It's well known that Zika spreads primarily through mosquito bites and occasionally via sexual contact, but it seems that someone in Utah became infected after caring for an elderly patient who had the virus, NPR reports. An elderly Utah resident died in late June of unknown reasons after visiting a country where the Zika virus is present, and lab tests revealed that the patient had a viral load 100,000 times greater than that usually seen in Zika-infected individuals. The Centers for Disease Control and Prevention (CDC) began an investigation when a family member who had been caring for the patient also tested positive for Zika. How this person contracted the infection is still not clear; he or she had not visited an area where the virus is circulating and did not have sex with anyone known to be infected. CDC investigators say that the case shows there is still more to learn about Zika, but emphasized that mosquitoes are still the virus's main mode of transmission.