Maryland health officials this week reported that 41 suspected cases of whooping cough, or pertussis, have been reported so far this year, compared to a single case reported last year.

The number of cases reported has increased steadily since March, and 19 cases were reported in August alone, health officials said. They said they have no explanation for the sudden increase.

The disease, which usually lasts from three weeks to two months, causes serious mucous buildup and a persistent cough characterized by the whoop, the gaspy intake of breath, during which breathing can stop for seconds at a time. The pertussis-causing bacteria also produce toxins that can cause permanent neurological damage. One case of brain damage as a result of whooping cough has been reported this year.

No District residents have reported the disease since 1973, according to Dr. Martin Levy, D.C.'s administrator for preventive health services. In Virginia, 18 cases of whooping cough have been reported so far this year, seven of them in Northern Virginia; last year, only six were reported.

Whooping cough, and the standard vaccination against it, the DPT vaccination for diphtheria, pertussis (whooping cough) and tetanus, has been the center of a controversy since a local television program in April discussed the sometimes-serious effects of the pertussis component of the vaccine.

Maryland immunization program coordinator Robert Longenecker said that after the television broadcast drug companies reported a 54 percent drop in sales of the DPT vaccine, and a 170 percent increase in sales of a similar drug that does not contain the anti-whooping cough component. Now, Longenecker said, doctors are asking for simple whooping cough vaccine.

Only one of the 41 cases had stopped the normal series of DPT vaccinations, Longenecker said.

John McAvinue, state health department spokesman, said more than half of Maryland's cases involved children too young to have completed the series of DPT vaccinations. The vaccinations, normally given at 2, 4, 6 and 18 months of age, are not considered effective against whooping cough until after at least three vaccinations have been given.

The health department vigorously supports the vaccination, which is required of all children entering Maryland schools. According to McAvinue, four of every thousand who have the disease suffer severe complications, while adverse reactions occur about once in every 310,000 times the vaccine is administered. Other estimates of adverse reactions to the vaccine range from one in 700 to one in 100,000.

Among the 41 reported cases of suspected whooping cough, 17 were in Baltimore City, five in Montgomery County, five in Frederick County, two in Prince George's, and one each in Anne Arundel, Howard and Charles counties.