The highest numbers of cases are in population centers such as New York and California. However, many areas with the highest rates of HIV -- that is, the highest proportion of people with the AIDS-causing virus -- are in the South, according to the data map, which has information for more than 90 percent of the nation's counties and Washington, D.C.
HIV infection rates are higher in black communities, and high minority populations in the South help explain the finding.
Though that's not surprising, the high rates seen throughout states including Georgia and South Carolina were, said Gary Puckrein, the president of the National Minority Quality Forum, the nonprofit research organization that put the map together.
Of 48 counties with the highest prevalence rates for HIV that had not progressed to AIDS, 25 were in Georgia. Those were counties in which more than 0.7 percent of the population was infected with HIV.
In the Augusta area, Richmond and Burke counties are among those with the highest prevalence of both HIV and AIDS.
Though Richmond County was not a surprise, Burke County was, said Sandra Wimberly, a public health educator with the East Central Health District in Augusta, which includes both counties.
"That is really interesting," she said.
The 13-county district had 2,521 HIV and AIDS cases as of last year.
The problem with some of the rural counties is "the people really don't come out to get the information or the education, and certainly not the test," Ms. Wimberly said. "Because they are so small, people are afraid that somebody in their little small county are going to know who they are."
Removing the stigma some people attach to testing is Ms. Wimberly's goal and one of the motives for National HIV Testing Day, which is Saturday.
Georgia, Florida, South Carolina and Virginia were heavily represented on another map of counties, which showed the highest prevalence rates for cases that had progressed to AIDS.
The map depicts reported numbers of people living with HIV and AIDS in 2006. Mr. Puckrein said the data came from state health departments and was checked against information from the U.S. Centers for Disease Control and Prevention.
Different states report data in different ways, and there might be case duplication that could affect some of the findings, Mr. Puckrein said.
The CDC's HIV and AIDS prevalence data is reported on a state level, not by county.
CDC officials were cautious about the data map, saying they hadn't seen all the organization's information.
"But we have long been part of the effort to identify geographic differences in the HIV epidemic, and we do see the need for efforts like these to facilitate better understanding of these differences," said CDC spokeswoman Elizabeth-Ann Chandler.
Staff Writer Tom Corwin contributed to this article.
PREPARING FOR THE TESTS
The Richmond County Health Department will hold a news conference at 11 a.m. today to talk about plans for National HIV Testing Day, which is Saturday. The event will be held in the training room at the Health Department's main clinic, 950 Laney-Walker Blvd. Augusta Mayor Deke Copenhaver and East Central Health District Director Ketty Gonzalez are expected to attend.
FOR MORE DETAILS on the HIV data map, go to: www.MapHIV.org.