NEW DELHI: More than 500 people across the country who had come in contact with a group of over 40 Islamic preachers, largely from Malaysia and Indonesia, during March 2-20 are under observation for possible coronavirus infection.The first Covid-19 casualty in the Kashmir Valley, a 65-year-old man from Srinagar, had travelled with the group to different states including Delhi and Uttar Pradesh, attending religious gatherings. Several others who attended the group’s events have also tested positive for the infection.Authorities are keeping a close watch on the students of the famous Deoband seminary in Uttar Pradesh’s Saharanpur district and families living in the area around the Mohammadi mosque, where the group is believed to have stayed during March 9-11.Saharanpur commissioner Sanjay Kumar said while the mosque had been sealed, all houses, shops and schools within a 1-km radius had been disinfected. "We have come to know that one meeting that was attended by the Kashmir patient was held here in a mosque. It was attended by a significant number of people,” he said. “In the first phase, after talking to people, we have been able to test 11 people who are all still quarantined in an administrative facility in Saharanpur and will stay there for two more weeks. All preliminary tests have come negative so far."Nearly ten houses in the area that the group visited have been quarantined. “We are still surveying the households to see if there is anyone who needs to be tested," Kumar said.The Kashmir man, who tested positive for Covid-19 on March 24 and died two days later, had left behind a trail of contacts, including his own family members and doctors. In Kashmir, at least 11 of his primary contacts were found positive and around 70 of his direct or indirect contacts are under quarantine. Most of the foreign preachers in the group too are currently quarantined in different states in the country.According to a resident of Khankah Muhallah where the Mohammadi masjid is located, those who were identified by the authorities as his active contacts included three Kashmiri students at a seminary there, the imam and muezzin of the masjid and a person from Tripura, who was also in the masjid.The chief medical officer in Deoband said they were all tested negative for infection.“Twenty-five contacts who he had met between 9 and 11 March were also examined and all of them are healthy and fine and haven’t shown any symptoms since March 11,” a local resident privy to the developments told ETIn Delhi, a sub-divisional magistrate in South Delhi said at least 51 people were part of a Markaz (event) on March 7 in Nizammuddin that was attended by the Kashmir patient and other members of the group. Of them, 11 have been identified and tested, along with their family members."Test results of over 120 of them, including family members of the 11, have come which are negative, but over 30 families here are under home quarantine," the SDM said.The group had also travelled to other states. Madhya Pradesh health officials said a group of 13 preachers had travelled from Bhopal to Ramagundam in Telangana to attend an event where seven members of the group had participated. "Since three of them were found positive, we have launched tracing of those who came in touch with the group which here for a day," an official said.Similar searches were being conducted by officials in Tamil Nadu, Telangana and Andhra Pradesh. So far 250 samples were tested, and 21 of those were found positive.The worst impact seems to have been on the Andaman & Nicobar Islands. Nine people from the islands had travelled to attend the Nizammudin markaz on March 7. "All nine have been tested positive, of which four stayed back in Delhi. They are being treated there," Avijit Roy, the medical nodal officer, told ET. One of the other Andamanese patients who was tested positive had travelled to Guntur, Roy added.The administration said measures were being taken to protect the tribes of the islands, as they are more vulnerable to getting infected.The possibility of the outbreak was also discussed at a recent meeting of Dar-ul-Uloom in Deoband. "After the news came out, we had also made arrangements for the asymptotic students to go home, in batches of 20, in 50 seater buses so there is no transmission. We have 15,000 students studying here at any given time, and hence we didn't want to take any risk," an official said. Tableeghi Jamaat, an apolitical organisation, believes in the message of ‘Deen ki Mehnat’ which means strengthening the Islamic way of life. The members are known to undertake extended travel to spread the message of the Quran among Muslims. Door-to-door campaigns and events in mosques are part of their functioning.