Food Borne Outbreak at a Salad Eatery, Ghana - 2009

Aim: We investigated a foodborne outbreak to determine its magnitude, source of infection and causative agent using laboratory confirmation.
Study Design: Descriptive cross-sectional study
Place and Duration of Study: Koforidua Township of the New Juaben Municipality, Eastern Region, 5th - 8th November 2009
Methodology: A case was defined as any person presenting with abdominal cramps, diarrhea and or nausea to the Eastern Regional Hospital between 5th and 8th November, 2009 and had eaten salad from the salad eatery. All the cases that reported to the hospital were interviewed and medical records reviewed. Four stool samples, portions of the different vegetables (cabbage, carrots, green pepper and onion) used in preparing the salad and a mixed salad portion were collected for laboratory diagnosis. Environmental assessment at the salad eatery was conducted. We assessed the site were the vegetables were prepared and the transportation process of vegetables to the salad eatery.
Results: A total of 40 cases were identified with an attack rate of 0.26/1000 population with no fatalities. This was a point source outbreak with an incubation period of 7-20hours. The most affected were cases aged 21-30years (35%) and females (55%). Laboratory diagnosis confirmed Clostridium perfringens (C. perfringens) as the probable causative agent in two stool samples. C. perfringens was also confirmed in the mixed salad portion and the cabbage. The spore count for the mixed salad was 107 CFU/gram of salad and the cabbage was 109 CFU/gram of cabbage. The vegetables were washed with ordinary water only and transported to the salad eatery with poor temperature control of warm cabbage.
Conclusion: We confirmed an outbreak probably caused by C. perfringens food poisoning. The inadequate washing of vegetables and poor temperature control of warm cabbage was the probable source of the outbreak. Education of food vendors on strict food hygiene was conducted in the Koforidua Township and the inspection of food eateries re-enforced.