Washington: College students in the US know enough about HIV transmission, but are less well informed about its testing, according to a University of Georgia study.

Su-I Hou, associate professor in the University of Georgia, surveyed more than 500 students and found that they scored higher on general questions related to HIV and AIDS (82 percent correct) than items specifically related to HIV testing (72 percent correct).

The results of the survey appeared in the July issue of the Journal of the National Medical Association.

A lack of knowledge about HIV testing can be dangerous, Hou said. She explained that most HIV tests do not measure or detect the virus itself but instead look for body's reaction to the virus - the presence of antibodies to HIV.

Antibodies generally appear within three months after HIV infection, but it may take up to six months in some people. During this "window period" an infected person may test negative yet still transmit the virus to others.

"We need to make sure our prevention messages are comprehensive," said Hou. "In addition to talking about avoiding transmission, health communication efforts should promote testing as well."

HIV disproportionately affects African-Americans, who account for 13 percent of US population but nearly half (49 percent) of the Americans who get HIV and AIDS, according to Centres for Disease Control and Prevention.

Hou noted that despite this disparity, there are surprisingly few studies that examine differences in HIV knowledge between black and white college students.

To fill this gap, she surveyed 222 black students from 15 historically black colleges and universities and 335 white students.

Because people can be reluctant to discuss sensitive information, Hou used an online survey. She recruited the students using flyers, classroom announcements, e-mail and even the social networking site Facebook.

"One of the best ways to find college students is on Facebook, since that's where they meet and interact with each other," Hou said. "We found that two thirds of our participants were recruited online, either through Facebook or through e-mail."

While the study found that there were no significant differences between groups in scores related to general or testing-specific knowledge of HIV, it did reveal that African-Americans rated significantly higher on their perceived knowledge of HIV.

The study also found that African-American students were nearly seven times more likely to be tested for HIV.

"Studies show that if you have higher perceived knowledge, you tend to be tested more," Hou said. "And that may partially contribute to the higher testing observed among black students in the study." IANS