Haiti’s cholera epidemic has spread into the capital endangering nearly three million people.
Nearly half of those in Port-au-Prince are camped in tents, still homeless after the January earthquake.
Health authorities said tests confirmed a three-year-old boy from a quake refugee tent camp who had not been out of the city had caught the disease. More than 100 other suspected cholera cases among city residents also were being tested.
The outbreak has already killed at least 544 people in Haiti.
The boy from the Route Batiment camp was tested after being taken to hospital last month suffering from severe dehydration, nausea, vomiting and diarrhoea. He was treated and antibiotics and was released.
He tested positive for cholera despite his family having not travelled in more than a year or having contact with anyone from the Artibonite Valley, where the epidemic was first registered and has wreaked its most damage.
Many of the patients taken to hospital in the capital with cholera are believed to have recently arrived from the Artibonite Valley, an agricultural area where more than 6,400 of Haiti’s known 8,138 cases have been recorded.
At least 114 of the people suspected of having the disease in the capital are in the Cite Soleil slum, the large oceanside shantytown closest to the valley.
Since its discovery in late October, the disease has spread to half of Haiti’s 10 administrative regions, or departments. More than 200 people have been hospitalised in the West department, where Port-au-Prince is located.