FOODBORNE OUTBREAK ASSOCIATED WITH FRIED RICE, HARDIN COUNTY, MAY 2006

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FOODBORNE OUTBREAK ASSOCIATED WITH FRIED
RICE,HARDIN COUNTY, MAY 2006

• ASHOKA INDUKURI
• EPIDEMIOLOGIST
• LINCOLN TRAIL DISTRICT HEALTH DEPT

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Foodborne Outbreak

• On May 8th , Hardin County Environmental office
  receives reports of acute gastroenteritis among 6
  people who ate at a local restaurant.
• Illness started within 1-6 hrs after eating
  dinner on May 7th.
• More reports of illness received on May 9th.

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Foodborne Outbreak

• Patients complain of the following symptoms
  developing within a short incubation period of lt
  6 hrs.
• Nausea
• Vomiting
• Diarrhea
• Abdominal Cramps
• Fever Chills

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Foodborne Outbreak

• Hardin County Environmental Health Department
  contacts Environmental Director and
  Epidemiologist of Lincoln Trail District Health
  Department.
• Outbreak Investigation initiated.
• Environmental staff visit the restaurant to
  collect food samples.

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Outbreak Investigation

• 32 people were identified who ate at the
  restaurant.
• These individuals were interviewed by telephone
  using a Foodborne disease questionnaire.
• Local Hospital was alerted about the acute
  gastroenteritis outbreak.

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Outbreak Investigation

• Interviews revealed that all people who were sick
  ate dinner at the restaurant on May 7th.
• No reports of illness among people who ate lunch.
• The food items consumed include fried rice,
  chicken, vegetables and salad.

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Outbreak Investigation-Case definition

• Based on the initial investigation a Clinical
  case of illness is defined as Acute
  gastrointestinal illness characterized by nausea,
  vomiting, abdominal cramps, and diarrhea
  occurring within 12 hours of food consumption at
  the restaurant.
• 26 out of the 32 people interviewed matched the
  case definition.

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Outbreak Investigation

• Food samples of steamed rice, chopped vegetables
  and uncooked chicken were collected from the
  restaurant on May 8th and sent to State Lab.
• Stool specimens of sick patients, and a carry-out
  box with fried rice were also submitted.

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Outbreak Investigation

• Environmental inspection of restaurant was
  performed on May 9th with extensive review of
  food preparation, handling and storage
  procedures.
• Based on the inspection the restaurant was issued
  a notice of suspension the same day.

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Outbreak Investigation-Results

• 26 people were sick.
• The median incubation period was 3 hours and the
  symptoms resolved in 12 hours after onset.
• The main symptoms included nausea(88.5),
  vomiting(88.5), diarrhea(65) and abdominal
  cramps(62).
• None of the sick people were hospitalized.

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Table 1 Epi Curve for B.cereus Foodborne
Outbreak
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Outbreak Investigation-Results

• Fried rice was only food significantly associated
  with illness.
• Of those who consumed fried rice 93 were ill.
• Food specific attack rate among ill was 100 for
  persons who ate fried rice.
• Other food items with some association were
  vegetables and salad.

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Outbreak Investigation-Results

• Environmental inspection revealed improper
  handling and storage of rice.
• Rice cooked during lunch was stored at improper
  temperatures and served during dinner.
• There were many food code violations in the
  kitchen and the equipment was not well maintained.

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Outbreak Investigation-Results

• The restaurant scored low rating score of 57/100
  and was immediately closed.
• The owner was advised to rectify the violations
  and apply for re-instatement.
• Re-inspection was performed on May 11th.
• Restaurant was reopened after securing a rating
  score of 97/100.

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Outbreak Investigation-Lab Results

• Lab results of the food samples revealed 4.1
  million colony forming units (CFU) of Bacillus
  cereus/gram of steamed rice.
• The carry-out box sample and chopped vegetables
  had 75,000 CFU/gram and 120 CFU/gram of B. cereus
  respectively.
• No additional foodborne pathogens were detected.

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Bacillus cereus

• Bacillus cereus is a rare infectious case of
  foodborne illness.
• Accounts for less than 1 of foodborne outbreak
  cases reported to CDC.
• Spore-forming bacterium found in soil, vegetation
  and many raw and processed goods.

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Bacillus cereus

• Spores of B.cereus survive multiply in
  contaminated food and cause two types of illness
  by production of exotoxins or enterotoxins. They
  are
• 1.Emetic syndrome
• 2. Diarrheal syndrome

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Bacillus cereus

• Emetic syndrome is associated with consumption of
  toxin in boiled or fried rice.
• Short incubation period of 1-5 hours and 6-24
  hour duration of illness.
• It mostly has Upper gastrointestinal symptoms
  such as nausea, vomiting and can also cause
  diarrhea and abdominal cramps.

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Bacillus cereus

• Diarrheal syndrome is associated with consumption
  of contaminated meat products, soups, sauces, and
  vegetables.
• Onset of symptoms occurs within 8-16 hours and
  subsides within 12-24 hours.
• Symptoms include watery diarrhea, abdominal
  cramps and occasional nausea vomiting.

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Bacillus cereus

• Diagnosis of B.cereus food poisoning can be
  confirmed by isolation of more than 105
  B.cereus organisms/gram of contaminated food.

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Discussion

• Positive lab test of 4.1 million CFU of
  B.cereus/gram of fried rice confirmed B. cereus
  as the causative organism of this outbreak.
• Improper storage of cooked rice at room
  temperature, preparing food several hours before
  serving might have predisposed the production of
  heat-stable toxin of B.cereus.
• This resulted in the Emetic syndrome type of
  B.cereus food poisoning.

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Closing Notes

• Consider B.cereus in your investigation /
  differential diagnosis in a foodborne outbreak
  with a very short incubation period and
  consumption of fried rice.

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References

• Foodborne Outbreak Associated with Fried rice in
  Hardin County, KY, May 2006-Volume 41, Number 11,
  Kentucky Epidemiology Notes Reports.