Test results on the 49th cholera case this year have so far ruled out contaminated shellfish as the source. A 20-year-old man from Western developed diarrhoea on April 15 and was admitted to Princess Margaret Hospital two days later. Last Wednesday, laboratory tests confirmed him to be the 17th local cholera case, bringing the total to 49 including 32 cases of returning travellers who became sick. Investigations have taken health officials to 10 food premises. Tests have been carried out on the man's family, dinner companions and restaurant workers. All tests for contaminated bi-valves have been negative, a Government health spokesman said, adding that further results would be available within two days.