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Appendix B -- Guidelines for Confirmation for Foodborne-Disease Outbreaks


Appendix B Guidelines for Confirmation of Foodborne-Disease Outbreaks

A foodborne-disease outbreak (FBDO) is defined as an incident in which two or more persons experience a similar illness resulting from the ingestion of a common food. Before 1992, three exceptions existed to this definition: one case of botulism, chemical, or marine toxin poisoning constituted an FBDO if the etiology for that type of FBDO was confirmed. Since the beginning of 1992, two or more persons must become ill for the incident to be classified as an FBDO.

The following table (Table_1) provides information concerning incubation periods, clinical syndromes, and criteria for confirming the etiology once an FBDO has been identified. The information on incubation periods and clinical syndromes is provided as a guideline and should not be included in the confirmation criteria. These guidelines may not include all etiologic agents and diagnostic tests.

FBDOs should be reported to the Foodborne and Diarrheal Diseases Branch at CDC on form 52.13 (i.e., Investigation of a Foodborne Outbreak). Provision of other documents describing the outbreak investigation also is encouraged. For information regarding collection of laboratory specimens and for additional information on viral agents, refer to other CDC publications (i.e., "Recommendations for Collection of Laboratory Specimens Associated with Outbreaks of Gastroenteritis," MMWR 1990:39{No. RR-14} and "Viral Agents of Gastroenteritis: Public Health Importance and Outbreak Management," MMWR 1990;39{No. RR-5}).




Table_1
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Table B-1. Guidelines for confirmation of foodborne-disease outbreaks
==============================================================================================================================================
Etiologic agent                 Incubation Period       Clinical Syndrome               Confirmation

Bacterial

1. Bacillus

 a. Vomiting toxin              1-6 hrs                 Vomiting, some patients with    Isolation of organism from stool of
                                                        diarrhea; fever uncommon        two or more ill persons and not
                                                                                        from stool of controls
                                                                                                     OR
                                                                                        Isolation of >= 10^5 organisms/g from
                                                                                        epidemiologically implicated food,
                                                                                        provided specimen properly handled

 b. Diarrheal toxin             6-24 hrs                Diarrhea, abdonimal cramps,     Isolation of organism from stool of
                                                        and vomiting in some patients;  two or more ill persons and not
                                                        fever uncommon                  from stool of controls
                                                                                                     OR
                                                                                        Isolation of >=10^5 organisms/g from
                                                                                        epidemiologically implicated food,
                                                                                        provided specimen properly handled

 c. Brucella                    Several days to         Weakness, fever, headache,      Two or more ill persons and isolation
                                several mos, usually    sweats, chills, arthralgia,     of organism in culture of blood or bone
                                > 30 days               weight loss, splenomegaly       marrow, greater than fourfold increase
                                                                                        in standard agglutination titer (SAT)
                                                                                        over several wks, or single SAT titer
                                                                                        >=1:160 in person who has compatible
                                                                                        clinical symptoms and history of exposure

3. Campylobacter                2-10 days, usually      Diarrhea (often bloody),        Isolation of organism from clinical
                                2-5 days                abdominal pain, fever           specimens from two or more ill persons
                                                                                                     OR
                                                                                        Isolation of organism from epidemiologically
                                                                                        implicated food

4. Clostridium botulinum        2 hrs-8 days, usually   Illness of variable severity;   Detection of botulinal toxin in serum,
                                12-48 hours             common symptoms are diplopia,   stool, gastric contents, or implicated food
                                                        blurred vision, and bulbar                   OR
                                                        weakness; paralysis, which is   Isolation of organism from stool or intestine
                                                        usually descending and
                                                        bilateral, may progress
                                                        rapidly

5. Clostridium perfringens      6-24 hrs                Diarrhea, abdominal cramps;     Isolation of >=10^6 organisms/g in stool of
                                                        vomiting and fever are          two or more ill persons, provided specimen
                                                        uncommon                        properly handled
                                                                                                     OR
                                                                                        Demonstration of enterotoxin in the stool of
                                                                                        two or more ill persons

6. Escherichia coli

 a. Enterohemorrhagic           1-10 days, usually      Diarrhea (often bloody),        Isolation of E. coli O157:H7 or other
    (E. coli O157:H7 and        3-4 days                abdominal cramps (often         Shiga-like toxin-producing E. coli from clinical
    others)                                             severe), little or no fever     specimen of two or more ill persons
                                                                                                     OR
                                                                                        Isolation of E. coli O157 or other Shiga-like
                                                                                        toxin-producing E. coli from epidemiologically
                                                                                        implicated food

 b. Enterotoxigenic (ETEC)      6-48 hrs                Diarrhea, abdominal cramps,     Isolation of organism of same serotype,
                                                        nausea; vomiting and fever      which are demonstrated to produce heat-stable
                                                        are less common                 (ST) and/or heat-liable (LT) enterotoxin, from
                                                                                        stool of two or more ill persons

 c. Enteropathogenic (EPEC)     Variable                Diarrhea, fever, abdominal      Isolation of same enteropathogenic
                                                        cramps                          serotype from stool of two or more ill
                                                                                        persons

 d. Enteroinvasive (EIEC)       Variable                Diarrhea (may be bloody),       Isolation of same enteroinvasive
                                                        fever, abdominal cramps         serotype from stool of two or more ill
                                                                                        persons

7. Listeria monocytogenes

 a. Invasive disease            2-6 weeks               Meningitis, neonatal sepsis,    Isolation of organism from normally
                                                        fever                           sterile site

 b. Diarrheal disease           Unknown                 Diarrhea, abdominal cramps,     Isolation of organism of same serotype
                                                        fever                           from stool of two or more ill persons
                                                                                        exposes to food that is epidemiologically
                                                                                        implicated or from which organism of same
                                                                                        serotype has been isolated

8. Nontyphoidal                 6 hrs-10 days,          Diarrhea, often with fever      Isolation of organism of same serotype
   Salmonella                   usually 6-48 hours      and abdominal cramps            from clinical specimens from two or more
                                                                                        ill persons
                                                                                                     OR
                                                                                        Isolation of organism from epidemiologically
                                                                                        implicated food

9. Salmonella typhi             3-60 days, usually      Fever, anorexia, malaise,       Isolation of organism from clinical
                                7-14 days               headache, and myalgia;          specimens or two or more ill persons
                                                        sometimes diarrhea or                        OR
                                                        constipation                    Isolation of organism from epidemiologically
                                                                                        implicated food

10. Shigella                    12 hrs-6 days,          Diarrhea (often bloody),        Isolation of organism of same serotype
                                usually 2-4 days        frequently accompanied by       from clinical specimens from two or more
                                                        fever and abdominal cramps      ill persons
                                                                                                     OR
                                                                                        Isolation of organism from epidemiologically
                                                                                        implicated food

11. Staphylococcus aureus       30 min-8 hours,         Vomiting, diarrhea              Isolation of organism of same phage type
                                usually 2-4 hours                                       from stool or vomitus of two or more ill persons
                                                                                                     OR
                                                                                        Detection of enterotoxin in epidemiologically
                                                                                        implicated food
                                                                                                     OR
                                                                                        Isolation of >=10^5 organisms/g from
                                                                                        epidemiologically implicated food, provided
                                                                                        specimen properly handled

12. Streptoccus                 1-4 days                Fever, pharyngitis, scarlet     Isolation of organism of same M- or T-type
    Group A                                             fever, upper respiratory        from throats of two or more ill persons
                                                        infection                                    OR
                                                                                        Isolation of organism of same M- or T-type
                                                                                        from epidemiologically implicated food

13. Vibrio cholerae             1-5 days                Watery diarrhea, often          Isolation of toxigenic organism from
    a. O1 or O139                                       accompanied by vomiting         stool or vomitus of two or more ill persons
                                                                                                     OR
                                                                                        Significant rise in vibriocidal, bacterial-
                                                                                        agglutinating, or antitoxin antibodies in
                                                                                        acute- and early convalescent-phase sera among
                                                                                        persons not recently immunized
                                                                                                     OR
                                                                                        Isolation of toxigenic organism from
                                                                                        epidemiologically implicated food

    b. non-O1 and non-O139      1-5 days                Watery diarrhea                 Isolation of organism of same serotype
                                                                                        from stool of two or more ill persons

14. Vibrio parahaemolyticus     4-30 hrs                Diarrhea                        Isolation of Kanagawa-positive organism
                                                                                        from stool of two or more ill persons
                                                                                                     OR
                                                                                        Isolation of >=10^5 Kanagawa-positive
                                                                                        organisms/g from epidemiologically
                                                                                        implicated food, provided specimen properly
                                                                                        handled

15. Yersinia enterocolitica     1-10 days, usually      Diarrhea, abdominal pain        Isolation of organism from clinical specimen
                                4-6 days                (often severe)                  of two or more ill persons
                                                                                                     OR
                                                                                        Isolation of pathogenic strain or organism
                                                                                        from epidemiologically implicated food

Chemical

1. Marine toxins

 a. Ciguatoxin                  1-48 hrs, usually       Usually gastrointestinal        Demonstration of ciguatoxin in epidemiologically
                                2-8 hrs                 symptoms followed by            implicated fish
                                                        neurologic symptoms                          OR
                                                        (including paresthesia          Clinical syndrome among persons who have eaten
                                                        of lips, tongue, throat,        a type of fish previously associated with
                                                        or extremities) and             ciguatera fish poisining (e.g., snapper, grouper,
                                                        reversal of hot and             or barracuda)
                                                        cold sensation

 b. Scombroid toxin             1 min-3 hrs, usually    Flushing, dizziness,            Demonstration of histamine in epidemiologically
    (histamine)                 <1 hr                   burning of mouth and throat,    implicated food
                                                        headache, gastrointestinal                   OR
                                                        symptoms, urticaria, and        Clinical syndrome among persons who have eaten
                                                        generalized pruritus            type of fish previously associated with
                                                                                        histamine fish poisoning (e.g., mahi-mahi or
                                                                                        or fish of order Scomboidei)

 c. Paralytic or                30 min-3 hrs            Parasthesia of lips, mouth,     Detection of toxin in epidemiologically
    neurotoxic shellfish                                or face, and extremities;       implicated food
    poison                                              intestinal symptoms or                       OR
                                                        weakness, including             Detection of large numbers of shellfish-
                                                        respiratory difficulty          poisoning-associated species of dinoflagellates
                                                                                        in water from which epidemiologically implicated
                                                                                        mollusks are gathered

 d. Puffer fish,                10 min-3 hrs,           Parasthesia of lips,            Demonstration of tetrodotoxin in
    tetrodotoxin                usually 10-45 mins      tongue, face, or extremities,   epidemiologically implicated fish
                                                        often following numbness;                    OR
                                                        loss of proprioception or       Clinical syndrome among persons who have
                                                        "floating" sensations           eaten puffer fish

2. Heavy metals                 5 min-8 hrs, usually    Vomiting, often metallic        Demonstration of high concentration of
   a. Antimony                  <1 hr                   taste                           metal in epidemiologically implicated food
   b. Cadmium
   c. Copper
   d. Iron
   e. Tin
   f. Zinc

3. Monosodium                   3 mins-2 hrs, usually   Burning sensation in chest,     Clinical syndrome among persons who
   glutamate (MSG)              <1 hr                   neck, abdomen, or               have eaten food containing MSG (i.e.,
                                                        extremities; sensation of       usually >= 1.5g MSG)
                                                        lightness and pressure over
                                                        face or heavy feeling in
                                                        chest

4. Mushroom toxins

 a. Shorter-acting toxins:      <=2 hrs                 Usually vomiting and            Clinical syndrome among persons who
                                                        diarrhea, other symptoms        have eaten mushroom identified as toxic
                                                        differ with toxin:              type
                                                                                                     OR
    Muscimol                                            Confusion, visual disturbance   Demonstration of toxin in epidemiologically
    Muscarine                                           Salivation, diaphoresis         implicated mushroom or mushroom-containing
    Psilocybin                                          Hallucinations                  food
    Cobrinus artrementaris                              Disulfiram-like reaction
    Ibotenic acid                                       Confusion, visual disturbance

 b. Longer-acting toxin         6-24 hrs                Diarrhea and abdominal cramps   Clinical syndrome among persons who
                                                        for 24 hrs followed by hepatic  have eaten mushroom identified as toxic
                                                        and renal failure               type
                                                                                                     OR
                                                                                        Demonstration of toxin in epidemiologically
                                                                                        implicated mushroom or mushroom-containing
                                                                                        food

Parasitic

1. Cryptosporidium parvum       2-28 days, median:      Diarrhea, nausea, vomiting,     Demonstration of organism or antigen in
                                7 days                  fever                           stool or in small-bowel biopsy of two or more
                                                                                        ill persons
                                                                                                     OR
                                                                                        Demonstration of organism in epidemiologically
                                                                                        implicated food

2. Cyclospora cayetanensus      1-11 days, median:      Fatigue, protracted             Demonstration of organism in stool of two
                                7 days                  diarrhea, often relapsing       or more ill persons

3. Giardia lamblia              3-25 days, median:      Diarrhea, gas, cramps,          Two or more ill persons and detection of
                                7 days                  nausea, fatigue                 antigen in stool; or demonstration of
                                7 days                  fatigue                         organism in stool, duodenal contents, or
                                                                                        small-bowel biopsy specimen

4. Trichinella spp.             1-2 days for            Fever, myalgia,                 Two or more ill persons and positive
                                intestinal phase;       periorbital edema,              serologic test or demonstration of larvae
                                2-4 wks for systemic    high eosinophil count           in muscle biopsy
                                phase                                                                OR
                                                                                        Demonstration of larvae in epidemiologically
                                                                                        implicated meat

Viral

1. Hepatitis A                  15-50 days, median: 28  Jaundice, dark urine,           Detection of lgM anti-hepatitis A virus in
                                days                    fatigue, anorexia, nausea       serum from two or more persons who consumed
                                                                                        epidemiologically implicated food

2. Norwalk family of viruses,   15-77 hrs, usually      Vomiting, cramps, diarrhea,     More than fourfold rise in antibody titer to
   small round-structured       24-48 hrs               headache                        Norwalk-like virus in acute and convalescent
   viruses (SRSV)                                                                       sera in most serum pairs
                                                                                                     OR
                                                                                        Visualization of small, round-structured viruses
                                                                                        that react with patient's convalescent sera but
                                                                                        not acute sera -- by immune-electron microscopy.
                                                                                        Assays based on molecular diagnostic (e.g.,
                                                                                        polymerase-chain reaction ›PCR|, probes, or
                                                                                        assays for antigen and antibodies from expressed
                                                                                        antigen) are available in reference
                                                                                        laboratories.

3. Astrovirus, calcivurus,      15-77 hrs, usually      Vomiting, cramps, diarrhea,     Visualization of small, round-structured
   others                       24-48 hrs               headache                        viruses that react with patient's
                                                                                        convalescent sera but not acute sera -- by
                                                                                        immune-electron microscopy. Assays based on
                                                                                        molecular diagnostics (e.g., PCR, probes, or
                                                                                        assays for antigen and antibodies from expressed
                                                                                        antigen) are available in reference
                                                                                        laboratories.
==============================================================================================================================================

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