An epidemiologist is interested in the frequency of an event – the number of times a disease was detected in a population. The attack rate is an important statistic because it can help determine the extent of a disease. It also provides information on how often the disease occurs and how often it affects a population. An attack rate of food poisoning is one of the most common ways to estimate the prevalence of a disease.

IRBM workhop at Ikhwezi Training Centre

An IRBM workhop at the Ikhwezi Training Centre in Bulawayo in August 2014 was the cause of an outbreak of food poisoning. During this event, 53 employees contracted diarrhoea, with the median age of the participants being 45 years. Most of the affected employees were married and had at least some tertiary education.

The event was hosted by the Bulawayo City Council and its employees. At the Ikhwezi Training Centre, food handlers were trained and assessed to ensure that they were medically fit to handle food. Council employees were encouraged to use licensed catering companies. The food safety standards of the Bulawayo Market are being monitored through intensifying food sampling. Meanwhile, outbreak surveillance systems should be strengthened to detect conditions of public health importance, and specimens should be collected and evaluated timely.


The attack rate of food poisoning among the group who participated in a barbecue was analyzed through two epidemiological studies. The first took place within a week after the initial report to the Health Protection Unit (HPU). The second study, conducted within a month after the first, collected data from those who attended the barbecue and reported symptoms. The questionnaires asked participants about their age, sex, food intake, symptoms, and the date/time of onset and duration of illness.

Using a dendrogram to determine the similarity of the three strains, the outbreak’s cause was determined. Of the three strains identified, the Bubba-Qs sauce triggered the most attacks, while the dry-rubbed barbecue was the least likely to cause food poisoning. However, the results of these two studies did not rule out the possibility that the barbecues had been prepared before the outbreak.