San Juan, May 14 (IANS): Puerto Rican health officials have detected of the island's first case of severe microcephaly in a foetus infected by the Zika virus.

Health Secretary Ana Rius on Friday said the reason for the deformation was discovered by the US Centres for Disease Control and Prevention (CDC) from samples taken from the foetus of an expectant mother, EFE news reported.

"CDC has confirmed the first case of Zika virus disease in a foetus in Puerto Rico. CDC conducted the laboratory test that confirmed the diagnosis and has shared the results with the Puerto Rico department of health," the department said in a statement.

Rius said 128 pregnant women have now tested positive for the virus, which in most of the population produces hardly any symptoms, but which has been linked to microcephaly and other congenital disorders in babies born of infected mothers.

Last week, 18 more pregnant women with Zika were detected on the island. A total of 785 have been affected since the beginning of this year.

"I want to urge any pregnant women with even the slightest concern of infection to go see a doctor," Rius said.