Outbreak Investigation and Surveillance Methods

Outbreak Investigation

• Laboratory tests involve culture, toxin studies, and microscopic examination to detect pathogens and toxins
• Specimens can be from people or samples from suspected foods, surfaces, etc.

Surveillance

• National Enteric Surveillance Program (NESP) monitors laboratory-confirmed cases of specific enteric pathogens
• Canadian Notifiable Disease Surveillance System collects data on outbreaks involving multiple diseases
• FoodNet Canada has 3 sentinel sites collecting comprehensive data from public health, labs, farms, retail food, and drinking water
• PulseNet Canada is a network of labs reporting "fingerprint" data (PFGE patterns) of specimens submitted

Nationally Reportable Foodborne & Waterborne Diseases

• List of diseases includes Brucella spp., Hepatitis A, Campylobacter spp., Salmonella spp., Clostridium botulinum, and others

Host Defenses

• Enzymes within the body, such as hydrolases (pepsins) and lysozyme, can digest and denature pathogen proteins
• Weakened host defenses, such as damaged GI cells, can increase the risk of infection

Incidence of Food-borne and Waterborne Diseases

• Estimated 1 in 8 Canadians (4 million people) develop a domestically acquired illness each year
• Most illnesses are mild and resolve in 1-2 days
• Most are thought to be acquired in the home

Symptoms

• Severe diarrhea is characterized by fever, bloody stools, and systemic illness
• Greater than 6 diarrheal episodes/day for more than 5 days

Diagnosis & Laboratory Tests

• Most clinical guidelines advise against routine stool culture/testing due to cost and potential false-negative results
• Indications for testing include severe diarrhea, mild-moderate diarrhea lasting more than 5 days, and certain high-risk groups

Foodborne Diseases

• Defined as a wide spectrum of illnesses caused by consumption of foods contaminated with microorganisms or other chemicals
• Contamination can occur at any point in food production: "Farm to fork"
• Most common symptoms are gastrointestinal (e.g., abdominal pain/cramps, diarrhea, nausea, vomiting)

Waterborne Diseases

• Defined as a wide spectrum of illnesses caused by consumption of contaminated water
• Contamination can occur at any point in water system: "Source to tap"
• Overlap with foodborne diseases, as many enteric illnesses are transmitted through contaminated food or water

Explore methods used in outbreak investigations and surveillance, such as laboratory tests, culture techniques, toxin studies, microscopic examinations, and national surveillance programs like the National Enteric Surveillance Program (NESP) and Canadian Notifiable Disease Surveillance. Learn how specimens are tested from individuals and various sources to identify pathogens.