Like much of Southeast Asia, Cambodia is struggling with an epidemic of dengue fever, which has killed scores of children and is threatening to overwhelm the country's fragile health care system. Experts say that early monsoon rains and heavy migration are spreading the mosquito-borne virus, while some also blame the authorities for not acting quickly enough to control the outbreak. Rory Byrne reports from Phnom Penh and Ker Yann narrates in Khmer.

Cambodian women with their children, many of whom are sick with dengue fever, wait for treatment outside a children's hospital in Phnom Penh. (AP Photo)

Every day thousands of people arrive at Kantha Bopha hospital in Phnom Penh seeking free treatment for dengue fever. They come from all over Cambodia. Almost all of the most serious dengue patients are children. Most of Southeast Asia has seen a surge in dengue cases this year, in part because of heavy rains.

Cambodia is one of the hardest hit countries, with new cases up 94 percent so far from last year. Since January, about 200 people have died from dengue, which causes high fever and bleeding. There is no vaccine or cure. Dengue is spread by a type of mosquito that breeds in urban areas.

Phnom Penh is experiencing a building boom and construction sites make perfect breeding grounds for the mosquitoes in areas where water collects and stagnates. Migration from the countryside to the city also helps spread the disease as people infected with the virus carry it into crowded neighborhoods with poor sanitation. The only way to prevent dengue is to destroy the mosquitoes' breeding grounds. Most patients are infected near their homes.

Dr. Beat Richner is the director of Kantha Bopha hospital. He says the authorities did not act quickly enough to prevent the disease.

DR. BEAT RICHNER, KANTHA BOPHA HOSPITAL: "We give all addresses of all patients to the Ministry of Health so they could go, and they should go there, together with the WHO (World Health Organization) to neutralize the breeding places but unfortunately nothing was done until the month of June, and then I made announcements in the newspapers and outcries and now they start, but it's too late."

The government says it is doing all it can but it needs help from the public and aid donors. Dr. Ngan Chantha is the head of Cambodia's National Dengue Control Program.

DR. NGAN CHANTHA, CAMBODIA'S NATIONAL DENGUE CONTROL PROGRAM: "I would like to say that even though the situation is very difficult, the Ministry of Health and the departments in the 24 provinces have tried their best to fight the disease and we are determined to act to keep the lives of the children safe."

Experts say that with the wettest months of the rainy season still ahead, the dengue epidemic will only get worse, and more children may die.