Experts
believe that a substantial proportion of new HIV infections are transmitted by
people who are themselves in the earliest stages of infection. Newly infected
people tend to have high HIV viral loads -- a known risk factor for transmission
-- and since they may not yet know they are infected, they may fail inform their
sexual partners or employ safer sex precautions.
As
reported in the July 31, 2007 issue of AIDS, Steven Pinkerton, PhD, of
the Center for AIDS Intervention Research at the Medical College of Wisconsin
designed a mathematical model to estimate the number of persons in the U.S. who
acquire HIV as a consequence of high-risk sexual activities with an acutely infected
partner.
Estimates
of the number of incident infections due to transmission during the acute phase
of infection were derived from a simple mathematical model that combined epidemiological
data with information regarding the relative transmission rates for 3 groups:
•
Acutely infected individuals;
•
Individuals with non-acute
(chronic) infection who are unaware of their serostatus;
•
Individuals who do
not know their serostatus.
Results
•
The model suggested that approximately 2760 (8.6%) of the estimated 32,000 sexually
acquired HIV infections in the U.S. each year are due to transmission during the
acute phase of infection.
•
Multivariate sensitivity
analyses with a liberal range of values for key parameters produced an upper bound
of 5537 infections, representing 17.3% of all sexually acquired infections.
Conclusion
In
conclusion, Pinkerton wrote, "Acute-phase HIV transmission accounts for fewer
sexually-acquired infections in the USA than is generally assumed."
8/21/07
Reference SD
Pinkerton SD. How many sexually-acquired HIV infections in the USA are due to
acute-phase HIV transmission? AIDS 21(12): 1625-1629. July 31, 2007.
