NJDOH - Communicable Disease Service
Outbreak Reporting Format and Sample Final Report
TO:
FROM:
DATE:
SUBJECT:
SUMMARY
(Brief – usually 5 or 6 sentences)
INTRODUCTION
(Who reported the outbreak? Who took the initial steps? What groups were involved?)
BACKGROUND
(Include useful information that will shed light on the outbreak, e.g. information about a restaurant or setting of the outbreak)
METHODS
Epidemiologic Investigation
- Case Definition
- Case Ascertainment
(How were the case and others exposed but not ill found?)
- Survey
(Who was surveyed? What was asked? Where the interviews conducted in person or by telephone?)
- Analysis (What statistical methods were used?)
Odds ratios were calculated and statistical significance was tested using the Fisher’s exact test or hi-square test as indicated. P<0.5 was considered significant.
Human Microbiology
(What types of specimens were collected? What microbiological tests were performed on these specimens?)
Environmental Investigation
(Who conducted the sanitary investigation? What methods were used?)
RESULTS
(What were the results of the epidemiologic, laboratory, and environmental investigations?)
A. Case characteristics (How many persons were interviewed? How many fit the case description? What were the ages of the cases? What were the symptoms of the cases? How long did the symptoms last? Was anyone hospitalized? Did anyone die?)
A total of ____ persons were interviewed. # (__%) met the case definition. The median age of cases was ___ years old with a range of ___ to ___ years. Among the persons not meeting the case definition, the median age was ___ years old, with a range of ___ to ___ years. ______, ______, and ______, were the most common symptoms reported. Symptoms reported by cases are listed in table 1. The time of onset of illness is shown in figure 1. The assumed period of exposure was ______. In persons meeting the case definition the illness was reported to last from ___ hours to ___ days, with a median of ___ hrs./days. # (___%) were hospitalized. No cases died.
Table 1. Symptoms Reported by Cases
Symptom / _#_ & (%) of cases reporting each symptom (N= )Diarrhea
Abdominal Pain
Weakness
Nausea
Fever
Vomiting
Chills
Muscle Aches (Myalgia)
Figure 1. Approximate Time of Onset of Illness Among Cases
#
of
cases
AM PM AM PM AM PM AM PM AM PM
/ / / / /
Time of Onset of Illness
X = ____
B. Food Histories
Food-specific attack rates and odds ratios were calculated for the following foods:
1
2
3
4
5
Of these, _#_ had both an elevated odds ratio and a p-value < 0.05. All foods are listed below in Table 2.
Table 2. Exposure Information for All Foods
Exposed Not Exposed
(foods eaten) (foods not eaten)
Risk Ill Well Attack Rate Ill Well Attack Rate Relative P-Value
Factor
(Food) _
Food A B A C D C A(C+D)
A+B C+D C(A+B)
Human Microbiology
(What were the results of the specimens taken?)
Environmental Investigation
(What were the results of the sanitary investigation?)
DISCUSSION
(What is the conclusion of the investigation?)
CONTROL MEASURES
(List all control measures)
OUTCOME
(Did the control measures end the outbreak? Was there any evidence of a continuing problem?)
Sample Report
MEMORANDUM
TO: Jane Jones
NJDOHSS Communicable Disease Service
FROM: Juan Rodgers
Cattaw County Department of Health
DATE: June 1, 2005
SUBJECT: E7905 - Salmonella Outbreak
SUMMARY
An outbreak of Salmonella Group D occurred among employees of the ABC Restaurant in Blackwood. Mashed potatoes were epidemiologically implicated as the vehicle. Salmonellaenteritidis was isolated from two samples of the mashed potatoes and from veal patties. Both the mashed potatoes and the veal patties were made with raw eggs.
INTRODUCTION
On Friday, April 8, 2005, Jane Jones of the NJDOHSS was informed by Juan Rodgers of the Cattaw County Health Department that 20-30 employees of the ABC Restaurant in Blackwood, NJ were reportedly ill with symptoms of gastroenteritis. An epidemiologic investigation was immediately initiated.
BACKGROUND
The ABC Restaurant in Blackwood, NJ has banquet facilities. All ill employees had eaten in the company cafeteria where the following food items were offered: veal patty with gravy, mashed potatoes, and salad with oil and vinegar on 4/7. This same meal had been scheduled to be served to patrons on 4/8. After reports of illness were received on 4/8, the menu was changed and no food from the suspect meal was served. The restaurant was scheduled to serve 1500 meals from 4/7 through 4/9/05.
METHODS
Epidemiologic Investigation
A. Case Definition
A case was defined as an individual with vomiting or diarrhea occurring within 96 hours of eating at the ABC Restaurant.
Table 1. Symptoms Reported by Cases
Symptom / _#_ & (%) of cases reporting each symptom (N= 10 )Diarrhea / 10 (100%)
Vomiting / 9 (90%)
Fever / 8 (80%)
Abdominal Pain / 7 (70%)
Headache / 7 (70%)
Figure 1. Approximate Time of Onset of Illness Among Cases
#
of X
cases XX XX
XX XX X
PM AM PM AM PM AM PM AM PM
4/7 4/8 4/9 4/10
Time of Onset of Illness
X = 1
B. Food Histories
Food-specific attack rates and odds ratios were calculated for the following exposures: veal patty, mashed potatoes, salad. Only mashed potatoes had a significant p value <0.05 (Table 2).
Table 2. Exposure Information for All Foods
Exposed Not Exposed
(foods eaten) (foods not eaten)
Risk Ill Well Attack Rate Ill Well Attack Rate Relative Risk P-Value
Factor
(Food) ______
Mashed
Potatoes 10 4 .71 0 9 0 N/A .0008__
Veal
Patty 8 6 .4 2 7 .22 2.59 .11____
Salad 4 6 .4 6 7 .46 .87 .55
Environmental Investigation
J. Smith of the Cattaw County Health Department performed a sanitary inspection of the ABC Restaurant on 4/8/05; no violations were noted upon inspection.
B. Case Ascertainment
An attempt was made to contact all employees present at the ABC Restaurant on 4/7/05. All employees interviewed by 4/10/05 were included in the analysis. Employee names and phone numbers were supplied by the owners of the restaurant.
C. Survey
The following information was sought by telephone or personal interview: age, sex, symptoms of illness, duration and onset of illness and food history.
D. Analysis
Odds ratios were calculated and statistical significance was tested using the fisher’s exact test.
Human Microbiology
Stool specimens were collected by treating hospitals and the Cattaw County Health Department and cultured for Salmonella by either the New Jersey Department of Health PHEL or private hospital laboratories. Private hospitals were requested to send all specimens to the PHEL for serotyping.
RESULTS
A. Case characteristics
It is estimated that approximately 40 employees were working on April 7, 2005. A total of 23 of these employees were interviewed. 10 (44%) met the case definition. The median age of cases was 26 years old with a range of 20 – 34 years. Among the employees not meeting the case definition, the median age was 36 years old with a range of 24 – 61 years. Diarrhea and vomiting were the most common symptoms reported. Symptoms reported by cases are listed in Table 1. The time of onset of illness is shown in Figure 1. The assumed period of exposure was April 7, 2005 12 noon to 8 p.m. Three (30%) of the interviewed cases were hospitalized.
At ABC Restaurant, boiled potatoes are mashed with raw eggs and seasonings and placed into potato skins and baked at 350 degrees for 45 minutes. In this case, however, the employees consumed the mashed potato mixture after they were placed into a steamer and heated for 25 minutes.
The veal patties were made by mixing ground fresh veal with raw eggs used as a binder. The patties were then cooked in a 350 degree oven for 30 minutes.
Two samples of mashed potatoes were positive for Salmonellaenteritidis on initial culture plates. One sample was the mashed potato mixture before any further cooking and the second sample came from an employee who had taken her mashed potatoes home for later consumption. In addition, a sample of veal patties embargoed from the restaurant on 4/9 was positive by culture for Salmonella enteriditis. The Salmonella enteriditis from the veal required two different enrichment steps to grow. This indicates that the veal had a much lower quantity of Salmonella than the potatoes.
No food handlers reported any symptoms prior to eating on 4/7/05.
The eggs were supplied by Cookies Wholesale Dairy Products in, Toronto, N.J. The code XX23 was on the cases of eggs. This code indicates that the eggs came from house 23 of the Pickin' Chicken farm in Steelford, N.J. This hen house was inspected by the Department of Agriculture. Chicken tissue cultures obtained during the inspection grew Salmonella enteriditis.
Human Microbiology
One hundred stool samples were submitted to the state laboratory as of 4/30/05. Many of the specimens were duplicates. Stools from thirty-six individual employees were positive for Salmonella enteriditis at least once.
DISCUSSION
In this outbreak, the epidemic curve suggests a common source outbreak.
The epidemiologic evidence strongly points to the mashed potatoes as the vehicle of infection.
In addition, Salmonella enteriditis was found in two samples of mashed potatoes as well as in the stools of ill individuals. The mashed potatoes were made with raw eggs. The veal patties were also made with raw eggs, grew Salmonella enteriditis and may have been responsible for some of the illnesses. The fact that the veal was cooked at 350 degrees for 30 minutes could explain the difficulty in isolating Salmonella. Raw eggs have been linked to numerous other Salmonella enteriditis outbreaks in the northeast.
CONTROL MEASURES
1. All food handlers with symptoms of gastroenteritis were excluded from work until they were cultured for Salmonella on three occasions and were negative.
2. All food handlers were cultured for Salmonella and those whose stools were Salmonella positive were excluded from work.
3. Raw eggs were not permitted to be used in uncooked products.
OUTCOME
No additional cases were reported to either the state or local health departments from patrons of the ABC Restaurant.