Introduction
On Monday 20th of June 2011 more than 200 cases were reported in Jizan General Hospital, more than 50 cases from King Fahed Central Hospital in Jizan and more than 30 cases from Sabia, Ahadalmasarehah and Damad Hospitals. These were complaining of diarrhea, vomiting, abdominal pain, fever and headache, after taking meals from a known restaurant in Jizan city. After suspecting that the source was contaminated food served by that restaurant, a team fromthe Field Epidemiology Training Program ( FETP) visited the area to conduct a case control study to investigate the outbreak.
Methodology
A descriptive study followed by case control was conducted with interviewed Questionnaire, 100 cases were randomly selected compared with 50 controls who had eaten from the restaurant with no development of symptoms. The questionnaire included information about type of food item eaten in the restaurant, time food was eaten, time of symptoms following the meal including upper and lower gastrointestinal tract symptoms, type of sample taken from the patient, hospital admission and lab result. A case definition was defined as any person who had eaten from the restaurant during 20th and 21st of June 2011 and showed any gastrointestinal tract symptoms such as abdominal pain, diarrhea, vomiting, or fever. Any person who had eaten from the same restaurant at the same time and had not developed any gastrointestinal symptoms was considered as a control.
Results
A total of 100 cases and 50 controls were interviewed, the result showed that all the 100 cases ate from the same restaurant, 98% of the cases developed diarrhea, 90% of them developed abdominal pain, 81% developed vomiting, 74% developed nausea, 89% developed fever and 76% headache. The incubation period was from 5 to 26 hours, 80% of cases were males, 20% were females, all the cases ( 100% ) ate the mixed sandwich, the mixed sandwich included falafel in 96% of the cases ( OR =22.1 & 95% CI = 7.0 - 69.5 ), tomato salad in 88% ( OR=29,3 & 95% CI= 11.7 - 73.5 ), boiled eggs in 85% ( OR=10.1 % 95% CI=3.9 - 25.9 ) in those three items Salmonella was isolated, while tuna salad was in the mixed sandwich in 17% of the cases ( OR=1.8 & 95% CI = 0.6 - 5.3 ) and hummus in 1% ( OR=0.07 95% CI= 0.0 - 0.6) in those two items E-Coli was isolated, while the results of the other samples taken from the other items were negative. Salmonella also was isolated from 26 out of 50 samples of stool taken from 50 cases, while the rest were negative( figure 1 )( figure 3 ) ( table 1 ) ( table 2 ) ( table 3 ). Epidemic curve shows two peaks the 1st peak for the cases that had taken breakfast on 20th of June from the restaurant and the 2nd peak for the cases who had taken the dinner in the evening of the same day (figure 2).
Conclusion
Salmonella enteritis was the causative agent of the outbreak. Improper food handling contributed to the cross contamination after isolation of salmonella species from more than one item, the tomato salad, boiled eggs and the falafel were found to be the implicated items.