At least four adults and two teen-agers in Minnesota appear to have contracted toxic shock syndrome after suffering from influenza this winter, health officials said, spurring a national health alert to see how widespread the problem may be.

This serious and sometimes deadly complication of influenza has not been reported since toxic shock syndrome first was identified in the late l970s, according to the Minnesota Department of Health and the federal Centers for Disease Control.

Officials of both agencies are asking physicians nationwide to be alert to possible combinations of the illnesses.

In addition to Minnesota's six possible cases, which included two deaths, the CDC said that it is investigating 14 suspicious cases.

Although the Minnesota cases offer the first link between the two illnesses in modern times, the reports follow an intriguing theory advanced recently that a disastrous plague in Athens about 430 B.C. may have been caused by influenza outbreaks followed by toxic shock syndrome.

Dr. Michael Osterholm of the Minnesota Department of Health said yesterday that the outbreak in Minnesota appears to be a "serious health problem," unrecognized thus far because it occurs so rarely.

"I think it may have been there before. We have just not put it together. It took an extreme influenza year to put it all together," said Osterholm, among those who first linked toxic shock syndrome with use of high-absorbency tampons.

"It has not been previously reported, but it is not too surprising," said Carol Ciesielski of CDC's special pathogens branch. She noted that Staphylococcus aureus, the toxin-producing bacteria known to cause toxic shock syndrome, also is known to produce pneumonia as a complication of influenza.

Toxic shock syndrome is a severe illness characterized by the sudden onset of high fever, vomiting, severe diarrhea and a drop in blood pressure that can produce shock. A "sunburn-like" rash is followed by flaking of the skin more than a week later.

Although the disease most often is identified with the use of tampons, Ciesielski noted that, of 2,815 cases reported since 1979, 146 have occurred in men. Non-menstrual toxic shock has been reported in cases involving infections, abcesses, burns and abrasions in which the common staph infection gains a foothold. Ciesielski and Osterholm said that the upper respiratory tract may be more susceptible to the syndrome after the onset of influenza.

"We don't think it's a widespread problem," said Ciesielski, who added that the unusually high number of flu cases in what is considered the worst national outbreak since January 1981 "would increase the chance of detecting it . . . . It's something physicians should be aware of."

The CDC said yesterday that the national flu outbreak appears to have peaked.

Osterholm said the influenza B outbreak in Minnesota last month was the worst there in a decade, particularly among school children. He said that two teen-age boys contracted toxic shock syndrome after having the flu and that one died two weeks after being hospitalized.

Four other probable cases occurred in women from 34 to 56 years old, and one of them died, he said. In addition, he said, four other suspicious cases in which deaths occurred suddenly at home followed flu in girls and boys from 3 to 11.

After learning of the cases, Osterholm said, he dug out a prescient October medical journal article in which a well-known disease expert, Dr. Alexander Langmuir, concluded that the plague in ancient Athens had been caused by influenza and toxic shock, and warned that the combination "may not be extinct."

"It may have occurred in the past," Langmuir wrote, "and may be present now at such a low frequency that no one has yet identified a sufficient number of cases to make a convincing series."