A group of government doctors, determined to get medical supplies and care to people in communities isolated by the recent downpours and mudslides here, harnessed themselves and their baskets of antibiotics onto cables Wednesday and swung across the Nahualate River, where a major bridge had been half-destroyed by the torrential rains and flooding.

"They need everything -- water, food and clothes," Eduardo Mendez, a doctor from the national social security service, said as he prepared to launch himself over the water. He was headed for shelters in the towns of Mazatenango and Retalhuleu near Guatemala's Pacific Coast, cut off since the bridge collapsed last week.

In Nahualate, a large town near the coast, Mendez and his medical team handed out painkillers, antibiotics and antifungal medicines to ailing survivors of the natural disaster caused by Hurricane Stan. The rain and mudslides have left at least 652 Guatemalans dead and another 600 missing and feared dead.

"We are finding skin diseases everywhere," Mendez said. Medical teams are trying to avert the spread of contagious diseases and infections caused by standing water, sewage, decomposing animals and wet mud.

Officials said the storms had left tens of thousands of people homeless.

In many areas, murky water has been standing for nearly two weeks, mixing with trash and the corpses of livestock. The government has been declaring mass burial grounds in areas where the floods buried hundreds of people alive in mud. Guatemalan newspapers reported Wednesday that villagers had been given lime and chemicals to sanitize those sites.

Health officials are also concerned about the spread of malaria, because mosquitoes could breed quickly in the dark waters that have filled riverbeds, ditches and other low-lying areas. The Health Ministry said 400 medical volunteers, 500 Cuban physicians and volunteer firefighters from Spain were helping to care for the sick and sanitize affected areas.

Salvador Lopez, the vice minister of health, told the Prensa Libre newspaper in Guatemala City, the capital, that the agency was trying to organize a mass vaccination program for children and to fumigate stricken areas to kill insects that could spread malaria, dengue fever and other diseases. Health officials said they needed more antibiotics, penicillin, painkillers and disinfectants.

In areas along Guatemala's Gulf Coast, there have been few deaths but many people left homeless after floodwaters swept away their tin and adobe dwellings. Some were rescued by helicopters, but many left their villages on foot and are now living in shelters.

"They already have fungus on their skin and some have infections, and we have a few cases of people with diarrhea," said Carlos Culajay, a physician who has been traveling to shelters on the coast. Bronchitis and respiratory infections are also a problem, he said.

In shelters set up in churches and schools throughout the southern coastal region, families are sleeping on sponge beds, eating donated food and hoping medicine will arrive.

Salvador Ranzan, 77, said he left his village near the Pacific Coast before the rain-swollen river washed his home away. He arrived safely in a shelter in Patutul, a small town in the department of Suchitepequez, eight days ago.

"My head hurts. My knees hurt," he said Wednesday. "I want some medicine."

Pain medicine has not been easy to come by, but some shelter residents said they had been treated for contagious infections so they would not spread. Marta Galleras, 38, had a dark rash on her feet after she trekked from her flooded home. When she arrived at the shelter in Patutul, she received antibiotics and her feet have healed, she said.

Juan Carlos Figueroa, a physician who has been operating a shelter at the Catholic church in Patutul, said that once evacuees heard the water was starting to recede in some communities, some people returned home even though they were still sick.

"We saw a lot of people with respiratory problems," he said. "We had a few antibiotics, and we gave them all out."

A woman holding her child stands beside a demolished house in Itzapa. The storms have left tens of thousands of people homeless, authorities said.