provides details on the number of HIV/AIDS cases diagnosed and reported and the completeness of HIV testing history and BED test results, data elements used to estimate HIV incidence by year in each of the three California HIS jurisdictions. As the HIS systems matured in each jurisdiction, the proportion with complete testing and treatment history and BED results improved. For all years San Francisco County reported the highest completeness rate for HIV testing history collection and BED test results followed by Los Angeles and all other California counties. Following CDC’s recommendation to restrict the calculation of incidence to years in which BED results were available for at least 15% of newly diagnosed HIV cases, we calculated incidence in San Francisco County for 2006–2009, in Los Angeles County for 2007–2009 and the remaining California counties for 2008–2009.
Number of reported newly diagnosed HIV/AIDS cases and non-AIDS HIV diagnoses, with completeness data for HIV testing history and BED test results, for the three HIV Incidence Surveillance areas in California, 2006–2009.
We estimate that there were approximately 2426 new HIV infections (95% CI 1871–2982) among adults and adolescents in Los Angeles County in 2007, 1669 (95% CI 1309–2029) and 1898 (95% CI: 1452–2344) new infections in 2008 and 2009, respectively. The decline in incidence between 2007 and 2009 was statistically significant (trend p<0.01). The rate of new HIV infection in Los Angeles County (per 100,000 residents) was 29 in 2007, 20 in 2008, and 23 in 2009 ().
Estimated number and rate per 100,000 of new HIV infections by HIV Incidence Surveillance area and year.
In 2006, there were an estimated 492 new HIV infections among adults and adolescents (95% CI 327–657) in San Francisco, and 490 new infections (95% CI: 335–646), 458 new infections (95% CI: 342–574), and 367 new infections (95% CI 261–473) in 2007, 2008, and 2009, respectively. The change in incidence between 2006 and 2009 was not statistically significant (trend p
0.14). The rate of new HIV infection in San Francisco (per 100,000 residents) was 70 in 2006, 70 in 2007, 65 in 2008 and 52 in 2009 ().
There were 2526 new HIV infections among adults and adolescents in the remaining California counties in 2008 (95% CI: 1688–3364) and 2993 new infections (95% CI 2141–3846) in 2009. The rate of new HIV infection (per 100,000 residents) was 13 in 2008 and 15 in 2009 ().
The estimated HIV incidence rates (per 100,000 residents) among sub-populations in Los Angeles and San Francisco counties are presented in and . In both counties and in every year when stratification was possible, MSM had the highest rates of HIV infection: 447 and 493 in Los Angeles in 2008 and 2009, respectively, and 807, 783, 788, and 626 in San Francisco in 2006, 2007, 2008 and 2009, respectively. The rates among MSM in Los Angeles were 9 to 111 times the rate of HIV infection in other demographic groups in Los Angeles and the MSM rate in San Francisco was 3 to 18 times higher than rates in all other demographic groups in San Francisco. African Americans appeared to experience higher rates of HIV infection compared with whites and these findings reached statistical significance in Los Angeles. In Los Angeles, the rate of HIV infection among African Americans in 2008 and 2009 (44 and 56 per 100,000, respectively) was more than twice that of both whites (17 and 20 per 100,000, respectively) and Latinos (20 and 23 per 100,000, respectively). In San Francisco, the higher rate of HIV infection among Latinos compared to whites in 2008 and African Americans compared to whites in 2009 was not statistically significant. In both Los Angeles and San Francisco, persons 40 years or older had lower rates of HIV infection compared to younger age groups, although in San Francisco this difference was not statistically significant.
Estimated rate of new HIV infections by sex, race/ethnicity, age group and mode of transmission, Los Angeles County, 2008–2009.
Estimated rate of new HIV infections by sex, race/ethnicity, age group and mode of transmission, San Francisco County, 2006–2009.