State health department officials said on Thursday that 21 new coronavirus cases had been reported in north Bengal in the past 24 hours.

Most of the Covid-19 patients were from North Dinajpur district. After a gap of almost a month, four new cases of the pathogen were recorded in Alipurduar district.

In North Dinajpur, 14 persons, all residents of Islampur subdivision and migrant workers, have been found infected with the novel coronavirus. The number of Covid-19 persons in the district is 97 now.

In Malda district, a resident of Habibpur block was detected with Covid-19.

“In north Bengal, the concentration of coronavirus patients is quite high in Malda and North Dinajpur districts. Most of them are migrant workers,” said a health official.

In Jalpaiguri, two persons, both residents of Maynaguri block, tested positive for Covid-19. One of them is a student who has recently come from Calcutta while the other is a rural health worker.

In Alipurduar, officials of the district health department said four persons — all from Falakata block — tested positive for the coronavirus.

One of the patients had returned from Delhi while the other three had been to Chopra in North Dinajpur, Baxirhat in Cooch Behar and Maynaguri of Jalpaiguri in recent weeks.

“So far, around 30 persons who had come in contact with them have been identified and kept in isolation at Falakata,” said an official.