To include foodborne illness in the passive surveillance system, the following steps have to occur: A person becomes ill, and the patient must go to a doctor. The doctor must request specimens for analysis. The laboratory must analyze the specimen, the positive results must be reported to the health department, and the reports must be forwarded to the CDC. (Editor's comment: Some reporting systems do not require lab confirmation. Also, some states require that clinically diagnosed ailments be reported, even when laboratory confirmation is not available.) Some labs can test for a variety of microorganisms and use biomolecular typing to determine whether isolates are related to the same outbreak. Usually, tests for toxins, viruses, and parasites are run only if specifically ordered. Other labs have a more limited capacity and can run only routine tests.

Another example of passive surveillance is when someone becomes ill after eating at a restaurant and then complains to the health department. People who are concerned enough to take the time to file a report to a surveillance program want assurance that the appropriate person will be notified and that immediate action will be taken. Surveillance programs should be organized to receive and respond to complaints. The process for reporting should be quick and traceable to ensure that the appropriate person is informed regardless of the point of the first contact. The surveillance system should be "triage-oriented" (respond differently depending upon the circumstances) and should be able to proceed smoothly from one level of action to the next.

The surveillance system should have a referral process that ensures a timely and competent public health response. And finally, the system must be able to terminate effectively when resolution is reached and have a mechanism for feedback notification. If you try to analyze calls and complaints on an individual basis, it's difficult to determine the source of an exposure. That's where the surveillance log comes in. A surveillance log is simply a record of illness complaints.

Basic information in surveillance log:

Part of surveillance is being prepared for emergencies because we all know, sooner or later, you'll have an outbreak. Being prepared for an outbreak includes having your equipment and team ready to go. The investigation will go a lot smoother if you have the necessary equipment, documentation forms, and sampling kits ready for use when you need them. In this module we're going to talk about developing an equipment checklist and collecting the necessary supplies so you can be ready to go at a moment's notice.

Make sure that you have your aseptic sampling equipment all set to go. An important point to remember is some sterile equipment and supplies have a limited shelf life, so pay attention to expiration dates. Talk with the laboratory and develop replacement schedules for supplies. Restock supplies as they are used up or exceed the expiration date. Sample integrity can be questioned if improper equipment or out-of-date supplies are used to collect the sample.

By following proper sample collection procedures, you will ensure that any microbial contamination found during analysis did not come from the sampling equipment. After all, it's better to be part of the solution than part of the problem! Sampling guidelines will identify the equipment used for collecting various samples. You can use the guidelines for organizing the outbreak equipment.

Food and environmental samples are collected primarily to identify or verify the agent. In other words, if your suspect pathogens are, let's say, Campy or Salmonella or Shigella, your environmental samples are taken to prove your suspicions. There is an extensive list of forms and equipment in the course manual.

Having the necessary equipment to perform the inspection and aseptically collect samples is important. If improper equipment is used to collect samples, then sample integrity will be questioned and samples will be meaningless. The following is a suggested equipment checklist. The list should be modified depending on product and inspection requirements.

How your team is formed with the breakdown of roles and responsibilities will depend upon how it works best for you. For example, not every jurisdiction has an epidemiologist, but every state has one. Many teams will have to establish protocols in consultation with their state epidemiologist, lab, and nurses and others. Someone has to be the leader and central hub for the flow of information and open the lines of communication. The position of team leader is not necessarily a supervisory role. Typically the team leader may not have direct authority over the individuals comprising the team. The members should view the arrangement as a temporary job matrix during the outbreak where team members provide input, perform specialty functions, and report findings to the team leader. At the conclusion of the investigation, individuals return to their routine assignments.

The team atmosphere should be open for consensus building. Encourage constructive input and brainstorming to generate all those wild and sometimes crazy ideas and potential "could be's" or "what if" scenarios in trying to figure out what happened. Also with this process, the pros and cons of a decision can be weighed by the group before its implementation: a kind of check-and-balance process to reduce the chance of error or overlook possibilities that should be considered.

Between outbreaks, team meetings can be regularly scheduled to build rapport within the team and fine-tune procedures. After your next outbreak, evaluate the investigation as a team, keep what worked well, refine what didn't work, and conduct in-house training to enhance skills. Attending seminars keeps staff current and provides opportunities for networking with other agency personnel. It's also a good idea to start a library with information on foodborne illness and keep it current as new and emerging pathogens are reported. Once an outbreak occurs, the team should be prepared to go. Holding daily meetings to review findings and keep everyone up to date is important.

The foodborne illness investigation can be visualized as a three-legged stool. The investigation process has three components: EPI, laboratory, and environmental.

Without all three legs secure, the stool will fall over, toppling the team. Sometimes an outbreak will cross jurisdictional lines and require cooperation between investigation teams on the local, state, and federal levels. For example, in 1997, a Hepatitis-A outbreak in the Midwest involved strawberries served with the school lunch program. What started out as a local outbreak went multistate, and the investigation ended up including many state and federal agencies. When multiple agencies are working on the same outbreak, interagency communication becomes extremely important. Before the next outbreak, identify cooperating agencies, establish two-way communication and coordination procedures with these agencies, and include a contact person, emergency phone and fax numbers, and e-mail addresses.

The success of an investigation comes down to thorough work, notification protocols, and networking. Leaving a department out of the loop can hinder an investigation; besides, it's an exercise in courtesy and diplomacy. Would you rather be questioned on a pending outbreak by the press or informed by a counterpart? Everyone knows the answer to that question. Typically, large outbreaks initiated at the local level progress to the state level.

Depending on the circumstances such as interstate commerce, the size of the outbreak, and the agent involved, federal notification by the state may take place.

If the implicated or suspected food item is meat, poultry, or some egg products from a USDA-regulated plant, then the USDA would be notified through compliance officers in the field or directly into USDA's Consumer Surveillance Information System. Consumer complaints are also received on USDA's Meat and Poultry Hotline. So there are several channels through which information can flow.

Generally speaking, all other food products except domestic meat, poultry, and some egg products in interstate commerce fall under the FDA's jurisdiction. Typically, the state would contact its FDA District Office, and the district office would then notify the Division of Emergency and Investigational Operations in the FDA's headquarters. The district offices and DEIO also receive complaints from the public. If a complaint goes to the wrong agency, both FDA and USDA forward appropriate complaints back and forth and work together in investigations as necessary. Another example of teamwork!

In waterborne and environmental related outbreaks, the state may notify the Environmental Protection Agency (EPA). If there is a potential of contaminated drinking water coming into contact with foods in a processing plant or slaughterhouse, then both FDA and USDA would become involved. An example of interagency cooperation was the Cryptosporidium waterborne outbreak in Milwaukee, Wisconsin.

Depending on the size and nature of the outbreak, the pathogen involved or the need for certain lab tests, CDC can provide expert advice and assistance when requested. All federal agencies network and assist each other and the states, as appropriate, for foodborne illness investigations. The federal, state, and local agencies have developed a network called FORC-G, (pronounced "force-gee") "Foodborne Outbreak Response Coordination - Group." This outbreak evaluation group consists of the heads of various federal, state and local agencies to improve and coordinate the approach to multistate outbreaks. The FORC-G group reviews operations and networking after interstate outbreak investigations to see what worked well and what procedures could be improved or refined to develop standard operating procedures.

Good teamwork and strong communication are vital for resolving foodborne outbreaks. If your department does not already have a foodborne illness investigation team, then develop a plan. If you already have a team, then reevaluate procedures to make sure everything is the way it's supposed to be. Now that we've discussed planning for the investigation, let's move on to beginning the investigation.

Reports of illness can come into the health department piecemeal. When a complaint is received, try to get as much information as possible up front. Trying to establish the relevant facts is difficult enough when you have all the information, but trying to establish the facts when reports are incomplete is next to impossible. To standardize data collection, most departments use a general complaint form to record information.

The booklet entitled Procedures To Investigate Foodborne Illness, published by IAMFES, the International Association Of Milk, Food and Environmental Sanitarians, shows an example of a general illness complaint form.

Categories in illness complaint form include the following:

Start with basic identification information on the caller such as name, address, and phone number for home and work. Additional information may be needed from the caller as the investigation progresses. Plan a follow-up contact. If the caller wants to remain anonymous, tell them it may be difficult to keep in touch as the investigation continues. Attempt to identify additional cases. Ask if the caller knows of anyone else who is ill. If you suspect an outbreak, get information about the event, the exposure, the number affected. Ask for the names of both ill and well individuals who attended the event, and be sure to get telephone numbers of the persons affected. The goal of a case investigation is to get as much relevant information as possible. Timing is important. Each bit of information may lead to more cases or contacts. If you can't get all the information on the first contact, then get the basics on the caller, the illness, and the food operation.

Knowing demographic characteristics allows you to describe the people affected by an outbreak. Some demographic characteristics include, for example, age, gender, occupation, race, and education.

Take time to talk with the caller about their clinical signs and symptoms. Discuss initial impressions and find out how the caller learned about the illness, possible diagnosis and any medical assistance sought, specific symptoms, time of onset, duration of illness. Have they seen a doctor? If yes, who? What was the diagnosis? Were they hospitalized? What tests or samples were done? What were the results? Was any treatment provided? Also ask about chronic conditions, allergies, or medications that could mimic the symptoms of foodborne illness.

Find out if samples were submitted for analysis and if results are available. If samples have not been submitted, you may want to request a sample. A follow-up call to the physician can confirm the information you have, and you may be able to obtain the results of any pending tests.

Let the caller tell you what they believe happened. Then work to obtain the full history. When you're busy, you may not want to spend a lot of time on a single case that could be a dead-end. But you never know. The single report could be the tip of an iceberg. If a second case is identified and verified, you won't want to waste time re-interviewing the initial caller. So when a complaint is received, get as much information as possible up front. Remember, the better the initial information, the more likely your chances of early identification of an outbreak.

For a variety of reasons, when foodborne disease is suspected, information of foods consumed in the 72 hours prior to the onset of symptoms is requested. People have trouble remembering what they have eaten. It's not easy to obtain a food history, but the details contained in the food history are necessary for identifying potential exposures. The 72-hour time frame is used because recall gets very unreliable for foods consumed more than two to three days before an interview. Most people lead fairly routine lives, and a five- to seven-day food history could capture virtually everything they ever ate, increasing the difficulty in implicating a food vehicle. Also, the incubation period for many foodborne pathogens is 72-hours or less. Of course, there are exceptions. The incubation period for Hepatitis-A is 15 to 50 days; E. coli O157:H7 has an incubation of 3 to 8 days; and Trichinosis has an incubation range of 5 to 45 days.

The 72-hour food history should include all meals, snacks, and beverages, including water and ice eaten at commercial operations, as well as in the home. Find out where the foods came from. Were meals prepared on-site or catered, and did food come from outside sources? Ask if they noticed anything unusual about the foods, such as, off taste, texture, color, or odor. Find out if hot foods appeared fully cooked and were served hot and if cold foods were cold. If there is leftover food, give instructions for labeling and storing the food before it is taken to the lab for analysis.

When individuals can't recall the specific foods they ate, see if you can help them out: Ask about their food preferences, what they usually eat and where they have eaten lately. If you can't obtain a full 72-hour history, then try to obtain a facility-specific history. Ask about meals eaten out and then ask about meals eaten at home. A good wrap-up question could be "Is there any other information that may be relevant that you could provide?" Make sure that the caller knows that you may be calling them back if you need additional information. Also ask them to call you if they remember any other information about the event.

Many callers will attribute their illness to the last place they ate and may have already decided what food made them ill. We often assume that illnesses are foodborne in nature, but we need to keep an open mind to the idea that other factors may play a role. You don't want to put all your eggs in one basket. For example: there was a Salmonellosis outbreak, but the investigation did not reveal any food associations. The EPI evidence showed the common item among the cases was marijuana. The lab found the same type of Salmonella in both the marijuana and cases. So remember, the source of illness may not be food-related. Ask the caller if they have done anything unique or different recently. Ask about domestic or international travel and whether they've had contact with ill persons or with animals.

When an illness complaint is received, examine the symptoms, onset times, and the 72-hour food history. Use the food history to see what was consumed prior to onset of symptoms. Try to match up foods, incubation times, and symptoms that could be associated with the possible pathogens. Of course, you should go through this exercise when the caller reports a self-diagnosis and the pathogen and source are unknown. But even if you do have a medical diagnosis with a known pathogen and possible source, play "devil's advocate" and review the data for consistency. (Editor's comment: Make a distinction between an investigation that supports the first plausible explanation you think of and a legitimate investigation. It is bad form to identify a food vehicle and cause of illness based on incubation period and symptoms and then to design an investigation to prove the association.)

For example, say the illness report concerns a person complaining of tingling and burning sensations around the mouth, facial flushing, dizziness, headache, and vomiting about one hour after consuming a large tuna steak. Is this complaint plausible? A review of reference materials would indicate they are plausible. These symptoms and onset time suggests a toxin or chemical poisoning. Specifically, the symptoms and onset are similar to that of scombroid-type poisoning, where histidine is converted to histamine. That type of poisoning is most often associated with fish in the Scombroid family, of which tuna is a member. As a general rule, symptoms of chemical and toxin poisonings occur within one hour of ingestion. But keep in mind that some toxins and poisons can have a longer incubation period.

Here's another situation. Say the illness report concerns a person complaining of only nausea and vomiting. You have a 72-hour food history. What part of the food history would you concentrate on? Look at what was consumed in the six hours prior to onset. Pathogens such as Staphylococcus aureus or the emetic form of Bacillus cereus would be good candidates for this time frame.

Say the illness report concerns a person complaining of only cramps and diarrhea. What incubation times would you expect? In general, for cramps and diarrhea only, look at what was consumed between six and 20 hours prior to symptom onset. Possible suspects may be Clostridium perfringens or the diarrhetic form of Bacillus cereus. If fever and diarrhea are symptoms, consider a possible infection. Illness with fever generally indicates an infection rather than intoxication.

Diarrhea and Fever, 12 to 72 Hours After Eating

Pathogens that infect typically require a longer incubation time to allow the organism to multiply in the body. Look at foods consumed about 12 to 72 hours prior to onset. Keep in mind that these are general rules. They give us a place to start; they're not absolutes.

Decide whether further investigation of a complaint is warranted.

There's a lot to consider here, including the number of cases, the agent, the severity of illness, and how long ago the illness occurred, not to mention the department's policies, investigation criteria, and resources. Determining whether you actually have a foodborne illness outbreak and deciding when to initiate action can be challenging. If you' re investigating a serious illness, the investigation could begin based on a single report. But for a less-serious illness, follow-up may be postponed until additional reports are received. Analysis and interpretation of surveillance data can help identify potential problems. For example, if a decision to follow up is made based on analysis of log entries, the investigator should determine whether an increase has actually occurred and whether the increase can be linked to an obvious common exposure. Evaluate the data to ensure that there is a plausible basis for the potential association and verify the diagnosis. It may be necessary to find more cases, collect more data.

Case report data from the surveillance log can be organized with respect to time, place, and person to find possible associations among cases with the same diagnosis or similar symptoms. For example, when you review reports, trust that "deja-vu" feeling. If individuals experience similar symptoms and onset times, they may have a common association with a particular place or event.

If there appears to be a meal in common that is associated with the illnesses, then the time between ingestion of the agent and the onset time provides the incubation period. The incubation period and symptoms are helpful clues in determining which diseases "could be" or "definitely are not" involved with the illness. Incubation times will vary among cases. That's why incubation periods are given over a range of time. The time frame the investigation team is concerned with is related to the suspected agent's incubation time. For example, let's say several reports of confirmed Salmonellosis were received over the last week and onsets for these cases occurred within 60 hours of each other. It is possible that these cases could share a common source of exposure, because all the onsets fall within one incubation period for Salmonella, typically 12 to 72 hours.

When illness complaints are organized by time, the data may be displayed on a graph. Graphs show visually the relative size and trend of the problem and can be constructed to show daily or seasonal trends or time intervals that span several years. Graphing the data a few different ways will help you decide on the most appropriate and revealing time interval to use. Graphs are very useful for showing past trends and for predicting future trends. They can also provide insights into what may have caused the problem.

Let's say several reports for a cluster of suspected Shigella illnesses were received, and the diarrhea onset times for the ill college students were graphed. The illnesses occurred Saturday, Sunday, and Monday. The typical incubation period for Shigella is between 24 and 72 hours. It is possible that the students shared a common source of exposure, as all of the cases fall within one incubation period. So if they ate any meals together Friday, one or more of the meals could be associated with the illnesses.

Reviewing illness reports with the same diagnosis or similar symptoms and onset times may show a common association with a particular place or event. Association by place refers to the attributes or factors that describe the environment in which the disease occurred, such as geographic location, county, town, food-service facility, business, residence, social event, purchasing food from the same place, or consumption of a specific brand of food. The data can be mapped, graphed, or tabulated to help you gain insight into the geographic extent of the problem.

Analyzing data by place may help you identify the most likely pathogen and may give you insight as to how illness could be spread. If the illness is associated with a particular place, then it's a safe place to start investigating to see whether the risk factors of illness are or were present.

If the students ate a meal together, the place associated with the illness can be determined as well. However, the only information the team may know about the source of illness is that cases are currently occurring over a broad locality such as the state, county, township, or college campus.

Person associations refers the characteristics of ill individuals with similar symptoms or diagnoses of those who were exposed to the agent or suspect agent. Some categories used to group data by person are age group, gender, occupation, immune status, affiliations or group membership, extracurricular activities, or any other unique characteristic. It turns out that personal characteristics sometimes can be used to predict who is at greatest risk of becoming ill from a particular pathogen. You may have to group your data several different ways before deciding on the most appropriate and revealing person-category to use to get a better picture of the situation.

There are times when an outbreak may not be limited to a particular group of people. For example, the students who reported diarrhea may have eaten off campus, and possibly there are other nonstudents out there who may have also become ill. Once the associations for time, place, and person are known, control and prevention methods can be implemented.

Refer the example of the surveillance log. Remember, we had three entries of Hepatitis-A in two weeks with all having some association with the Hillside day-care center. Here, the association by place is easily identified, but sometimes the cases must be interviewed before time, place, and person associations can be identified. The question, "What is the correlation between Hepatitis-A and the day care?" can be answered only with follow-up.

Definition of Foodborne Illness Outbreak