The first case of Zika virus was confirmed in Los Angles County on Tuesday within days of a warning from the Pan American Health Organization (PAHO) that predicted the spread of the virus throughout the Americas.

A young Los Angeles County girl traveled to El Salvador last November, where county health officials suspect she contracted the disease, according to the Los Angeles Times. Zika infections usually do not have symptoms–but that is part of the worry say health experts.

Despite a lack of symptoms, the mosquito-born virus has been linked to severe birth defects. The Times reported that the U.S. Centers for Disease Control and Prevention (CDC) has warned pregnant women to avoid Zika-affected regions. A Brazilian mother recounted the discovery of her son’s severe “small head,” a birth defect called microcephaly: “It was only after he was born and swiftly taken away from me for emergency treatment that we understood that it was Zika.”

“Zika virus is transmitted to people through the bite of an infected mosquito from the Aedes genus, mainly Aedes aegypti in tropical regions. This is the same mosquito that transmits dengue, chikungunya and yellow fever,” according to the World Health Organization.

“PAHO [the Pan-American Health Organization] anticipates that Zika virus will continue to spread and will likely reach all countries and territories of the region where Aedes mosquitoes are found,” according to a PAHO/WHO statement issued this week. Chile and Canada are the only two North American countries exempt from Zika warnings due to the absence of Aedes mosquitos.

Dangers from non-native mosquitos carrying diseases like dengue fever, chikungunya and yellow fever have been on the minds of California health officials. Last October warnings were put in place for the Asian tiger (Aedes albopictus) and yellow fever (Aedes aegypti) mosquitos.

Three cases of Zika have been documented in New York as well. Just one patient has fully recovered.

Texas officials have reported multiple cases of Chikungunya illustrating the potential of similarly spread diseases coming to America. Celebrity Lindsay Lohan contracted Chikungunya while on vacation in Bora Bora, and in January ended up hospitalized in London.

Follow Michelle Moons on Twitter @MichelleDiana