Slaughterhouse zoonoses: Are workers reservoirs of zoonotic disease?

Slaughterhouse workers are considered a high risk group for zoonotic disease due to increased contact with animals, animal products and excreta. Globally, slaughterhouse workers have been shown to have an increased seroprevalence to zoonotic pathogens, though no such studies exist in Kenya. Slaughterhouse workers may also act as reservoirs of these zoonotic organisms and asymptomatic carriage of pathogenic bacteria has been demonstrated. This study aimed to determine the carriage of enteropathogens in slaughterhouse workers in rural western Kenya and to determine if there was asymptomatic carriage of Staphylococcus aureus specifically Methicillin Resistant S. aureus (MRSA). This study was conducted in the Lake Victoria Crescent region of western Kenya. Five hundred slaughterhouse workers from this region were asked a comprehensive questionnaire regarding risk factors for zoonotic disease, faecal samples were collected for examination and culture and a nasal swab was cultured for S. aureus. This study reports on the seroprevalence of Salmonella spp, Shigella spp, pathogenic Escherichia coli and Campylobacter spp. in these individuals as well as reporting the nasal carriage of S. aureus and MRSA. This is the first community based study regarding S. aureus and MRSA in Kenya. The asymptomatic carriage of these organisms in slaughterhouse workers highlights a reservoir that may be important in the dissemination of these pathogens. The study further comments on the risk factors for infection with these pathogens and suggestions are made for simple hygiene interventions that can reduce disease in slaughterhouse workers and dissemination to the wider communit

Bayesian latent class estimation of sensitivity and specificity parameters of diagnostic tests for bovine tuberculosis in chronically infected herds in Northern Ireland

Publication history: Accepted - 26 April 2018; Published online - 1 May 2018.In the European Union, the recommended ante-mortem diagnostic methods for bovine tuberculosis (bTB) include the single intradermal cervical comparative tuberculin (SICCT) test and the interferon-gamma (IFN- g) test as an ancillary test. The SICCT test has a moderate sensitivity (Se) and high specificity (Sp), while the IFN-g test has good Se, but a lower Sp than the SICCT test. A retrospective Bayesian latent class analysis was conducted on 71,185 cattle from 806 herds chronically infected with bTB distributed across Northern Ireland (NI) to estimate the Se and Sp of the common ante-mortem tests and meat inspection. Analyses were also performed on data stratified by farming type and herd location to explore possible differences in test performance given the heterogeneity in the population. The mean estimates in chronically infected herds were: (1) ‘standard’ SICCT: Se 40.5–57.7%, Sp 96.3–99.7%; (2) ‘severe’ SICCT: Se 49.0%–60.6%, Sp 94.4–99.4%; (3) IFN-g(bovine–avian) using a NI optical density (OD) cut-off difference of 0.05: IFN-g(B–A)NI: Se 85.8– 93.0%, Sp 75.6–96.2%; (4) IFN-g(bovine–avian) using a standard ‘commercial’ OD cut-off difference of 0.1: IFN-g(B–A)0.1: Se 83.1–92.1%, Sp 83.1–97.3%; and (5) meat inspection: Se 49.0–57.1% Se, Sp 99.1–100%. Se estimates were lower in cattle from dairy farms than from beef farms. There were no notable differences in estimates by location of herds. Certain population characteristics, such as production type, might influence the ability of bTB tests to disclose truly infected cases.This study is part of a larger project on the evaluation of the performance characteristics of the test in chronic bTB herds in NI from 2004 to 2010. It was financed by DAERA (E&I grant code 11/ 03/10)

Between farm contacts in western Kenya: Implications for disease transmission

The transmission dynamics of infectious disease depends on the frequency and type of contacts between susceptible and infectious individuals or groups. Between-farm contact structures have been defined in several countries, and have been widely used to model disease spread. In this study, we describe the farm contact structure in an area of western Kenya where the frequency and range of between-farm contacts was previously unknown. We focus on the specific between-herd contacts that are thought to be risk factors for the transmission of Brucella spp.. Through door-step interviews, all cattle farmers within a single 30 km2 administrative area, chosen as being representative of the diversity of cattle production systems present within the wider Western province of Kenya, were asked to report the identity and frequency of contacts with neighbouring herds, including co-grazing, the use of shared water points, and shared bulls. Moreover, the on and off-farm movement of cattle from within and outside the area under study, as well as a range of farm husbandry and production practices, were characterised. The between-farm contact network was investigated using social network analysis. To test for non-random interactions based on production type, we used multivariate statistical approaches to classify farms into distinct ‘sub-groups’ based on animal and farm management practices. This was followed by a set of ‘mixing matrix’ approaches in which herd assortativity based on sub-group membership was assessed. The contact network defined by this study will be used to inform disease transmission models for brucellosis in western Kenya. In particular, understanding the mixing patterns of different animal production systems in this mixed farming area will contribute to models describing animal reservoir dynamics for human brucellosis

Human brucellosis in urban and peri-urban areas of Kampala, Uganda

A retrospective case–control study of human brucellosis in urban, peri-urban, and rural areas in Kampala, Uganda was undertaken to find the risks associated with the disease using the medical records of Mulago National Referral Hospital (Mulago Hospital). From the Brucella agglutination test (BAT) records between June 2004 and May 2006, 652 positive results were found. The case–control study showed that living in urban areas was a risk factor for brucellosis. The numbers of improved and cross-breed cattle per 1000 households were calculated on the basis of data obtained from interviews of 75 randomly selected local councils (LCls) in an area between 5 and 20 km radii from the city center of Kampala. Cattle-keeping activities were, however, unpopular in urban areas compared to peri-urban and rural areas. Poor correlation between the distribution of human brucellosis cases and the distribution of cattle suggested that most of the brucellosis cases resulted from consumption of raw milk transported from peri-urban and rural areas of Kampala and/or dairy production areas outside Kampala