A traveling salesperson helped to spread the coronavirus in Maine and several other states early in the outbreak last month.
The salesperson was a so-called "super spreader," a single person responsible for a significant number of exposures to the virus, said Dr. Nirav Shah said, director of the Maine Center for Disease Control.
"This traveling salesperson visited a particular establishment in Maine and had a series of meetings and infected a certain number of individuals, all of whom we traced," Shah said.
The person was linked to infections outside of Maine, as well, Shah said. He declined to release details, citing privacy concerns.
More on the Coronavirus in Maine
The discovery highlights how the spread of the coronavirus can often be traced to individuals and gatherings.
One of the concerns is that the virus can be easily spread by infected people who are not showing symptoms.
For most people, the coronavirus causes mild or moderate symptoms, such as fever and cough that clear up in two to three weeks. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia, or death.
In Maine, more than 550 people have been infected with the virus and at least 16 people had died as of Thursday.