From: http://www.aidscience.org/Articles/AIDScience032.asp

Examining the hypothesis that sexual transmission drives Africa's HIV epidemic

By David Gisselquist,1 John J. Potterat,1 Richard Rothenberg,
2 Ernest M. Drucker,3 Stuart Brody,4Devon D. Brewer,
5 Steven Minkin6

The belief that sex is the primary mode of humanimmunodeficiency
virus (HIV) transmission in sub-Saharan Africa is an assertion so
widely accepted and has remained unquestioned for so long that
it has taken on the status of a received truth.

The World Health Organization (WHO) and the Joint U.N.
Programme on HIV/AIDS (UNAIDS) recently convened
an expert consultation to review issues raised in a series
of papers published in the International Journal of STD
& AIDS (1-4) that questioned the validity of that assertion.
After examining the papers, WHO and UNAIDS issued
a press release announcing that "the vast majority of
evidence [supports the view] that unsafe sexual practices
continue to be responsible for the overwhelming majority
of infections" (5). As co-authors of the controversial
articles (1-4), and as participants in the Geneva meeting
(three of us), we state that WHO's conclusion is premature.
It is neither based on those discussions, nor on a more
considered review of the relevant literature.

In our articles we have pointed out that anomalies in the
evidence, and failure to demonstrate an overwhelming
role for heterosexual transmission from available data,
create a gap that requires evaluation. We have also
noted that most studies on HIV in Africa that have
assessed the risks associated with health care exposures
such as medical injections, transfusions, and scarifications,
have reported substantial relative risks and (depending on
the proportion exposed) corresponding crude attributable
risks. The breadth and depth of evidence undermining the
dominant paradigm calls for a review of the issue.

The assertion that heterosexual transmission accounts for
over 90% of HIV in African adults lacks supporting
empirical evidence linking HIV to sexual behaviors.
The evidence WHO/UNAIDS uses to buttress the
heterosexual paradigm is mostly indirect and circumstantial,
and much of it seems aimed at debunking the role of health
care rather than substantiating the role of heterosexual contact.
For example, the press release asserts, "children between
5 and 14 years, who are generally not sexually active yet,
have very low infection rates." In fact, few surveys have
screened for HIV in African children, and some (but not all)
have reported substantial HIV prevalence. For example,
4.2% among urban children 6-15 years old in Rwanda in
1986 (6) and 5.6% among 2-14 year old children in a
national survey in South Africa in 2002 (7). These rates,
which are much higher than could be expected from
vertical transmission, point to other means of transmission,
possibly health care transmission. It should be noted that
observed rates are not likely due to substandard tests
(Rwandan cases were confirmed by Western blot, and
tests used in South Africa have over 99% specificity) or
to child sexual abuse or early sexual activity (8).

According to WHO/UNAIDS, HIV behaves like other
sexually transmitted diseases (STD), and populations
with high HIV prevalence (prostitutes, long-distance
truck drivers, soldiers, and migrant workers) suggest
sex as the principal risk. Such arguments are inferential,
indirect and ignore conflicting epidemiologic observations.
For example, in Zimbabwe during the 1990s, STD and
HIV followed opposite epidemic trajectories (2).

Without attention to parenteral exposures, observations
linking sexual activity to HIV infections are inconclusive.
For example, sexually active populations, especially
including prostitutes and their customers, are at risk
for STD, which is commonly treated throughout Africa
by injections in formal or informal health care settings.
Recent estimates from WHO suggest that 17-50% or
more of injections in Africa may reuse equipment without
sterilization (9, 10). As a consequence, the risk of HIV
infection in STD clinics, where background HIV prevalence
among patients is often high, may be considerable. Medical
procedures during pregnancy, including drawing venous
blood for syphilis tests, multiple tetanus vaccinations, and
gamma globulin shots, add another set of potential health
care risks. When health care is unsafe, HIV case distribution
may reflect sexual activity circumstantially rather than causally.
Studies that sort out this potential source of confounding are
rare. Furthermore, there has been no consideration of the
potential multiplier effect that may result from interaction
between sexual and health care transmission in Africa.

The WHO/UNAIDS press release states, "there is no
consistent association between higher HIV rates and
lower injection safety standards." We are unaware of
any studies that have systematically examined this
correlation; we would welcome them. Specifically, we
encourage studies to determine the frequency of health
care exposures and level of infection control standards
in different countries with generalized epidemics. This
may require monitoring contamination of equipment
ready for use, testing mothers of children with AIDS
to see if any are HIV-negative, investigating clinics
and hospitals suspected as the source of iatrogenic
HIV infections, etc.

The press release claims that "modeling of the epidemic
with the best available information also shows that the
overwhelming majority of infections are due to unsafe sex"
(5). The accuracy of models depends crucially on their
assumptions and on the quality of the data used to estimate
parameters (11); indeed, models have often been used to
justify orthodoxy by using estimates for key parameters
that are at considerable odds with empiric evidence (3).
For example, models purporting to describe heterosexual
HIV transmission in Africa have supposed ulcerative STDs
to amplify transmission risk by as much as 100 times (12, 13).

Finally, the idea that penile-vaginal sex is driving HIV
epidemics in Africa is a hypothesis (3) that requires
renewed scrutiny, not defensiveness. Studies seeking
properly controlled empiric evidence need to be conducted
to support or oppose this hypothesis. In our view, the
published evidence suggests that: (a) two decades into the
epidemic, such studies have yet to be done; (b) the
heterosexual hypothesis is inadequate to explain fully the
observed epidemic trajectories, especially in regions of
intense transmission; and (c) irrespective of the precise
proportions of HIV attributable to sexual activity or to
unsafe health care, priority should be given to assuring
safe health care in formal and informal medical settings
world-wide, if only as a human rights issue (14).

References and notes

1. D. Gisselquist, R. Rothenberg, J.J. Potterat, E. Drucker, Int. J. STD AIDS 13, 657 (2002). PubMed
2. D.D. Brewer, et al., Int. J. STD AIDS 14, 144 (2003). PubMed
3. D. Gisselquist, J. Potterat, S. Brody, F. Vachon, Int. J. STD AIDS 14, 148 (2003). PubMed
4. D. Gisselquist, J.J. Potterat, Int. J. STD AIDS 14, 162 (2003). PubMed
5. "Expert group stresses that unsafe sex is primary mode of transmission of HIV in Africa,"
WHO/UNAIDS statement [online], March 14, 2003. Available online
6. Nationwide community-based serological survey of HIV-1 and other human retrovirus infections in a
central African country. Rwandan HIV Seroprevalence Study Group, Lancet i, 941 (1989). PubMed
7. O. Shisana, et al. [online], "Nelson Mandela/Human Sciences Research Council Study of HIV/AIDS:
South African National HIV Prevalence, Behavioural Risks and Mass Media: Household Survey (Human
Sciences Research Council, Cape Town, 2002)." Available online
8. S. Brody, D. Gisselquist, J.J. Potterat, E. Drucker, Br. J. Obstet. Gynecol., 110, 450 (2003).
PubMed
9. G. Dziekan, D. Chisholm, B. Johns, J. Rovira, Y.J.F. Hutin, Bull. World Health Organ. 81, 277
(2003). PubMed
10. L. Simonsen, A. Kane, J. Lloyd, M. Zaffran, M. Kane, Bull. World Health Organ. 77, 789 (1999).
PubMed
11. R. Rothenberg, Sex. Transm. Dis. 24, 201 (1997).
12. N.J. Robinson, D.W. Mulder, B. Auvert, R. Hayes, Int. J. Epidemiol. 26, 180 (1997). PubMed
13. E.L. Korenromp, AIDS 14, 573 (2000). PubMed
14. "HIV transmission in the medical setting: a white paper by Physicians for Human Rights,"
[online], (PHRUSA, Washington, DC, 2003) March 27, 2003. Available online