MADISON, Wis. — Rural counties in northern Wisconsin that had largely been immune from the coronavirus pandemic are now seeing a surge in cases, with Iron County now having the state's highest rate of active confirmed COVID-19 infections.

The number of confirmed infections in Iron County was in the single digits for four months before spiking in July, with 75 total cases. Of those, 68 are of residents and seven are of nonresidents. The cases are spread throughout the county. Thirty-eight people have recovered, three have been hospitalized and one has died, Wisconsin Public Radio reported Thursday.

Zona Wick, the former county health officer who has been rehired as a public health nurse during the crisis, said the spike is a result of "quarantine fatigue." That led to people casting aside social distancing for graduation parties, Fourth of July gatherings and other social events where the disease spread, Wick said.

The low numbers "lulled people into complacency, into saying, 'Hey, things are safe here. It's just our family. It's just our friends. It's just people we know.' … And the virus doesn't care," Wick said.

Only four of Wisconsin's 72 counties showed more active cases than recovered ones, according to the state Department of Health Services. Those were Iron, Juneau, Langlade and Menominee counties. Two others, Taylor and Washburn counties, had the same number of active and recovered cases. All six are rural counties.

On Wednesday, Trempealeau County public health nurse Kaila Baer said in a statement that the western Wisconsin county was "on the edge of moving to severe risk." It had the seventh-highest case rate in Wisconsin per 100,000 people, Baer said.

Wisconsin has had more than 52,000 confirmed cases of the COVID-19 virus and 919 deaths as of Thursday. That death count is the 28th highest in the country overall and the 35th highest per capita at nearly 16 deaths per 100,000 people. Over the past two weeks, the rolling average number of daily new cases has gone up by 90, an increase of more than 11%.

The number of infections is thought to be far higher because many people have not been tested, and studies suggest people can be infected with the virus without feeling sick.