A Hancock County resident who traveled to a tropical country has been infected with the Zika virus, the Maine Center for Disease Control and Prevention reported Thursday.

The person, who is over 65 years old, wasn’t hospitalized and is recovering at home, the CDC said.

“The illness itself is mild and only one in five develop any symptoms,” said Dr. Siiri Bennett, the state epidemiologist. However, health officials are concerned about the potential connection between the Zika virus and birth defects, which is why the spread of the virus in Brazil and tropical countries has made international news in recent months.

The mosquito that carries the virus – aedes aegypti – cannot live in Maine because it isn’t warm enough, experts say. Although the disease is primarily transmitted by the mosquito, it can be passed on from a mother to her fetus during pregnancy, and from a man to his sex partners, according to the U.S. Centers for Disease Control and Prevention.

Bennett said the disease is “highly unlikely” to spread in Maine because of the state’s cold climate.

Symptoms of the virus include fever, rash, joint pain, conjunctivitis, muscle pain and headache, the CDC said. The illness usually begins two to seven days after a mosquito bite and the symptoms subside without treatment after several days to a week.

The CDC is not providing more details on the person or what countries were visited because of patient confidentiality laws.

Twenty-five Maine residents have been or are being tested, the CDC said. The Hancock County resident was the first to test positive for the Zika virus. The other cases were negative, but several test results are pending.

Bennett said most of the people being tested are women who are pregnant or could be pregnant.

There may be a link between pregnant women infected with Zika and microcephaly, a neurological birth defect in which the baby’s head is abnormally small. Health agencies are investigating to determine whether there is a connection.

Meanwhile, health agencies are encouraging pregnant women not to travel to affected countries, and if they do, to get tested for the virus.

“The common link to this virus is travel, and this finding is not unexpected,” Bennett said. “Several countries in the Caribbean, Central and South America are experiencing outbreaks, and Mainers like to travel to warm places in the winter.”

Bennett said more cases are expected in Maine, especially as people return from tropical vacations.

Charles Lubelczyk, a field biologist with the Maine Medical Center Research Institute’s vector-borne disease lab, said the aedes aegypti mosquito dies quickly once outside of tropical climates, so there’s no cause for concern in Maine even during the summer.

“It’s always been a very tropical mosquito. The eggs need quite a bit of warmth to develop and hatch,” he said.

The mosquito – which also carries yellow fever and dengue fever – would even have a difficult time living in some parts of Florida and the Carolinas, Lubelczyk said. There are no known cases of someone in the United States contracting the Zika virus from a mosquito bite.

In southern Maine’s warm summer months, it might be possible for an “extremely localized” concentration of the aedes aegypti mosquito to arrive at Maine’s ports from warmer climates, but the mosquitoes would be wiped out as soon as there was a cold night, Lubelczyk said.

As of Feb. 17, there had been 82 reported cases of Zika in 20 states and Washington, D.C., according to the federal CDC.

Those at risk of contracting the Zika virus – especially women who are pregnant or could be pregnant – should wear protective clothing and insect repellent when traveling to a Zika-infected country, the federal CDC said.