Hepatitis B Transmission at School

This case report describes an elementary school teacher who acquired hepatitis B virus from a student. Laboratory tests confirmed that teacher and student had the same HBV subtype with identical DNA sequences. However, the teacher reported none of the usual high risk factors for acquiring HBV infection.

Person-to-person transmission of HBV has been well documented in situations of close personal contact, specifically among household members. It is presumed that in these settings transmission occurs from skin lesions (such as eczema or impetigo) or sharing of blood-contaminated objects (such as toothbrushes or razors), although the specific pathway of transdermal exposure is rarely identified. Since HBV is stable on environmental surfaces for at least 7 days, indirect inoculation may occur via inanimate objects.

The epidemiologic investigation in this report supports the conclusion that the teacher acquired HBV infection in the school setting from the HBV-infected student. While the teacher recalled no overt exposure to blood, she reported an instance when the student¡¯s saliva and nasal secretions had come into contact with her chapped hands. Although the concentration of virus in saliva of HBV-infected persons is several orders of magnitude lower than that found in blood, it is possible that transmission occurred through exposure of the teacher¡¯s nonintact skin to the student¡¯s saliva. The risk of transmission may have been increased because of the relatively high titer of virus in the student¡¯s blood (and possibly microscopic blood in the saliva). Transmission from saliva has not been documented before except through percutaneous exposures (e.g., a bite that breaks the skin).

Hepatitis B virus is present in high titers in blood and serous fluids and in moderate titers in saliva, semen, and vaginal secretions of infected individuals. The most frequently reported risk factors for acquisition of hepatitis B in the United States remain high-risk sexual activity and injection drug use.

(Williams I et al. Hepatitis B virus transmission in an elementary school setting. JAMA 1997; 278(24):2167-2169)