Hepatitis A

 

Literature Recommendations

Exclusion-Case in SOS*
(Symptomatic)

Yes [1,2,3,4,5,6,7,12d,14,17,18]
Grade II-A

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

No, if past communicable period. [7,12d,14,15,18]
Exclusion in Special Case [6a]
Grade II-A

Clearance-Case in SOS*

No Clearance.
Exclude until 7 days after onset of jaundice and/or until diarrhea resolves. [1,2,3,4,5,6,7,18]
Grade II-A

Exclusion of Contact
(Symptomatic)

Yes [1,2,3,4,5,6,7,12,14,17,18]
Grade II-A

Exclusion of Contact
(Asymptomatic)

No [12d,14,15,18]
Exclusion in Special Cases [6a]
Grade II-A

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

Yes [1,2,3,4,5,7,8b,9c,10]
Grade II-A

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

No [8c,9c,20]
For Post exposure Prophylaxis (PEP) Recommendations see Preventive measures 16.
Grade II-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 See number five under the Preventive Measures
b See number seven under the Preventive Measures
c See number eight under the Preventive Measures
d See number nine under the Preventive Measures and number one under the Outbreaks.
e See number six and seven under the Outbreak

Disease Trends in the U.S.:

According to the Red Book published by the American Academy of Pediatrics, “In the pre-vaccine era in the United States, hepatitis A was one of the most commonly reported vaccine-preventable diseases, but its incidence has declined in recent years. In 2004, 5683 cases were reported to the Centers for Disease Control and Prevention (CDC), compared with an average of approximately 26,000 cases per year during the pre-immunization era.” [2]

Wesley et al. (2007) states that since 1995, the incidence of reported acute hepatitis A cases has declined by 88%, to the lowest rate ever recorded (2005: 1.5/100,000 population). Declines were greater among children and in states where routine vaccination of children was recommended beginning in 1999, compared with the remaining states.  Wesley also reported that the most frequent risk factor identified for hepatitis A was international travel, followed by sexual or household contact with hepatitis A patients, then suspected food or waterborne outbreak, contact of day care child/employee, child/employee in day care center and injection drug users at 15.1%, 11.9%, 10.9%, 6.5%, 5.5%, and 4.8% respectively. [11]

Outbreaks:

  1. The article by Patnaik et al. talks about a laboratory confirmed case that was reported to Tri-County Health Department (TCHD) on Monday, December 30, 2002 in Colorado.  TCHD subsequently determined that the source was a food handler who worked in a local restaurant during the period of infectiousness.  After considering the public health risk, TCHD decided to offer immune globulin (IG) to all potentially exposed restaurant patrons. Also, all employees of the restaurant were either given IG or removed from work for the duration of the Hepatitis A incubation period of 50 days. [12]
  2. The article by Massoudi et al. presents a case reported to Kentucky health department on October 1994, of a food handler with hepatitis A, working for a catering company. Kentucky health department decided not to offer immune globulin to the patrons because the foodhandler’s hygiene was assessed to be good and he denied having diarrhea. In a retrospective cohort study, the author found a total of 91 cases of hepatitis A among residents of northern Kentucky and southern Ohio who reported having eaten food prepared by the caterer where the infected food handler worked. The overall attack rate was 7% among the 1318 people who attended these events. [13]
  3. LaPorte et al. discusses an outbreak that started with Massachusetts Department of Public Health being notified that a worker at restaurant A in county X had hepatitis A on October 26, 2001. On the basis of the worker’s reported hygiene practices, work duties, and lack of gastrointestinal symptoms, health officials considered Hepatitis A contamination of food prepared by this food handler unlikely and did not issue a public notification or recommend PEP for restaurant patrons. The worker denied any change in bowel habits; however, assessment was difficult because the worker had a colostomy and normally produced unformed stool that collected in an ostomy appliance. The worker reported that the appliance was secured under several layers of clothing and was never changed at work. This situation led to an outbreak of 46 cases by December 3. [14]
  4. Jones et al. reported outbreaks of Hepatitis A in Alaska, Florida, North Carolina, and Washington.  [15]
    1. Between June 18 and July 20, 1988, 32 serologically confirmed hepatitis A cases among persons who resided in or had visited Peters Creek, Alaska (population 4000), were reported to the Alaska Department of Health and Social Services.  Alaska Department of Health and Social Services conducted a case-control study to figure out the potential sources of the outbreaks. The outcome pointed towards consummation of ice-slush from a local convenience store, which was prepared by possible infected employees.
    2. In August 1988, the Alabama Department of Public Health noted an increase in cases of serologically confirmed hepatitis A in persons living in several areas of the state.  A case-control study conducted by the Alabama Department of Public Health found that the source of the infection was oysters that apparently had been illegally harvested from unapproved coastal waters of Bay County.
    3. Beginning September 30, 1988, hepatitis A cases among employees of businesses located in east Greensboro were reported to county health departments in central North Carolina. Only day-shift employees became ill. A total of 32 outbreak-associated cases were eventually reported.   A case-control study conducted by the North Carolina Department of Human Resources, found no real source of the infection, but possibly Hepatitis A infected IV-Drug user who worked as food handler.
    4. In May 1989, the Seattle-King County Department of Public Health (SKCDPH) received reports of and investigated 213 cases of Hepatitis A— noting a threefold increase over the average of 68 cases reported in each of the first 4 months of 1989. The Onset of the illness was clustered around April 28-May 5. Of the cases, one hundred seventeen (55%) of the patients had eaten at one outlet of a Seattle-area restaurant chain (chain A).  Since four of the cases were employees of the restaurant chain they were considered a possible source for the outbreak.
  5. Skala et al. refers to three outbreaks reported between 1990-1992 in Missouri, Wisconsin, and Alaska. In all three, the outbreaks were linked to infected food handlers.  [17]
  6. Fiore in his article the “Hepatitis A Transmitted by food” examined outbreaks from 1968 to 2001 caused by infected food handler.  There were 17 outbreaks he looked during this time frame of which 6 were linked to food handlers who were asymptomatic while working. [18]
  7. Staes et al. reviewed Hepatitis A cases from May 1996 to December 1996 in Salt Lake County, Utah, with no identified source of infection.  What he found was 70 household contacts (20%) were IgM anti-HAV-positive, including 52% of children 3 to 5 years old and 30% of children <3 years old. In multivariate analysis, the presence of a child <3 years old (odds ratio [OR]: 8.8; 95% confidence limit [CL]: 2.1, 36) and a delay of >14 days between illness onset and reporting (OR: 7.9; 95% CL: 1.7, 38) were associated with household transmission. Of 18 clusters of infections linked by transmission between households, 13 (72%) involved unrecognized infection among children <6 years old.  Staes et al. concluded that “In households of persons reported with Hepatitis A with no identified source, Hepatitis A infection among young children was common and frequently undetected.  Nearly one half of household contacts under 6 years of age who underwent serologic testing were found to be IgM anti-HAV-positive. Although asymptomatic infection was unusual, the symptoms of infected children were nonspecific and, in most cases, not recognized as Hepatitis A.  These Hepatitis A-infected children were frequently the source of infection for others. The presence of children, 3 years of age was associated with transmission within the household, consistent with reports that implicate diapered children as the most important vectors of Hepatitis A transmission in child care centers.” [19]

Hepatitis A:  the infection typically causes acute fever, malaise, anorexia, nausea and abdominal discomfort.  This usually leads to jaundice and dark urine in few days.  Severe illness is rarely seen except in patients with pre-exciting liver disease. Infants and young children normally have very mild to no symptoms (asymptomatic) and jaundice is almost always absent. [1, 2, 3, 4, 11]

Organism: Hepatitis A virus (HAV) is classified under the enterovirus group of the Picornaviridae family.  Hepatitis A is a single molecule of RNA surrounded by a small protein capsid.  [1, 2, 3, 4, 5, 11]

Reservoir of infection: Humans, especially asymptomatic children.  Rarely, chimpanzees can be carrier of the virus. [1, 2, 3, 5]

Modes of transmission:

  • Among cases of Hepatitis A reported to the Center for Disease Control and Prevention (CDC), the identified risk factors include close personal contact with a person infected with Hepatitis A, household or personal contact with a child care center, international travel, a recognized foodborne or waterborne outbreak, male homosexual activity, and I.V. drug use. [2,3,4,5,11]
  • Infectious food handlers may contaminate non-cooked foods such as salads.  Infection can also occur through ingestion of contaminated food, water or seafood such as oysters raised in contaminated waters. [1,5,11]
  • Massoudi et al. stated that “factors to consider in assessing the risk of transmission to patrons include whether the infected foodhandler handled foods that were not subsequently cooked; whether he or she had diarrhea, which might increase the risk of transmission; and his or her hygienic practices. If a foodhandler with Hepatitis A who handles high risk foods (foods that are handled and not subsequently cooked) during the infectious period is judged to have poor hygiene or has diarrhea, the Centers for Disease Control and Prevention (CDC) recommends considering notification of exposed members of the public to offer them IG if IG can be administered within two weeks of exposure.”[13]

Attack rates: Literature related to attack rates was unavailable in the public domain.

Infectious dose: The infectious dose is unknown but presumably, 10-100 virus particles. [1]

Incubation Period:  An average of 28-30 days (ranging from 15-50 days). [1, 2, 3, 4, 5]

Infectious Period: The latter half of the incubation period to a few days after the onset of jaundice. [1, 2, 3, 4, 5]

Asymptomatic carrier state:  

  • According to the Red Book published by the American Academy of Pediatrics, in approximately 50% of the cases reported to CDC, the source cannot be determined. Fecal-oral spread from people with asymptomatic infections, particularly young children, likely accounts for many of these cases with an unknown source. Most infected children younger than 6 years of age in child care are asymptomatic or have nonspecific manifestations. Hence, spread of Hepatitis A infection within and outside a child care center often occurs before recognition of the index case(s) [2]
  • Wesley et al. states that the majority (>70%) of infections among young children are asymptomatic. [11]

Diagnosis: A blood test indicating IgM anti-HAV antibodies confirms recent infection. These antibodies are usually found in the blood 5-10 days after the exposure and are present for two to four months after infection. [1, 2, 3, 4, 5]

 

Preventive Measures
Exclusions:

  1. Australian Blue Book-Guidelines for the control of infectious diseases states that all infected cases should be excluded from childcare, school, or work for at least one week after the onset of illness or jaundice, until they are well. It is also stated that infected persons should not prepare meals for others while infectious, nor share utensils, toothbrushes, towels and face washes. They also recommend that when the case involves a food handler, consider serological testing of co-workers to determine whether they have been infected or are susceptible and place uninfected susceptible co-workers under surveillance and administer IG prophylaxis. [1] Guidelines and Consensus Document {Grade III-A}
  2. The Red Book published by the American Academy of Pediatrics states that Children and adults with acute Hepatitis A infection who work as food handlers or who attend or work in child care settings should be excluded for 1 week after onset of the illness. [2] Guidelines and Consensus Document {Grade III-A}
  3. Bolyard EA, et al. stated that personnel who have acute Hepatitis A should be excluded from duties until 1 week after the onset of jaundice.  And health care workers should be restricted from patient contact, contact with patient’s environment and food handling. [3] Evidence based reviews with guidelines formed out of reviewed literary sources {Grade III-A}
  4. Communicable Disease Control Hepatitis A published by BCCDC states the following exclusions: [4] Guidelines and Consensus document {Grade III-A}
    1. “The Medical Health Officer should exclude the case from occupations involving the handling of food or milk for 14 days from the onset of illness, or 7 days after the onset of jaundice, whichever is the longer, unless it is demonstrated that the person’s serum has anti-HAV (Total) and no anti-HAV IgM”
    2. “The Medical Health Officer should consider the exclusion of children and adults with Hepatitis A from a child care facility for 14 days from the onset of the illness, or for 7 days after the onset of jaundice (whichever is the longer), or until Hepatitis A vaccine or IG has been provided to all the children and staff at the centre.”
    3. “If the case is a food handler, the Medical Health Officer may consider issuing a media release to alert patrons of the need for Hepatitis A vaccine or IG for those situations in which:
      1. The person was infectious while working, AND handled foods which were not cooked after handling, AND the food handler’s practices were not hygienic, OR the food handler has had diarrhea, AND the contacts can be identified and receive immunoprophylaxis within 14 days of the last exposure to the case while the case was in the infectious period.”
    4. “The Medical Health Officer may consider excluding a contact from food or milk handling duties, until it is demonstrated that the contact has received Hepatitis A vaccine or IG, or has demonstrable anti-HAV (Total) and no anti-HAV IgM.”
  5. A guideline produced by Ontario Medical Association and the Ontario Hospital Association states the following exclusions for Hepatitis A: [6] Guidelines and Consensus Document {Grade III-A}
    1. “If symptoms or circumstances are suggestive of Hepatitis A, the food handler or HCW must remain off work until 7 days following onset of jaundice. Hepatitis A virus vaccine should be given for post-exposure prophylaxis of contacts (including other food handlers) as soon as possible and preferably within 7 days of exposure to the infected person (National Advisory Committee on Immunization, 2001). Administration of immune globulin (IG) is recommended for immunocompromised contacts who may not respond fully to the vaccine.”
    2. 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 after 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.”
  6. Exclusion and Inclusion of ill children in child care facilities by APHA, AAP, & NRCHS state the following exclusion for children with Hepatitis A infection: [7] Guidelines and Consensus Document {Grade III-A}
    1. “A child who develops jaundice (when the skin and the white areas of the eyes are yellow) while attending child care should be separated from other children and the child's parent or legal guardian shall be called to remove the child.  The child shall remain separated from the other children as described above until the parent or legal guardian arrives and removes the child from the facility. Exclusion for acute diarrhea shall continue until either the diarrhea stops or the continued loose stools are deemed not to be infectious by a licensed health care professional.  Exclusion for Hepatitis A virus (HAV) shall continue for one week after onset of illness or until immune globulin has been administered to appropriate children and staff at the facility” (symptomatic)
    2. “Children and caregivers who excrete intestinal pathogens but no longer have diarrhea generally may be allowed to return to child care once the diarrhea resolves” (Asymptomatic)
  7. Guidelines on the Management of Communicable Diseases in Schools and Nurseries by HPA states that Exclusion is not recommended in older children because Hepatitis A is generally a mild illness. Furthermore, exclusion would be largely ineffective because patients are most infectious in the prodrome period, therefore, the asymptomatic cases being involved in the transmission. However, exclusion should still be attempted in nurseries because of the risk to adults [8] Guidelines and Consensus Document {Grade III-A}
  8. Richardson M and et al. concluded in the evidence base research that Exclusion of children from schools and preschool is largely ineffective, but recommended in day-care centers and preschools because of the risk to adults.  The reasons for exclusion being ineffective are as follows: [9] Evidence based reviews with guidelines formed out of reviewed literary sources{Grade II-A}
    1. Exclusion will not be fully effective because cases may be infectious before the onset of disease.
    2. Exclusion is not required as this is generally a mild illness in childhood.
    3. Exclusion will not be fully effective because asymptomatic infections occur and may be involved in transmission
  9. Patnaik et al. stated, “TCHD decided to offer immunoprophylaxis to restaurant patrons since the ill food worker had been infectious while preparing ready-to-eat foods and had not practiced proper hand hygiene. The Advisory Committee on Immunization Practices (ACIP) recommends considering prophylaxis for people who consume food prepared by an infected person if 1) the food worker has directly handled uncooked food or cooked food, 2) the food worker has had diarrhea or poor hygiene practices and 3) patrons can be identified and treated within two weeks of the exposure (CDC, 1999).” [12] Review of Outbreaks and Epidemiology {Grade III-A}
  10. Massoudi et al. stated, “The peak of infectivity of a person infected with Hepatitis A occurs during the two weeks before the onset of illness. When a case of Hepatitis A is recognized in a foodhandler, immune globulin (IG), which is effective in preventing Hepatitis A if given within two weeks of exposure, should be administered to the foodhandler's co-workers to reduce the possibility of transmission.” The author also stated that all of the other employees of Catering Company were tested for antibodies to Hepatitis A (ant-HAV), and they all received IG. [13] Review of Outbreaks and Epidemiology {Grade II-A}
  11. LaPorte et al. states that, “During 1992–2001, approximately 230,000 cases of Hepatitis A were reported in the United States. Although food handlers are not at higher risk for Hepatitis A infection because of their occupation, approximately 8% of adults reported with hepatitis A are identified annually as food handlers (CDC, unpublished data, 2003), indicating that thousands of food handlers have Hepatitis A each year. Unlike the majority of persons with Hepatitis A who transmit Hepatitis A only to close contacts, a Hepatitis A-infected food handler potentially can transmit Hepatitis A to many others and cause a substantial economic burden to public health.” The author also pointed out that none of the 20 food handlers at the restaurant had symptoms of Hepatitis A, although none were tested serologically for evidence of recent Hepatitis A infection.  The restaurant reopened after 19 food handlers received IG and one had been excluded from work. [14] Review of Outbreaks and Epidemiology {Grade III-A}
  12. Jones et al. suggests that, “Measures to prevent foodborne hepatitis A outbreaks include training of food handlers regarding proper hygiene and foodhandling practices, investigation of food handlers who have symptoms of hepatitis or are otherwise ill, prompt reporting by health-care providers to local health departments of patients with suspected foodborne Hepatitis A and prompt investigation by health departments of possible sources of infection. Consistent maintenance of good hand washing and other personal hygiene measures by foodhandlers is important because the patient source in foodborne outbreaks is often asymptomatic (as apparently occurred in North Carolina and Alaska). Prevention of Hepatitis A outbreaks associated with shellfish relies on surveillance of water beds where shellfish are harvested to ensure that there is no evidence of fecal contamination. Transmission and infection from shellfish also can be prevented by thorough cooking and proper storage and handling before and after cooking” [15] Review of Outbreaks and Epidemiology {Grade III-A}
  13. Dembek et al. suggest that, “A positive IgM anti-HAV test result in a person without typical symptoms of Hepatitis A might indicate asymptomatic acute Hepatitis A infection, previous Hepatitis A infection with prolonged presence of IgM anti-HAV, or a false-positive test result. Hepatitis A infection can manifest as a broad clinical spectrum, ranging from asymptomatic infection to typical hepatitis with fever and jaundice. Although an estimated 70% of children aged <6 years with Hepatitis A infection are asymptomatic, older children and adults usually have symptoms and 70% are jaundiced. Studies conducted during Hepatitis A outbreaks or among family members exposed to Hepatitis A indicate that Hepatitis A infection can cause asymptomatic infection with or without abnormal liver tests, primarily among young children.”[16] Review of Outbreaks and Epidemiology {Grade III-A}
  14. Skala et al. suggests that, “Foodborne Hepatitis A outbreaks are most often caused by contamination of food during preparation by an infected food handler. An important method of prevention is attention to personal hygiene, including frequent hand washing during all phases of food preparation. In addition, when Hepatitis A is diagnosed in a food handler, IG should be administered to all other food handlers at the establishment. The administration of IG to patrons should be considered if 1) the infected person is directly involved in handling, without gloves, foods that will not be cooked before they are eaten; 2) the hygienic practices of the food handler are deficient or the food handler has had diarrhea; and 3) patrons can be identified and treated within 2 weeks of exposure.” [17] Review of Outbreaks and Epidemiology {Grade III-2}
  15. Fiore suggests that, “Exclusion from duties that involve contact with food for at least 1–2 weeks after the onset of jaundice or until symptoms resolve is reasonable. Asymptomatic food handlers who are IgM anti-HAV positive are sometimes identified during investigations and measurements of ALT levels, in combination with likely dates of exposure, might be used to estimate whether the food handler has had recent infection and is potentially still capable of transmission. However, the validity of this approach is unknown.” [18] Review of Outbreaks and Epidemiology {Grade II-A}
  16. According to the latest ACIP Recommendation “Persons who recently have been exposed to HAV and who previously have not received hepatitis A vaccine should be administered a single dose of vaccine or IG (0.02 mL/kg) as soon as possible. Information about the relative efficacy of vaccine compared to IG post-exposure is limited, and no data are available in persons > 40 years of age or those with underlying medical conditions. Therefore, decisions to use vaccine or IG should take into account patient characteristics associated with more severe manifestations of hepatitis A, including older age and chronic liver disease. Additionally, the magnitude of the risk of HAV transmission from the exposure should be considered.
    1. For healthy person’s age ≥ 12 months – 40 years, hepatitis A vaccine at the age appropriate dose is preferred to IG because of vaccine’s advantages, including long term protection and ease of administration.
    2. For persons > 40 years of age, IG is preferred because of the absence of information regarding vaccine performance and the more severe manifestations of hepatitis A in this age group. Vaccine can be used if IG cannot be obtained.
    3. IG should be used for children age < 12 months, immunocompromised persons, persons who have been diagnosed with chronic liver disease, and persons for whom vaccine is contraindicated.
    Persons administered IG for whom hepatitis A vaccine is also recommended should receive a dose of vaccine simultaneously with IG. For persons who receive vaccine, the second dose should be administered according to the licensed schedule to complete the series. The efficacy of IG or vaccine when administered > 2 weeks after exposure has not been established.”[20] Guidelines and Consensus Document {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. Bolyard EA, Tabian OC, Williams WW, et al. Guideline for Infection Control in Health Care Personnel, 1998. AJIC 1998;26;289-354  Evidence based reviews with guidelines formed out of reviewed literary sources
      4. British Columbia Centre for Disease Control. Communicable Disease Control Hepatitis A June 2005. Accessed at http://www.bccdc.org/download.php?item=1057  Guidelines and Consensus Document
      5. Public Health Laboratory Service 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
      6. Ontario Medical Association and the Ontario Hospital Association. Enteric Diseases Surveillance Protocol for Ontario Hospitals. Published November 1989/Revised/Reviewed June 2005 Guidelines and Consensus Document
      7. APHA, AAP, & NRCHS. Exclusion and Inclusion of Ill Children in Child Care Facilities and Care of Ill Children in Child Care. National Health and Safety Performance Standards: Guidelines for Out-of-Home Child Care. Second Edition. 2002. A Joint Collaborative Project of The American Academy of Pediatrics Elk Grove Village, IL., The American Public Health Association Washington, D.C. & The National Resource Center for Health and Safety in Child Care, University of Colorado Health Sciences Center at Fitzsimons Campus Aurora, CO. Guidelines and Consensus Document
      8. UK’s Health Protection Agency.  Guidelines on the Management of Communicable Diseases in School and Nurseries.  Accessed at http://www.hpa.org.uk/infections/topics_az/schools/schools.pdf  Guidelines and Consensus Document
      9. 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
      10. AAP.  Managing Infection Diseases in Child Care and Schools: A Quick Reference Guide Aronson SS, Shope TR eds. Chapter 5.  Accessed on 7/30/07 at www.aap.org  Guidelines and Consensus Document
      11. Wasley A, Miller JT, Finelli L. Surveillance for Acute Viral Hepatitis- United States, 2005 MMWR March 16, 2007/Vol. 56/ No. SS-3 Evidence Based Literature
      12. Patnaik JL, Dippold L, Vogt RL. Hepatitis A in a Food Worker and Subsequent Prophylaxis of Restaurant Patrons. Journal of Environmental Health 2006; Vol. 69/No. 1: 16-18 Review of Outbreaks and Epidemiology
      13. Massoudi MS, Bell BP, Paredes V, et al. An Outbreak of Hepatitis A Associated with an Infected Foodhandler. Public Health Reports 1999; Vol. 114: 157-164 Review of Outbreaks and Epidemiology
      14. LaPorte T, Heisey-Grove D, Kludt P, et al. Foodborne Transmission of Hepatitis A-Massachusetts.  MMWR 2003; Vol. 52/No. 24: 565-567 Review of Outbreaks and Epidemiology
      15. Jones ME, Jenkerson SA, Middaugh JP, et al. Epidemiologic Notes and Reports Foodborne Hepatitis A – Alaska, Florida, North Carolina, Washington. MMWR 1990; 39(14);228-232 Review of Outbreaks and Epidemiology
      16. Dembek ZF, Hadler JL, Castrodale L, et al. Positive Test Results for Acute Hepatitis A Virus Infection Among Persons with n Recent History of Acute Hepatitis-United States, 2002-2004. MMWR May13, 2005/Vol. 54/ No. 18 Review of Outbreaks and Epidemiology
      17. Skala M, Collier C, Hinkle CJ, et al. Foodborne Hepatitis A Missouri, Wisconsin, and Alaska, 1990-1992. MMWR July 16, 1993 Vol. 42/ No. 27 Review of Outbreaks and Epidemiology
      18. Fiore A. Hepatitis A Transmitted by Food. CID 2004;38:705-715 Review of Outbreaks and Epidemiology
      19. Staes CJ, Schlenker TL, Risk I, et al. Sources of Infection among Persons with acute hepatitis A and No identified risk factors during a sustained community-wide outbreak. Pediatrics 2000; 106;e54 Review of Outbreaks and Epidemiology
      20. Centers for Disease Control and Prevention. ACIP MEETING SUMMARY Tom Harkin Global Communications Center June 27 – 28, 2007 . Retrieved on 9/20/07 at http://www.immunize.org/acip/ACIP_meeting_summary607.pdf. Guidelines and Consensus Document