CHENGDU, China (Reuters) - The onset of the rainy season is swelling dangerous "quake lakes" and compounding the difficulties of reconstruction after China's worst earthquake in decades.
The 7.9 magnitude tremor of May 12 and thousands of aftershocks changed the landscape of northern Sichuan province forever, blocking rivers, weakening mountain walls and creating unstable lakes where there was once dry land.
The death toll had topped 55,000, with almost 25,000 missing and more than 281,000 injured, Sichuan vice governor Li Chengyun said on Friday as fears grew that disease, rain and aftershocks could bring yet more disaster to the southwestern province.
A landslide triggered by an aftershock in Wenchuan county, at the epicenter, on Thursday crushed a house, killing two people, state media said on Friday.
Premier Wen Jiabao, making his second visit to the disaster zone, visited hospitals and tents sheltering quake refugees on Friday in Beichuan county, one of the worst-hit areas.
In a temporary shelter for the Beichuan Middle School, which lost up to 1,000 students and teachers in the quake, Wen tried to cheer up children, writing a line on the blackboard reading "Deep distress resurrects a nation".
Wen, a trained geologist, had earlier ordered rescue workers to eliminate the danger of the lakes "through engineering means" while swiftly evacuating people in their path.
In Hongguang, in northeastern Sichuan, the earthquake caused both sides of a valley to slide, burying three villages and 900 people. The Qingzhu River is trapped behind.
"The mountains merged," said Gao Xiao, who barely escaped a landslide that roared past her house.
The Qingzhu landslides have formed five lakes, the biggest of which is almost 30 meters (98 feet) deep. A flood control team monitors the natural dams constantly, for fear they will burst and unleash a wall of water on the valley below.
"It's a lucky thing we haven't had a downpour recently," said Lu Lujun, an official with the Guangyuan county propaganda department.
But heavy rain is forecast, making life even more difficult for rescuers, relief workers and the millions either living in tents or under makeshift cover as their mourn their dead.
Sichuan has been on high alert for rodent diseases, Xinhua news agency said, with large amounts of bait spread around the ruins.
More than 5,000 health workers have fanned out to disinfect ruined villages. Doctors and nurses are stationed round the clock in refugee camps to try to prevent survivors from falling sick.
(Additional reporting by Guo Shipeng in Beijing; Writing by Ian Ransom; Editing by Nick Macfie and Roger Crabb)