Pujehun, in the south east, has had no cases for 42 days after early decision to clamp down on public gatherings

A district in Sierra Leone has been declared Ebola-free, the first to be given the all-clear after 42 days with zero recorded cases of the virus.

Pujehun, in the south-east of the country, was hit by Ebola in August and suffered 24 deaths from 31 cases – but it has not had a recorded case since 26 November. This means it has achieved the World Health Organisation’s benchmark for Ebola-free status.

District council chairman Sadiq Silla credited an early decision to close markets, and ban social activities and worship in churches and mosques. He put the emergency measures in place before Sierra Leone’s president took action, and suffered strong local opposition and death threats as a result.

“My house was physically attacked and I have to thank the police who protected me from the mobs,” he said.

Pujehun’s achievement is a glimmer of hope for the country, where the disease is thought to have killed almost 3,000 people, with almost 10,000 confirmed, probable and suspected cases. The virus can kill within five days.

“We must treat this milestone with caution as well as hope. We have a long way to go to even start turning the tide on Ebola in Sierra Leone,” said Nik Hartley, head of Restless Development, a British-based charity that employed more than 70 people in the district.

But James Fofanah, country director for the charity, told the Observer: “We are all quite excited about it given the level of effort that went into it since the start. It’s quite a relief to have reached 42 days.”

Hesaid district leaders were “hesitant about celebrations”: there remained a high risk that a new case would come from a neighbouring district, or from Liberia, and begin a new infection chain.

Hopes are high that the disease is on the retreat in eastern Sierra Leone: neighbouring Kailahun district – the centre of the epidemic last summer – is now 27 days without a case. Freetown and other parts of the west and north, including Port Loko and Bombali, are still seeing relatively large numbers.

“There are signs that case incidence may have levelled off in Sierra Leone,” said the United Nations Mission for Ebola Emergency Response in its latest situation report. Warning against complacency, it said 11 of Sierra Leone’s 14 districts had new confirmed cases.

Sierra Leone has been hardest hit by the Ebola crisis, with 7,718 cases confirmed up to 9 January, more than neighbouring Guinea and Liberia combined. The capital had 89 cases in the week to 9 January, compared with 153 the previous week and 199 cases in the first week of December.

The fragility of the countdown is illustrated in the districts of Kenema and the remote diamond mining district of Kono. Kenema recorded a new case on 4 January, after 19 clear days.

Kono had few cases until early December, when someone travelling from another district infected a family. The lack of hospital facilities for Ebola led to rapid infection, with 87 bodies discovered after the alarm was raised. Red Cross workers were helicoptered in and evacuated the local hospital. The UN says Kono has suffered 32 confirmed cases during the last reporting week and 84 confirmed cases in the past 21 days.