The District’s efforts to prevent new HIV infections appear to be stagnating in some key areas, according to a report to be released Thursday.

The advocacy group D.C. Appleseed called it “troubling” that recently released D.C. Health Department data for 2010 show slight increases instead of decreases in three measures that track progress in prevention: the HIV transmission rate, the number of new HIV diagnoses and the proportion of new AIDS diagnoses that had progressed from HIV to AIDS in less than 12 months.

“There are a lot of things being done in Washington to address this epidemic that are very cutting-edge, and the District deserves a lot of credit for that,” said Walter Smith, Appleseed’s executive director. He acknowledged that some statistics have not been reported long enough to show conclusive trends. He added: “While progress is being made, these numbers are nowhere near where they need to be.”

D.C. health officials disputed that conclusion. They said Appleseed did not understand how data were calculated and interpreted them incorrectly. “Their conclusions are in error,” said Gregory Pappas, the health department’s senior deputy director, in an e-mail.

There has been a decline in the total number of new HIV and AIDS cases, officials said, among other signs of progress.

Washington is hosting the 19th International AIDS conference, which starts Sunday at the Walter E. Washington Convention Center. The global gathering is returning to the United States for the first time in more than two decades. D.C. officials want to highlight the city’s progress in fighting HIV/AIDS, which is at epidemic levels in the nation’s capital.

About 2.7 percent of D.C. residents older than 12 were living with HIV or AIDS in 2010, according to the latest annual report, released last month. That prevalence rate — the total percentage of people in a population with the condition or disease at a given time — is among the highest for any U.S. city. Among African Americans, just under half of the city population, the rate is considerably higher, 4.3 percent.

Health officials say the total number of HIV and AIDS cases has dropped slightly, from 853 in 2009 to 835 in 2010. Other signs of progress: No children have been born with HIV since 2009, and there has been a big drop in newly diagnosed HIV cases attributable to injection-drug use because of the District’s needle-exchange program.

Appleseed said some measures suggest progress has slowed. For example, the HIV transmission rate went up from 2009 to 2010. Health officials said the increase was due to a change in calculation, not an actual increase. The District has been switching to a different system for reporting cases to eliminate duplication; those numbers were used to calculate the 2010 transmission rate but not for 2009.

The number of newly diagnosed HIV cases also increased, rising from 575 in 2009 to 617 in 2010, the data show. Instead of being “troubling,” health officials said, the increase reflects the success of expanded testing among people newly diagnosed as HIV-positive, but who have not progressed to AIDS.

Pappas said the data show the District is finding people with the disease earlier. Early treatment with anti-HIV drugs not only improves individual health, but also can prevent the virus from being transmitted to others.

The District also monitors new AIDS cases that were diagnosed so late that the disease progressed from HIV to AIDS in less than 12 months after initial diagnosis. Without treatment, it takes an average of 10 years for someone with HIV to develop AIDS.

About 52 percent of 474 newly diagnosed AIDS cases in 2010 were these advanced infections, an increase from 50 percent of 506 cases the year before.

Even though the percentage of those cases has increased, the total pool of new AIDS cases has fallen, so proportions are less reliable statistically, health officials said.