Incidence estimates indicate that new HIV infections in Texas are stable at an average of 4,400 new infections per year
From 2006 to 2009, there were an estimated 4,400 new HIV infections (HIV incidence) each year in Texas. These estimates are based on a model developed by the CDC which combines results from a laboratory test which indicates recent or long-term infections on the population-level with testing and treatment history from newly diagnosed HIV cases. In Figure A below, the estimated number of new infections for each year is shown with its 95% confidence interval, which is the range of values in which the estimated incidence number will fall 95% of the time (i.e. 19 times out of 20).
Methods for Estimating HIV Incidence
Historically, HIV incidence has been approximated using information about the number of new diagnoses of HIV. However, an individual can be infected for many years before being tested and diagnosed with HIV; therefore, new diagnoses do not necessarily reflect HIV incidence. Since 2005, Texas has participated in a national initiative funded by the Center for Disease Control and Prevention (CDC) to estimate HIV Incidence. This initiative collects information about newly diagnosed cases in order to make annual estimates about the number of new HIV infections. Using an approach known as the Serologic Testing Algorithm for Recent HIV Seroconversion (STARHS), results from a lab based test (the BED HIV-1 Capture Enzyme Immunoassay), which classifies newly diagnosed infections as being recent or long-standing, are combined with testing and treatment history information from newly diagnosed cases to estimate the number of new infections of HIV.
By applying the CDC model, we are able to estimate HIV incidence in Texas from 2006 until 2009, and for each year we estimate that HIV incidence in Texas has been relatively stable at an average of approximately 4,400 cases per year. During that same time period, the number of adults and adolescents living with HIV (HIV prevalence) has increased by 16% (from 53,089 in 2006 to 61,705 in 2009) (Figure B). The relatively stable HIV incidence numbers seen during these years, despite the increasing number of persons living with HIV who are able to transmit the virus, could be an indication that HIV prevention efforts are working and that these efforts have contributed to keeping the estimated number of new infections stable. However, in spite of the relative stability of the HIV incidence estimates seen between 2006 and 2009 both in Texas and nationally, researchers at the CDC and Johns Hopkins maintain that this current level of stability cannot be maintained without additional prevention efforts and a reduction in the HIV transmission rate. As a result, reducing the number of new HIV infections is a national priority and is identified as one of the primary goals in the National HIV/AIDS Strategy.
Center for Disease Control and Prevention
HIV Incidence Surveillance: www.cdc.gov/hiv/topics/surveillance/incidence.htm
CDC Fact Sheet: www.cdc.gov/nchhstp/newsroom/docs/HIV-Infections-2006-2009.pdf
National Estimates: www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017502
National HIV/AIDS Strategy www.whitehouse.gov/sites/default/files/uploads/NHAS.pdf
Healthy People 2020 www.healthypeople.gov/2020/topicsobjectives2020/overview.aspx?topicid=22
 Prejean J et al. 2011 Estimated HIV Incidence in the United States, 2006–2009. PLoS ONE 6(8): e17502. doi:10.1371/journal.pone.0017502
 Hall HI et al. J Acquir Immune Defic Syndr. 2010 Oct 1;55(2) :271-6
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