Gaydos expects an uptick in kit users in April, national sexually transmitted infections awareness month, following federally funded newspaper and radio ads.
The site may not yet be big enough to significantly bring down the infections, but users have praised the service in e-mails. They say they've relied on it after finding out a partner had sex with other people or they've had unprotected sex. Many say they don't want their parents to know they are having sex and might be infected.
Some say they can't afford to go to the doctor for testing. One thought it was an easy way for both partners to be tested before they had sex.
Gaydos and her colleagues would like to add syphilis or HIV to the program, which is paid for with government grant money. Each kit costs Hopkins about $65-$70, which includes the mailing, test and lab worker time. Those STDs, however, requires a blood test that would make an in-home kit tougher.
She also would like to continue expanding the program beyond the cities and states it now serves.
"A lot of these young women are poor with little to no health insurance, and seldom see a physician or undergo a health checkup, so this is a free means of getting them tested and cared for quickly and before they potentially pass the infection on to someone else," said Gaydos.
Gaydos said Maryland was a logical place to launch the program because of its high infection rates. CDC surveys of risky behavior show almost a third of students in Baltimore are sexually active by the ninth grade.
CDC data shows that Maryland ranks in the top 20 states for STD cases. Many of the cases are in Baltimore, where there were 2,889 cases of gonorrhea in 2009, 7,889 cases of chlamydia and 244 cases of syphilis in 2009, according to the Baltimore City Health Department — though only chlamydia cases have been rising in recent years.
They all remain a challenge for local officials, said Sherry Ketemepi, the city's assistant commissioner for clinical services.
She said the city works with Hopkins and others on programs to reach those most at risk. She said schools offer health education and encourage testing in their clinics. And city health officials sought permission from the state legislature three years ago to join the CDC's Expedited Partner Therapy program.
Another program rewards youth for referring a friend for testing at a city clinic with a movie ticket or other prize.
But she said the Hopkins program eliminates a main barrier to testing because it's anonymous.
"There's a stigma to going to a clinic to be tested for an STD," she said. "It's an easier way to get people tested."