Example of Foodborne Disease Diagnostics

Question 2. Speculate on the patient's potential exposures. Provide four potential exposures (4 points)

The patient's potential exposures include:

Food furnished by the local caterer at the party. Since there were several food items provided by the caterer, there is a likelihood that there was cross-contamination that occurred as a result of mixing certain food items. Also, the preparation and handling of these food items may have been the source of contamination and spread of the foodborne disease.

Home-cooked goodies brought by the parents. The food items which the parents brought may have been contaminated since some of them may not have employed the necessary steps needed in proper handling and preparation of food.

Apples used in the bobbling game. The apples may not have been rinsed properly under running water hence contain some bacteria that can cause foodborne diseases. Also, the apples may have been left unrefrigerated for a long time thereby allowing bacteria to creep in hence contaminating them.

The water utilized in the apple bobbing game. Since everyone playing the game is back-washing into the water, they may be spreading the diseases that they may be having at the time.

Public health units have a legal responsibility for communicable disease control, including investigation of reported cases, so you proceed to collect further information.

Question 3. What would be the next IMMEDIATE steps in your investigation? Provide six next steps and be specific. (6 points)

Verify the diagnosis.

Define the cases.

Determine the population which is at risk.

Describe the epidemiology.

Develop a hypothesis.

Evaluate the hypothesis.

Question 4. You do not yet have laboratory results on the etiologic agent. Which agents (bacteria, viruses, parasites, should you consider in the differential diagnosis of this illness? Fill out the following table. Identify at least four bacteria, one virus, and one parasite (12 points)

Some of the common pathogens that cause foodborne diseases include Bacillus cereus, Clostridium perfringens, Escherichia coli, Shigella spp., Norovirus, and Cryptosporidium spp. (Tauxe, 2002).

Pathogen Incubation Period

Bacterium

Bacillus cereus 1-6 hours

Bacterium

Clostridium perfringens 6-24 hours

Bacterium

Escherichia coli 6-48 hours

Bacterium

Shigella spp. 12 hours 6 days

Virus

Norovirus 12-48 hours

Parasite

Cryptosporidium spp. 2-28 days

Question 5. Why are you hypothesizing potential agents? Provide two important reasons. (2 points)

There are several reasons for hypothesizing potential agents. According to Torok (n.d.), two of the most important reasons are:

The hypothesis will assist in the selection of relevant facts with regard to the problematic situation.

Hypothesizing potential agents provides direction for carrying out research so as to have a better understanding of the problem and its causes.

Ten more patients with onset of diarrhea and vomiting have been reported since October 31, 2016, and it was determined they also attended the Halloween party. On November 4th, the coordinator for the community center informs you over 100 people participated in the party. However, she does not have a list of names. She provides you with a list of the food furnished by the caterer (Appendix 1) and informs that some parents brought home-cooked baked goods (cakes, cookies, cupcakes) for sale to raise funds for the center. All other food was prepared at the caterers food premise (off-site from the community center) and brought to the community center in hot holding and cold holding units. The coordinator confirms that the center has an operational kitchen with working fridges and running water. The food handlers were the caterers, as well as three staff members from the community center. Apples for the apple bobbing station were purchased at the local farmers market, and the water was municipal water from the community centers kitchen faucet. A local farmer provided the horse and carriage. She provides you with the following contact (name/number) information: caterer, a local farmer, kitchen supervisor at the community center, and the parent organizing the baked goods sale. She provides you with the name of the farmers market where she and the caterer purchased some items (Appendix 2).

Question 6. Describe your next steps. Provide eight next steps and be specific. (8 points)

Contacting the persons who had a role in the preparation of the suspected food items and interviewing them. This step is important as it will provide information on how the food was prepared and handled hence be able to determine the possible points at which the food was contaminated.

Reviewing if any individuals were ill during that period. Reviewing the illness of people who were present at the party will allow the health inspector to understand if there was the spread of any disease causing micro-organisms during the apple bobbing game while preparing the food, and during food handling and service.

Assessing the water supply system. A local farmer provided the horse and carriage for the water supply. The farmer may have used this equipment in various activities in the farm which may have resulted in them not being clean hence contaminating the water.

Review the operations and hygiene of the different processes of food preparation. Hygiene is important in preventing foodborne disease. Poor hygiene will result in the spread of disease-causing micro-organisms which will eventually lead to contamination of food items.

Determine the equipment used in the preparation of suspected food items. Apart from fresh and clean food items, the equipment used in food preparation can also contaminate the food. Therefore, determining the cleanliness of this equipment will assist in understanding if they were responsible for the food contamination.

Carry out environmental and food sampling. Sampling will allow determination of the food items that might have resulted in the spread of the diseases. Environmental sampling will look at the immediate environment used in the preparation and serving of food while food sampling will take into consideration the food items that were consumed during the party.

Determining the temperatures to which the foods were exposed. Temperature is critical in preventing food contamination. Certain foods need to be refrigerated if they will not be used for some time. On the other hand, other foods need to be cooked up to a certain temperature so as to prevent contamination by bacteria and other disease-causing microorganisms.

Advising on the samples to take to the laboratory for testing. Certain food items have a higher likelihood of being contaminated if not handled properly hence the need to prioritize the food items that need to be sampled in the laboratory.

Question 7. Based on your hypothesized potential agents and intrinsic/extrinsic factors, what food items might you exclude as possible vehicles? Why? List 4ss food items and provide an explanation (4 points)

Hamburgers might be exempt from possible vehicles since the patties used were well cooked to 710C hence killed most bacteria that might be present.

Vanilla ice-cream is another potential agent that can be excluded since it was refrigerated when bought.

Pork sausages might be excluded because it was purchased from the supermarket and grilled after a short period without adding any extra ingredients to them.

Finally, just like pork sausages, hot dogs might be excluded since they were grilled shortly after being bought from the supermarket without adding any extra ingredients.

Using information obtained from the initial twelve patients you and the outbreak team construct a case definition as follows:

A case is defined as a person who attended the community center Halloween party on October 31st, 2016 and subsequently developed diarrhea and vomiting.

None of the patients had traveled abroad within two weeks before the party. And none of the food handlers reported illness.

You agree to assist in undertaking an epidemiological investigation to test the following hypothesis: People who attended a Halloween party at the Community Centre X on October 31st and subsequently became unwell did so as a result of consuming food served at the Halloween party. You develop a questionnaire to obtain information for descriptive epidemiology and also on food histories.

After active case finding and intensive telephoning, it is established that approximately 100 people attended the barbecue of which 91 can be identified. A questionnaire is successfully administered by telephone to 81/91, a response of 89%. Forty-five of those interviewed met the case definition.

Question 8. Using the line list provided in the Excel spreadsheet (ENH 733 Assmt_Line list), calculate the food-specific attack rates (AR) and relative risks (RR) for each food item. Note in the line list: 0= Not Eaten, 1= Eaten; 2 = Dont know or Not applicable. (15 points)

Food Eaten Food Not Eaten

FOOD Cases Total Attack rate Cases Total Attack rate Relative Risk

HAMBURGER 21 42 0.50 23 39 0. 59 0.85

MACARONI AND CHEESE (with eggs) 30 44 0.68 15 37 0.41 1.66

PORK CHOP 25 43 0.58 20 38 0. 53 1.09

PORK SAUSAGE 19 37 0. 51 26 44 0. 59 0.86

CHICKEN SKEWERS 21 42 0. 50 23 39 0. 59 0.85

HOT DOGS 19 42 0.45 26 39 0.67 0.67

EGG SALAD 26 33 0.79 19 48 0.40 1.98

POTATO SALAD 27 45 0.60 18 36 0. 50 1.20

SPINACH SALAD 18 38 0.47 27 43 0.63 0.75

ORANGE JUICE 23 38 0.61 22 43 0. 51 1.20

WATER 24 46 0. 52 21 35 0.60 0.87

BREAD 27 46 0. 59 18 35 0. 51 1.16

CORN ON THE COB 25 40 0.63 20 41 0.49 1.29

APPLES 25 47 0. 53 20 34 0. 59 0.90

VANILLA ICECREAM 27 47 0. 57 18 34 0. 53 1.08

Question 9. Comment on your results (2 points)

A high relative risk implies that a food item is associated with a disease (Pires et al., 2009). The food items which have h...