Officials in North Texas have tested four additional patients for Zika virus and are awaiting the results, according to the Dallas County Health and Human Services.
The specimens were submitted to the Centers for Disease Control and Prevention for testing. County health officials said the four cases are not connected to the previous two cases announced earlier this week and that they involve people who recently traveled out of the country.
The county's two previous Zika patients have fully recovered from the virus, according to the DCHHS. Those cases involved a person who traveled to Venezuela and had sexual contact with another person upon returning to Dallas, officials said. Not much is known about the Dallas patients except that neither was pregnant and there was no risk to a developing fetus.
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County health officials conducted mosquito surveillance near where those patients lived and did not identify any mosquito activity.
The Zika virus is usually spread through mosquito bites. DCHHS said Tuesday that the Centers for Disease Control and Prevention confirmed the second Zika diagnosis, while the county health department confirmed through a follow-up interview with the patient that the virus had been sexually transmitted.
The CDC previously said it was aware of reports of the virus being spread through sexual contact, but had not confirmed the transmission method.
Common symptoms of Zika virus include fever, rash, joint pain, and conjunctivitis (red eyes). The illness is usually mild with symptoms lasting several days to a week, Dallas County health officials said.
Those with symptoms, or those who have had sexual contact with someone who has symptoms, are urged to seek immediate medical care, to protect themselves from further mosquito bites and to avoid unprotected sexual contact.
NBC 5's Jocelyn Lockwood contributed to this report.