NEW DELHI: One of the key measures to limit the spread of Covid-19 has been tracing contacts of persons affected by it and the central and state governments have launched an intensive exercise, often tracking down seat numbers in buses and even dhabas to identify and observe those who came in contact with affected patients.TOI spoke to health ministry officials who have been tracking each and every case from a ‘war room’ where data of patients and the place he or she may have visited is minutely analysed for subsequent action by local health authorities.For example, on February 20, a data scientist in Bengaluru, a resident of Telangana, returned from Dubai. He became symptomatic for Covid-19 two days later and took self-medication for a couple of days before approaching a family physician and subsequently reached Apollo Hospital.The data scientist was referred to the Gandhi Hospital in Hyderabad where samples for Covid-19 were confirmed, leading to local authorities identifying 76 of his contacts in Telangana and 10 in Bengaluru within hours. All were put under surveillance for Covid-19 symptoms but tested negative.The contact tracing of 23 Italian tourists, of which 16 were found positive for Covid-19 and are admitted in different hospitals, was more challenging. The group arrived at IGI Airport in Delhi on February 21. The group, along with a driver, a helper and a guide, visited various cities in Rajasthan and also went to Agra.“We tracked down even the dhaba where the driver, travelling with the Italian group, got his dinner packed. They too have been put under surveillance,” a senior official in the Delhi public health division said.A group member was ill at the start of the tour but did not report this. He travelled with the group to multiple destinations in Rajasthan and reached Jaipur on February 29. After tests confirmed Covid-19, the Integrated Disease Surveillance Programme (IDSP) of Rajasthan immediately started contact tracing. A total of 361 contacts from eight hotels and staff of hospitals were identified in the state and the hotels sanitised as per protocol and staff de-rostered.A total of 43 contacts were identified in Agra at the hotel where the group stayed. All are under surveillance and the hotel was sanitised. In Delhi, the two hotels where the group stayed were sanitised, the staff serving the group de-rostered and all contacts put under surveillance.The Covid-19 patient’s wife stayed back with him in Jaipur while rest of the group travelled to Agra and stayed in a hotel there for a night. The wife also became a positive case later on.The group was finally taken to the quarantine facility at ITBP Camp, Chhawla. There, 14 Italians and one Indian was found to be positive.