Boston: The cholera epidemic in Haiti that broke in the aftermath of the devastating earthquake last year has taken an alarming proportion. It is estimated to affect nearly 800,000 people by end of this year, almost double the cases initially estimated by the UN.

According to new estimates in a study conducted by Harvard Medical School and University of California, Haiti's cholera epidemic could last through November when the diarrhoeal disease could spread to 779,000 people, double the UN projections of 400,000 cases.

The study author and University of California, San Francisco medical resident Sanjay Basu said, "The epidemic is not likely to be short-term," adding "It is going to be larger than predicted in terms of sheer numbers and will last far longer than the initial projections".

Basu, who conducted the study with Jason Andrews, fellow at the Massachusetts General Hospital and Harvard Medical School, said as per their calculations, "without additional
intervention, 779,000 new cases and more than 11,000 deaths would result from the epidemic from March through November 2011".

The study, which will be published this week in the journal Lancet, comes at a time when the world is grappling with the catastrophic consequences of last week's massive earthquake and tsunami that wrecked havoc in Japan.

Possibility of widespread nuclear radiation, following fire at Japan's nuclear plants, has become a cause of concern for people from Japan to the US.

The UN, which in October last year had projected that 200,000 people would be infected by cholera in Haiti, later doubled that projection to 400,000. In the three months between October and December 2010, around 150,000 people in Haiti contracted cholera and about 3,500 died.

The UN estimates are critical because those are used to determine how resources are allocated, the researchers said.

According to Basu, the UN projections were based on estimates that the disease would infect 2-4 per cent of Haiti's population of 10 million people.

The researchers said UN estimates did not take into account the asymptomatic nature of some infections, potential impact of vaccination or treatment and the immunity that
develops in those who recover from the disease.

Cholera is spread through water or food that has been contaminated by human feces. Left untreated, cholera causes acute diarrhoea and can be fatal.

Before the devastating earthquake of January 2010, cholera had not been reported in Haiti for more than 100 years but the aftermath of the earthquake, which largely destroyed
the country's already inadequate water and sewer systems, set the stage for the cholera outbreak that began in October.

To arrive at more accurate estimates, the researchers devised a mathematical model based on information from previous cholera outbreaks that incorporates current understanding of the disease and also includes data from the first months of the Haitian outbreak.