GENEVA, Jan 4 (AFP) - The World Health Organisation on Tuesday put at 500,000 the number of people believed to have been injured in the Indian Ocean tidal waves and warned of a "health disaster" if survivors are not given quick access to clean drinking water.
The WHO is to launch a new appeal for donations of around 60 million dollars (44.8 million euros) over the next six months "in order to avoid a major health disaster if the problems of water and purification are not dealt with quickly," said WHO spokeswoman Fadela Chaib.
It will also set up a regional network to spot potential epidemics to try to head off their spread among a devastated population.
"The WHO estimates the number of injured at 500,000," she told reporters.
The UN agency has already sent emergency supplies for around two million people as well as surgical kits, anti-diarrhoea medicines and "millions of water-purifying tablets". Though they had arrived in the disaster zone, Chaib conceded "difficulties had been met in getting them to the places where they were needed most".
She stressed that offering clean water was a key to heading off epidemics.
"For the moment we do not have any information on the cholera epidemic or other illnesses in the region," she said. "But diarrhoea alone can kill a child in a few hours if he is dehydrated," the spokeswoman warned.
The WHO had already noted "an increase in cases of diarrhoea in camps of displaced people in Sri Lanka and in India."
The organisation sees the immediate threats as diarrhoeal illness, such as diarrhoea, dysentery, typhoid and cholera, as well as acute respiratory ailments, followed "in the coming weeks by malaria and dengue fever" as stagnant water leads to the proliferation of mosquitos that carry these illnesses, she said.
Sri Lanka, she said, was particularly at threat from cholera.
One key preventive measure WHO will put in place is a system to detect any sudden rise in communicable diseases, called the Global Outbreak Alert Response Network, the spokeswoman said. It will be based in New Delhi and link hundreds of laboratories around the world.
The quake and tidal waves that struck December 26 have officially killed 145,000 people, and left millions displaced or homeless in south Asia and the Indian Ocean area.
A senior WHO official warned Saturday that epidemics triggered in the disaster's aftermath could claim another 50,000 lives.
WHO's initial appeal launched last Thursday was for 40 million dollars in aid for populations hit by the tsunami.
WHO's general director Lee Jong-wook has been in Jakarta since Monday and was Wednesday to head to one of the worst-hit zones, Bada Aceh on the Indonesian island of Sumatra.
On Thursday, he will take part in the crisis meeting on the disaster called in Jakarta by ASEAN, the Association of Southeast Asian Nations.