A Dallas, Texas, resident who recently returned from Nigeria has tested positive for monkeypox, a rare virus similar to smallpox, local officials said Friday. Though this is the first confirmed case of the virus in the U.S. since 2003, officials said the public should not be concerned. 

“While rare, this case is not a reason for alarm and we do not expect any threat to the general public,” Dallas County Judge Clay Jenkins said in a statement from Dallas County’s health department. Because passengers were wearing masks on the flight and in the airport, the health department said, “It’s believed the risk of spread of monkeypox via respiratory droplets to others on the planes and in the airports is low.” 

Monkeypox, which is in the same family of viruses as smallpox, is a rare but potentially deadly viral infection that begins with flu-like symptoms and progresses to a rash on the face and body, according to the CDC. It tends to last two to four weeks. People who do not have symptoms are not capable of transmitting the virus, the health department said. 

Laboratory testing confirmed the patient is infected with a strain of the virus that is mainly seen in West Africa, which includes Nigeria. Monkeypox infections of that strain are fatal in about 1 in 100 people, affecting those with weakened immune systems more strongly, according to the CDC. 

Prior to this case, there have been six other cases of monkeypox in travelers returning from Nigeria. The CDC said this case is not believed to be related to any of the prior cases. 

This is the first reported case of monkeypox in Dallas County, according to the health department’s statement. The person is currently in isolation at a hospital in Dallas and is in stable condition. The CDC said it is working with local health officials to contact airline passengers and others who were in contact with the infected traveller during their flights from Lagos, Nigeria, to Atlanta on July 8, and Atlanta to Dallas on July 9.

The last time monkeypox was seen in the U.S. was in 2003. Nearly 50 people fell ill after imported African rodents infected prarie dogs, which subsequently infected humans, the CDC said. This launched a government search across 15 states for infected prairie dogs.

Despite past incidences of the virus, Dallas County Health and Human Services Director Dr. Phillip Huang said there’s no reason to worry. “We have determined that there is very little risk to the general public,” he said in the health department’s statement. “This is another demonstration of the importance of maintaining a strong public health infrastructure, as we are only a plane ride away from any global infectious disease.”