President Jeanine Anez takes a blood test before donating blood on Blood Donor Day, at the presidential palace in La Paz. File / AP

Bolivia's interim President Jeanine Anez became the latest world leader to test positive for the coronavirus, as the United States notched yet another record-breaking surge of cases while global infections and fatalities continued their relentless rise.

The Bolivian government confirmed that at least seven ministers, including its health minister, had tested positive and were either undergoing treatment or recuperating at home.

Jeanine Anez poses for a photograph during an event in La Paz. File

COVID-19 has now claimed more than 550,000 lives across the planet, and infected more than 12 million people since it first emerged in China in late 2019 -— among them Brazilian President Jair Bolsonaro, British Prime Minister Boris Johnson and now Bolivia's Jeanine Anez.

In a video on Twitter Anez said she was "fine" and would continue working from isolation. Bolsonaro said he was feeling "very well" on Thursday after announcing he had the virus earlier this week, and Johnson, who contracted the respiratory disease in March, has recovered.

Bolivia is gearing up for a general election, despite the country of 11 million recording almost 43,000 virus infections and more than 1,500 deaths.

By the time the polls are held in less than two months, the government expects there to be 130,000 cases.

The United States notched up half that figure in just one day on Thursday, with 65,551 new cases recorded by Baltimore-based Johns Hopkins University — a new high.

The country, the hardest-hit in the world by the pandemic, has a total caseload of more than 3.1 million, with 133,195 deaths.

It has seen a spike in infections in recent weeks, and health experts worry the death rate may soon follow the same trajectory.

"We're in a very difficult, challenging period right now," top US infectious diseases expert Anthony Fauci said.

"I would think we need to get the states pausing in their opening process," he said, although he added: "I don't think we need to go back to an extreme of shutting down."

US President Donald Trump, who has publicly disagreed with Fauci, has downplayed the spike.

"For the 1/100th time, the reason we show so many Cases, compared to other countries that haven't done nearly as well as we have, is that our TESTING is much bigger and better," he tweeted.

"We have tested 40,000,000 people. If we did 20,000,000 instead, Cases would be half, etc."

Agence France-Presse