A Utah resident infected with the Zika virus has died, becoming the first Zika-related fatality in the continental United States, officials said on Friday.
The elderly victim, who had an underlying health condition, died in late June after traveling to a country where the mosquito-transmitted virus is active, the Salt Lake County health department said.
"While this individual did test positive for Zika virus, the exact cause of death has not been determined, and it may not be possible to determine how the Zika infection contributed to the death," the health department said in a statement.
The victim's identity and travel history would not be released, it added.
The Centers for Disease Control and Prevention (CDC) reported in April that a man in his 70s infected with the Zika virus had died of complications from the infection on the Caribbean island of Puerto Rico, which is part of US territory.
The virus is spreading fast on the island, infecting as many as 50 pregnant women per day, health officials said earlier this week.
So far, however, no cases of locally transmitted, mosquito-borne Zika have been reported in the continental United States, the CDC said in a statement on Friday.
As of July 6, a total of 1,132 cases of people who contracted the virus while traveling abroad had been registered in the United States, it said.
However, health officials are bracing for outbreaks of the virus among local mosquito populations.
"CDC has been working with state, local, and territorial health officials to prepare for the possibility of locally-acquired Zika infection in the United States," the CDC said.
No vaccine or treatment for the Zika virus currently exists and many of those infected will not show symptoms, the CDC says.
Pregnant women are the focus of greatest concern because the virus causes birth defects.
US President Barack Obama has requested $1.9 billion to fight the virus, but lawmakers are deadlocked over the issue and there are fears Congress will fail to address the growing health crisis until after its summer recess in September.