Reports on HIV/AIDS: 1990

FEBRUARY 23, 1990, MMWR, Vol. 39, No. 7, pp. 110-112, 117-119
Reported by: Div of HIV/AIDS, Center for Infectious Diseases, CDC.
Editorial Note: Estimates of the number of HIV-infected persons, the number with
laboratory evidence of immune dysfunction, and the projected number of persons
with AIDS are used to assess current and future health-care needs. Although these
estimates cannot be made precisely, ongoing studies will provide additional data to
improve the estimates and test the assumptions on which they are based.
Current HIV prevalence estimates and AIDS case projections are influenced by the
slowing of the rapid upward trend in AIDS incidence that occurred in 1987. The
number of AIDS cases diagnosed per month continued to increase in 1987, but the
rate of increase declined in the middle of that year, particularly in non-IV-drug-using
homosexual/bisexual men (6). Reasons for this change in trend include: 1) a decline
in the incidence of new HIV infections in homosexual/bisexual men in the early 1980s,
leading to a subsequent decline in AIDS case incidence (12); 2) use of antiretroviral
and other therapies by mid-1987, leading to a lengthening of the incubation period
from infection to AIDS; and 3) possible decreases in the completeness or timeliness
of reporting. The accuracy of HIV prevalence estimates and AIDS case projections
depends in part on the determination of the relative contribution of these or other
factors.
After the workshop, additional data became available on zidovudine use in
mid-1987, and estimates were made of the possible effect of medical therapy on the
change in trend in AIDS incidence that occurred in that year. One study estimated that
zidovudine treatment given during early 1987 to 5000-7000 homosexual/bisexual
men with severe immunodeficiency but without AIDS could account for the change in
the trend in AIDS incidence in that group in the last half of 1987 (13). More than
10,000 persons received zidovudine from the manufacturer under a limited drug
distribution system during March-September 1987. Data from a 4% systematic
sample of this group indicate that about 4000 homosexual/bisexual men who were
infected with HIV and had low CD4+ counts but who had not yet developed AIDS
received zidovudine during that time (14). While this suggests that medical therapy
could have made a substantial contribution to the change in trend in AIDS incidence
in this group since 1987, the relative contribution of this and the other factors noted
above requires further study.
Despite the apparent change in reported AIDS incidence in 1987, needs for current
and future health-care services are expected to increase. AIDS has been diagnosed in
no more than 10% of the approximately 1 million persons currently infected with HIV.
Recent studies indicate that early treatment with zictovudine can slow disease
progression in asymptomatic persons with CD4+ counts <500/mm3 (NIAID, unpublished data). As discussed in the report, about 60% of the estimated 1 million
HIV-infected persons in the United States-including about 500,000 persons without
AIDS-may have CD4+ counts <500/mm3 and may benefit from such therapy.
In addition to the suffering and health-care burden involving those already
infected, a major concern is the number of new infections that continue to occur.
Currently an estimated 1500-2000 new infections occur each year in newborns as a
result of perinatal transmission, and a minimum of 40,000 new infections occur each
year in adults and adolescents. Comparing the estimate of about 750,000 HIV-infected
persons alive at the beginning of 1986 with the current estimate of about 1 million
alive in mid-1989 suggests that an average of more than 80,000 new infections have
occurred yearly since 1986.

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