Disease sleuths are sifting through clues. The Utah man who died had a very high level of virus in his body, which may have increased the risk that his bodily fluids could infect others. But while the virus has been detected in blood, semen, vaginal fluid, saliva and urine, it had not been known to infect others through nonsexual contact.

“We don’t have any evidence that suggests Zika can be passed from one person to another by sneezing or coughing or kissing or sharing utensils,” said Dr. Thomas R. Frieden, the director of the Centers for Disease Control and Prevention, which has a team investigating the case. Dr. Frieden said other people who had come into contact with the Utah man were being tested. The results will take a few weeks.

The continental United States has become a useful laboratory for unusual transmission of Zika. There has yet to be a local spread through mosquitoes, making sexual and other transmission easier to trace. There are more than 1,300 case of the Zika in the continental United States — all acquired through travel abroad.

“This raises some interesting questions,” said Dr. William Schaffner, an infectious disease specialist in Tennessee. “Was there a needle stick or injury? Or if not, possible contact with other bodily fluid like urine or saliva?”