WASHINGTON - THE cholera outbreak in Haiti that has killed 135 people is 'likely to get much larger' because the population does not have collective immunity, a leading health organisation said on Friday.

'We expect it to get bigger. We have to expect that and react to it,' Jon Andrus, deputy director of the Pan American Health Organisation (PAHO), told reporters in Washington.

The outbreak 'is likely to get much larger given our experience with cholera... particularly in a population that has really no protective immunity,' he added.

Haiti's Health Minister Alex Larson said earlier that tests on the outbreak north of the capital by the World Health Organisation confirmed the 01 strain of cholera - its most lethal form.

Dr Andrus said the PAHO was in place to provide adequate medical supplies to the Haitian government, and stocks of medication are at the international airport in Port-au-Prince.He also voiced optimism the outbreak could be contained.

'Fortunately we have a partnership that has never been stronger as a consequence of the earthquake and it is a disease that can be prevented if community participation is engaged,' he said.

Haiti cholera outbreak to grow