MANILA, Philippines » More than a week after Typhoon Ketsana devastated the Philippines, followed by a second damaging storm, large areas of Manila and nearby provinces remain flooded, and survivors — some gathered in evacuation centers and others marooned in their homes — face a host of other problems, including disease and ruined crops.

The high floodwaters and uncollected debris, especially in hard-to-reach areas, have resulted in higher numbers of illnesses such as diarrhea, skin diseases, coughs and colds, government and relief officials say. The presence of mosquitoes and the spread of the diseases they carry, such as dengue fever and malaria, has also become a serious concern.

While efforts are under way to alleviate the suffering of survivors, supplies and money for relief operations are disappearing fast, prompting the United Nations to appeal to other countries for help, saying that the Philippines needs an additional $101 million to cope with the disaster.

The food supply is also under threat. Ketsana and the second typhoon, Parma, destroyed $128 million worth of crops, mostly rice, and the government has said it will have to import more rice to replenish stocks for next year.

The two storms killed more than 300 people and damaged an estimated $57 million worth of property and infrastructure in addition to the damage to agriculture, according to the National Disaster Coordinating Council. In addition, many workers have been kept away from their jobs, according to the Ibon Foundation, a nonprofit economic research group. The disaster “;could cause lasting poverty and severe difficulties”; for those affected, particularly the poor, the foundation said.

For the moment, the government and aid organizations are focusing on distributing relief goods — food, water, medicine, clothing — before tackling the clearing of debris and the rebuilding of infrastructure and homes. The Metropolitan Manila Development Authority said it would take at least two months to clean the capital of tons of debris.

But funds are in short supply.

The World Food Program, the U.N. agency, estimates that it alone would need $26 million more for its relief operations. Stephen Anderson, its country director for the Philippines, said it might be tougher now to get funds because of recent disasters in other countries like Indonesia, Vietnam and Samoa. “;The donor community is stretched,”; he said.

An area of concern for relief and rescue operations right now are the communities around the Laguna Lake, where water levels have not significantly decreased since the storm. Many of the towns surrounding the bay still have chest-deep water, Anderson said.

He said he visited the town of Santa Cruz, in Laguna province, south of Manila, over the weekend, where many people were holding out in their inundated homes instead of going to in evacuation centers.

“;The water was not receding,”; Anderson said. “;Clearly, there will be issues brought about by the water being stagnant,”; he added, saying that eventually the holdouts would have to be moved.

Anderson said two helicopters and some boats were to arrive Wednesday to help reach such people.

On Monday, officials said that they would prohibit the rebuilding of the huts that used to block the waterways of the Manila metropolitan area, which officials say were a major reason the floodwater rose so fast and hardly decreased in many areas. The illegal dumping of garbage and other waste has also been cited as a major reason for the blockage of waterways that were designed to ease flooding.

Jose Atienza, the environment secretary, said mayors of the 17 towns and cities that comprise Metro Manila should be sued for violating the country's law on proper waste disposal. “;They have allowed this pollution to happen, and that is why they have to answer for it,”; Atienza said in an interview.