On Friday 7th October 2022, the food safety program in the Ministry of Health (MOH) informed by Najran Public Health team about an increased number of gastroenteritis cases reported from Yadamah hospital north Najran region. 45 cases were registered on October 7th early morning, reaching 100 by 12:00 A.M., October 8th. All cases had gastroenteritis symptoms including diarrhea, fever, vomiting, nausea, and abdominal pain. All reported a history of eating from a restaurant in Yadamah city the previous evening. A team from FETP was assigned to investigate this outbreak.
The team firstly visited Yadamah hospital and reviewed the patients’ records for demographic data, clinical presentation, and laboratory investigations with the Najran public health team in the hospital. A list of patients' names and telephone numbers was obtained from the hospital. Active surveillance was conducted to collect further data. After that, the team visited the incriminated restaurant that had already been closed by the local authorities, which appeared to be generally clean.
A case series study was conducted to identify this outbreak's extent, source, and cause. A probable case was defined as any person who had eaten from the restaurant in Yadamah between 4:00 PM on October 6th to 12:00 AM, on October 7th, 2022, and developed abdominal pain, diarrhea, fever, nausea, and vomiting.
Data were collected both by face-to-face interviews with the cases and guardians of the children at Yadamah Hospital. Blood and stool Cultures and a rectal swab of patients and food handlers were taken. Nail and throat swabs also had been taken from all food handlers at the restaurant and Various food specimens from the restaurant had been sent to a laboratory for investigation.
A total of 100 exposed people, all sick, 58 were Males and 42 were Females, among the cases 90% were Saudi nationals. The age of cases ranged between 1- 50 years (mean of 16 years), More than half of cases were aged between 5-19 years old. All had developed symptoms of Fever 99 cases, Abdominal pain 98, diarrhea 95, vomiting 80, and nausea 73.
The first case had onset of symptoms at 2:00 AM on Friday, October 7th, while the last 2cases had onset at 11:00 PM the same day. The incubation period ranged between 6 to 29 hours, the mean was 17:35 hours, median = 18 hours; mode = 24 hours.
During our investigation on questioning the restaurant food handlers regarding the procedures for food storage, handling, preparation, and serving, they stated that a food handler who prepares a chicken for shawarma could not provide the correct steps in front of the investigation team.
Salmonella enterica was isolated from rectal swap obtained from eight patients and one food handler. No pathogens were isolated from the restaurant food items. the positive food handler involved in preparing the shawarma and serving it to customers was a strong contaminating factor. Although no salmonella was isolated from food, this might have been due to an improper way to take samples.
Food-borne illness is caused by food contamination and occurs at any stage of the food production, delivery and consumer chain1. Most result from infections caused by bacteria, viruses, parasites, or poisonings caused by toxins or chemicals contaminating the food2.
In the present outbreak, Laboratory investigations were positive in one of the food handlers of Salmonella enteritis, which explains the suspected restaurant as a possible source of this outbreak. However, no shared source was found.
Clinical and epidemiological features give important signs to etiology. salmonella incubation period ranged from 6–96 hours (usually 1–3 days). That referred to salmonella enterica as the causative agent with high probability, Fever was the most common symptom, followed by abdominal cramps, diarrhea, vomiting, and headache3.
Figure 1: Epidemic curve of the food-borne salmonella outbreak, Yadamah, Najran region,2022 .
References:
1. https://www.who.int/news-room/fact-sheets/detail/salmonella-(non-typhoidal)
2. Center for Diseases Controls and Prevention. Fact sheet: Foodborne illnesses. Atlanta. Available from URL: http://www. cdc. gov/n cid od/d bmd/ diseaseinfo/foodborneinfections_g.htm.
3. World Health Organization 2008. Foodborne disease outbreaks: Guidelines for investigation and control.