A National Guard member was told he likely had a virus. He actually had malaria.

Stationed near the Texas-Mexico border as part of the National Guard, Christopher Shingler first noticed a fever, trouble eating and vomiting in May.

Medics gave the 21-year-old tests for Covid-19, and at a hospital the Brazoria County resident was told he likely had a viral infection. In early June, after symptoms persisted, tests at a different hospital made it official: Shingler had malaria.

“I would wake up really early in the morning and I would start shaking,” Shingler said. A high fever would follow and lead to vomiting.

“It was a lot of just trying my best to make myself eat something, as small as I could, which usually I was unsuccessful, or trying to drink water, which, again, I was unsuccessful,” Shingler said.

The disease, transmitted by mosquitoes, sickens more than 200 million people annually around the world and kills hundreds of thousands. Shingler is one of handful of people in the U.S. recently diagnosed with malaria without having traveled recently.

Shingler does not know how he got malaria or from where. He said the Centers for Disease Control and Prevention has been in contact with him as officials try and find the source.

Read the full story on NBCNews.com here.