The official Xinhua news agency says former Shanghai Mayor Ying Yong will replace Jiang, who had been criticized by the public for his handling of the outbreak of the COVID-19 virus.
As of Friday, the number of reported cases outside of China were Japan (203), Hong Kong (53), Singapore (50), Thailand (33), South Korea (28), Taiwan (18), Malaysia (18), Germany (16), Vietnam (16), Australia (15), the United States (14), France (11), Macau (10), the UK (nine), the UAE (eight), Canada (seven), India (three), the Philippines (three), Italy (three), Russian Federation (two), Spain (two), Cambodia (one), Finland (one), Nepal (one), Sri Lanka (one), Sweden (one) and Belgium (one), according to the European Centre for Disease Prevention and Control.
Six of the workers have died, Zeng Yixin, vice director of the National Health Commission, said at a news conference.
The 12 Canadians who contracted the virus on board the ship have been moved to Japanese health facilities, and at least three require hospitalization, Champagne said.
The sharp one-day increase "does not represent a significant change in the trajectory of the outbreak", said Michael Ryan, head of the WHO's health emergencies program.
He said that other parts of China, however, would still need to wait for cases to be confirmed in laboratories before they could be officially counted.
The WHO said the numbers included cases going back weeks.
China's health commission said the change in counting methodology was aimed at identifying suspected cases in which the patient has pneumonia so they can be treated more quickly and reduce the likelihood of more serious illness or death.
Japan is one of the worst affected of more than two dozen countries and territories outside mainland China that have seen hundreds of infections. "It is important that these also be counted", she told Reuters.
Some cities in Hubei tightened restrictions this week, sealing off neighborhoods in what they liken to "war-time" measures.
Some 26 billion Chinese yuan (US$3.7 billion) has been spent on medical equipment, protective gear and improving conditions in medical facilities, said Ou Wenhan, a finance ministry official.
World Health Organization chief Tedros Adhanom Ghebreyesus greeted news of the slowdown with caution Wednesday, saying the outbreak "could still go in any direction".
It was "an example of the worldwide solidarity we have consistently been calling for", he said.
"I think we will find a vaccine", she said.
On Tuesday, top Chinese epidemiologist Zhong Nanshan said the epidemic should peak in China this month before subsiding. Though Chinese authorities initially stipulated that only Canadian passport holders would be able to leave the quarantined region, they seem to have relaxed that rule, Champagne said, but he did not elaborate on whether Canada would make arrangements to fly more of them out.
The US State Department said it was "deeply concerned" about the vulnerability of China's northern neighbor, North Korea, and offered to support aid work in the country.
Forty-four more passengers aboard the Diamond Princess have tested positive as the cruise ship remains docked and quarantined near Yokohama, Japan.