Six people have contracted bovine tuberculosis in an outbreak in Birmingham which has killed one man.
Three of the cases are linked to the same bar and nightclub
Three are thought to have picked up the infection at a bar and nightclub, two had visited the same venue and one was acquainted with others infected.
Most of those who were affected suffered from other diseases.
The Health Protection Agency (HPA) said measures were taken to halt the spread of the infection and there was no continuing public health risk.
New DNA investigation techniques showed all six cases were linked either by person-to-person spread or by being infected by a common source.
The source of the outbreak is thought to have been a man who drank untreated, unpasteurised milk.
Professor Peter Hawkey, from the Regional Centre for Mycobacteriology at Birmingham Heartlands Hospital which made the discovery, said the six were connected by a "complex social web".
All were young people, with an average age of 32, and were known to go to nightclubs or pubs, two were found to be a couple.
Prof Hawkey said most cases of TB are usually found in people in their 60s and 70s but said people using pubs and clubs in the Birmingham area should not be concerned.
"The risk is tiny," he said. "But the health message is that anyone who experiences persistent weight loss with night sweats, tiredness and a cough should seek medical attention as it is just possible they might have TB."
The last case was reported in February this year and it is thought the outbreak is over, said BBC Midlands Today science and environment correspondent David Gregory.
The outbreak was first thought to be a blip in the TB figures because the rate of infection was more than the amount expected for cases of bovine tuberculosis.
The HPA investigation was launched after one case was reported in 2004, four in 2005 and one at the beginning of this year.
It said on average three cases a year are reported in the West Midlands.
Dr David Hunt, from HPA West Midlands, said: "Each of these cases was thoroughly investigated at the time and all appropriate measures were taken to ensure that there would be no further spread of infection.
"We have no reason to believe that there is a continuing public health risk."