Foodborne disease (FBD) has emerged as a growing public health concern worldwide. Non-typhoidal Salmonella spp. cause an estimated 1.4 million cases of FBD in the United States alone each year. Salmonella enterica, subspecies enterica, serotype Enteritidis (Salmonella Enteritidis) is one of the most commonly reported NTS serotypes associated with FBD worldwide. Since the first poultry-associated outbreak in 1991, in humans, the incidence of Salmonella Enteritidis in South Africa has increased. In a study conducted on samples collected between December 2002 and March 2003, Salmonella Enteritidis was the second most common serotype to be isolated. Although it is not feasible to reduce all risk for all foods, food industry and risk assessment managers need to identify the risks that have the largest impact on public health Food safety and risk assessment needs to play an integral role in containing foodborne outbreaks.
On 20 January 2014, a group of 49 nurses, and two training facilitators from the District Department of Health checked into a lodge in Mokopane, Limpopo Province to attend a training workshop. They found 62 college students who had already been staying at the lodge since October 2013. Some of the lodgers started to feel ill shortly after midnight on 22 January 2014. They were taken to the nearest hospital for management. This incident was reported to the Limpopo Provincial Department of Health (LPDoH) Epidemiology Office on the same Friday, 24 January 2014. An outbreak response team (ORT) was assembled and activated to respond to the suspected FBD outbreak. A National Institute for Communicable Diseases (NICD), a division of the National Health Laboratory Services (NHLS), Outbreak Response Unit (ORU) staff member and a South African Field Epidemiology and Laboratory Training Programme (SAFELTP) resident joined the ORT on 28January 2014.
During the outbreak investigation, a line listing was created to capture epidemiological, clinical and laboratory information on all the lodgers that were interviewed during the outbreak. Laboratory and environmental investigations were also conducted. A retrospective cohort analysis was used to determine the risks of illness associated with consuming foods and/or beverages at the lodge. The at-risk population were contacted to complete a standard questionnaire related to food and beverages consumed at the lodge, symptoms of illness, visits to healthcare facilities and specimen submission for pathogen testing. Food and water samples were tested, as well as completion of an environmental assessment questionnaire by staff and external caterers. The data was categorised and STATA version 12 was used for multivariable analyses.
A total of 73 ill persons, including 3 laboratory-confirmed infections, were identified: 69/109 (63%) of the selected cohort were seen at health facilities. Of the at-risk population 87% (109/124) completed the standard questionnaire: 66 cases of gastrointestinal illness and 43 healthy individuals were identified, with a corresponding attack rate of 61%. Most of the cases were females (86%, n=57) with a mean age of 33 years (S.D=7.1), and 36% (n=24) of the cases were hospitalised. Epidemiological data suggested a point source outbreak with no further transmission. Statistical analysis of survey data indicated consumption of diluted fruit juice (from concentrate) adjusted by other food and beverage items, presented a risk ratio of 1.5 (95% CI, 1.1-1.8, p=0.032). Environmental analysis indicated increased risks for cross-contamination. Guidelines on food hygiene and safety were not in use. Training of staff as well as supervision of operations in the kitchen was insufficient.
The outbreak was possibly due to contamination of food/ beverages prepared in the lodge kitchen, and fruit juice consumption was the main exposure associated with ill cases. Feedback on food safety and hygiene practices to prevent contamination at the kitchen lodge were provided. The importance of utilisation of the food safety guidelines, training of staff prior to recruitment and on-going supervision were emphasised to ensure food hygiene and safety. A tool for regular monitoring of quality of food service at the lodge and similar settings needs to be developed and implemented.