Aedes aegypti mosquitoes, which transmit the Zika virus and have been the subject of studies at the Fiocruz Institute in Brazil
Mario Tama/Getty Images

Health officials are stumped after a Utah caregiver became infected with the Zika virus after caring for an elderly patient who has the disease.

The Utah Department of Health said that the caregiver, a family member of the patient, tested positive for the virus, which, until now, was believed to be transmitted only through sex or mosquitoes, ABC News reports.

The U.S. Centers for Disease Control and Prevention is investigating how the caregiver contracted the virus if the caregiver had never been to a country with a history of Zika-infected mosquitoes and did not have sex with a person who had the virus.

Advertisement

In almost all the 1,133 cases of Zika in the U.S., people became infected by mosquitoes while traveling abroad, according to a CDC report. A small number of cases show that the virus was transmitted through sexual contact. There have been no cases of mosquitoes transmitting the disease in the U.S., ABC News reports.

Read more at ABC News