A Houston-area woman who traveled in November to El Salvador has been diagnosed with the Zika virus, public health officials said, raising concern that the mosquito-borne illness linked to a health crisis in Brazil could spread through the Americas.

The woman contracted the virus during the trip to the Central American nation and visited a doctor after returning to the U.S. with a rash, joint pain and muscle aches, said Umair Shah, executive director of the Harris County Public Health & Environmental Services department in Texas. A preliminary test showing she might have Zika virus was confirmed late last week, he said.

The virus, usually treated with bed rest and liquids, is rarely fatal. The woman didn’t need hospitalization and has recovered, Dr. Shah said.

The virus is transmitted by mosquitoes that bite infected people and then pass it on to others. “We do not have any evidence that we have Zika virus in our current pool of mosquitoes,” Dr. Shah said.

At least 22 U.S. cases have been reported since 2007 in travelers who were infected in other countries, according to the U.S. Centers for Disease Control and Prevention.