BioEd Online

As communities across the Indian Ocean struggle to deal with the effects of last Sunday's tsunami, relief organizations are embarking on one of the biggest humanitarian efforts ever seen. The most immediate fear is that without a supply of clean drinking water, many thousands of those who survived the waves will die from illnesses such as cholera.

More than 70,000 people are reported to have perished when monstrous waves triggered by an earthquake of magnitude 9.0 swept across the Indian Ocean, hitting the coasts of Indonesia, Sri Lanka, India and Somalia. But even as volunteers help to bury the bodies, concern grows about the spread of disease. Children, especially those left orphaned, and the elderly are thought to face the greatest risk.

The floods destroyed many hospitals, as well as contaminating drinking water and disrupting sewage systems. And the hundreds of thousands of people sleeping in overcrowded temporary camps will aid the spread of mosquito-borne malaria and dengue fever, the World Health Organization has warned, although cholera and other causes of diarrhoea are thought to pose the biggest danger.

"As time passes, faeces start to contaminate the water supply and cholera will become a threat," says Soraya Bermejo, a spokeswoman in Geneva for Unicef, the United Nations agency devoted to helping children.

Cholera, which is caused by the bacterium Vibrio cholerae, can produce severe dehydration and diarrhoea. Without timely treatment, it can kill in a matter of hours.

Disease isn't the only threat, however. In Sri Lanka, landmines left over from the country's civil war are a serious concern as people try to return to their homes. The water has displaced these explosives, which are bound to cause serious injuries, says Bermejo.

Long-range mission

With over a million people affected by the tsunami in an area spanning over 5,000 kilometres, the scale of the operation is unprecedented.

"It spans two continents," says Lysbeth Holdoway, a spokeswoman for the charity Oxfam in London, UK. "It's so huge, it's difficult to quantify [how many people are at risk]." Aid agencies have warned that, without swift action, tens of thousands more people could die.

The ability to deliver relief is also hampered by the remoteness of affected areas such as the Maldives. "It's a huge logistical challenge," says Bermejo. "There are islands that haven't been reached yet."

The most urgent priority is to supply communities with clean drinking water, says Holdoway. She says that from today, Oxfam plans to send out emergency water tanks that can hold 11,000 litres each. The first six of these shipments will go to Sri Lanka and to the province of Aceh, in Indonesia.