HAMMOND | The virus that made a Hammond toddler gravely ill after exposure to his soldier father's smallpox vaccination poses no threat to the community, said Dr. Rodrigo Panares, Hammond's city health officer.

"It's a one in a million thing," he said Saturday.

"This is not smallpox virus but a related virus that is much less contagious and virulent than smallpox," he said. "In some circumstances, vaccinia virus can cause serious illness. In this case, the child is currently in intensive care in critical condition."

Panares said the child's mother also contracted the disease, but in a much milder form.

Panares said the child's father, an Army soldier, received several routine immunizations, including a smallpox vaccination, in Texas while preparing for deployment to Iraq.

Family members requested that their name be withheld.

Even though smallpox has been declared eradicated, some 1.2 million servicemen and first responders have received smallpox vaccinations in recent years because of the threat of bioterrorism, Panares said.

Because his departure to Iraq was delayed, the father returned to Hammond between Feb. 16 and 20, some three weeks after he was inoculated, according to Panares.

The child, who Panares said is 28 months old, took ill two weeks later after becoming infected with vaccinia, the virus used for vaccination.

The city's Health Department has been working the case for a little more than a week in conjunction with an epidemiologist from the Indiana State Department of Health and agents from the Centers for Disease Control, he said.

Marty Wieglos, chief of staff to Mayor Thomas McDermott Jr., also met with the CDC team and offered the administration's full support, Panares said.

Coordinating the community investigation are Bonnie Suter and Karen Siegfried, both registered nurses with the Hammond Health Department.

All members of the child's large extended family have been traced and contacted, Panares said. The child's father was recalled from Iraq since the child became ill and has been interviewed by health officials.

"Nobody else is sick except the little boy and his mother," he said.

The family will continue to be contacted daily by local health officials for a minimum of 21 days.

Panares said other family members in Hammond will be disinfected Tuesday under guidelines recommended by the CDC team who assessed the home's environmental situation.

The vaccinia virus can be spread only through close physical contact. Nonetheless, Dr. Madelyn Kahana, the University of Chicago's chief of pediatric intensive care, said the hospital was taking extraordinary measures to prevent any possible spread of the virus.

She said all staff members dealing with the boy and his mother were wearing face masks and gloves and that the two had been placed in a special room with negative air pressure, where all air blows inward.

Kahana said the boy had been treated with a potent antiviral drug, an anti-vaccinia agent supplied by the CDC and the experimental drug ST-246, which was untried as a therapy in humans.

She said the boy was improving this week, but will probably lose 20 percent of his outer skin layer.

The Associated Press contributed to this report.