Viral Gastroenteritis(Norovirus and others)

 

Literature Recommendations

Exclusion-Case in SOS*
(Symptomatic)

Yes [8,11,12,13,14,16,17,18,19, 20,25,27]
Grade III-A

Exclusion-Case in SOS*
(Asymptomatic or previously symptomatic but now recovered)

Yes [6,18,19b, 20]
Grade III-A

Clearance-Case in SOS*

No Clearance. Exclude until 48 hours after symptoms cease. [14,18,20,27]
Grade III-A

Exclusion of Contact
(Symptomatic)

Yes [8,11,17,19-20]
Grade III-A

Exclusion of Contact
(Asymptomatic)

No [13, 19]a
Grade III-A

Exclusion-Case in Children
(Group setting with children ≤ 5 years of age)
(Symptomatic)

Yes [11,19-20,25]
Grade III-A

Exclusion-Case in Children
(Group setting with children ≤ 5 years of age)
(Asymptomatic or previously symptomatic but now recovered)

Yes [10-11,19]
Grade III-A

◊ Applicable Code

None
* 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 Literature search revealed one outbreak where an asymptomatic contact was the cause [6]. The general guidelines recommend permitting individuals to return after symptoms have resolved and another outbreak where an asymptomatic foodhandler was implicated state that prolonged exclusion, especially among asymptomatic individuals would not be feasible [13].
b This guideline did not recommend exclusion of asymptomatic cases, the remaining literature suggested isolation because of the high attack rate and low infective dose of Norwalk virus.

Disease Trends in the U.S.:
Between 2000 and 2004, outbreaks were reported from 30 states, the District of Columbia, and Puerto Rico and from cruise ships docking at US ports. The 226 reported outbreaks occurred in a variety of setting, but most commonly in nursing homes, retirement centers, hospitals, restaurants and events with catered meals [2].

A review of Norovirus and Foodborne outbreaks from 1991-2000 found that 278 of 305 outbreaks were at sites where food was consumed or prepared [22].

According the Morbidity and Mortality Weekly Report, during 1998–2002, norovirus caused 657 of the 2,167 foodborne disease outbreaks with a known etiology and 39% of all outbreak related cases in these outbreaks [24].

A six-year study conducted in Finland reported 41 waterborne outbreaks between 1998 and 2003. Of the 28 outbreaks with samples available for analysis, 18 were determined to have been caused by norovirus [23].

During 2003-2004, of the waterborne disease outbreaks, six were of confirmed viral origins occurred in the United States. Five were found to have been caused by gastroenteritis; in all five norovirus was determined to be the causative agent. These five outbreaks resulted in 300 cases of gastroenteritis [25].

In 1992, 250 cases caused by Norwalk-like virus were associated with contaminated hamburger buns and cookies that were prepared by ill food handlers at a bakery [17].

According to Daniels et al. (2002), several outbreaks in schools have been attributed to contamination of food by the food-handlers who worked while ill. In total 57% of the outbreaks were attributed to likely contamination by a food-handler [15]. 

Norwalk Virus are the most common cause of infectious acute gastroenteritis and are transmitted fecal-orally through food and water, directly from person to person and by environmental contamination [21]. Norwalk viruses are associated with large outbreaks of gastrointestinal disease characterized by short-term symptoms of vomiting, diarrhea, abdominal pain and nausea [26].

Organism: Noroviruses (previously termed small round structure viruses (SRSV), Norwalk and Norwalk-like viruses) [20] are small single stranded viruses belonging to the Caliciviridae family [1]. Norwalk virus are grouped into five genogroups, of which three have been found in humans; genogroups I, II and IV [27].

Reservoir: Human gastrointestinal tract [18, 20]. 
Transmission: Fecal-oral spread is probably the primary Norwalk virus transmission mode, although airborne and fomite transmission might facilitate spread during outbreaks. Primary cases results from exposure to a focally contaminated vehicle, where as secondary and tertiary cases among contacts of primary cases result from person-to-person transmission [4-5, 8, 10-11, 18, 20].
Attack Rate: Attack rates are variable depending on outbreak setting. The attack rate for children exposed to the recreational fountain was 54% [3]. The secondary attack rate was 15%; this varied by school from 4% to 40% [3]. In an epidemiologic study that looked at outbreaks of viral gastroenteritis in cruise ships and on land for 2002, they found that the median attack rate for 4 outbreaks was 18% with a range of 13-30% [9].
According to Gotz et al, a food-borne outbreak that included 30-Day Care Centers, the overall attack rate was 37%, 30% in children and 62% in adults [12].
According Bruin et al, in food or water-borne outbreaks, attack rates have ranged from 30-80% [26].
Infective Dose: highly transmissible, requiring a low infectious dose of only 10 to 100 particles [4].
Incubation Period: incubations period is generally 24 to 48 hours with a range from 18 to 72 hours [4, 7-8, 10].
Length of the Disease: mean duration of illness of 12 to 60 hours [4, 8, 10].
Infectious Period: Norwalk virus shedding in stool detected by immune electron microscopy is maximal over the first 24 to 48 hours after illness and is rarely detected beyond 72 hours after the onset of vomiting and diarrhea; can sometimes last up to three weeks [4, 10].
Carrier State:  Insufficient evidence in literature regarding Norwalk virus carrier state.
Diagnosis: For large numbers of clinical samples, such as during an outbreak, enzyme-linked immunosorbent assays (ELISA) kits maybe be useful; however for routine diagnosis of Norwalk in samples from patients with gastroenteritis, reverse transcription polymerase chain reaction (RT-PCR) remains the ‘gold standard’ [27]. RT-PCR can provide information on the molecular epidemiology or outbreaks for Norwalk [23].
According to the California Department of Health Services Division of Communicable Disease Control, Norwalk virus can be identified by polymerase chain reaction (PCR) which is available at the California Department of Health Services (CDHS) and some local health departments. This test requires fresh unfrozen stool [27].

Preventive Measures
Exclusions:
Symptomatic

  1. All patients of a pediatric oncology ward were tested for norovirus and were isolated in cohorts if found positive. In all confirmed cases, the stool sample tests were repeated weekly until they became negative [8]. Review of Outbreaks and Epidemiology {Grade III-A}
  2. According to a joint collaborative project of The American Academy of Pediatrics, American Public Health Association & National Resource Center for Health and Safety (2002), “in child care settings, caregivers with diarrhea (defined as 3 or more stools in 24 hr or blood in stool) shall be excluded from childcare. Exclusion for acute diarrhea shall continue until diarrhea stops or stools are deemed non-infectious by appropriate public health professional. Children who develop diarrhea should be isolated from other children pending arrival of parent who should remove them from the facility. Children and caregivers who excrete intestinal pathogens but no longer have diarrhea generally may be allowed to return once diarrhea stops" [19]. Guidelines and Consensus Document {Grade III-A}
  3. Cases occurring in institutions should be isolated where practicable. Infectivity lasts for 48 hours after resolution of symptoms [20]. Guidelines and Consensus Document {Grade III-A}
  4.  According to California Department of Health Services Division of Communicable Disease Control in Consultation with Licensing and Certification Program (2006) “Confine symptomatic residents to their rooms until 48 hours after symptoms cease. Exclude non-essential staff from entering room. Request symptomatic staff, visitors and volunteers to stay home until symptom-free for at least 24 hours [27]. Staff should be allowed to return to work after being symptomatic free for at least 24 hours. Virus may be excreted in stool for 2 or more weeks. Testing for norovirus is not required before staff returns to work. Because of continued excretion of virus, the need for good hand hygiene should be stressed to staff returning from illness” [27]. Guidelines and Consensus Document {Grade III-A}
  5. According to Bolyard et al (1998) “Restriction from patient care and the patient’s environment or from handling food is indicated for personnel with diarrhea or acute gastrointestinal symptoms regardless of causative agent” [16]. Evidence based reviews with guidelines formed out of reviewed literary sources {Grade III-A}
  6. According to Gotz et al (2002) “Transmission between food handlers within a kitchen and transmission from asymptomatic and post-recovery persons complicated outbreak control efforts. Current advice is to stay home for at least 2 days after having had symptoms of gastroenteritis in order to prevent spread of pathogens” [12]. Review of Outbreaks and Epidemiology {Grade III-A}
  7. According to Parashar et al (1998) “Exclusion of sick food handlers from work for 48-72 hours after cessation of diarrhoea and vomiting has been considered adequate to prevent and control Norwalk-like virus outbreaks related to food handling” [13]. Review of Outbreaks and Epidemiology {Grade III-A}
  8. Patterson et al (1993) stated, “The Public Health Laboratory Services (PHLS) has recommended that food-handlers should not return to work for at least 48 hours after recovery” [14].  Review of Outbreaks and Epidemiology {Grade III-A}
  9. According to Center for Disease Control and Prevention (2006) “The outbreak in Florida associated with a waterslide (May 2004) demonstrated that the use of these slides by a person infected with a fecal-oral transmissible microbe (in this case, norovirus) contaminated the waterslide, so it became an ideal venue for spreading disease. As with pools, spas, and fountains, appropriate treatment of recreational water venues and exclusion of persons with diarrhea is needed to prevent disease transmission” p.21 [25].  Review of Outbreaks and Epidemiology {Grade III-A}
  10. According to Cheng et al (2006) “…all symptomatic patients were immediately isolated in the infectious disease ward (Ward B) with private toilet facilities. They were kept in isolation until free from any enteric symptom for at least 24 hours” [11]. Review of Outbreaks and Epidemiology {Grade III-A}
  11. According to the Center for Disease Control and Prevention (1996), “In several Minnesota schools, one viral-disease outbreak (250 cases) caused by a Norwalk-like virus was associated with contaminated hamburger buns and cookies that were prepared by ill food handlers at a bakery” [17]. Review of Outbreaks and Epidemiology {Grade III-A}

Asymptomatic

  1. According to Cheng et al (2006) “…all symptomatic patients were immediately isolated in the infectious disease ward (Ward B) with private toilet facilities. They were kept in isolation until free from any enteric symptom for at least 24 hours. Ward A was closed to new admissions once the norovirus outbreak was suspected. Asymptomatic patients were kept in Ward A and were closely monitored for any gastroenteritis symptoms” [11].    Review of Outbreaks and Epidemiology {Grade III-A}
  2. According to California Department of Health Services Division of Communicable Disease Control in Consultation with Licensing and Certification Program “Asymptomatic, exposed residents should not be moved from an affected to an unaffected nursing unit. The value in moving asymptomatic resident who have been exposed is uncertain since they may already be infected” [27]. Guidelines and Consensus Document {Grade III-A}
  3.  Parashar et al (2001) state, “The low infectious dose of (Norwalk) readily allows spread by droplets, fomites, person-to-person transmission and environmental contamination, as evidenced by the increased rate of secondary and tertiary spread among contacts and family members. Prolonged duration of viral shedding that can occur among asymptomatic persons increases the risk of secondary spread and is of concern in foodhandler-related transmission” [10]. Review of Outbreaks and Epidemiology {Grade III-A}
  4. According to the American Academy of Pediatrics, “Children and caregivers who excrete intestinal pathogens but no longer have diarrhea may be allowed to return to child care once the diarrhea resolves” [19].  Guidelines and Consensus Document {Grade III-A}
  5. Parashar et al (1998) state, “The demonstration of a common viral strain in the stool specimens from the asymptomatic food handler, and 5 company employees and an immune response to the virus obtained from company employees in paired sera from the sick food handler strongly suggest a common source of infection and link the company outbreak to the sandwich facility…The Exclusion of infectious food handlers from work for prolonged periods is theoretically possible but is hard to implement, and is not feasible for infected food handlers who are asymptomatic” [13]. Review of Outbreaks and Epidemiology {Grade III-A}
  6. According to Lo et al (1994), “The available evidence indicates that the probable source of contamination of the salad on 7 March in the hospital was a salad food handler who contaminated food pre-symptomatically. She had nursed her baby who was ill with vomiting and diarrhoea on 6 and 7 March and developed symptoms of gastrointestinal illness herself on 8 March, when she vomited in the Kitchen” [6].   Review of Outbreaks and Epidemiology {Grade III-A}     
  7. According to Patterson et al (1993),“ In this outbreak the analysis of the food specific attack rates identified two food that were independently associated with illness; ham and coronation chicken, with the latter being most strongly implicated. Foodhandler A used her hands without gloves to slice the ham on 19 April the day after cessation of illness. The coronation chicken was prepared on the morning of 20 April when she was still symptom-free; she boned cooked chicken using bare hands. It is improbable that other serving staff were responsible for the outbreaks as none had served foods while ill or within 48 hours of gastrointestinal illness” [14]. Review of Outbreaks and Epidemiology {Grade III-A}
  8. According to the Communicable Disease Report (1995), “do not transfer patients during incubation period” [20]. Guidelines and Consensus Document {Grade III-A}
  9. According to the PHLS Advisory Committee (2004), “do not transfer patients during incubation period. Authorities must satisfy themselves of the adequacy of hygiene and toilet facilities and arrangements” [18]. Guidelines and Consensus Document {Grade III-A}

References

    1. Lopman BA, Reacher MH, Vipond IB et al. (2004). Clinical Manifestation of Norovirus Gastroenteritis in Health Care Settings. Clinical Infectious Diseases, 39, 318–24. Review of Outbreaks and Epidemiology
    2. Blanton LH, Adams SM, Beard S et al. (2006). Molecular and Epidemiologic Trends of Caliciviruses Associated with Outbreaks of Acute Gastroenteritis in the United States, 2000–2004. The Journal of Infectious Diseases, 193, 413–21. Review of Outbreaks and Epidemiology
    3. Hoebe CJPA, Vennema  H, Roda Husman AM de, and Van Duynhoven, YTHP.  Outbreak among Primary Schoolchildren Who Had Played in a Recreational Water Fountain. The Journal of Infectious Diseases, 189, 699–705.  Review of Outbreaks and Epidemiology;
    4. Blacklow, N. (2007). Epidemiology of viral gastroenteritis in adults. UpToDate.com, 1-8. Evidence Based Literature
    5. Matson, D. (2007). Epidemiology, pathogenesis, clinical presentation and diagnosis of viral gastroenteritis in children. UpToDate.com, 1-8. Evidence Based Literature
    6. Lo SV, Connolly AM, Palmer SR et al. (1994). The role of the pre-symptomatic food handler in a common source outbreak of food-borne SRSV gastroenteritis in a group of hospitals. Epidemiology and Infection, 113, 513-521. Review of Outbreaks and Epidemiology
    7. Treanor, J. (2007).Clinical features of gastroenteritis due to Noroviruses (Norwalk-like) and other small viruses. UpToDate.com, 1-7. Evidence Based Literature
    8. Simon A, Schildgen O, Eis-Hubinger A, Hasan C et al. (2006). Norovirus outbreak in a pediatric oncology unit. Scandinavian Journal of Gastroenterology, 41, 693-699. Review of Outbreaks and Epidemiology
    9. Widdowson MA, Cramer E, Hadley L et al. (2004).Outbreaks of Acute Gastroenteritis on Cruise Ships and on Land: Identification of a Predominant Circulating Strain of Norovirus--United States, 2002. J Infect Dis. 2004 Jul 1;190(1):27-36. Epub 2004 Jun 8. Review of Outbreaks and Epidemiology
    10. Parashar U, Quiroz E, Mounts A, Monroe S et al. (2001). Norwalk-Like Viruses: Public Health Consequences and Outbreak Management. Morbidity and Mortality Weekly Report, 50, RR-9. Review of Outbreaks and Epidemiology
    11. Cheng F, Leung T, Lai R, et al. (2006). Rapid Control of norovirus gastroenteritis outbreak in an acute paediatric ward. Acta Paediatrica, 95, 581-586. Review of Outbreaks and Epidemiology
    12. Gotz H, Jong B de, Lindback J et al. (2002). Epidemiological Investigation of Food-borne Gastroenteritis Outbreak Caused by Norwalk-Like Virus in 30 Day-care Centers. Scandinavian Journal of Infectious Diseases, 34, 115-121. Review of Outbreaks and Epidemiology
    13. Parashar UD, Dow L, Fankhauser RL et al. (1998). An outbreak of viral gastroenteritis associated with consumptions of sandwiches: implications for the control of transmission by food handlers. Epidemiology and Infection, 121, 615-621. Review of Outbreaks and Epidemiology
    14. Patterson T, Hutchings P and Palmer S. (1993). Outbreaks of SRSV gastroenteritis at an international conference traced to food handled by a post-symptomatic caterer. Epidemiology Infection, 111,157-162. Review of Outbreaks and Epidemiology
    15. Daniels NA, Mackinnon L et al.(2002). Foodborne disease outbreaks in United States Schools. Pediatric Infectious Disease Journal, 21, 623-628. Review of Outbreaks and Epidemiology
    16. Bolyard EA, Tablan OC, Williams WW et al.(1998). Guidelines for Infection Control In Health Care Personnel. American Journal of Infection Control, 26, 289-354. Evidence based reviews with guidelines formed out of reviewed literary sources
    17. Center for Disease Control and Prevention. (1996). Surveillance for Foodborne-Disease Outbreaks United States, 1988–1992. Morbidity and Mortality Weekly Report, 45, SS-5. Review of  Outbreaks and Epidemiology
    18. Public Health Laboratory Service, Advisory Committee on Gastrointestinal Infections. (2004). Preventing Person-to-Person Spread Following Gastrointestinal Infections: Guidelines for Public Health Physicians and Environmental Health Officers. Communicable Disease and Public Health , 7 (4), 362-384. Guidelines and Consensus Document
    19. APHA, AAP and NRCHS. (2004). Child Care Provider's Health and Well Being. National Health and Safety Performance Standards: Guidelines for Out-of-Home Child Care. Second Edition. American Academy of Pediatrics, the American Public Health Association and the National REsoiurnce Center for Health and Safety in Child Care , 1-95. Guidelines and Consensus Document
    20. Communicable Disease Report Review. The prevention of human transmission of gastrointestinal infections, infestations, and bacterial infestations. A Guide for Public Health Physicians and Environmental Health Officers in England and Wales. 1995; Volume 5  Number 11: R158-72. Guidelines and Consensus Document
    21. Isakebaeva ER, Widdowson MA, Beard SR et al. (2005). Norovirus Transmission on Cruise Ships. Emerging Infectious Diseases, 11(1), 154-7. Review of Outbreaks and Epidemiology
    22. Widdowson MA, Sulka A, Bulens SN et al. (2005). Norovirus and Foodborne Disease, United States, 1991-2000. Emerging Infectious Diseases, 11 (1), 95-102. Review of Outbreaks and Epidemiology
    23. Leena M, Miettinen IR and Von Bonsdorff CH. (2005) Norovirus Outbreak from Drinking Water. Emerging Infectious Disease, 11(1), 1716-1721. Review of Outbreaks and Epidemiology
    24. Center for Disease Control and Prevention. (2002). Surveillance for Foodborne-Disease Outbreak-United States, 1998-2002. Morbidity and Mortality Weekly Report, 55(SS-10), 1-48. Review of Outbreaks and Epidemiology
    25. Center for Disease Control and Prevention (2006). Surveillance for Waterborne Disease and Outbreaks Associated with Recreational Water — United States, 2003–2004 and Surveillance for Waterborne Disease and Outbreaks Associated with Drinking Water and Water not Intended for Drinking —United States, 2003–2004.  Morbidity and Mortality Weekly Report, 55 (2), 1-68. Review of Outbreaks and Epidemiology
    26. Bruin E de, Duizer E, Vennema H and Koopmans MPG. (2006). Diagnosis of Norovirus outbreaks by commercial ELISA or RT-PCR. Journal of Virological Methods, 137, 259-264. Evidence Based Literature
    27. California Department of Health Services Division of Communicable Disease Control in Consultation with Licensing and Certification Program. (2006). Recommendation for the Prevention and Control of Viral Gastroenteritis Outbreaks in California Long-Term Care Facilities.1-9. Guidelines and Consensus Document