The report of first known case of Zika virus transmission in the United States came from Texas on Tuesday. Local health officials, who reported the case, said that it was probably contracted via sex, and not a mosquito bite. The report has come a day after the World Health Organization announced an international public health emergency.

In the Americas, the virus associated with severe birth defects in thousands of babies in Brazil, has been spread at a very fast pace. On Tuesday, the WHO officials expressed concern that it may hit Africa and Asia also.

It was though that the virus spreads by the bite of mosquitoes of the Aedes genus, so sexual contact called a mode of transmission would be a likely alarming development.

CDC Director Dr. Tom Frieden wrote on Twitter that the US Centers for Disease Control and Prevention has given confirmation that it was the first US Zika case in an individual, who had not visited to any foreign country in the present outbreak. But, the CDC has not investigated the cause of the virus transmission.

After this case, the agency has recommended men to consider using condoms after visiting the areas hit by the Zika virus. Pregnant women must avoid going in touch with semen from men exposed to Zika.

On Twitter, the Dallas County Department of health said that the person contracted the infection via sexual contact with somebody, who had visited Venezuela. County health officials said that the person infected did not travel to the South American country.

In a statement, the Texas Department of State Health Services cautiously said, “Case details are being evaluated, but the possibility of sexual transmission from an infected person to a non-infected person is likely in this case”.