Program Supplement [International Conference on AIDS (14th: 2002: Barcelona, Spain)]

LBOR02
The potential impact of Antiretroviral therapy and HIV
vaccines on adult HIV incidence; model estimates for a rural
population in Rakai District, Uganda
Gray, Ronald', Wawer, Maria', Serwadda, David2, Sewankambo,
Nelson2, Li, Xianbin', Wabwire Mangen, Fred2, Lutalo,
Tom2, Quinn, Thomas' (United States; 2Uganda)
Background: ART or HIV vaccines could reduce or potentially
control the epidemic. We modeled effects on transmission using
data from Rakai, Uganda.
Methods: A stochastic simulation model estimated H IV
incidence, probabilities of transmission/ coital act and the
reproductive number (Ro) with ART and HIV vaccines. Projection
models estimated H IV prevalence to 2020.Empirical model
inputs included HIV transmission probabilities/coital act by HIV
viral load, age and gender, and sexual behaviors in a population
with known distributions of HIV viral loads. Treatment scenarios
used DHHS guidelines (viral loads 55,ooo copies/mL) or earlier
initiation, and varying levels of population coverage. The impact
of therapy on viral load and continuity of treatment were derived
from U.S. programs. Vaccine assumptions included preventive
efficacies ranging from 25-75%.
Results: Model estimated HIV incidence (1.57/100lo py)
approximated the observed incidence, and model estimated
probability of transmission/act (0.0012) approximated observed
probabilities. Using DHSS treatment guidelines, HIV incidence
declines to 1.27/100 py, but Ro remained >1.o, and the numbers
of HIV+ persons increased over time. A preventive vaccine, with>
5o% efficacy and > 5o% population coverage could reduce
Ro <t1.o. A preventive vaccine combined with ART, can decrease
Ro 1.o at moderate levels of population coverage. However,
disinhibition, modeled as increased numbers of sex partners,
in either the treated/vaccinated or total population, markedly
diminishes intervention effectiveness.
Conclusion: ART alone cannot control the HIV epidemic and
persons in need of therapy will increase over time. ART in
combination with a low efficacy vaccine can control the epidemic.
Behavioral disinhibition could offset these public health benefits.
Corresponding author: Gray, Ronald, Johns Hopkins University,
Bloomberg School of Public Health Suite 4o30, 615 N. Wolfe
Street, Baltimore MD212o5, United States,
Tel: + 1 410 955 7818, Fax: + 1 410 614 7386,
Email: [email protected]
[ LBOR03I
Prevalence of HIV/STD among men who have sex with men
and female sex workers - The central American multicenter
study of HIV/STD and behavior
Nuffez, Cesar A', Soto, Ramdn ]2, Foreit, Karen G3, Ghee,
Annette ES, Astete, Sabina3, Lucas, Dory', Bonilla,
Gladys4, Alvarenga, Marco A2, Romdn, Matilde5, Guerrero,
Gladys6, Aguilar, Sergio', Palma, Luis4, Padilla, Iris2, Avilds,
Federico5, Grajales, Biverly6, Holmes, King K
('Guatemala; 2Honduras; 3United States; <El Salvador;
5Nicaragua; Panama)
Background: To determine prevalence of HIV and syphilis among
men having sex with men (MSM) and female sex workers (FSW).
Methods: Between May 2001-April 2002, MSM in capital cities of
El Salvador, Guatemala, Honduras, Nicaragua, and Panama; and
FSW in capital and port cities of the same countries were
interviewed and biological specimens collected.

Results: The sampling designs permitted stratification of MSM by
sexual self-identification and FSW by place of work and city.
Preliminary analyses found considerable inter- and intra-country
variability. HIV rates among MSM varied from 2% (heterosexuals
in El Salvador) to 25-26% (gays in El Salvador, transvestites in
Honduras), while syphilis prevalence showed a smaller range from
3-4% (transvestites in Honduras, gays and bisexuals in Panama)
to 15% (gays in El Salvador and Guatemala). There were mixed
associations between sexual self-identification and HIV
prevalence, few associations between self-identification and
syphilis, and no correlation between HIV and syphilis in any
country or in any stratum. Among FSW, HIV prevalence varied from
1% (Panama capital city; Guatemala capital city fixed) to 15%
(Honduras capital city ambulatory), while syphilis prevalence
varied from 2% (Panama capital city fixed; Honduras port cities) to
25% (Nicaragua capital city ambulatory). Again, there was
virtually no correlation between HIV and syphilis in any country or
in any stratum. In capital cities, both HIV and syphilis rates were
higher among ambulatory FSW than fixed; comparisons of fixed
FSW between capital and port cities showed mixed results.
Conclusions: HIV and syphilis rates among MSM and FSW tended
to be high for the region. The intra-sample variability in prevalence
points up the need for better understanding of sub-groups in
order to tailor specific interventions for prevention of transmission
and support to those already affected by HIV. These data are
available for the first time in most countries surveyed.
Corresponding author: Nufiez, Cesar, 3a. avenida 20-96 Zona
1o, Ciudad Guatemala, Guatemala,
Tel: [phone], Fax: [phone],
Email: [email protected]
[LBOR04I
Sexual health and risk behaviour of full-time street children
in Khartoum, Sudan
Kudrati, Mustafa', Plummer Mary', Dafaalla El Hag Yousif,
Nassrin2, Mohamed Adam Adham, Ashraf>, Mohamed Osman
Khalifa, Wisal2, Khogali Eltayeb, Al Hadi2, Mohamed Jubara,
jubara2, Omujwok Apieker, Vincensio2, Ali Yousif,
Shihab2, Mohamed Elnour, Samah2 ('Tanzania; 2Sudan)
Background: Little is understood about the lives of street
children in Khartoum, Sudan, particularly as relates to sexual
health and risk behaviour.
Methods: 13 adult researchers and 11 child researchers
interviewed more than 500oo street children in qualitative
interviews, and 2,200 street children in a quantitative survey.
Participant observation, role-plays and drawing were also used.
Results: An estimated 6,oo000 children live on the streets full-time,
lo% of whom are girls. Children reported living on the streets
because of "push" factors such as poverty, war, or abuse, and
"pull" factors such as following friends or desiring drugs. 14% of
girls and 1% of boys identified sexual abuse as their greatest
challenge on the streets. However, qualitative research suggests
that the majority of girls routinely experience rape, while many
boys are occasionally raped. To protect themselves, girls may
take boyfriends, while boys may become aggressive. Boys may
engage in heterosexual or homosexual activities for pleasure,
sometimes mistakenly believing male-to-male anal intercourse is
safe from STDs. 17% of girls reported their main means of
earning money was "taking risks" (mujazafa), or sex work.
However, qualitative research suggests sex work may be the
main source of income for girls, as they have few alternatives, are
constantly approached, and it is a quick and lucrative way to earn
money. Boys engage in sex work less, but are more likely to do so

20 Program Supplement