ARCHIVED - Possible Transmission of Hepatitis A in a School Setting

15 November 2006

Volume 32

Number 22

E Brodkin, MD (1), M Lindegger, RN, MSc (2), S Kassam, BTech, REHO (2), R Gustafson, MD (2)

1. Community Medicine Residency, Faculty of Medicine, University of British Columbia

2. Vancouver Coastal Health, Vancouver, British Columbia

Acute hepatitis A results from infection of the liver by the hepatitis A virus (HAV). Transmission is person to person through the fecal-oral route. Outbreaks have been linked to contaminated food and water. Post-exposure prophylaxis is offered to those contacts of an acute case of hepatitis A considered to be at increased risk of infection. Currently in British Columbia post-exposure prophylaxis consists of hepatitis A vaccine within 14 days of the last contact. It is not generally offered to teachers and students in contact with a case of hepatitis A in a school setting because the risk of transmission in school settings is considered low.We report on two cases of hepatitis A in an elementary school, which illustrate the importance of good hygiene in schools and raise implications for post-exposure prophylaxis recommendations.

Case Descriptions

Case 1: On 11 November, 2005, a 9-year-old Vancouver boy had symptoms of fatigue and anorexia. Liver enzyme tests and serologic tests for hepatitis A were undertaken, as his mother had been given a diagnosis of hepatitis A the previous day. Serologic tests for the case were reported to be positive for anti-HAV IgM on 14 November. Two potential exposures were identified during the incubation period. The family had visited South America in September, and the boy and his mother had eaten raw fish dishes at the end of their stay, probably on 25 and 28 September. Other family members who did not eat the fish were not ill. The mother had also visited Central America between 15 and 22 October, and it is possible that she acquired the infection there, which would mean that her son was a secondary case. The boy remained home from school after the diagnosis had been confirmed but had attended school up to 11 November.

Case 2: On 5 December, 2005, an 11-year-old boy presented to the Emergency Department with a 2-day history of malaise, fatigue, right upper quadrant pain and vomiting. Blood samples showed elevated bilirubin and transaminase levels. Serologic testing for anti-HAV IgM was positive. An initial investigation into possible sources revealed no risk factors for hepatitis A. There was no known close contact with another case, no travel history, no drug use or history of sexual contacts. Restaurants where the case had eaten were inspected, but there was no evidence to suggest that any might have been the source of the infection. A search for any links was undertaken through the Vancouver Coastal Health records of recent cases of hepatitis A. It revealed that case 2 attended the same school as case 1, although they were not in the same grade and the two boys did not know each other.

Environmental investigation

An Environmental Health Officer visited the school attended by the two boys. She noted that their classrooms were in the same corridor, two doors apart, and that they shared a common bathroom and drinking fountain. The bathroom had three sinks but only one soap dispenser and one paper towel dispenser. The cleaning materials used by the maintenance staff in the bathroom were adequate if used according to the manufacturer's instructions, but there was no formal cleaning schedule in place for either the bathroom or the drinking fountain. There was very little signage encouraging the students to wash their hands and no program in place to ensure that they washed their hands before eating lunch.

Discussion

Post-exposure prophylaxis is not currently recommended for teachers and students in contact with a case of hepatitis A in a school unless there is evidence that transmission is occurring in the classroom or the school ¹. The probability of secondary cases in a school setting is believed to be low enough that the potential benefits of mass immunization do not outweigh the risks and the costs. A review of the literature found that there have been some reports of hepatitis A outbreaks in schools, the critical exposure usually being a common bathroom ^2-5. Lack of soap, hand towels and toilet paper make it more likely that an outbreak will occur in this setting³. There is also evidence that good hygiene practices in school settings, particularly handwashing, can prevent and control outbreaks^2,6.

The two cases in this report are linked by a common school. Case 1 either acquired his infection from eating raw fish in South America, with an incubation period of 44 to 47 days, or he was a secondary case to his mother with a short incubation period. Case 1 attended school before the onset of his symptoms on 11 November and was infectious during the latter half of his incubation period, which probably lasted from mid-October to mid- November. Case 2 became symptomatic on 3 December with an exposure some time between mid-October and mid-November. The infectious period of Case 1 overlaps with the exposure window of Case 2, and the two cases were almost certainly sharing a bathroom and a drinking fountain during this time. Despite careful investigation, we were unable to identify any other risk factors for Case 2 and believe that the exposure at school is the most likely source of his infection. The Environmental Health Officer did identify several deficiencies at the school that would increase the risk of hepatitis A transmission, including inadequate soap and paper towel dispensers in the bathrooms and a lack of programs to promote handwashing.

Recommendations and orders were drafted by the Environmental Health Officer and communicated to the school. These included increasing the number of soap and paper towel dispensers in the bathrooms, formalizing the cleaning schedule for the bathrooms and drinking fountains, posting more signage encouraging handwashing, and implementing a program to ensure that students washed their hands before eating lunch. The events described in this report also raise the issue of whether current recommendations to not offer post-exposure prophylaxis to teachers and students in contact with a case of hepatitis A in a school should be revisited. Outbreaks have occurred in schools, and previous reports and our experience suggest that when transmission does occur the critical factor is usually a shared bathroom. Perhaps consideration should be given to offering prophylaxis to all those who share a bathroom with a case of hepatitis A in a school setting. As post-exposure prophylaxis is now carried out with hepatitis A vaccine rather than immune globulin, it may be that in this situation the risk:benefit ratio has shifted in favour of prophylaxis.

Acknowledgments

The authors thank the following for their assistance: C. O'Reilly, and the Vancouver School Board, Vancouver, British Columbia.

References

1. National Advisory Committee on Immunization (NACI). Statement on the prevention of hepatitis A infections. CCDR 1994;20(16):133-43.

2. Leoni E, Bevini C, Degli Esposti S et al. An outbreak of intrafamiliar hepatitis A associated with clam consumption: Epidemic transmission to a school community. Eur J Epidemiol 1998;14(2):187-92.

3. Rajaratnam G, Patel M, Parry JV et al. An outbreak of hepatitis A: School toilets as a source of transmission. J Public Health Med 1992;14(1):72-7.

4. Naus M, EverettW, Davies S et al. A school outbreak of hepatitis A in southwestern Ontario. CDWR 1989;15(45):225-8.

5. Reid J, Carter JM. Hepatitis A - investigation and control of outbreaks in two primary schools. Public Health 1986;100(2):69-75.

6. Marks PJ, Fey RE, Parry JV et al. Use of hygiene advice and active immunisation to control an outbreak of hepatitis A. Commun Dis Public Health 2001;4(3):158-62.