HANOVER, N.H. (AP) – A Dartmouth Medical School expert on toxic shock syndrome has doubts about recent studies that indicate cases of the potentially fatal bacterial infection are on the rise.

But Dr. Jeffrey Parsonnet nevertheless is urging health care providers to be cautious of a new antibiotic-resistant strain of the bacteria that causes the illness.

“People should have their antennas up, but we’re not seeing national phenomena. I’ve seen those reports and I think they have to be viewed with skepticism,” said Parsonnet, an associate professor of infectious disease.

“Not that they aren’t correct, but they are the project of one person’s passive surveillance,” he said.

Toxic shock syndrome is rare. Cases of the illness peaked during the early 1980s during an epidemic associated with the use of high-absorbancy tampons. When the tampons were taken off the market, the number of infections sharply declined.

The federal Centers for Disease Control and Prevention was so convinced that the illness was no longer a public health threat that it stopped collecting data on the infection in 1987.

But two recent studies reported the illness is increasing in some parts of the country, leading the authors to claim toxic shock syndrome is making a national comeback and affecting men and women with the same frequency.

California researchers reported a spike in cases from 10 in 2003 to 41 in 2004. And a Minnesota scientist documented an 18 percent increase in the illness from 2000 to 2004 in the Twin Cities area.

But Parsonnet said the data are from doctors voluntarily reporting cases, which is vastly different than an active or nationwide surveillance system in which doctors are encouraged to report cases consistently.

“To conclude from a local area that this is an emerging problem is really a leap of faith,” said Parsonnet, who has spent 22 years studying the bacteria that cause toxic shock.

He’s more concerned with reports of a stronger, antibiotic-resistant strain of the bacteria in other parts of the country.

While toxic shock does not appear to be showing up more frequently, the bacteria that cause it is being discovered in places it hasn’t been seen before, Parsonnet said. And it is resisting antibiotics typically used for treatment.

“It used to be that this was mainly an infection you got in a hospital. Now, nationwide, there are reports of more and more people getting it (the antibiotic resistant infection) from the community. That’s a major problem,” he said.

Parsonnet’s lab, which receives reports from the Northeast and across the country, confirmed seven to 10 patients during the past six months, a bit higher than normal, he said. “But I wouldn’t draw any conclusions,” he said.

Most adults are immune to the toxin from the bacteria that causes toxic shock. The bacteria are found naturally on skin and in mucous membranes. But children, who lack developed immune systems, are susceptible, Parsonnet said.

Adults recovering from surgery, childbirth, the flu or respiratory infections also are at risk.