Toddler improving on experimental smallpox drug

By Julie Steenhuysen

CHICAGO (Reuters) - An experimental pill appears to be helping a toddler who had a near-fatal skin reaction to his father's smallpox shot, doctors said on Monday.

The drug, an antiviral made by Siga Technologies called ST-246, worked when more conventional treatment failed, the doctors said.

The 2-year-old, still in critical condition at the University of Chicago's Comer Children's Hospital, developed the rare serious reaction called eczema vaccinatum after being with his father, a soldier vaccinated for deployment in Iraq.

"He's making slow improvement every day. He's still in the pediatric intensive care unit," said Dr. John Marcinak, pediatric infectious disease specialist at the hospital.

Marcinak said the rash now consumes 80 percent of the child's body. "He's lost a lot of the superficial areas of his skin called the epidermis. There is still a lot of healing that needs to be done," he said.

The child, from Indiana, was admitted to the hospital on March 3, and the U.S. Centers for Disease Control and Prevention confirmed he was infected with the virus used in the smallpox vaccine.

Smallpox vaccines do not use the smallpox virus, but instead use a related virus called vaccinia that is weakened but can still infect some people.

The child was given an intravenous form of vaccinia immune globulin -- developed in the 1960s to treat complications of smallpox vaccinations. He also received a treatment of the antiviral drug cidofovir, made by Gilead Sciences Inc.