BURLINGTON, N.H. - A New Hampshire elementary school teacher unknowingly contracted hepatitis B virus (HBV) from one of her students.
State and federal health officials tested the school staff, students and immediate family members of the teacher and discovered a student with HBV who had the same viral subtype (way1-2) and identical HBV-DNA sequences as the teacher. Epidemiologists could not determine the mode of transmission. None of the student's classmates exhibited any signs of HBV infection.
The New Hampshire State Division of Public Health and the Centers for Disease Control and Prevention (CDC) began an investigation to find the source of infection in the teacher and the extent of transmission, if any, from the HBV-infected student to other students and faculty.
Serum samples were obtained from the teacher's family, the infected student and other students and school staff. Serologic testing included total anti-HBc, HBsAg and antibody to HBsAG. Samples positive for HBsAG were tested for HBeAG and HBsAg subtype and examined for HBV DNA.
The teacher denied any HBV risk factors like multiple sex partners and intravenous drug use. She had three children, including a full-term infant born three weeks before her infection was diagnosed. No invasive procedures were performed during the course of her pregnancy. A routine screening in the first trimester was HBsAg negative.
When she was diagnosed, her infant received HepB immune globulin and began HepB vaccine (at 1 month of age). The infant's vaccine series was completed at 7 months of age. At 8 months, follow-up testing revealed the infant to be HBsAg positive. The teacher's husband and two older children had no evidence of infection, researchers said.
Researchers discovered the child had sneezed large amounts of nasal secretions and saliva onto the chapped, cracked hands of the teacher shortly before the onset of her infection. The teacher said she immediately washed her hands but did not see the school nurse because she saw no blood in the child's body fluids.
The student's mother was chronically infected with the virus. It appears the child was infected at birth. The student showed no signs of poor dental hygiene, nosebleeds, cuts or abrasions.
Of the 108 classmates of the infected student, 102 were tested for serologic markers of HBV infection, and none were positive. None of the children tested had detectable anti-HBs or a history of hepatitis B vaccination. From the 150 faculty, 94 were tested and only one had serologic markers of HBV infection The staff member had no contact with either the teacher or student, but her husband was found to be chronically infected with HBV, researchers said.
"Hepatitis B virus can be present in high titers in blood and serous fluids and in moderate titers in saliva, semen and vaginal secretions in those who are infected," said Ian Williams, PhD, program officer at the Hepatitis Branch, Division of Viral and Rickettsial Diseases at the CDC. "But this case does not suggest that the current [American Academy of Pediatrics] and ACIP recommendations advocating inclusion of HBV-infected children in schools should be changed or that routine screening is called for."
What should be considered, said Williams, is prophylaxis after exposure in instances of percutaneous or permucosal exposure to HBsAg-positive blood or body fluids. As the pool of HBV-susceptible children is reduced through vaccination, the risk of virus transmission in schools will be low.
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