With fear of infection rising among factory workers, and few customers shopping for cars, several automakers on Wednesday decided to idle their plants in the United States, Canada and Mexico for at least a week. The decisions will put tens of thousands of people out of work and add to the coronavirus outbreak’s growing economic toll.

The country’s largest automakers — General Motors, Ford Motor and Fiat Chrysler — decided to close plants after the United Auto Workers union pressured them to do so to protect workers. That pressure intensified after it was revealed on Wednesday that a worker at a Ford truck plant in Dearborn, Mich., had tested positive for the virus.

In addition to G.M., Ford and Fiat Chrysler, Honda, Toyota and Nissan also said they would idle their North American factories. The shutdown of car plants will force hundreds of companies that produce parts and components to follow suit over the coming days.

“This is another big blow to the economy,” said Patrick Anderson, president of Anderson Economic Group in East Lansing, Mich.