|Aid groups have warned of an outbreak due to unsanitary conditions in and around the country's tent cities [EPA]
At least 135 people have died in Haiti in the last two days from an outbreak of a deadly disease that authorities say bears all the hallmarks of cholera.
Al Jazeera's Sebastian Walker, reporting from outside a hospital in the city of Saint Marc where some 1,400 people are seeking treatment, said officials have not officially confirmed the presence of the disease.
But he said the death toll has risen very quickly in the city north of the capital, Port-au-Prince.
"The number of cases has now gone up to more than 1,000, so the situation here really is very serious indeed. Scenes at the hospital today really are something of a nightmare scenario.
"There is no confirmation yet that it is cholera. We are waiting still for the final confirmation of tests that are being done back in the capital."
Health officials earlier said that at least 114 people had died from acute diarrhoea and almost a thousand were being treated in local hospitals as laboratory tests are carried out to determine the cause of the illness.
The outbreak of illness was found outside the capital, which was ravaged by a devastating earthquake in January, leaving more than 250,000 people dead and another 1.2 million homeless.
Our correspondent said that there is a real fear that the disease could be spreading.
"Aid groups are extremely worried that if it is cholera, that it may spread into the camps, and will hit very quickly due to low hygiene standards," he said.
Cholera is transmitted by water but also by food that has been in contact with unclean water contaminated by cholera bacteria.
It causes serious diarrhoea and vomiting, leading to dehydration. With a short incubation period, it can be fatal if not treated in time.
The World Health Organisation defines cholera as "an extremely virulent disease. It affects both children and adults and can kill within hours".
Aid groups have voiced concern for months that any outbreak of disease could spread rapidly in Haiti due to the unsanitary conditions in the makeshift camps housing the homeless, with little access to clean water.
The impoverished Caribbean nation has also been hit in recent days by severe flooding, adding to the misery of those struggling to survive in the scores of tent cities now dotting the country.
Reconstruction has barely begun despite billions of dollars pledged for Haiti in the wake of the disaster. Less than 15 per cent of money promised at a UN donor's conference in March has been delivered.