9.5. Foodborne Outbreak

Updated 2 October 2025

Title: Standard Operating Procedure for the Surveillance of Foodborne Outbreak

Effective Date: [Date]

Version: 1.0

Prepared by: [Name/Department]

Approved by: [Name/Department]

Status	Definition
A	Tested / reflects current policy and updates
B	Possible gaps / may not reflect latest policies and updates / users need to apply due diligence
C	Outline / being updated / users should cross reference other materials (job aids, training resources)
D	Draft / consider as being under development
E	Work in progress / template created

FOODBORNE ILLNESS OUTBREAK

Internationally notifiable:	No
Reporting interval:	Immediately
Report to (country level):	National Epidemiologist
Report to (regional level):	CARPHA’s Epidemiology Division / PAHO Barbados / ECC Office

Overview

Foodborne illnesses include, but are not limited to, foodborne intoxications and foodborne infections acquired by the consumption of bacteria in contaminated food, or drink. Other causes of foodborne illness which are not covered in this manual include chemical contaminants such as heavy metals, pesticides; organic poisons found for example in ackee, cassava, mushroom or fish – ciguatoxin mainly in large reef fish; viruses and parasitic or protozoal infections.

Epidemics of foodborne illness may be explosive or gradual depending on the causative agent, hygienic practices, and environmental factors. Minor epidemics are sometimes unrecognized depending on severity of illness, or surveillance sensitivity level (in which clusters of illness which may be related to a common source are unreported and therefore not epidemiologically linked). Signs and symptoms and the incubation period depend upon the aetiologic agent.

Surveillance Procedures:

Step 1: Case Detection and Reporting – Healthcare Providers / Laboratory Personnel

Immediately report all suspected cases. Reports should be shared with laboratory personnel for confirmation.

Case Definition

Probable case - An event in which two or more people experience a similar illness, after ingestion of a common food or drink and epidemiologic analysis implicates the food or drink as the source of the illness.
Confirmed case - A confirmed case is a probable case with laboratory confirmation. Criteria depend upon the aetiologic agent.

Note: One case of botulism or chemical poisoning linked to food constitutes an outbreak.

Table 1. Clinical Aspects of Some Foodborne Illnesses

Agent	Incubation period	Signs and Symptoms	Transmission	Disease confirmation
Entamoeba histolytica	24 – 72 hours up to 1 – 4 weeks	Lower abdominal pain, frequent diarrhoea that is often bloody. Duration: weeks to several months	Contaminated water, uncooked food or food contaminated by an ill food handler after cooking	Demonstration of cysts and parasites in stool; ideally 3 samples should be collected. Serology may be helpful in long-term infections.
Bacillus cereus	10 – 16 hours	Nausea, vomiting, diarrhoea, abdominal cramps. Duration: 24 to 48 hours.	Inadequately cooked or stored seafood, especially rice, meats stews, gravies and vanilla sauce.	Isolation of organism from stool OR Isolation of 105 organisms/g from epidemiologically implicated food, provided specimen is properly handled
Brucella	5 days to 6 months	Fever, headache, chills, joint pains, weakness, weight loss, enlarged spleen	Undercooked meats, dairy products	Isolation of organism in culture of blood or bone marrow. Greater than fourfold increase in standard agglutination titre (SAT) over several weeks, or single SAT 1:160 in person who has compatible clinical symptoms and history of exposure
Campylobacter jejuni	2 – 10 days but usually 2 – 5 days	Diarrhoea (may be bloody), abdominal cramps, nausea, vomiting, fever and malaise	Contaminated water, raw and undercooked poultry, unpasteurized milk	Isolation of organism from clinical specimens or from epidemiologically implicated food
Ciguatera toxin	2 – 6 hours	Nausea, vomiting, abdominal pain and diarrhoea Paraesthesia, pain, reversal of sensation of hot and cold, weakness and pain. 2 – 5 days later: Bradycardia, hypotension, T wave abnormalities. Duration: weeks to months	Reef fish such as barracuda, red snapper, grouper, etc.	A consistent clinical history, Identification of ciguatera toxin in fish by radioassay.
Clostridium botulinum	2 hours-8 days; usually 12-48 hours	Vomiting, diarrhoea, blurred vision, double vision, difficulty in swallowing, muscle weakness. Can result in respiratory failure and death	Improperly canned foods, especially home canned vegetables, fermented fish, baked potatoes in aluminium foil Grows in anaerobic foods and produces toxin	Detection of botulinum toxin in serum, stool, gastric contents, or implicated food OR Isolation of organism from stool or intestine
Clostridium perfringens	8 – 16 hours	Abrupt onset, intense abdominal cramps, nausea, vomiting, diarrhoea Duration: usually 24hrs	Inadequately cooked or stored foods. Meats, poultry, gravy, dried or precooked foods, time and/or temperature-abused foods	Isolation of 106 organisms/g from stool or demonstration of enterotoxin in the stool of ill persons, or isolation of 105 organisms/g from epidemiologically implicated food, provided specimen is properly handled
Cryptosporidium spp.	2-28 days; median: 7 days	Watery diarrhoea, abdominal cramps, nausea, vomiting, slight fever	Contaminated water, uncooked food or food contaminated by an ill food handler after cooking	Demonstration of oocysts in stool or in small-bowel biopsy of ill persons, or demonstration of organism in epidemiologically implicated food
i– Enterotoxigenic (ETEC) (common cause of “traveller’s diarrhoea”)	6 – 48 hours	Abdominal cramps, watery diarrhoea, nausea and vomiting Duration: 3 days to a week	Contaminated food and water	Isolation of organism of the same serotype, demonstrated to produce heat-stable (ST) and/or heat-labile (LT) enterotoxin, from stool of ill person
Escherichia coli Enterohemorrhagic (E. coli O157:H7 and others)	1-10 days; usually 3-4 days	Diarrhoea (often bloody), abdominal cramps, vomiting, Little or no fever. E. coli 0157: H7 produces toxin — may cause haemorrhagic colitis Duration: 5 – 10 days	Contaminated water, undercooked beef (especially hamburger), unpasteurized milk and juice, raw fruits and vegetables (e.g. sprouts)	Isolation of E. coli O157:H7 or other Shiga-like toxin-producing E. coli from clinical specimen from ill persons or from epidemiologically implicated food
Giardia intestinalis	3-25 days; median: 7 days	Diarrhoea, gas and bloating, abdominal cramps, nausea, fatigue	Contaminated food and water	Demonstration of the parasite in stool or small-bowel biopsy specimen of ill persons
Hepatitis A	15-50 days; median: 28 days	Fever, anorexia, nausea, vomiting, diarrhoea, muscle aches, jaundice, dark urine, fatigue	Contaminated food (e.g. shellfish and salads) and water	Detection of immunoglobulin M antibody to hepatitis A virus (IgM anti-HAV) in serum from persons who consumed epidemiologically implicated food
Listeria monocytogenes – Invasive disease	9-48 hours for GI symptoms, 2-6 weeks for invasive disease	Fever, muscle aches, nausea, diarrhoea, abdominal cramps. Pregnant women may have mild flu-like illness, and infection can lead to premature delivery or stillbirth. The elderly or immunocompromised patients may develop bacteraemia or meningitis	Dairy products such as unpasteurized milk, soft cheeses made with unpasteurized milk, also, ready-to-eat deli meats	Isolation of the organism from a normally sterile site, or from stool of ill persons exposed to food that is epidemiologically implicated or from which organism of the same serotype has been isolated
Norovirus	12 – 48 hours	Nausea, vomiting, diarrhoea, abdominal cramps, fever, headache. Diarrhoea is more prevalent in adults, vomiting more common in children Duration: 12 – 60 hrs.	Contaminated water, raw produce, uncooked foods and cooked foods that are not reheated after contact with an infected food handler; shellfish from contaminated waters	Detection of viral RNA in bulk stool or vomitus specimens by RT-PCR, or stools positive by commercial enzyme immunoassay (EIA)
Salmonella spp.	6 – 48 hours	Diarrhoea, low grade fever, vomiting, abdominal cramps Duration: 4 – 7 days	Contaminated water, eggs, poultry, meat, cheese, unpasteurized milk or juice, contaminated raw fruits and vegetables	Isolation of organism of the same serotype from clinical specimens from ill persons or from epidemiologically implicated food
Shigella spp.	12 hours to 6 days; usually 2-4 days	Diarrhoea (often bloody), nausea, vomiting, abdominal cramps, fever Duration: 4 – 7 days	Contaminated water, raw produce, uncooked foods and cooked foods that are not reheated after contact with an infected food handler	Isolation of organism of the same serotype from clinical specimens from ill persons or from epidemiologically implicated food
Staphylococcus aureus	30 min-8 hrs; usually 2-4 hours	Abrupt onset of nausea, abdominal cramp, vomiting, diarrhoea. Fever may or may not be present Duration: 24 – 48 hrs.	Inadequately cooked or unrefrigerated or improperly refrigerated foods; pastries, cream, processed foods, meats, potato and egg salads,	Isolation of organism of the same phage type from stool or vomitus of ill persons, or detection of enterotoxin in epidemiologically implicated food, or Isolation of 105 organisms/g from epidemiologically implicated food, provided the specimen is properly handled.
Vibrio parahaemolyticus	6 – 96 hours	Watery diarrhoea (occasionally bloody), abdominal cramps, nausea, vomiting, fever Duration: 2 – 5 days	Inadequately cooked or raw seafood especially e.g. shellfish such as crabs, or food exposed to contaminated seawater	Isolation of Kanagawa-positive organism from stool of ill persons or Isolation of 105 Kanagawa-positive organisms/g from epidemiologically implicated food, provided the specimen is properly handled

Adapted from US “FDA Foodborne illness-causing organisms in the US” (FDA, n.d.) and CDC “Guidelines for Confirming Cause of Foodborne Disease Outbreaks” (CDC, 2015)

Step 2. Laboratory Confirmation

Samples should be taken to the labs to be tested (collection and transport details below)

Laboratory diagnosis

Specimen Collection and Transport:

Stool and/or vomitus: Collect in a clean, dry container and transport at 4°C within 24 hours.
Rectal Swabs (Only to be used if stool is not available): Place in Cary-Blair transport medium and transport at 4°C within 24 hours.
Leftover foods or other foods: Samples should be collected aseptically and put into sterile jars or plastic bags. Perishable food which are not frozen at the time of collection should be rapidly chilled to 4°C and kept at this temperature until examined. (Do not freeze these samples as certain bacteria such as C. perfringens die off rapidly during frozen storage. Keep frozen foods frozen until examined.

The laboratory should be alerted, and all samples should be received at the laboratory within the shortest possible time.

Laboratory confirmation

Isolation of the causative organism from clinical specimens and from food samples.

Step 3: Treatment

Use current guidelines (international / national)

Step 4: Reporting

Reports of all confirmed cases should be shared with the Epidemiology Unit

Note: Syndromic Surveillance

Foodborne diseases are reported under the Acute Gastroenteritis syndrome.
Outbreaks of acute gastroenteritis are facilitated in congregate settings such as nursing homes, schools and day care centres, and in social events.

Step 5: Data Management (Epi Unit)

Data should be cleaned and analysed
Preparation of a report should be done on the evolution of the epidemiological situation of the disease
Dissemination of a weekly situation report

Notes:

Environmental Health

The training of food handlers and inspection of food establishments are important public health activities to prevent foodborne disease outbreaks. Lack of potable water and poor hygiene and sanitation standards favour the spread of foodborne diseases.
See control and prevention
Collect environmental samples for investigation as appropriate
- Left over foods
- Ice
- Eggs
- Other Raw ingredients

Traveller’s Health

The main cause of travel related illness is traveller’s diarrhoea. It usually starts on average 3 days to 5 days into travel but can extend to 2 weeks. Traveller’s diarrhoea is usually a self-limited illness, lasting between 1 – 5 days. The consumption of contaminated food or water is generally the cause (4). Although many organisms may cause traveller’s diarrhoea, enterotoxigenic E. coli is the most significant.
Congregate facilities such as hotels and cruise ships are important settings for foodborne disease outbreaks.
The food and beverage industry are central elements of tourism. Ensuring the safety of meals prepared is important to prevent guests from falling sick. However, the prevention of foodborne diseases is an effort that starts from the farm to the plate and controls at all stages are required for the process to be effective.

Control and Prevention

Food hygiene is defined as “all conditions and measures necessary to ensure the safety and suitability of food at all stages of the food chain.” The microbiologic safety of foods is principally ensured by control at the source, product design, process control, and good hygienic practices during production, processing, handling, distribution, storage, sale, preparation and use. The application of the Hazard Analysis and Critical Control Points (HACCP) system is now an integral component of food hygiene programs. Hazard analysis is defined as “The process of collecting and evaluating information on hazards and conditions leading to their presence to decide which are significant for food safety.” This preventive system offers more control than end product testing because of the limited effectiveness of microbiologic examination to assess the safety of food. HACCP can be used as a corrective risk management option: a risk is identified, and a management option is selected and implemented. HACCP is also used as a preventive risk management tool. In this case, hazard analysis identifies potential hazards in raw materials, production line, and line-environments to the consumer.

Control and prevention of food borne illnesses, regardless of the specific cause, are based on principles directed towards the avoidance of food contamination, destruction or denaturation of contaminants and the prevention of spread or multiplication of contaminants.

Basic food safety practices include the following:

Choose foods processed to ensure safety.
Cook food thoroughly.
Eat cooked foods immediately.
Store cooked foods carefully.
Reheat cooked foods thoroughly.
Avoid contact between raw and cooked foods.
Wash hands repeatedly.
Keep all kitchen surfaces meticulously clean
Protect food from insects, rodents and other animals.
Use safe water.

Some areas of specific action include the following:

Educate food handlers in strict food hygiene, sanitation and cleanliness of kitchens, proper temperature control, handwashing, cleaning of fingernails; and to the danger of working with exposed skin, nose and eye infections and the need to cover wounds.
Reduce food-handling time (preparation to service) to an absolute minimum, with no more than 4 hours at ambient temperatures.
Keep hot foods hot (> 60°C) and cold foods cold (< 10°C).
Temporarily exclude people with boils, abscesses and other purulent lesions of hands, face or nose from food handling.
Seafood:
- ensure that cooked seafood reaches a temperature of at least 70°C for at least 15 minutes.
- handle cooked seafood in a manner that prevents contamination with raw seafood or contaminated sea water.
- keep all seafood, raw and cooked, adequately refrigerated before eating.
- avoid the use of sea water in food handling areas.
Refrigerate leftover foods promptly and reheat rapidly and thoroughly before use.