Introduction
By morning of Sunday 03/05/2009 the health authorities in Asir governorate had noticed an increase of number of cases complaining of gastroenteritis symptoms that were reported in the same day by Asir general hospital. The cases continue to be reported to reach about 21 reported cases. All patients have a recent history of eating in local restaurant which was closed by the local authorities on the same day. FETP was assigned to assess severity and extent of this outbreak and to identify its source and cause.
Methodology
A case-control study was conducted in Asir region. A case was defined as any person who ate from the restaurant at 9:00 to 11:30 PM on 02/05/2009 and developed one of gastrointestinal symptoms e.g. (Abdominal pain, diarrhea, fever, vomiting, nausea) within one day of food consumption. A control was defined as any person who ate from the same restaurant and during the same period and did not develop any of gastrointestinal symptoms e.g. (abdominal pain, diarrhea, fever, vomiting, nausea and stool with blood) during the period of the outbreak. Cases were identified by reviewing the hospital ER records, and any available laboratory results for cases treated over the outbreak period and through asking them for any one who accompanied them and discovered later to develop the symptoms but did not visit the hospital.
Results
We were able to identify 43 cases, for each case one members from his/her family or friend was chosen as a control. As the patients have been discharged at the time of FETP arrival, we reviewed their records for contact number. Phone interview was initiated to collect data from cases and controls. The team visited the implicated restaurant to conduct inspections and interview restaurant staff regarding food handling practices. Rectal, under nail, throat and nasal swabs were taken from all the restaurant workers and cases for culture and sent to regional laboratory for investigation. No food items were available for testing. 43 persons cases and 44 controls were interviewed and their data were presented. The ages of the cases ranged from 9-47 years, with a median age of 22 years and mean of 23.5 years (SD 10.1 years). Males were 28 (65.1%) and females 15 (34.9%). Most of the cases were Saudis 35 (81.4%) while non-Saudis were 8 (18.6%). Students were 19 (44.2%) then employees (11; 25.6%). The most common symptoms reported were diarrhea (42; 97.7%) followed by vomiting (41; 95.3%), fever (29; 67.4%), abdominal pain (32; 74.4%), and nausea (23; 53.5%). The Incubation Period (IP) ranged from 4 to 25 hours, with a median IP = 12 hours and mean 13.2 hours (SD= 5.1 hours). This is demonstrated in the Epidemic Curve. After calculation of OR and 95% Confidence Intervals (CI) regarding exposure of the cases and controls to certain food items, a high OR was found for eating Russian salad (OR =51.6, 95% CI = 12.944 - 205.936), lamb kabab (OR= 35.438, 95% CI= 7.541 - 166.535), fries (OR= 5.738, 95% CI= 2.246 - 14.656), and chicken kabab (OR= 5.014, 95% CI= 1.754 - 14.335). Mutabbal, hommos and shawerma had no significant OR (Table 1). 24 cases were positive for salmonella Spp (rectal swap). No pathogen were isolated from the restaurant food handlers On interviewing the restaurant chef about the way of food storage, handling, preparation, and serving, he explained that Russian salad was prepared by mixing hand-made mayonnaise in the restaurant with the other ingredients. Eggs had been stored at room temperature. Staffs were also interviewed, no one had been ill with diarrhea in the previous few weeks. With regarded to facility food handlers hygiene, clothing was satisfactory and nail short and clean.
Conclusion
Based on clinical and epidemiological features, the present outbreak is suggestive of salmonella food poisoning. This is supported by the laboratory findings which grew salmonella enteritidis group D from 24 patients.