi, Kenya(Journal Article, 2012-09) Kimani, V.N.; Mitoko, G.; McDermott, B.; Grace, Delia; Ambia, J.; Kiragu, M.W.; Njehu, A.N.; Sinja, J.; Monda, J.G.; Kang'ethe, Erastus K.The aim of the study was to investigate the social and gender determinants of the risk of exposure to Cryptosporidium from urban dairying in Dagoretti, Nairobi. Focus group discussions were held in six locations to obtain qualitative information on risk of exposure. A repeated cross-sectional descriptive study included participatory assessment and household questionnaires (300 randomly selected urban dairy farming households and 100 non-dairying neighbours). One-hundred dairy households randomly selected from the 300 dairy households participated in an additional economic survey along with 40 neighbouring non-dairy households. We found that exposure to Cryptosporidium was influenced by gender, age and role in the household. Farm workers and people aged 50 to 65 years had most contact with cattle, and women had greater contact with raw milk. However, children had relatively higher consumption of raw milk than other age groups. Adult women had more daily contact with cattle faeces than adult men, and older women had more contact than older men. Employees had greater contact with cattle than other groups and cattle faeces, and most (77 %) were male. Women took more care of sick people and were more at risk from exposure by this route. Poverty did not affect the level of exposure to cattle but did decrease consumption of milk. There was no significant difference between men and women as regards levels of knowledge on symptoms of cryptosporidiosis infections or other zoonotic diseases associated with dairy farming. Awareness of cryptosporidiosis and its transmission increased significantly with rising levels of education. Members of non-dairy households and children under the age of 12 years had significantly higher odds of reporting diarrhoea: gender, season and contact with cattle or cattle dung were not significantly linked with diarrhoea. In conclusion, social and gender factors are important determinants of exposure to zoonotic disease in Nairobi.Item Prevalence of cryptosporidiosis in dairy cattle, cattle-keeping families, their non-cattle keeping neighbours and HIV-positive individuals in Dagoretti Division, Nairobi, Kenya(Journal Article, 2012-09) Kang'ethe, Erastus K.; McDermott, B.; Grace, Delia; Mbae, C.; Mulinge, E.; Monda, J.; Nyongesa, C.; Ambia, J.; Njehu, A.This paper reports a study estimating the prevalence of cryptosporidiosis, an emerging zoonosis, in people and cattle in Dagoretti, Nairobi. A repeated cross-sectional survey was carried out among randomly selected cattle keepers in Dagoretti, their dairy cattle and their non-cattle-keeping neighbours in the dry and wet seasons of 2006. A survey was also carried out among a group of people living with human immunodeficiency virus (HIV). Faecal samples were examined for Cryptosporidium oocysts using the modified Ziehl–Neelsen method; 16 % of the samples were also examined using immunofluorescence antibody (IFA) technique. Quality control consisted of blind reviews of slides, examining split samples and confirming slide results with IFA. We found that members of dairy households had a dry season cryptosporidiosis prevalence of 4 % and wet season prevalence of 0.3 %, and non-dairy households, a prevalence of 5 and 0 %, respectively. The cattle dry season prevalence was 15 %, and the wet season prevalence, 11 %. The prevalence in people living with HIV was 5 %. The laboratory quality control system showed some inconsistency within and between different tests, indicating challenges in obtaining consistent results under difficult field and working conditions. In conclusion, this is the first reported study to simultaneously survey livestock, livestock keepers and their neighbours for cryptosporidiosis. We failed to find evidence that zoonotic cryptosporidiosis is important overall in this community. This study also draws attention to the importance of quality control and its reporting in surveys in developing countries.Item A trans-disciplinary study on the health risks of cryptosporidiosis from dairy systems in Dagoretti, Nairobi, Kenya: Study background and farming system characteristics(Journal Article, 2012-09) Kang'ethe, Erastus K.; Kimani, V.N.; McDermott, B.; Grace, Delia; Lang'at, A.K.; Kiragu, M.W.; Karanja, N.; Njehu, A.N.; Randolph, Thomas F.; Mbugua, G.; Irungu, T.W.; Ombutu, P.This paper characterises the dairy farming system in Dagoretti, Nairobi. Characterisation was part of a broader ecohealth project to estimate the prevalence and risk of cryptosporidiosis and develop risk mitigation strategies. In the project a trans-disciplinary team addressed epidemiological, socioeconomic, environmental and policy aspects of cryptosporidiosis, an emerging zoonosis. This paper also provides background and describes sampling methods for the wider project. Three hundred dairy households were probabilistically sampled from a sampling frame of all dairy households in five of the six locations of Dagoretti, one of the eight districts of Nairobi Province. Randomly selected households identified 100 non-dairy-keeping households who also took part in the study. A household questionnaire was developed, pre-tested and administered in the dry and wet seasons of 2006. An additional study on livelihood and economic benefits of dairying took place with 100 dairy farmers randomly selected from the 300 farms (as well as 40 non-dairy neighbours as a control group), and a risk-targeted survey of environmental contamination with Cryptosporidium was conducted with 20 farmers randomly selected from the 29 farmers in the wider survey who were considered at high risk because of farming system. We found that around 1 in 80 urban households kept dairy cattle with an average of three cattle per household. Cross-breeds of exotic and local cattle predominate. Heads of dairy-keeping households were significantly less educated than the heads of non-dairy neighbours, had lived in Dagoretti for significantly longer and had significantly larger households. There was a high turnover of 10 % of the cattle population in the 3-month period of the study. Cattle were zero grazed, but productivity parameters were sub-optimal as were hygiene and husbandry practices. In conclusion, dairy keeping is a minor activity in urban Nairobi but important to households involved and their community. Ecohealth approaches are well suited to tackling the complex problem of assessing and managing emerging zoonoses in urban settings.Item Participatory probabilistic assessment of the risk to human health associated with cryptosporidiosis from urban dairying in Dagoretti, Nairobi, Kenya(Journal Article, 2012-09) Grace, Delia; Monda, J.; Karanja, N.; Randolph, Thomas F.; Kang'ethe, Erastus K.We carried out a participatory risk assessment to estimate the risk (negative consequences and their likelihood) from zoonotic Cryptosporidium originating in dairy farms in urban Dagoretti, Nairobi to dairy farm households and their neighbours. We selected 20 households at high risk for Cryptosporidium from a larger sample of 300 dairy households in Dagoretti based on risk factors present. We then conducted a participatory mapping of the flow of the hazard from its origin (cattle) to human potential victims. This showed three main exposure pathways (food and water borne, occupational and recreational). This was used to develop a fault tree model which we parameterised using information from the study and literature. A stochastic simulation was used to estimate the probability of exposure to zoonotic cryptosporidiosis originating from urban dairying. Around 6 % of environmental samples were positive for Cryptosporidium. Probability of exposure to Cryptosporidium from dairy cattle ranged from 0.0055 for people with clinical acquired immunodeficiency syndrome in non-dairy households to 0.0102 for children under 5 years from dairy households. Most of the estimated health burden was born by children. Although dairy cattle are the source of Cryptosporidium, the model suggests consumption of vegetables is a greater source of risk than consumption of milk. In conclusion, by combining participatory methods with quantitative microbial risk assessment, we were able to rapidly, and with appropriate ‘imprecision’, investigate health risk to communities from Cryptosporidium and identify the most vulnerable groups and the most risky practices.Item Development and delivery of evidence-based messages to reduce the risk of zoonoses in Nairobi, Kenya(Journal Article, 2012-09) Kang'ethe, Erastus K.; Kimani, V.; Grace, Delia; Mitoko, G.; McDermott, B.; Ambia, J.; Nyongesa, C.; Mbugua, G.; Ogara, W.; Obutu, P.This paper describes a trans-disciplinary process of co-generating and disseminating evidence-based messages for reducing the risk from cryptosporidiosis and other zoonoses in an urban community in Nairobi. Research findings about disease prevalence, risk factors and observed risky and risk-mitigating practices were analysed by a team comprising researchers, community members and local policy- and decision-makers. Using participatory planning, multiple strategies were developed for disseminating key information. We identified five vulnerable groups at higher risk of exposure to cryptosporidiosis and other cattle zoonoses with similar transmission pathways (women, children, elderly people, immunosuppressed people and male farm workers). For each group, targeted messages were developed. Good practices already in use, as were also practices as practices to improve environmental conditions. These messages were disseminated through printed material, in a workshop, through community campaigners and also an edutainment soap opera episode broadcast on Kenyan television. In conclusion, a participatory and trans-disciplinary process can help transform the findings of research into messages that are targeted, attractive and understandable.Item Outcome mapping for fostering and measuring change in risk management behaviour among urban dairy farmers in Nairobi, Kenya(Journal Article, 2012-09) Nyangaga, J.N.; Grace, Delia; Kimani, V.; Kiragu, M.W.; Lang'at, A.K.; Mbugua, G.; Mitoko, G.; Kang'ethe, Erastus K.A study was undertaken to investigate and mitigate the risk from zoonotic Cryptosporidium associated with dairy farming in Dagoretti division, Nairobi, Kenya. Outcome mapping (OM), a relatively new tool for planning and evaluation, was used to foster and then monitor changes in farmer management of health risks. Elements of the OM framework, including the vision, mission and expected progress markers, were developed in participatory sessions and a set of progress markers was used for monitoring behaviour change in farmers participating in the project (the boundary partners). Behaviour change (the outcome challenge) was supported by a range of awareness and educational campaigns, working with strategic partners (extension agents and administrative leaders). The farmers the project worked with made considerable progress according to the markers; they demonstrated an understanding of cryptosporidiosis, established or maintained clean and well drained cattle sheds, and took conscious effort to reduce possible infection. Farmers who did not participate in the project (non-contact farmers) were found to be less advanced on the progress marker indicators. Non-contact farmers who carried out risk-reducing practices had done so independently of the project team. The administration leaders, as strategic partners, had a positive attitude towards the project and confidence in their ability to support project objectives. The study demonstrates the utility of OM in helping to identify and support behavioural change.Item Participatory and integrative approaches to food safety in developing country cities(Journal Article, 2012-09) Grace, Delia; Kang'ethe, Erastus K.; Waltner-Toews, D.Item Modular process risk models for better management of Cryptosporidium parvum - An emerging zoonotic pathogen(Journal Article, 2008-01) Grace, Delia; Randolph, Thomas F.; Karanja, N.; Kang'ethe, Erastus K.Cryptosporidium parvum is an emerging disease which is of particular concern because of its ability to contaminate milk, food-crops and water sources; to persist in the environment; to survive water treatment including chlorination; and to cause serious and sometimes fatal disease in children and the immuno-compromised. Understanding of disease epidemiology is rapidly advancing but uncertainties remain especially concerning the relative importance of zoonotic and anthroponotic transmission. A study is being carried out in Dagoretti in Nairobi to evaluate the contribution of urban dairying to disease burden and some preliminary results related to the risk analysis component are reported in this paper. The study is being carried in a population of around 1,000 urban cattle-keepers and their neighbours, with data collected at cow, farm, household and environmental levels. This paper details the construction, analysis and interpretation of process diagrams in order to show spatial and temporal linkages between pathogen, reservoir host, environment and populations. We show how by incorporating and modelling pathogen survival information, process diagrams allow greater understanding of the risk of disease and better targeting of interventions to successfully manage Cryptosporidium parvum in urban Kenya.