Ramon Espinosa, Associated Press
A worker sprays with disinfectant a woman with symptoms of cholera as she is held by a relative at the entrance of St Catherine hospital in Cite Soleil in Port-au-Prince, Haiti, Wednesday, Nov. 10, 2010.

PORT-AU-PRINCE, Haiti — A mentally ill man who bathed in and drank from a contaminated river most likely was the first person to be infected in the Caribbean country's deadly cholera outbreak, a Boston humanitarian group said Monday.

Partners in Health reported the case Monday in a study it did on the outbreak and published in the American Journal of Tropical Medicine and Hygiene.

Officials say the cholera outbreak that began in 2010 has killed 7,000 people and sickened nearly 500,000. The disease surfaced in Haiti months after a powerful earthquake struck the country two years ago this week.

The humanitarian group's Dr. David Walton, who co-authored the study with Dr. Louise Ivers, said information points to a 28-year-old mentally ill man from the central town of Mirebalais as the first person infected.

He said the man's family had access to clean drinking water but his auditory hallucinations and paranoia went without treatment and he bathed in and drank frequently from a river into which the Meye River fed. The Meye has been identified as the likely source of the epidemic.

"It's a striking example of how mental health, infectious disease and community health affects overall well-being," Walton, an internist, said by telephone.

The case serves as a reminder of how mental health services are often an afterthought in health services planning, he added.

The mentally ill man developed acute diarrhea on Oct. 12, 2010, and died at his home without seeking medical attention less than 24 hours later.

He was buried the next day and two people who prepared the body for the wake developed severe diarrhea in less than 48 hours.