Athenahealth said that the "vast majority" of Zika tests it has identified to date "is done on women of childbearing age."
A total of 89 percent of the tests have been done on women, of which 93 percent were for women between the ages of 19 and 44, according to the company.
"The second-most tested group is men ages 19-44, perhaps as a precaution against infecting women," Athenahealth said. Sixty-two percent of men being tested are in that age group.
Athenahealth said that it plans to publish information about initial Zika patterns that it has observed within the company's network on Thursday.
On Wednesday, Athenahealth said that it had partnered with a Miami health-care provider to do outreach and encourage Zika screening for more than 1,300 women and men age 45 and younger who live in a small neighborhood that the CDC has identified as being the site of mosquito-borne virus transmissions.
Another 500 or so such people at risk of Zika have also been identified by Athenahealth as living in that neighborhood. The company is in talks with other health providers to do outreach to many of those patients.