At least 56 per cent of the people who have tested positive for COVID-19 in West Bengal are migrant workers who returned from other states, a senior official of the state health department said on Wednesday.
According to him, 10 out of every 100 migrant workers examined have tested positive for COVID-19 but most of them are asymptomatic.
"Around 56 per cent of the people who have tested positive for COVID-19 in the state are migrant workers, according to the data we have received from the districts. But what is crucial is that most of them are asymptomatic and this is making the current situation quite difficult," the official said.
Over 6.60 lakh migrant workers have returned to West Bengal from different states by Shramik Special trains while several lakhs have come back by road.
"Districts like Purulia, Birbhum, Coochbehar, Bankura, Dakshin and Uttar Dinajpur were green zones until the migrant workers started returning, after which the number of positive cases went up in those areas," the official said.
Most of these people, who have tested positive for the disease, have returned from states with a high number of coronavirus cases such as Maharashtra, Tamil Nadu, Gujarat, Madhya Pradesh and Delhi.
The state government had earlier made it mandatory to test everyone returning from states with a high number of coronavirus cases, but later stopped the practice for asymptomatic people following an Indian Council of Medical Research (ICMR) advisory.
However, it has set up "safe homes" for the asymptomatic people who have tested positive for COVID-19 to provide them with a temporary shelter and prevent the virus from spreading.
West Bengal has registered 11,909 COVID-19 cases and 495 fatalities due to the disease till Tuesday.
The number of active cases in the state has risen to 5,386 while 6,028 people have recovered from the disease, according to a bulletin issued by the health department.