DOVER — Officials have identified the first known case of the Zika virus in Delaware.

The illness, spread by mosquitoes, is believed to cause birth defects.

An outbreak of the Zika virus has caused the Centers for Disease Control and Prevention to issue travel warnings for more than two dozen countries in the Caribbean, Central America and South America.

Though the majority of people who are infected do not display symptoms, and those that do generally suffer only from mild symptoms, the illness has been linked to children born with a damaged nervous system.

Dr. Karyl Rattay

In some cases, babies born after outbreaks began have suffered from Guillain-Barré syndrome, a condition that weakens the nervous system.

While the virus has not threatened the United States, it has begun appearing in the country after people visiting affected countries returned.

The Delaware Division of Public Health first confirmed the case of a Delaware woman infected with the Zika virus Tuesday.

The woman had traveled to an affected area and was tested within the past week with the CDC determining she had contracted the virus. She has since recovered.

State officials stress there is no known risk to others.

Officials provided more details Wednesday, although they declined to share any information about the woman including where she lives, how old she is and where she had traveled.

“Delaware is announcing our first lab-confirmed travel-related Zika case from a mosquito bite,” Division of Public Health Director Karyl Rattay said in a conference call.

“This is not unexpected given the number of reported cases nationally and internationally,” she added. “I want to emphasis that there is no threat of local infection from this case and that additional confirmed cases are possible given the level of international travel these days.”

Officials would not confirm if other cases in Delaware were being tested. Further announcements only will be made if additional infections are confirmed.

In Delaware, the woman, who is not pregnant, saw her doctor after suffering from symptoms. A subsequent test conducted as a result of her symptoms and travel history revealed she had contracted the virus.

There is no specific treatment and people suffering from the virus seldom need to be hospitalized.

Symptoms, if they appear, include mild fever, rash, joint pain and conjunctivitis. About 80 percent of people infected with the virus show no signs of it.

At least 36 cases in 12 states have been identified in the United States. All of the confirmed occurrences so far have involved travel rather than local mosquitoes, according to the CDC.

However, the federal government is investigating two instances where “it is highly probable” an infected man spread the virus to a woman through sexual intercourse, Dr. Rattay said.

There are no known cases of the virus being transmitted through blood transfusions, she said, although she did caution the “science is evolving.”

The CDC has recommended pregnant women avoid travel to affected areas and those who do get tested upon return.

Men who spend time in affected countries should use protection during sex.

Anyone who has visited an area where an outbreak is occurring should not give blood for a 30-day period as a precaution.

Officials said it is most important at this stage to be informed and stay aware of the risks. Individuals who do travel abroad should use insect repellent, long clothes and bed nets to simply avoid being bitten in the first place.

“As things warm up here in Delaware it’s also going to be important for us here in Delaware, especially for Zika but for other infections like West Nile,” said DPH Medical Director Awele Maduka-Ezeh.

It is possible there have been prior cases in Delaware but individuals did not show any symptoms and so were unaware they should be tested, officials said.