Twenty staff members of ATN News, a private TV channel, have been sent on home-quarantine after one of their colleagues has tested positive for coronavirus.   The journalist of the television channel returned home from abroad on March 21 after attending a one-month training course there, said its Executive Editor Munni Saha.   He went to his residence straight from the airport and maintained a 15-day home-quarantine period, she said.   The reporter started suffering from fever four days after he rejoined office on April 5, Munni Saha said, adding that he later developed cough and body ache.   As he approached the Institute of Epidemiology, Disease Control and Research (IEDCR), they collected his samples from his home on April 10 and he was informed on Saturday night that he had tested positive for Covid-19, she said.   The ATN News executive director said the reporter is now receiving treatment staying in isolation at his home.   She also said they sent 20 staff members who came in contact with him on home-quarantine.