A woman in Brownsville, Texas, has a confirmed case of Zika even though she didn’t travel to any Zika-stricken areas or have any other risk factors, Texas health authorities announced Monday. Her case is likely the first known instance of Zika transmission by local mosquitoes in the state.

But, if true, that transmission is entirely unsurprising, officials there said. Brownsville sits at the southern most tip of Texas, directly on the border of Mexico, which is experiencing ongoing transmission of the Zika virus by local mosquitoes.