The Texas Department of Health added the requirement earlier this year, after disease surveillance showed the rate of hepatitis A in Bexar County is increasing.

Children born on or after Sept. 2, 1992, who reside in the county, will be required to receive two doses of hepatitis A vaccine administered on or after their second birthday.

The shots must be given at least six months apart, which means children who will enroll in school next August must get their first shot by February.

Health officials have notified school nurses and clinics, but don't know if the message is getting through, said Tom Fink, a public health adviser with the federal Centers for Disease Control and Prevention who works at the Bexar County Metropolitan Health District.

"We're trying to encourage healthcare providers and parents not to wait, because the shots do have to be given six months apart," Fink said.

"If they don't get started by February, it's going to be hard to get both their doses in before school starts," said Mark Ritter, immunization program manager for the San Antonio Metropolitan Health District.

Since 1999, the Texas Department of Health has required hepatitis A immunizations for schoolchildren in 32 border counties. That is based on CDC recommendations that states mandate immunizations in areas where the annual incidence of the disease is more than 20 cases per 100,000 population.

Bexar County was one of eight counties added, based on hepatitis A surveillance data from 1991 through 2000. That data showed a rate of 22 cases per 100,000 population, said Rita Espinoza, a state health department epidemiologist.

Hepatitis A is a serious and highly contagious viral infection of the liver that is spread by close personal contact or contaminated food and water. Children are at risk because of close contact with other children in day care centers and schools.

Unlike adults, who become outwardly ill, children may not show symptoms of the disease, and thus can be carriers to adults, said the CDC's Fink.

In a recent pilot project, the local health department vaccinated about 7,000 children in 27 targeted San Antonio census tracts between 1997 and 2000. The number of hepatitis A cases in children fell dramatically in those census tracts — from 40 cases in 1997 to five in 2000, said Nancy Walea, the program coordinator.

"We showed that if we immunized children between the ages of 2 and 8 or 9, we could really bring down the rate of hepatitis A," Walea said.

ctumiel@express-news.net