The growing demand for thermometer guns and infrared cameras that can detect fevers has caused shortages across the world, from the center of the outbreak in Wuhan to a small supplier in Texas.

A host of Chinese companies make thermometer guns, which have become more expensive as demand has increased from both government and private customers like schools and factories.

Alicn Medical (Shenzhen), a manufacturer in the Chinese city of Shenzhen, makes 2.5 million thermometer guns a year and is one of only a handful of companies in China that can achieve that level of production, said Mo Yingchun, its general manager. Still, raw material costs have surged and many workers can’t get around China’s outbreak containment efforts to show up for their jobs, meaning the company isn’t producing at full capacity.

“Even the governments are fighting for the products among themselves,” Mr. Mo said, noting that prices had climbed to three to five times the usual level. “Local governments want to guarantee their own needs first.”

Typically, he added, the company’s thermometers are used indoors to check on babies. “The thermometer guns are used only for quick screening and are not as accurate as traditional thermometers,” Mr. Mo said. “It was a small industry, and if it weren’t for the outbreak, it will not be put in the spotlight.”

Thousands of miles from the heart of the outbreak, a small technology supplier in Beaumont, Texas, has also been feeling the crush of demand. The company, Infrared Cameras, makes high-tech imaging equipment as well as infrared thermometers, which cost $25 apiece.

In a normal month, the company sells about 100 infrared cameras, according to its chief executive, Gary Strahan. Since January, the company has sold more than 1,000, supplying schools, cruise ships, factories, offices, hospitals and theaters in countries like China and South Korea.