Research notes drop in serious infections including meningitis

10/07/2002

By LAURA BEIL / The Dallas Morning News

SAN DIEGO – A new immunization appears to be sparing young children from meningitis and other serious infections, although the vaccine hasn't yet had the impact doctors are hoping for.

The vaccine targets the bacterium Streptococcus pneumoniae, often called pneumococci, which can infect the central nervous system and bloodstream. Strains of pneumococci are also the most common cause of ear infections.

Before the vaccine, Streptococcus pneumoniae caused an estimated 6 million ear infections annually among young children. In addition, the bacterium was responsible for about 3,000 cases of meningitis, an infection of the central nervous system, and 53,000 bloodstream infections.

In 2000, doctors started using a new vaccine, called Prevnar, that could protect against the seven most threatening strains of pneumococci. Data presented to scientists last week suggest that rates of so-called invasive disease – meningitis and bloodstream pneumococcal infections – are dropping among children younger than 2 years. Children receive the first of four doses of the vaccine when they are 2 months old.

Surveys in seven states suggest that rates of invasive pneumococcal disease among children under 2 dropped 35 percent to 85 percent, depending on the area surveyed, between 1999 and 2001.

"It's what we were hoping for," said Dr. Cynthia Whitney of the U.S. Centers for Disease Control and Prevention, noting that vaccine availability may have caused the difference in rates. She presented her data about pneumococcal disease last week in San Diego, during an infectious-disease meeting hosted by the American Society for Microbiology.

At Children's Medical Center of Dallas, rates of invasive pneumococcal disease among children under 2 dropped from 41 per 100,000 children in 1999 to 30 in 2002, according to Dr. Tess Barton. "I think the vaccine is working," she said in San Diego.

Rates of invasive pneumococcal disease in older children, however, haven't significantly declined, either nationally or in Dallas. Health experts believe this is because older children would not have gotten the shot.

Dr. Barton thinks disease rates among young children would be even lower if more children were vaccinated. Data from the Texas Department of Health suggest only about half of eligible children are receiving the Prevnar vaccine.

Pneumococcal bacteria are commonly found in the nose. The vaccine protects against the worst of the more than 80 pneumococcal strains. While the bacteria can live harmlessly in a child's nose, they can cause misery when they shift to the ears or can even be fatal in the nervous system or blood.

Data from one researcher suggest that the pneumococcal bacteria colonizing the noses of vaccinated children undergo a change. When the strains targeted by the vaccine retreat, different pneumococcal strains move in. The new strains aren't known causes of disease, said Dr. Faryal Ghaffar of the University of Texas Southwestern Medical Center at Dallas.

Dr. Ghaffar released her data, based on a study of more than 130 Dallas children, in San Diego.

The CDC's Dr. Whitney predicts that the benefits of the Prevnar shot will broaden over the next decade. "As children that are vaccinated get older, the rates will come down," she says.

E-mail lbeil@dallasnews.com