Experts have warned this could be the start of an “explosive” outbreak in the country, which does not have a mass Covid vaccination campaign like most other countries.
The country’s dictator, Kim Jong-un, visited the anti-virus command centre on Thursday, after declaring a "gravest state of emergency" and ordering a national lockdown, state media reported.
About 187,800 people are being treated in isolation after a fever of unidentified origin “explosively spread nationwide” since late April, the official KCNA news agency said.
Around 350,000 people have shown signs of that fever, including 18,000 who reported symptoms for the first time on Thursday, KCNA said.
It did not specify how many of these cases were confirmed to be Covid. North Korea has previously denied having Covid cases.
At least six people who showed the fever symptoms have died, with one of those confirmed to have contracted the Omicron variant of the virus, KCNA said.
As North Korea has limited testing capacity, the true number of infections could be significantly higher.
North Korean officials have said the outbreak began in the capital of Pyongyang in April. The city hosted several mass public events on April 15 and 25.
In broadcasts on state television, Kim said the government’s top priority was to actively isolate and treat people with ‘fevers’.
In another dispatch, KCNA said health authorities were trying to organise testing and treatment systems and improve disinfection work.
The rapid spread of the virus could prove a major crisis in a country that lacks medical resources, has refused international help with vaccinations and has kept its borders shut.
The outbreak could also deepen the isolated country’s food shortages, as the lockdown would hamper its “all-out fight” against drought.
North Korea said last year it had developed its own PCR tests, but it refused vaccines from the global Covax supply.
Kwon Young-se, South Korea’s new nominee to be the unification minister, said Thursday that he was willing to push for humanitarian assistance for the North, including Covid treatment, syringes and other medical supplies.