Nontyphoidal Salmonellosis ◊

	Literature Recommendations
Exclusion-Case in SOS* (Symptomatic)	Yes [1,2,3,4,6,8,10,11] Grade III-A
Exclusion-Case in SOS* (Asymptomatic or previously symptomatic but now recovered)	Yes ◊ (Disagreement exists.[11] Code requires this, but literature does not support) Clearance required in SOS* [8b] Exclusion in Special Cases [4a] Grade III-C
Clearance-Case in SOS*	Yes Disagreement exist between sources c Grade III-A
Exclusion of Contact (Symptomatic)	Yes [1,2,3,4.6,8,10,11] Grade III-A
Exclusion of Contact (Asymptomatic)	No [11] Clearance Required in SOS* [8b] Exclusion in Special Cases [4a] Grade III-C
Exclusion-Case in Children (Group setting with children ≤ 5 years of age) (Symptomatic)	Yes [1,2,3,4,8] Grade III-A
Exclusion-Case in Children (Group setting with children ≤ 5 years of age) (Asymptomatic or previously symptomatic but now recovered)	Insufficient evidence for recommendation
◊ Applicable Code	CCR 2612
* SOS (Sensitive Occupations or Situations) is not defined precisely in either the Code of Regulations or Health & Safety Code. See Attachment 2 for the definition of food workers. ◊ See California Code of Regulations, Attachment 1, for details. + Local health departments may elect to follow more restrictive exclusion and clearance criteria

a See number four under the Preventive Measures Exclusions.
b See number seven under the Preventive Measures Exclusion.
c Two sources [4, 8] state that 2 stools/24 hours apart (taken minimum of 48 hours after stopping antibiotic) but one source [3] state that no microbiological clearance required.

Disease Trends in the U.S.:

The Surveillance for Foodborne-Disease Outbreaks in United States provides trends from 1982-2002. It should be kept in mind that these are only a small fraction of the cases that are reported to Center for Disease Control and Prevention (CDC) through passive surveillance systems. If one were to take into account 1) asymptomatic cases, 2) symptomatic cases that do not seek medical care, 3) diarrheal illnesses are treated without stool confirmation and 4) not all positive laboratory results are reported to public health officials, the estimated cases of Nontyphoidal Salmonellosis per year would likely be much higher.

• In 1982, 656 outbreaks (19,380 cases) of foodborne disease were reported to CDC. The etiologic agent was confirmed in 34% of the outbreaks (11,050 cases). Bacterial pathogens accounted for 151 outbreaks (5,501 cases). The most frequently isolated bacterial pathogen was Salmonella (55 outbreaks, 2,056 cases). [12]
• In 1983, 505 outbreaks (14,898 cases) of foodborne diseases were reported to CDC.  Bacterial pathogens accounted for 127 outbreaks (7,082 cases). Salmonella caused most of the bacterial foodborne disease outbreaks (72 outbreaks, 2,427 cases) [13] 
• In 1984, 543 outbreaks (16,420 cases) of foodborne disease were reported to CDC. The etiologic agent was confirmed in 185 (34%) of the 543 outbreaks.  Bacterial pathogens accounted for 128 outbreaks (7,307 cases). Salmonella caused most of the bacterial foodborne disease outbreaks (78 outbreaks, 4,479 cases).  An outbreak of Salmonella typhimurium infection affected over 700 persons in a small Oregon town. Most ill persons had eaten at a salad bar in one of 10 implicated restaurants, which was found to have been deliberately contaminated.  [13]
• In 1985, 495 outbreaks (31,079 cases) of foodborne disease were reported to CDC. The etiologic agent was confirmed in 220 (44%) of the 495 outbreaks. Bacterial pathogens accounted for 143 outbreaks (22,132 cases). Salmonella caused most of the bacterial foodborne disease outbreaks (79 outbreaks, 19,660 cases).  The largest single foodborne outbreak ever reported to CDC was caused by S. typhimurium in 1985. The outbreak was associated with 2% low-fat pasteurized milk produced by a dairy plant in Chicago. The number of ill persons was estimated to be greater than 150,000. There were greater than 16,000 culture-confirmed cases, at least 2,777 persons were hospitalized and there were 14 deaths in which salmonellosis may have been associated. The use in the month before the illness of antimicrobials, to which the organism was resistant, had increased the risk for acquiring the illness. A statewide outbreak of chloramphenicol-resistant Salmonella newport infection occurred in California. The illness was associated with ground beef eaten during the week before onset and with the use of penicillin or tetracycline during the month before onset. The epidemic strain was traced from humans back through hamburger meat processors and abattoirs to dairy farms where chloramphenicol was used. [13]
• In 1986, 467 outbreaks (12,781 cases) of foodborne disease were reported to CDC. The etiologic agent was confirmed in 181 (39%) of the 467 outbreaks. Bacterial pathogens accounted for 119 outbreaks (4,855 cases). Salmonella caused most of the bacterial foodborne disease outbreaks (61 outbreaks, 2,833 cases).  A multistate outbreak of Salmonella enteritidis infections caused by commercially frozen pasta affected greater than 100 persons. Thirteen were hospitalized and one person died. The implicated pasta was labeled as fully cooked, although it contained raw eggs. [13]
• In 1987, 387 outbreaks (16,500 cases) of foodborne disease were reported to CDC. The etiologic agent was confirmed in 136 (35%) of the 387 outbreaks. Bacterial pathogens accounted for 83 outbreaks (8,928 pathogens). Salmonella caused most of the bacterial foodborne disease outbreaks (52 outbreaks, 1,846 cases), of the many outbreaks caused by S. enteritidis, one involved 40 people who ate eggs at a restaurant in Delaware. [13]
• In 1988, 451 outbreaks involving 15,732 cases of foodborne diseases were reported to CDC.  The etiology was confirmed in 183 (41%) of the 451 outbreaks.  Bacterial pathogens accounted for 139 of the outbreaks (7,156 cases). Salmonella was responsible for most of the bacterial Foodborne Disease Outbreaks (FBDOs) (94 outbreaks, 2,987 cases). [14]
• During 1989, 505 outbreaks involving 15,867 cases of foodborne diseases were reported to CDC.  The etiology was confirmed in 221 (44%) of the 505 outbreaks.  Bacterial pathogens accounted for 171 outbreaks (6,557 cases). Salmonella caused most of the bacterial FBDOs (117 outbreaks, 4,920 cases).  An outbreak in a nursing home in Maryland, caused by both S. Enteritidis and S. Schwarzengrund, resulted in 69 cases, 11 hospitalizations, and four deaths. A multistate outbreak (295 cases) of S. Chester infections was traced to cantaloupes imported from Mexico. A multistate outbreak (164 cases) of S. Javiana and S. Oranienberg infections was caused by mozzarella cheese that had been contaminated during shredding before it was distributed. [14]
• During 1990, 532 outbreaks involving 19,885 cases of foodborne diseases were reported to CDC.  The etiology was confirmed in 237 (45%) of the 532 outbreaks.  Bacterial pathogens were responsible for 196 of the outbreaks (9,002 cases). Salmonella caused most of the bacterial FBDOs, total of 136 outbreaks with 6,290 cases.  An outbreak of S. Agona infections among conventioneers attending a buffet catered by a South Carolina restaurant was caused by improperly handled turkey meat; 851 persons became ill and 18 of these persons were hospitalized. An outbreak of S. Montevideo infections apparently occurred when salad-bar ingredients were cross-contaminated by uncooked meat and poultry in a restaurant kitchen; 320 persons became ill and eight of these persons were hospitalized. [14]
• During 1991, 528 outbreaks involving 14,876 cases of foodborne disease were reported to CDC.  The etiology was confirmed in 214 (41%) of the 528 outbreaks. Bacterial pathogens accounted for 173 of the outbreaks (6,335 cases). Salmonella caused most of the bacterial FBDOs, total of 122 outbreaks with 4,146 cases.  Inadequately cooked bread stuffing containing pooled raw eggs caused an outbreak of S. Enteritidis infections in a New York prison; 393 persons became ill and nine of these persons were hospitalized. An outbreak (673 cases) of S. Heidelberg infections was caused by tainted chicken and beef fajitas that had been improperly stored and cooked by a food vender at a festival in Connecticut. Two outbreaks of Salmonella were associated with eating contaminated melons; S. Poona (143 cases) infections were associated with eating cantaloupes and S. Javiana (39 cases) infections were associated with eating watermelon. [14]
• During 1992, 407 outbreaks involving 11,015 cases of foodborne diseases were reported to CDC. The etiology was confirmed in 146 (36%) of the 407 outbreaks.  Bacterial pathogens accounted for 117 outbreaks (4,156 cases). Salmonella caused most of the bacterial FBDOs (80 outbreaks, 2,834 cases).  S. Enteritidis was the etiologic agent in four other outbreaks: one outbreak (191 cases) in a New Jersey prison was associated with banana pudding that contained undercooked eggs; two outbreaks (130 cases)—one at a picnic in New York and one at a college in New Hampshire—were associated with eating egg sandwiches; one outbreak (105 cases) at a convention in Vermont was associated with an unidentified food vehicle. Undercooked, pooled eggs in a rice pudding also resulted in an outbreak (113 cases) of S. Infantis infections in a state prison in Georgia. An outbreak of S. Typhimurium associated with homemade ice cream containing raw eggs resulted in 31 cases and one death. [14]
• During 1993–1997, a total of 2,751 outbreaks of foodborne disease were reported (489 in 1993, 653 in 1994, 628 in 1995, 477 in 1996 and 504 in 1997). These outbreaks caused a reported 86,058 persons to become ill. Among outbreaks for which the etiology was determined, bacterial pathogens caused the largest percentage of outbreaks (75%) and the largest percentage of cases (86%). Salmonella serotype Enteritidis accounted for the largest number of outbreaks, cases and deaths; most of these outbreaks were attributed to eating eggs. A massive outbreak of Salmonella serotype Enteritidis infections was linked to commercially distributed ice cream made from a liquid premix that had been transported in tanker trucks used previously to haul liquid raw eggs. Salmonella caused 357 (55%) of the 655 bacterial FBDOs with a known etiology during 1993–1997; 55% of these 357 outbreaks were caused by S. Enteritidis. S. Enteritidis was the most frequently reported cause of FBDOs, accounting for 7% of all outbreaks and 22% of outbreaks for which an etiology was determined. S. Enteritidis also resulted in more deaths than any other pathogen; four of the ten persons (40%) who died from S. enteritidis infection were residents of nursing homes. [15]
• During 1998–2002, the annual number of reported outbreaks ranged from 1,243 to 1,417. The average annual number of outbreaks reported during this period (1,329) was substantially greater than the average annual number of outbreaks reported during 1993–1997 (550). The average number of cases per outbreak during 1998– 2002 was lower than the average number of cases per outbreak during 1993–1997. During 1998–2002, a total of 2,167 (33%) of the 6,647 outbreaks reported to CDC had a known etiology; these outbreaks accounted for 68,981 (54%) of 128,370 illnesses. S. Enteritidis, the most frequently reported bacterial cause of FBDOs, caused 204 outbreaks, with 9% of the outbreaks having a determined etiology. Eggs caused more S. Enteritidis outbreaks than any other food item. Salmonella caused a total of 585 outbreaks with 16,821 cases of which there were 20 deaths. [16]

Outbreaks

1. Ontario Medical Association and the Ontario Hospital Association in their “Enteric Diseases Surveillance Protocol for Ontario Hospitals” state that although outbreaks related to possible transmission from an asymptomatic food handler have been described, these are rare in the health care setting.  Similarly, there is little evidence that asymptomatic personnel excreting Salmonella transmit infection to patients, with the possible exception of newborn infants, where the incidence of disease is high. [4]
2. Daniels et al. looked at outbreaks in the primary and secondary schools, colleges and universities from January 1, 1973 to December 31, 1997.  Local health departments reported 604 outbreaks of foodborne disease in the schools. In 60% of the outbreaks an etiology was not determined and in 45% the specific food vehicle of transmission was not determined.  The most commonly reported food preparation practices that contributed to these school-related outbreaks were improper food storage and holding temperatures and food contaminated by a food handler.  Salmonella was the most commonly identified pathogen, accounting for 87 (36%) of 242 outbreaks, 7529 (37%) of 20,476 illnesses and 484 (48%) of 998 hospitalizations. [6]
3. Musher et al. stated that “an outbreak in a day-care facility was associated with an uncertain number of secondary cases and long-term surveillance of 54 permanent carriers of Nontyphoidal Salmonella identified 10 instances of transmitted infection.” [9]
4. Rooney et al. conducted a review of outbreaks on passenger ship from January 1, 1970 through June 30, 2003. They looked at 50 outbreaks of which 41 were linked to bacterial pathogens. Fifteen outbreaks were linked to Salmonella leading to 1847 cases total.  Rooney also stated that an infected food handler was a possible factor in contributing to five outbreaks. In an outbreak of Salmonellosis that occurred on a ferry in 2002 and affected 352 passengers, eight food handlers were found to be carriers of the pathogen. 

Nontyphoidal Salmonellosis The most common illness associated with Nontyphoidal Salmonella infection is acute gastroenteritis with fever, vomiting, nausea, abdominal pain, headache and diarrhea.  The site of infection usually is the small intestine, but colitis can occur. Sustained or intermittent bacteremia can occur and focal infections are recognized in as many as 10% of patients with Salmonella bacteremia.  Infection may also present as septicemia and occasionally may be localized in other body tissues resulting in endocarditis, pneumonia, septic arthritis, cholecystitis and abscesses. Symptoms will usually last three to five days. [1, 2, 7, 8, 9]

Organism: Salmonella organisms are gram-negative bacilli that belong to the Enterobacteriaceae family. Currently, there are more than 2460 Salmonella serotypes; most serotypes causing human disease are divided among O-antigen groups A through E, a small number of which usually account for the majority of infections.  [1, 2, 7]

Reservoir of infection: The principal reservoirs for Nontyphoidal Salmonella organisms include poultry, livestock, reptiles and pets. [1, 2, 3, 7, 9]
           
Modes of transmission:

• The major vehicle of transmission is food of animal origin, such as poultry, beef, eggs and dairy products. Other food vehicles (e.g., fruits, vegetables, and bakery products) have been implicated in outbreaks, in which the food was contaminated by contact with an infected animal product or human. Other modes of transmission include ingestion of contaminated water, contact with infected reptiles, amphibians (e.g., pet turtles, iguanas, lizards, snakes, frogs, toads, newts, salamanders) or possibly rodents and exposure to contaminated medications, dyes and medical instruments. [1,2.7]
• Person-to-Person transmission is important, especially where cases have diarrhea. Infants and fecally-incontinent adults pose a greater risk of transmission than do asymptomatic carriers. The risk of transmission to neonates and infants from family members, who are chronic carriers or who have been recently infected, is high. Infected (but not necessarily symptomatic) food handlers have been implicated in outbreaks of Salmonellosis. [3,9]

Attack rates:            

• Age-specific attack rates for Salmonella infection are highest in people 1 to 4 years of age. Rates of invasive infections and mortality are higher in infants, elderly people and people with immunosuppressive conditions, hemoglobinopathies (including sickle cell disease), malignant neoplasms and human immunodeficiency virus (HIV) infection. Most reported cases are sporadic, but widespread outbreaks, including nosocomial, institutional and nursery outbreaks, have been reported. [2,7]

Infectious dose: on the basis of epidemiologic studies, the infective dose of Nontyphoidal Salmonella is thought to be small, not exceeding 100 CFU. [9]
Incubation Period average 12 to 36 hours (range from 6-72 hours) [1, 2]
Infectious Period:

• The risk of transmission exists for the duration of fecal excretion of organisms. Twelve weeks after infection, 45% of children younger than 5 years of age excrete Salmonella organisms, compared with 5% of older children and adults; antimicrobial therapy can prolong excretion. Approximately 1% of patients continue to excrete Salmonella organisms for more than 1 year (chronic carriers). [2,7]
• Children aged less than 5 years may shed organisms for up to a year (median 10 weeks). Over the age of 5 years the maximum duration of shedding appears to be up to 12 weeks (median 4 weeks) [3,5]

Asymptomatic carrier state: Heymann (2004) states, “a temporary carrier state can continue for months, especially in infants. Depending on the serotype one percent of infected adults and five percent of children under five years old may excrete the organism for longer than one year.” [17]

Diagnosis: Isolation of Salmonella organisms from cultures of stool, blood, urine, and material from foci of infection is diagnostic. Gastroenteritis is diagnosed by stool culture. Rapid tests using enzyme immunoassay, latex agglutination, DNA probes, and monoclonal antibodies have been developed and are in use in some laboratories. Serologic tests for Salmonella agglutinins ("febrile agglutinins" [the Widal test]) are not recommended. [2, 7, 8, 9]

Preventive Measures
Exclusions:

1. The Australian Blue Book-Guidelines for the control of infectious diseases suggests to exclude symptomatic cases from handling food and direct care of children, the elderly and immunosuppressed patients until after the diarrhea has ceased. Children are excluded from school and child care until the diarrhea has ceased. [1] Guidelines and Consensus Document {Grade III-A}
2. The Red Book published by the American Academy of Pediatrics states that “antimicrobial therapy usually is not indicated for patients with either asymptomatic infection or uncomplicated (noninvasive) gastroenteritis caused by Nontyphoidal Salmonella species, because therapy does not shorten the duration of disease and can prolong the duration of fecal excretion. Although of unproven benefit, antimicrobial therapy is recommended for gastroenteritis caused by Salmonella species in people at increased risk of invasive disease, including infants younger than 3 months of age and people with chronic gastrointestinal tract disease, malignant neoplasms, hemoglobinopathies, HIV infection, or other immunosuppressive illnesses or therapies.” [2] Guidelines and Consensus Document {Grade III-A}
3. The Public Health Laboratory Service Advisory Committee on Gastrointestinal infections in their “Preventing Person to Person Spread Following Gastrointestinal Infections: Guidelines for Public Health Physicians and Environmental Health officers” suggests that exclusion of only 48 hours after first normal stool is required with no microbiological clearance. [3] Guidelines and Consensus Document {Grade III-A}
4. A guideline produced by the Ontario Medical Association and the Ontario Hospital Association suggests that individuals with good personal hygiene can return to work after being symptom free and do not require microbiological clearance except in two cases: [4] Guidelines and Consensus Document {Grade III-A}
   1. exclusion in outbreak situations
      1. Food handlers and epidemiologically-linked patient care workers may be asked to submit stools for examination. Symptomatic persons must remain off work until two stool specimens are negative for the outbreak pathogen; the stools must be collected at least 24 hours apart, with the first being collected following at least 24 hours without diarrhea. If the individual has been treated with antibiotics, the first stool must not be submitted until at least 48 hours following cessation of the antibiotic.
      2. Asymptomatic persons should not work during an outbreak if their stool specimens are positive for the outbreak pathogen. Once the outbreak is declared over by the Medical Officer of Health, asymptomatic carriers of the outbreak pathogen may return to work. Prior to returning to work, all staff must be assessed and instructed in personal hygiene and high-risk food preparation, either by hospital staff, or by public health inspection staff
   2. HCWs from areas with high risk patients (i.e., Salmonella sp. in nursery personnel).
5. Richardson M and et al. concluded with evidence-based research that exclusion of children from schools and preschool under age of 5 years was recommended with at least one negative stool before returning. [5] Evidence based reviews with guidelines formed out of reviewed literary sources {Grade III-A}
6. Daniels et al. states that “several outbreaks in schools have been attributed to contamination of food by food-handlers who worked while ill or had poor personal hygiene.  In our review of reported foodborne outbreaks in school, 57% of the outbreaks were attributed to likely contamination by a food-handler. The adoption of a work policy that includes paid leave for food handlers with gastroenteritis would probably increase compliance with illness related work exclusion policies. Training and certifying all food handlers in school cafeterias in specific techniques, such as good personal hygiene, adequate hand washing, proper cooling and reheating of foods and methods of preventing cross-contamination between cooked and raw foods, would also likely reduce the incidence of foodborne disease outbreaks.” [6] Review of Outbreaks and Epidemiology {Grade III-A}
7. Guerrant et al. suggested two preventive measures in the guidelines for the management of infectious diarrhea: [8] Evidence based reviews with guidelines formed out of reviewed literary sources {Grade III-A}
   1. Diagnostic fecal testing for Public Health reasons.
      1. Diagnostic testing of stool specimens is indicated for certain groups of people who are not themselves patients. Food-handlers in food service establishments and health care workers involved in direct patient care should be tested for bacterial pathogens if they have diarrhea because of their potential to transmit infection to large numbers of persons. Similarly, diarrheal illness in a day-care attendee, day-care employee, or resident of an institutional facility (e.g., psychiatric hospital, prison, or nursing home) should be evaluated for bacterial or parasitic infection, because gastrointestinal illnesses in these settings may indicate that a disease outbreak is occurring.
   2. Follow-up testing
      1. In certain situations, it should be verified that a patient with a laboratory-confirmed bacterial or parasitic diarrheal disease has been cured or is no longer a fecal carrier. Because food-handlers and health care workers can transmit bacterial and parasitic diseases even if they are asymptomatic, it is recommended that before returning to their jobs these persons have 2 consecutive negative stool samples taken 24 h apart and at least 48 h after resolution of symptoms. If the patient has received antimicrobial therapy, the first stool specimen should be obtained at least 48 h after the last dose. Furthermore, if food-handlers or health care workers are symptomatic, they should be excluded from directly handling food and from caring for high-risk patients.
8. Rooney et al. suggested that “strict hygiene measures, such as frequent hand washing, thoroughly washing ready-to-eat foods that require handling but no subsequent cooking (e.g., salads) and excluding infected food handlers from work, are necessary to ensure that food does not facilitate the spread of the infection on a ship.” [10] Review of Outbreaks and Epidemiology {Grade III-A}
9. Cruickshank states, “during the acute stages of gastroenteritis large numbers of organisms are excreted and by the nature of the disease are likely to be widely dispersed; clearly, food handlers who are symptomatically ill may present a real hazard and should be excluded from work. Given, however, that after an attack of salmonellosis half of those affected will still have detectable Salmonella in their stools after five weeks, it is less easy to advise on reasonable exclusions for convalescents and long term excreters without symptoms.” He also stated that “in line with other expert bodies, it’s concluded that asymptomatic carriers of non-typhoid Salmonella and Shigella organisms, Vibrio Cholerae, and enteric viruses who practice good hygiene do not constitute a significant risk.”[11] Evidence Based Literature. {Grade III-A}

References

1. The Communicable Diseases Section, Public Health Group, Victorian Department of Human Services, Australia.  Blue book - Guidelines for the control of infectious diseases Revised edition 2005. Guidelines and Consensus Document
2. American Academy of Pediatrics. Red Book – The Report of the Committee of Infectious Diseases. 2006 Edition.  Guidelines and Consensus Document
3. PHLS Advisory Committee on Gastrointestinal infections. Preventing Person to Person Spread Following Gastrointestinal Infections: Guidelines for Public Health Physicians and Environmental Health officers. Communicable Disease and Public Health 2004; 7(4):362-384. Guidelines and Consensus Document
4. Ontario Medical Association and the Ontario Hospital Association. Enteric Diseases Surveillance Protocol for Ontario Hospitals. Published November 989/Revised/Reviewed June 2005 Guidelines and Consensus Document
5. Richardson M, Elliman D, Maguire H, et al. Evidence base of incubation periods, periods of infectiousness and exclusion policies for the control of communicable diseases in schools and preschools. Pediatric ID Journal Vol. 20 April 2001; 380-391 Evidence based reviews with guidelines formed out of reviewed literary sources
6. Daniels NA, Mackinnon L, et al. Foodborne disease outbreaks in United States schools. Pediatr Infect Dis J, 2002;21:623-8 Review of Outbreaks and Epidemiology
7. Dennehy, PH. Acute Diarrheal Disease in Children: Epidemiology, Prevention, and Treatment. Infect Dis Clin N Am 19 (2005) 585-602 Evidence Based Literature
8. Guerrant, RL, Gilder TV, Steiner TS.  Practice Guidelines for the Management of Infection Diarrhea. CID 2001;32:331-50 Evidence based reviews with guidelines formed out of reviewed literary sources
9. Musher DM, Musher BL. Contagious Acute Gastrointestinal Infections. N Engl J Med 2004;351:2417-27 Evidence Based Literature
10. Rooney RM, Cramer EH, Mantha S, et al. A Review of Outbreaks of Foodborne Disease Associated with Passenger Ships: Evidence for Risk Management. Public Health Reports, Volume 19, July-August 2004 Review of Outbreaks and Epidemiology
11. Cruickshank JG. Food handlers and food poisoning. BMJ January 1990, Volume 300 Evidence Based Literature
12. CDC. Foodborne Disease Outbreaks, Annual Summary, 1982.  MMWR December 01, 1986/35(1SS);7ss-10ss Review of Outbreaks and Epidemiology
13. CDC. Foodborne Disease Outbreaks, 5-Year Summary, 1983-1987. MMWR March 01, 1990/39 (SS01);15-23 Review of Outbreaks and Epidemiology
14. CDC. Surveillance for Foodborne-Disease Outbreaks – United States, 1988-1992. MMWR October 25, 1996 Vol. 45 / No. SS-5 Review of Outbreaks and Epidemiology
15. CDC. Surveillance for Foodborne-Disease Outbreaks – United States, 1993-1997.  MMWR March 17, 2000 /Vol. 49 /No. SS-1 Review of Outbreaks and Epidemiology
16. CDC. Surveillance for Foodborne-Disease Outbreaks – United States, 1998-2002. MMWR November 10, 2006 Vol. 55/ SS-10 Review of Outbreaks and Epidemiology
17. Heymann, D.L. ed. Control of Communicable Disease Manual, 18th edition.2004. American Public Health Association, Washington, DC. Pgs 139-141. Guidelines and Consensus document

 

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