CHICAGO, Oct. 15 (Reuters) - Wisconsin and other states in the US Midwest are battling a surge in COVID-19 cases, with new infections and hospitalisations rising to record levels in an ominous sign of a nationwide resurgence as temperatures get colder.

More than 22,000 new cases were reported on Wednesday across the Midwest, eclipsing the previous record of more than 20,000 on Oct 9. Hospitalisations in those states reached a record high for a 10th consecutive day, as some hospitals began feeling the strain.

More than 86 per cent of the beds in Wisconsin's intensive care units were in use as of Wednesday.

A field hospital opened in a Milwaukee suburb in case medical facilities become overwhelmed. Neat rows of makeshift cubicles enclosing beds and medical supplies occupied the fairgrounds in West Allis, which has been the home of the Wisconsin State Fair since the late 1800s.

Dr Paul Casey, the medical director of the emergency department at Bellin Hospital in Green Bay, Wisconsin, said entire wards full of COVID-19 patients were stretching resources "to the limit."

"It's going to get worse," he told CNN on Thursday. "We predict it will peak mid-November."

More than 1,000 people were hospitalised for COVID-19 in Wisconsin on Wednesday, the state's health department said. Health authorities recorded a near 25 per cent spike in coronavirus hospitalisations in the past seven days compared to the previous week.

Other Midwestern states were also setting grim records.

Since the start of October, North Dakota and South Dakota have reported more new COVID-19 cases per capita than all but one country in the world, tiny Andorra.

These states are reporting three times as many new cases per capita this month than the United Kingdom, Spain or France - where infections were also on the rise - according to a Reuters analysis.

"It's quite concerning," Dr Anthony Fauci, the top US infectious diseases expert, said in an interview with ABC television on Thursday. "We really got to double down on the fundamental public health measures that we talk about every single day because they can make a difference."

Fauci also warned about the risks of crowded gatherings, as President Donald Trump returned to the campaign trail after recovering from his own bout with the coronavirus.

COVID-19 hospitalisations hit a record high on Wednesday in Iowa as well, while the state also posted its biggest one-day increase in cases since Aug 28.

Trump, making a push in the final weeks before the Nov 3 presidential election after being hospitalised with COVID-19, held a large rally in Iowa on Wednesday with most in attendance not wearing masks. He has continued to minimise the threat to public health posed by the virus that has killed more than 216,000 Americans.

"CLUSTERS" THE NEW NORMAL

New York, once the US epicentre of the global health crisis, is now dealing with infection spikes in several "clusters". Governor Andrew Cuomo said he expected flare-ups to continue for at least a year.

"The way of the world going forward is going to be that the virus will constantly flare up in certain locations," Cuomo told reporters this week.

His efforts to stem local outbreaks of the coronavirus have put him in a two-front religious battle with Catholics and Jews, who are asking courts to void restrictions they argue limit religious freedom.

Cuomo, a Catholic, said his the measures, which restricted gatherings at religious institutions to as few as 10 people in certain targeted areas, were not intended to single out religious groups and were consistent with other steps he has taken to combat "clusters" where infections spread rapidly.

But he also blamed Orthodox Jewish communities for causing some of the infection spikes in their areas. An intensive care nurse at Mount Sinai hospital in New York City told Reuters on Thursday there are at least a dozen patients with the virus in critical care there, the majority of whom are Orthodox Jews.

There are about 50 patients with the virus in her hospital and that number is "increasing every day," she said, asking to not be named because she was not authorized to speak to media.