Dr George Nyale, chairman of the conference, confirmed the outbreak, saying there is no cause for alarm.
"We have contingency measures on the ground" he said.
He said tests are being run in the hotel and there are ambulances on standby to take people to the hospital.
A source who sought anonymity told Nation.co.ke that at least 47 were admitted to various hospitals in the city after they developed cholera-related symptoms.
The hotel’s management refused to talk to the Nation regarding the matter.
Director of Medical Services Jackson Kioko denied the allegations of the “an outbreak of Cholera at Weston”.
He said the victims were suffering from gastroenteritis, a common food related infection that is characterised by vomiting and diarrhoea.
Dr Kioko said the Ministry of Health’s department of Disease Surveillance and the National Public Health Laboratories have to conduct a “microbiological and other tests to confirm if it is really cholera”.
Nairobi County Executive for Health Bernard Muia said there was a team from the Ministry of Health at the hotel to contain the issue.
The forum, called “The Kenya International Scientific Lung Health Conference”, is organised by the Ministry of Health.
It began on Tuesday and is scheduled to end on Friday.
The over 500 doctors and scientists have been discussing Kenya’s vulnerability to respiratory diseases at the Weston Hotel, associated with Deputy President William Ruto, since Tuesday this week.
One of the victims admitted to Nairobi Hospital was barely audible, saying the diarrhoea started on Wednesday.
“I thought it was food poisoning, so I took water the whole day knowing it would pass,” he told the Nation.
The medic, a physician from Kisumu County, said he later realised that he could be suffering from Cholera from the colour of his loose stool.
The Nation has established that there are two other patients who are admitted to Nairobi Hospital and Karen Hospital.
A source in the conference told the Nation that there could be many more affected “but they are doctors so they are sorting themselves out”.
There was a notice at the entrance to the conference on first floor of the hotel directing anyone experiencing stomach aches to a presidential suite.
The same poster was placed in the toilets, an indicator that the hotel was aware of the matter.
At the entrance, there were three ambulances from Amref.