Democratic candidate Patricia Roberts Harris hammered away at Mayor Marion Barry's public-health record yesterday, claiming he has done virtually nothing to reduce the high rate of infant mortality and tuberculosis in the city and blaming him for closing four community health centers.

Harris, the mayor's leading challenger in the race for the Democratic mayoral nomination, injected the most somber note to a day marked by low-key and at times almost frivolous campaigning by the four Democratic candidates in the race.

With the primary only 10 days away, the candidates, including City Council members John Ray and Charlene Drew Jarvis, roamed through targeted precincts, greeting potential supporters at parks, apartment buildings, markets, and -- in the case of all but the mayor -- a dog show near the Carter Barron amphitheater at 16th and Kennedy streets NW.

Harris began the day with a morning press conference outside the J.B. Johnson Center for the elderly at 901 First St. NW. She told reporters that the mayor actually had contributed to the city's health problems by taking too long to fill some key public health posts, including that of health commissioner, and by allowing rapid turnover in others.

"As a result, the mayor's plan to reduce infant mortality has yet to get off the ground, hundreds of patients who are capable of living in the community continue to be institutionalized, and four popular community health clinics and one hospital Glenn Dale Hospital have been closed," Harris said.

She also said that the number of community health nurses working in schools and with the elderly and bedridden has been cut by 90 percent since Barry took office and that the mayor has been unable to control abuses in the Medicaid program.

"All of this has occurred while mismanagement in the Department of Human Services has produced cost overruns in the millions of dollars," Harris said. "After four years, the District is not a healthier place in which to live."

Ivanhoe Donaldson, Barry's campaign manager, insisted yesterday that some headway had been made in dealing with the public health problems cited by Harris. "Whatever public health clinics that have been closed were closed with the City Council's approval," he added.

Harris said yesterday that, if elected, she would put great emphasis on preventive health care and would launch an all-out effort to combat infant mortality. Her remarks picked up a theme sounded throughout the campaign by Jarvis, a Ward 4 Democrat and chairman of the City Council's housing and economic development committee, who has made health issues a major focus of her campaign.

Later in the afternoon, a dog show sponsored by a new group called Petowners Association of Metropolitan Washington (PAW) drew Harris, Jarvis and Ray, along with several candidates for the City Council.

Harris gave out the awards for the rarest breed of dogs (a Tibetan spaniel named Manchu and a Corgi named Smurf won the top prizes). Ray handed out the "ugliest dog" award to a pit bull. And Jarvis presented the award for the "tiniest dog" to the owner of a toy French poodle.

"Anywhere there's a crowd, that's where candidates go," Jarvis said.

Although Barry didn't attend the dog show, he issued an official Pet Owners Day proclamation. The mayor spent most of yesterday afternoon on walking tours of the Eastern Market area in Ward 6, and the 1800 block of Varnum Street NE in Ward 5. He also was scheduled to knock on doors and take part in several "meet the mayor" events in Wards 1, 2 and 4.

Donaldson said Barry's campaign organization is now devoting most of its energies to preparing its election day get-out-the-vote effort. He said he has discouraged workers from becoming overconfident in light of a recent poll showing Barry with a 15-point lead. "People know that if they keep pushing hard that they'll win."

Both Jarvis and Ray are planning mass mailings of campaign literature this week, according to aides, and are attending as many events as they can squeeze into their schedules.

Yesterday, Jarvis had four vans equipped with loudspeakers roaming throughout Wards 1, 2, 4, 5 and 8. She was also scheduled to address a Kiwanis International Club "Ladies Nite" at the Ramada Inn in Lanham.

Ray, meanwhile, shook hands with residents of an apartment complex and attended a candidates reception in Northeast Washington and a block party in LeDroit Park. He, too, is traveling around the city in a van with a sound system.

Margaret Gentry, Ray's press secretary, said campaign aides were heartened by a poll released last week showing that 71 percent of registered D.C. voters favor a mandatory sentencing initiative that Ray promoted.

"We're hoping some of that support will rub off on John," Gentry said.