The administration of Gadchiroli,which is the only district so far untouched by the scourge of coronavirus in Maharashtra, is now being more vigilant to ensure it retains the green zone tag.The authorities are mindful that if at all any COVID-19 case comes to light in the district, it will come from outside and hence, they have enhanced efforts and are closely monitoring migrant workers entering the territory.Maharashtra has total 36 districts.Gadchiroli, located over 900 km from Mumbai in the state's Vidarbha region and having a population of around 12 lakh, has not reported a single COVID-19 case yet."If at all any (positive) case comes here, it will come from outside the district now. So, we are strictly monitoring the labourers who are entering the district limits. We are being extra careful of people coming from non- containment zones of places which have reported more cases, Gadchiroli Collector Deepak Singla told PTI over phone.Singla said nearly 18,000 workers have entered the territory of Gadchiroli from neighbouring districts like Nagpur and Chandrapur and states like Telangana, Andhra Pradesh, Madhya Pradesh and Chhattisgarh since May 1.These people were allowed to enter the district only if they possessed medical certificates as per norms and were kept under institutional quarantine according to the guidelines, he said, adding that the workers are not allowed to enter their native villages directly."We have formed gram samitis (committees) of sarpanch, talathi (revenue officer), gram sevaks locally to keep a watch and people coming from outside are being quarantined at schools for a 14-day period, Singla said.Nearly 2,500 migrant workers have been sent to their native states like Uttar Pradesh, Bihar, Madhya Pradesh, Chhattisgarh, and other districts in Maharashtra from Gadchiroli till now, he said.The district authorities had earlier (before May 1) quarantined 18,000 to 20,000 people after the nationwide lockdown was announced, Singla said, adding that their quarantine period is over.The district administration has allowed markets in the district to remain open from 7 am to 5 pm with certain restrictions and on the condition of maintaining social distancing."We are, however, not allowing public events, the official said.As of Wednesday, Maharashtra reported 25,922 positive cases and 975 deaths -- highest in the country.Mumbai in the state has so far reported the highest number of COVID-19 cases and deaths.