Cause of infections still unknown after similar case is reported in Guangdong Health chiefs are investigating the deaths of two Hong Kong pig farmers from acute pneumonia caused by an unknown infection. The investigation was announced as a mainland paper reported that a pig farmer from Guangdong died of pneumonia on Tuesday and authorities there also had yet to find a cause. A hotline to collect information about similar pneumonia cases was set up as health experts warned it was essential to track down the cause quickly and avoid another outbreak like Sars, which also began as a series of mysterious pneumonia cases. Centre for Health Protection consultant Thomas Tsang Ho-fai confirmed yesterday that a 44-year-old pig farmer, surnamed Sin, had died in Northern Hospital on December 13 after developing a cough and high fever six days before. The cause of death was multiple organ failure caused by acute pneumonia. Sin, who farmed at Man Kam To, visited the Pearl River Delta city of Dongguan last month and Queen Elizabeth Hospital early this month to visit another pig farmer who was being treated for pre-existing lung disease and kidney problems. His symptoms were not similar to Sin's. Sin's death followed that of a Yuen Long pig farmer, Yip Kwong-king 65, in Yan Chai Hospital on June 4 after also showing symptoms of pneumonia. His wife, Chung Sou-mui, said Yip had been to a doctor twice for flu before going to the hospital where he was diagnosed with pneumonia. He was in hospital for a week before the illness turned acute. She said Yip had visited their flat in Shenzhen three or four times before he fell ill but there were no pig farms nearby. Initial laboratory tests for both men came back with negative results for influenza and the pig bacterium Streptococcus suis. 'We cannot identify a virus or bacterium which would cause the illness,' Dr Tsang said. He could not rule out the possibility the cases were connected, but said, 'the chance of contracting pneumonia from pigs is slim'. Infectious disease expert Lo Wing-lok said it was rare for diseases transmissible from pigs to humans to cause acute pneumonia. But he urged the government to find out the cause quickly. 'One has to bear in mind that Sars also originated from animals,' he said. Dr Tsang said neither case had been reported to the centre, which had sought the information after seeing newspaper reports yesterday. He said it was impossible to monitor all pneumonia cases as it was a common cause of death in Hong Kong. The Agriculture, Fisheries and Conservation Department yesterday visited the pig farm where Sin worked with staff from the Centre for Health Protection and found no abnormalities in the pigs. Sin's five family members and a colleague also showed no symptoms of pneumonia. Dr Tsang urged pig farmers to call the hotline at 2125 1133 if they had contracted pneumonia in the past six months. The centre has also contacted the National Ministry of Health and its Guangdong division for more information on a newspaper report of a pig farmer in Nanhai who died of pneumonia on Tuesday. Tests showed negative results for Sars and Streptococcus suis. The report said the farmer had taken care of a sick pig with asthma that died.