FOODBORNE OUTBREAK ASSOCIATED WITH FRIED RICE, HARDIN COUNTY, MAY 2006 ASHOKA INDUKURI EPIDEMIOLOGIST LINCOLN TRAIL DISTRICT HEALTH DEPT

FOODBORNE OUTBREAK FOODBORNE OUTBREAK ASSOCIATED WITH FRIED RICE,ASSOCIATED WITH FRIED RICE,

HARDIN COUNTY, MAY 2006HARDIN COUNTY, MAY 2006

ASHOKA INDUKURIASHOKA INDUKURIEPIDEMIOLOGISTEPIDEMIOLOGIST

LINCOLN TRAIL DISTRICT HEALTH LINCOLN TRAIL DISTRICT HEALTH DEPTDEPT

Foodborne OutbreakFoodborne Outbreak

On May 8On May 8thth , Hardin County Environmental , Hardin County Environmental office receives reports of acute gastroenteritis office receives reports of acute gastroenteritis among 6 people who ate at a local restaurant.among 6 people who ate at a local restaurant.

Illness started within 1-6 hrs after eating Illness started within 1-6 hrs after eating dinner on May 7dinner on May 7thth..

More reports of illness received on May 9More reports of illness received on May 9 thth..


Patients complain of the following symptoms Patients complain of the following symptoms developing within a short incubation period of developing within a short incubation period of < 6 hrs.< 6 hrs.

NauseaNausea

VomitingVomiting

DiarrheaDiarrhea

Abdominal CrampsAbdominal Cramps

Fever & ChillsFever & Chills


Hardin County Environmental Health Hardin County Environmental Health Department contacts Environmental Director Department contacts Environmental Director and Epidemiologist of Lincoln Trail District and Epidemiologist of Lincoln Trail District Health Department.Health Department.

Outbreak Investigation initiated.Outbreak Investigation initiated. Environmental staff visit the restaurant to Environmental staff visit the restaurant to

collect food samples.collect food samples.

Outbreak InvestigationOutbreak Investigation

32 people were identified who ate at the 32 people were identified who ate at the restaurant.restaurant.

These individuals were interviewed by These individuals were interviewed by telephone using a Foodborne disease telephone using a Foodborne disease questionnaire.questionnaire.

Local Hospital was alerted about the acute Local Hospital was alerted about the acute gastroenteritis outbreak.gastroenteritis outbreak.


Interviews revealed that all people who were Interviews revealed that all people who were sick ate dinner at the restaurant on May 7sick ate dinner at the restaurant on May 7 thth..

No reports of illness among people who ate No reports of illness among people who ate lunch.lunch.

The food items consumed include fried rice, The food items consumed include fried rice, chicken, vegetables and salad.chicken, vegetables and salad.

Outbreak Investigation-Case definitionOutbreak Investigation-Case definition

Based on the initial investigation a Clinical Based on the initial investigation a Clinical case of illness is defined as “Acute case of illness is defined as “Acute gastrointestinal illness characterized by gastrointestinal illness characterized by nausea, vomiting, abdominal cramps, and nausea, vomiting, abdominal cramps, and diarrhea occurring within 12 hours of food diarrhea occurring within 12 hours of food consumption at the restaurant”.consumption at the restaurant”.

26 out of the 32 people interviewed matched 26 out of the 32 people interviewed matched the case definition.the case definition.


Food samples of steamed rice, chopped Food samples of steamed rice, chopped vegetables and uncooked chicken were vegetables and uncooked chicken were collected from the restaurant on May 8collected from the restaurant on May 8 thth and and sent to State Lab.sent to State Lab.

Stool specimens of sick patients, and a carry-Stool specimens of sick patients, and a carry-out box with fried rice were also submitted.out box with fried rice were also submitted.


Environmental inspection of restaurant was Environmental inspection of restaurant was performed on May 9performed on May 9thth with extensive review of food with extensive review of food preparation, handling and storage procedures.preparation, handling and storage procedures.

Based on the inspection the restaurant was issued a Based on the inspection the restaurant was issued a

notice of suspension the same day.notice of suspension the same day.

Outbreak Investigation-ResultsOutbreak Investigation-Results

26 people were sick.26 people were sick. The median incubation period was 3 hours and The median incubation period was 3 hours and

the symptoms resolved in 12 hours after the symptoms resolved in 12 hours after onset.onset.

The main symptoms included nausea(88.5%), The main symptoms included nausea(88.5%), vomiting(88.5%), diarrhea(65%) and vomiting(88.5%), diarrhea(65%) and abdominal cramps(62%).abdominal cramps(62%).

None of the sick people were hospitalized.None of the sick people were hospitalized.

Table 1: Epi Curve for B.cereus Table 1: Epi Curve for B.cereus Foodborne OutbreakFoodborne Outbreak

EPI CURVE

0

5

12

4

1 1

0 0 0

1

2

00

2

4

6

8

10

12

14

1 2 3 4 5 6 7 8 9 10 11 12

Time of Onset of Symptoms (in Hours)

Nu

mb

er

of

Cases

Number of Cases


Fried rice was only food significantly Fried rice was only food significantly associated with illness.associated with illness.

Of those who consumed fried rice 93% were Of those who consumed fried rice 93% were ill.ill.

Food specific attack rate among ill was 100% Food specific attack rate among ill was 100% for persons who ate fried rice.for persons who ate fried rice.

Other food items with some association were Other food items with some association were vegetables and salad.vegetables and salad.


Environmental inspection revealed improper Environmental inspection revealed improper handling and storage of rice.handling and storage of rice.

Rice cooked during lunch was stored at Rice cooked during lunch was stored at improper temperatures and served during improper temperatures and served during dinner.dinner.

There were many food code violations in the There were many food code violations in the kitchen and the equipment was not well kitchen and the equipment was not well maintained.maintained.


The restaurant scored low rating score of The restaurant scored low rating score of 57/100 and was immediately closed.57/100 and was immediately closed.

The owner was advised to rectify the The owner was advised to rectify the violations and apply for re-instatement.violations and apply for re-instatement.

Re-inspection was performed on May 11Re-inspection was performed on May 11 thth.. Restaurant was reopened after securing a Restaurant was reopened after securing a

rating score of 97/100.rating score of 97/100.

Outbreak Investigation-Lab ResultsOutbreak Investigation-Lab Results

Lab results of the food samples revealed 4.1 Lab results of the food samples revealed 4.1 million colony forming units (CFU) of million colony forming units (CFU) of Bacillus cereus/gram of steamed rice.Bacillus cereus/gram of steamed rice.

The carry-out box sample and chopped The carry-out box sample and chopped vegetables had 75,000 CFU/gram and 120 vegetables had 75,000 CFU/gram and 120 CFU/gram of B. cereus respectively.CFU/gram of B. cereus respectively.

No additional foodborne pathogens were No additional foodborne pathogens were detected.detected.

Bacillus cereusBacillus cereus

Bacillus cereus is a rare infectious case of Bacillus cereus is a rare infectious case of foodborne illness.foodborne illness.

Accounts for less than 1% of foodborne Accounts for less than 1% of foodborne outbreak cases reported to CDC.outbreak cases reported to CDC.

Spore-forming bacterium found in soil, Spore-forming bacterium found in soil, vegetation and many raw and processed goods.vegetation and many raw and processed goods.


Spores of B.cereus survive & multiply in Spores of B.cereus survive & multiply in contaminated food and cause two types of contaminated food and cause two types of illness by production of exotoxins or illness by production of exotoxins or enterotoxins. They areenterotoxins. They are

1.Emetic syndrome1.Emetic syndrome

2. Diarrheal syndrome2. Diarrheal syndrome


Emetic syndrome is associated with Emetic syndrome is associated with consumption of toxin in boiled or fried rice.consumption of toxin in boiled or fried rice.

Short incubation period of 1-5 hours and 6-24 Short incubation period of 1-5 hours and 6-24 hour duration of illness.hour duration of illness.

It mostly has Upper gastrointestinal symptoms It mostly has Upper gastrointestinal symptoms such as nausea, vomiting and can also cause such as nausea, vomiting and can also cause diarrhea and abdominal cramps.diarrhea and abdominal cramps.


Diarrheal syndrome is associated with Diarrheal syndrome is associated with consumption of contaminated meat products, consumption of contaminated meat products, soups, sauces, and vegetables.soups, sauces, and vegetables.

Onset of symptoms occurs within 8-16 hours Onset of symptoms occurs within 8-16 hours and subsides within 12-24 hours.and subsides within 12-24 hours.

Symptoms include watery diarrhea, abdominal Symptoms include watery diarrhea, abdominal cramps and occasional nausea & vomiting.cramps and occasional nausea & vomiting.


Diagnosis of B.cereus food poisoning can be Diagnosis of B.cereus food poisoning can be confirmed by isolation of more than 10confirmed by isolation of more than 105 5 B.cereus organisms/gram of contaminated B.cereus organisms/gram of contaminated food.food.

DiscussionDiscussion

Positive lab test of 4.1 million CFU of Positive lab test of 4.1 million CFU of B.cereus/gram of fried rice confirmed B. cereus B.cereus/gram of fried rice confirmed B. cereus as the causative organism of this outbreak.as the causative organism of this outbreak.

Improper storage of cooked rice at room Improper storage of cooked rice at room temperature, preparing food several hours before temperature, preparing food several hours before serving might have predisposed the production serving might have predisposed the production of heat-stable toxin of B.cereus.of heat-stable toxin of B.cereus.

This resulted in the Emetic syndrome type of This resulted in the Emetic syndrome type of B.cereus food poisoning.B.cereus food poisoning.

Closing NotesClosing Notes

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

ReferencesReferences

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

Documents

FOODBORNE OUTBREAK ASSOCIATED WITH FRIED RICE, HARDIN COUNTY, MAY 2006 ASHOKA INDUKURI EPIDEMIOLOGIST LINCOLN TRAIL DISTRICT HEALTH DEPT