Fears grew on Sunday that epidemics would strike the millions marooned or forced from their homes by South Asia's catastrophic floods, as the death toll hit at least 330 and criticism of relief efforts spread.
The last two weeks have seen some of the worst flooding in living memory affecting about 35 million people in the region, 10 million of them made homeless or left stranded.
In India's poor Bihar state, four air force helicopters dropped food, medicines and clothing to some of the 10 million affected.
Each pilot is carrying out 12 sorties a day and they have reported huge devastation in central and north Bihar, said Ramesh Kumar Das, a Defence Ministry spokesman in Kolkata.
Marzio Babille, UNICEF's health chief in India who is coordinating U.N. work in Bihar, said aid agencies and authorities must do more to prevent outbreaks of measles, gastroenteritis, dengue fever and other diseases, or we will see many deaths. He said 20 helicopters were needed in Bihar, where 87 people have died.
Hundreds of thousands are camped out on elevated highways, railway tracks and field embankments as deep floodwaters swirl around them.
Annual monsoon rains are a mixed blessing, vital for farmers but killing hundreds every year. This year much of eastern India and two-thirds of Bangladesh have been inundated.
The Indian government says more than 1,100 people have died in this year's monsoon, not including the latest casualties.
Babille said in the 15 days to August 2, 90 cm (35 inches) of rain had fallen in Bihar's worst affected areas, compared to annual average rainfall of 1.3 meters.
TOO LITTLE, TOO LATE
UNICEF is mobilizing doctors by land and boat and is immunizing children against measles.
Those who were reached on Sunday showed their desperation.
I have been dividing one small piece of bread among four of my children, and I have been starving and somehow surviving, a sobbing Siraj Ahmed told a local television reporter in Bihar.
In the eastern Indian state of Assam, where up to 3 million people took refuge in emergency camps or were cut off in their villages, receding waters and soaring temperatures fed concerns of disease outbreaks as villagers returned to their homes.
We are really worried about the outbreak of an epidemic in Assam now, Chief Minister Tarun Gogoi said, but locals said the state government was not doing enough.
While we never expect a perfect government, the Chief Minister should have at least taken the trouble to visit the flood-affected areas, teacher Sanjiv Nath said by telephone.
In neighboring Orissa and Uttar Pradesh 39 people have died since Saturday.
In Bangladesh, 120 people are now confirmed dead, with 39 more drowning or dying from fatal snakebites, said a senior official at the government's flood monitoring cell.
At least 37 others were missing, and officials are facing the same health worries as their counterparts in India.
Government head Fakhruddin Ahmed called on the country to unite behind efforts to help the victims.
All of us, irrespective of (political) party, opinion, profession or religion, should come forward and unite behind coordinated efforts to tackle this grave situation, he said.
More than 20 million people in more than 40 of the country's 64 district were affected, while up to 300,000 had moved into relief camps or were living on raised highways and embankments.
Weather officials said the floods were receding in the north but the situation could worsen in central districts and in the capital, Dhaka.
The country's army-backed government has promised an all-out effort to save flood victims but relief efforts were inadequate, officials said. Political parties have refused to participate, demanding the government end a ban on their activity.
In Nepal, a U.N. body said weeks of rains had triggered floods and landslides that had killed 84 people.
(Additional reporting by Bappa Majumdar in Kolkata, Biswajyoti Das in Guwahati, Sharat Pradhan in Lucknow, and Reuters reporters in Patna, Bhubaneswar and Dhaka)