Estimated Prevalence of Undiagnosed HIV Infection: US, End of 2006
Michael Campsmith*, P Rhodes, and I Hall
CDC, Atlanta, GA, US
Background: †At the end of 2006, >1 million
persons age ≥13 years were estimated to be living with HIV infectionóboth
diagnosed and undiagnosedóin the US. Undiagnosed persons cannot benefit from
clinical treatments to prevent immune system damage and opportunistic
infections; they may also disproportionately transmit HIV to others as a result
of their unrecognized HIV status. This analysis presents estimates of the
prevalence of undiagnosed HIV infection in the US at the end of 2006.
Methods: †An extended back-calculation method was used
to estimate HIV prevalence, including the percentage undiagnosed, based on reported
HIV diagnoses and disease severity (whether the individual received an AIDS
diagnosis within the same year as the HIV diagnosis). AIDS data from all states
and the District of Columbia and HIV data from 40 states with confidential
name-based HIV surveillance were used; data were adjusted for reporting delays,
under-reporting, and redistribution of unknown HIV transmission categories.
Results: †Overall 21.0% (232,700 of 1,106,400) of
persons estimated to be living with HIV were undiagnosed, 21.6% for males and
19.1% for females. Whites had the lowest percentage undiagnosed (18.8%)
compared to Hispanics (21.6%), African Americans (22.2%), American Indians and Alaska
Natives (26.0%), and Asians and Pacific Islanders (29.8%) (all comparisons to
whites p <0.001). The majority of undiagnosed cases were among men
who have sex with men (53.7% overall). African Americans made up 48.6% of
undiagnosed persons with HIV, despite comprising only 12% of the US population.
Conclusions: †The number of persons in the United States living with HIV infection presents challenges for planners and providers of
medical, preventive, and social services. Differences in the percentage of undiagnosed
HIV were evident across race/ethnicity and behavior groups. Effective testing
programs, along with early access to treatment and prevention services, are
integral for reducing undiagnosed HIV infections. Recent national public health
activities have focused on expanding HIV testing in routine clinical settings,
and addressing racial disparities in the impact of HIV. Future analyses will
help determine the effect of prevention efforts on HIV prevalence in the United States.