Port-Au-Prince, Haiti (CNN) -- In the wake of Hurricane Tomas, cholera has reached the congested capital of Port-au-Prince, where as many as 73 people have come down with the potentially deadly infection.
Dehydration is one of its tell-tale signs.
In a camp in Cabaret, just east of Port-au-Prince, children lie on cots as life-sustaining fluids are pumped intravenously into their bodies.
The cholera outbreak in Haiti has now killed 583 people and another 9,123 people have been hospitalized, according to Gabriel Timothe, director general of Haiti's Ministry of Health.
Medical personnel fear rising waters over the banks of Haiti's Arbonite River, which they say is a source of contamination, have increased the risk of a wider rate of infections.
"We're doing everything we can to mitigate [the] spread," Dr. Jon K. Andrus, deputy director of the Pan American Health Organization, said during a press conference on Tuesday.
Health officials had braced for problems after Tomas, fearing the hurricane that battered the Caribbean nation over the weekend could worsen the cholera outbreak.
On Monday, Dr. Toni Eyssallenne of Hospital Bernard Mevs confirmed the first case of cholera -- in a 3-year-old boy -- to originate and manifest entirely in Port-au-Prince.
Two more cases were confirmed Tuesday by Eyssallenne.
A 41-year-old woman who contracted the disease has not traveled in a year, the official said. A 33-year-old who lives in a tent city uses a communal water source. She, too, did not bring the infection into the city.
Previous cases had been centered in Haiti's Artibonite and Central Plateau regions, including the city of St. Marc, north of the nation's capital. Until Monday, health officials said that those being treated for cholera in Port-au-Prince all contracted the disease elsewhere.
The young Port-au-Prince boy lived in a tent city across the street from a place that sells macaroni, and he had not traveled in over a year, and he hadn't had any contact with people from St. Marc or the Artibonite region, Eyssallenne said.
After suffering from nausea and diarrhea, the boy was treated and released from the hospital after his condition improved.
Hurricane Tomas' trek past Haiti killed 20 people and injured another 36, a Communications Ministry official said Monday. Seven people were missing and 5,954 were homeless, the official said.
Health officials fear that the water dumped by the storm will worsen the outbreak. The concern is that overflow from latrines and septic tanks could contaminate the supply of fresh drinking water and contribute to the spread of the bacteria.
In the capital, the canals were not overflowing, said American Red Cross spokeswoman Andrea Koppel. But that was not the case in cities west of the capital, which bore the brunt of Hurricane Tomas, she said.
Still, even Port-au-Prince looks and smells like a dump -- a caldron of water, garbage and human waste. "We get used to it," said one resident.
Ten months after a magnitude-7 earthquake laid waste to much of the nation, people compete with animals scavenging through the ubiquitous dumps for scraps of food.
"The quick solution is management," said Environment Minister Jean Marie Claude Germain. "Management meaning that you have a structure in place, but the structure was not conceived with the slums in mind."
But most of the residents of Port-au-Prince live in slums.
"We're working on it," Germain said. "We will work with the private sector."
CNN's Paula Newton contributed to this story.