NUFS 427: Lecture 20 - Food Safety Surveillance

What is surveillance in public health?

Ongoing, systematic collection, analysis, interpretation, and sharing of health data to identify changes and guide action.

Why is surveillance described as "information for action"?

Collecting data alone does not protect health. Information must reach decision-makers so they can respond to risks.

What are the three main components of veterinary surveillance?

Detection and analysis, information production and communication, and response.

Why is communication an essential part of surveillance?

Results must reach people responsible for taking action. Otherwise, even accurate disease data have limited value.

How does surveillance help estimate disease burden?

It tracks cases, hospitalizations, deaths, and disease patterns to show how strongly a population is affected.

How does surveillance help identify the distribution of a disease?

It shows where, when, and in whom disease occurs, helping identify affected populations and areas.

How can surveillance generate new research questions?

Unexpected trends or patterns suggest possible causes or risk factors that researchers can investigate.

Why is early detection a major goal of surveillance?

Detecting disease changes early allows faster intervention, limiting transmission and potential harm.

How can animal disease surveillance support international trade?

Surveillance can provide evidence of freedom from disease, helping countries meet market access requirements.

What are two ways to classify surveillance data collection?

By collection method (active versus passive) and by population or approach (human, animal, environmental, sentinel, targeted, or syndromic).

What is passive surveillance?

A system that relies on healthcare workers, veterinarians, or others to report detected cases rather than actively searching for them.

Does legally required disease reporting count as passive surveillance?

Yes. Even mandatory reporting is passive when authorities depend on others to detect and submit cases.

What are the main advantages of passive surveillance?

It is relatively simple and inexpensive and can cover large populations using existing reporting systems.

What are the major limitations of passive surveillance?

Under-reporting, reporting delays, incomplete information, and variable data quality.

Why can passive surveillance underestimate disease incidence?

Not every infected person seeks care, receives testing, or has their case reported, so many infections are missed.

What is active surveillance?

An organized system that actively searches for disease using a defined sampling strategy and target population.

Why does active surveillance usually provide more complete data?

It does not depend only on spontaneous reports; investigators deliberately collect information from the population.

What are the main disadvantages of active surveillance?

It requires more money, personnel, and time because data collection and testing must be organized.

When is active surveillance preferred over passive surveillance?

When more complete, higher-quality data or a better estimate of true disease incidence is needed.

A province routinely samples poultry farms for Salmonella. Is this active or passive surveillance, and why?

Active, because officials use planned sampling to look for infection rather than waiting for reports.

A physician reports a diagnosed Salmonella infection to public health. Is this active or passive surveillance?

Passive, because public health receives the reported case instead of actively searching for it.

What is the National Enteric Surveillance Program (NESP)?

A Canadian surveillance program that monitors reported enteric pathogens such as Salmonella, Campylobacter, Shigella, and STEC.

Why is monitoring several enteric pathogens useful?

It helps identify changes in different gastrointestinal infections and supports comparison of their public health burdens.

What is FoodNet Canada?

A national integrated food safety surveillance program using sentinel sites to study enteric illness and possible sources of infection.

What is a sentinel site in FoodNet Canada?

A selected geographic region where detailed surveillance data are collected to help understand disease patterns in a broader population.

Why does FoodNet Canada use urban-rural sentinel sites?

They allow surveillance of people, agricultural environments, food, and water to investigate different possible sources of enteric infection.

Why are sentinel sites located in different Canadian regions?

Geographic variation helps capture different agricultural, environmental, and disease patterns and improves broader relevance.

Which four regional sentinel sites are shown in the lecture?

BC Fraser Health, Alberta Calgary/Central zones, Ontario Middlesex-London, and Quebec Montérégie.

What is the role of PHAC's FoodNet Central in the sentinel-site framework?

It coordinates and integrates surveillance information gathered from the regional sentinel sites.

What are FoodNet Canada's four major surveillance components?

Human illness, retail food, on-farm animals, and environmental water.

Why does FoodNet Canada collect information from humans, food, farms, and water?

Comparing these sources helps identify where enteric pathogens occur and investigate possible routes of transmission to humans.

How does FoodNet Canada collect human surveillance information?

It gathers reportable human cases and enhanced risk-factor information through standardized questionnaires and laboratory testing.

How does FoodNet Canada collect retail food surveillance data?

By regularly sampling products such as chicken breasts, pork chops, ground beef, lettuce, and berries from grocery stores.

How does FoodNet Canada collect farm surveillance data?

Through manure sampling on beef, dairy, swine, and poultry farms, supported by farm questionnaires and laboratory testing.

What information is collected during FoodNet Canada's water surveillance?

Surface-water samples are tested for pathogens and physical water parameters.

Why are standardized questionnaires useful in human surveillance?

They collect comparable exposure and risk-factor information across cases, helping identify patterns associated with infection.

Why are harmonized laboratory methods important to FoodNet Canada?

They make results from different sites and surveillance components more comparable.

What types of pathogens does FoodNet Canada monitor?

Bacteria, parasites, and viruses, including Salmonella, Campylobacter, STEC, Giardia, Cryptosporidium, and norovirus.

Why does FoodNet Canada perform enhanced microbial subtyping?

To distinguish isolates more precisely and help compare pathogens found in human, food, farm, and water samples.

What is source attribution in food safety surveillance?

Estimating how much human illness from a pathogen is associated with particular reservoirs and transmission routes.

How does source attribution differ from real-time outbreak detection?

Source attribution estimates where disease burden originates; real-time outbreak detection aims to identify new outbreaks quickly.

What is the difference between a host reservoir and a transmission vehicle?

A reservoir maintains or carries a pathogen, while a vehicle is the route or material that transmits it to humans.

What are examples of reservoirs and transmission routes for enteric pathogens?

Reservoirs include food animals, pets, and wildlife. Routes include foodborne, waterborne, animal-to-person, and person-to-person transmission.

What disease outcomes can source attribution estimate?

Numbers of human cases, hospitalizations, deaths, and related economic costs associated with different sources.

Why is source attribution valuable for food safety policy?

It identifies important sources of illness so prevention efforts and resources can target the greatest disease burden.

What are the six source-attribution methods listed in the lecture?

Microbial subtyping, comparative exposure assessment, outbreak analysis, case-control studies, intervention studies, and expert elicitation.

How can microbial subtyping help with source attribution?

Comparing pathogen types from human cases and potential sources provides evidence about possible origins of infection.

How can outbreak investigations contribute to source attribution?

Outbreak data link illnesses with suspected exposures, helping estimate which sources contribute to disease.

What is QMRA, and how can it help source attribution?

Quantitative Microbial Risk Assessment uses data and models to estimate infection risks from particular microbial exposures.

What is syndromic surveillance?

Near-real-time monitoring of symptoms or related indicators, often using automated data and alerts, to detect possible outbreaks early.

How does syndromic surveillance differ from traditional case reporting?

It can identify unusual symptoms or indicators before laboratory-confirmed cases are formally reported.

What are examples of syndromic surveillance indicators?

Over-the-counter diarrhea medication sales, social media illness reports, and wastewater surveillance signals.

What is ARTSSN?

The Alberta Real-Time Syndromic Surveillance Network, an example of monitoring health indicators for early warning.

What is targeted surveillance?

Surveillance focused on a selected population or group considered more likely to have the disease of interest.

How does Canada's BSE surveillance program demonstrate targeted surveillance?

It focuses on higher-risk cattle, such as down, diseased, dying, or distressed animals, rather than sampling all cattle equally.

What clinical signs can make cattle relevant for targeted BSE surveillance?

Signs include poor coordination, trembling, unusual sensitivity, abnormal behavior, and loss of body condition despite appetite.

Why is targeted surveillance efficient for rare diseases such as BSE?

Testing higher-risk animals improves the chance of detecting disease without testing every animal.

What is sentinel surveillance in animal health?

Monitoring a selected population that can provide early warning of disease risk in another population.

Give two animal-related examples of sentinel surveillance.

Chickens monitored for West Nile virus and ticks monitored for Lyme disease risk.

How does sentinel surveillance differ from targeted surveillance?

Sentinel surveillance uses an indicator population to monitor wider risk; targeted surveillance focuses testing on a selected high-risk group.

What does NTS stand for?

Non-typhoidal Salmonella, the group of Salmonella infections discussed in the lecture, including Salmonella Enteritidis.

Why is Salmonella Enteritidis (SE) important in Canadian food safety?

It was the most frequently reported non-typhoidal Salmonella serotype in the lecture's Canadian surveillance data.

What proportion of Canadian NTS cases were SE in 2015 and 2016?

Approximately 42% in 2015 and 44% in 2016, according to the historical NESP data shown.

What is the typical incubation period for Salmonella Enteritidis infection?

Approximately 6-72 hours after exposure.

What are the common symptoms of Salmonella Enteritidis infection?

Diarrhea, abdominal cramps, fever, chills, nausea, vomiting, and headache.

How long does typical Salmonella Enteritidis illness last?

Usually 4-7 days, although infected individuals may remain infectious for several weeks.

What are two important complications of Salmonella Enteritidis infection?

Systemic infection and reactive arthritis, also called Reiter's syndrome.

What are the major possible sources of Salmonella Enteritidis infection?

Infected animals or people, contaminated food or surfaces, pet food or treats, and contaminated water.

Which foods are identified as high risk for Salmonella Enteritidis or salmonellosis?

Eggs, undercooked poultry, pork, ground beef, raw-egg products, unpasteurized dairy, and contaminated produce or juice.

Why are eggs and poultry especially important when discussing SE control?

They are highlighted as important high-risk foods, making poultry production a major target for SE surveillance.

To whom is human salmonellosis reported in Alberta?

The regional Medical Officer of Health.

To whom must Salmonella Enteritidis in Alberta poultry be reported?

The Chief Provincial Veterinarian.

Which two major Alberta poultry surveillance programs are discussed?

The Poultry Health Program and the Egg Farmers of Alberta surveillance program.

How can poultry Salmonella surveillance involve both federal and provincial authorities?

Federal regulations establish some requirements, while provincial authorities administer programs, collect samples, and conduct testing.

What is the Poultry Health Program?

A federally regulated hatchery supply-flock program administered provincially to monitor poultry health and support interprovincial trade.

Why must federally registered hatcheries register hatching egg supply flocks in Alberta?

Registration supports the approval system required to sell day-old chicks and hatching eggs across Canada.

Which two points in the poultry supply chain are monitored by the Poultry Health Program?

Breeder farms and hatcheries.

Why monitor breeder farms and hatcheries instead of only finished poultry products?

Surveillance at these earlier supply-chain stages helps identify infection before birds or eggs move farther through production.

What is Alberta's role in administering the Poultry Health Program?

Registering replacement breeder flocks, carrying out some sampling, and providing microbiological testing through the provincial laboratory.

What sample types are collected under the Poultry Health Program?

Replacement chicks, chick pads or liners, early chick mortalities, first-hatch culls, fluff, and litter.

Why are environmental samples such as chick fluff and litter useful in poultry surveillance?

They can provide evidence of pathogen contamination in the production environment without relying only on testing individual birds.

What is the Egg Farmers of Alberta (EFA) surveillance program?

An industry surveillance program involving Alberta agricultural authorities to monitor layer flocks, including for SE.

How many times is each layer flock sampled under the EFA program?

Three times: once as pullets before 19 weeks and twice as layers before 52 weeks.

Who collects and tests samples for the EFA program?

Trained EFA staff, sometimes Alberta government staff, collect samples; the Alberta government laboratory performs testing.

Why are the Poultry Health Program and EFA program classified as active surveillance?

Both deliberately collect samples from defined poultry populations using planned monitoring procedures.

What is PIEX, and what is its role in poultry health?

A poultry industry insurance and risk-management organization that provides protection such as business-interruption coverage after specified disease detections.

What happens when SE is detected in an Alberta layer flock under the response plan shown?

The case is reported to the Chief Provincial Veterinarian, followed by investigation, industry coordination, quarantine, flock destruction, and potential insurance payout.

Why can an SE-positive poultry flock trigger major economic consequences?

Quarantine and flock destruction interrupt production and create financial losses, making insurance and risk management important.

Why is human Salmonella surveillance in Alberta considered passive?

Healthcare cases are reported to public health rather than being identified through systematic population-wide active sampling.

How does human Salmonella information move from provincial to national surveillance?

Cases are reported to provincial health authorities, and provincial surveillance data are then reported and integrated nationally.

Why is provincial surveillance essential to national enteric surveillance?

Much of the initial case detection, reporting, and laboratory information is generated provincially before being combined at the federal level.

How do provincial and federal human surveillance laboratory roles differ?

Provincial laboratories are often the first line for detecting outbreaks; federal reference laboratories provide confirmation, specialized testing, and support.

What is PulseNet Canada, and why is it relevant to federal surveillance?

A national laboratory surveillance network that supports comparison of foodborne pathogen isolates and investigation of linked cases.

Why do provinces generally lead human outbreak responses?

Healthcare is a provincial responsibility, so provincial public health authorities handle local investigation and response.

What is PHAC's role when a foodborne outbreak involves multiple jurisdictions?

PHAC supports coordination and collaboration across jurisdictions, including through the Foodborne Illness Outbreak Response Protocol (FIORP).

Why is responsibility for animal disease outbreaks shared between provinces and the federal government?

Responsibility depends on whether the disease is federally or provincially reportable and whether facilities fall under federal or provincial oversight.

How do provincial and federal animal-health laboratory resources differ in the lecture?

Alberta has limited provincial animal-health laboratory capacity, while federal laboratories focus particularly on federally reportable animal diseases.

What is the CFIA's National Chemical Residue Monitoring Program?

An active surveillance program that tests food for veterinary drug residues, pesticides, metals, and other chemical contaminants.

How do antimicrobial drug residues differ from antimicrobial resistance (AMR)?

Residues are remaining drug chemicals in food; AMR is the ability of microorganisms to resist antimicrobial treatment.

Why are veterinary drug withdrawal periods important for meat safety?

They allow drug residues to decrease before slaughter, helping prevent unacceptable residues in food.