Bridging the Gap: Conference Record [Abstract book, International Conference on AIDS (12th: 1998: Geneva, Switzerland)]

12th World AIDS Conference

Abstracts 13128-13132 111

Conclusion: Bangkok IDUs remain at high risk for HIV despite active interventions. An HIV vaccine efficacy trial seems feasible in this setting and could
evaluate protection against HIV-1 subtypes B' and E.
S13128 1 Reported and estimated HIV and AIDS in the WHO
Western Pacific region
Gilles Poumerol1, S.O. Omi2, A.E.G. Ghee2, N.F. Fee2. 1United Nation Avenue
PO. Box 2932 1000 Manila; 2 World Health Organization Manila, Philippines
Background: Due to incomplete official reporting of HIV and AIDS, estimates of
HIV prevalence and AIDS incidence are needed to describe the status and trends
of the HIV epidemic in many countries.
Methods: Every six months the WHO Office for the Western Pacific Region
(WPR) receives reports from its 36 Member States on diagnosed HIV and AIDS
cases, HIV sentinel surveillance and ad hoc surveys. WPR works with Member
States to analyse this data, and to prepare country specific HIV prevalence and
AIDS incidence estimates. Prevalence and incidence rates for high risk groups
and the general population, and EpiModel (or back-projections for countries with
good reporting) are used to develop estimates.
Results: As of end 1996, 68 000 cumulative HIV infections had been officially
reported to WHO. The estimated HIV prevalence was over 450 000 (reporting
rate 15%). A total of 2270 cases of AIDS had been reported, and the estimated
AIDS incidence was over 16 000 cases (reporting rate 14%). Estimated country
HIV and AIDS reporting rates vary from less than 10% to more than 80%. The
relative proportion of reported HIV cases due to transmission from injecting drug
use has decreased from 52% in 1993 to 40% in 1996. And transmission due to
homo/bisexual sex decreased from 63% in 1988 to 6% in 1996. HIV transmission due to heterosexual sex had increased to 30% of all known HIV cases in
1996. Analysis shows that HIV transmission is heterogeneous between and within
countries. Transmission due to IDU predominates in southern China, Malaysia
and South Vietnam, while transmission due to heterosexual sex predominates
in Cambodia and Papua New Guinea. The highest HIV prevalence rate in the
Region is in Cambodia (1.9% of adult population). HIV transmission continues at
a low level in the Philippines, Japan, Korea and most Pacific Islands.
Conclusion: HIV and AIDS reporting rates remain low, but are still useful for
advocacy efforts. Analysis of reported cases, together with HIV serosurveillance
data provides a useful picture of the HIV situation for public health interventions.
13129 The long-term course of the HIV epidemic among
injecting drug users in Bangkok, Thailand
Don C. Des Jarlais1 3, Kachit Choopanya2, S. Vanichseni2, P. Friedmann3,
S. Raktham2, W. Subhachaturas2. First Av. at 16th Street Beth Israel Medical
Center; 3Beth Israel Medical Center New York NY, USA; 2Bangkok Metropolitan
Administration Bangkok, Thailand
Objective: To describe trends in prevalence and risk behaviors among injecting
drug users in Bangkok. Bangkok experienced the first large HIV epidemic among
IDUs in a developing country, with very rapid transmission occurring in 1988.
Methods: Cross-sectional prevalence and risk behavior surveys of patients
conducted in 1989, 1993 and 1997 with N's of 600, 600 and 300. Subjects
were recruited from patients entering drug abuse treatment clinics throughout the
city. Structured interviews were administered by trained interviewers and serum
samples were obtained for HIV testing. Risk behavior questions referred to the 6
month period prior to the interview.
Results: Seroprevalence has remained stable over the 10 year period, with
prevalences of 34%, 38% and 33% in the three studies. Injection risk behavior
has declined substantially; the percentage of subjects reporting injection with
equipment used by others declined from 54% in 1989 to 46% in 1993 to 36% in
1997 (p -.0001). Having multiple sharing partners declined from 31% in 1989 to
23% in 1993 to 22% in 1997 (p <.001). Use of pharmacies as the primary source
of new equipment increased from 69% in 1989 to 98% in both 1993 and 1997 (p <.001). Incarceration and injecting while incarcerated were associated with being
HIV seropositive, with odds ratios of 2.0 or higher in each of the studies. 70% of
subjects in all three studies reporting having been incarcerated. Estimates of HIV
incidence based on subjects with multiple HIV tests and prevalence among new
injectors were high in all three studies, ranging from 8 to 11/100 person-years at
risk. New initiates to injecting drug use formed a continuing supply of new susceptibles, with 41% of the 1997 subjects having begun injecting in the previous 5
years.
Conclusions: While seroprevalence has stabilized and risk behavior has declined among IDUs in Bangkok, prevalence and incidence remain unacceptably
high. Bringing this epidemic under public health control may require new interventions to further reduce risk behavior, to reduce the risk of incarceration, and
to reduce initiation into drug injecting.
13130 Genetic and serologic characterization of HIV-1 in
Myanmar (Burma)

Takebe Yutaka1, Shigeru Kusagawa1, Hironori Sato1, Min Thwe2, Rai Mra2,
Bo Kywe2, Shudo Yamazaki3. National Institute of Infectious Diseases, 1-23-1
Toyama, Shinjuku-ku 162, Tokyo; 3National Institute of Infectious Diseases,
Japan; 2AIDS Prevention And Control Programme, DOH, Yangon, Myanmar
Objectives: To study the molecular epidemiology of HIV-1 spread in Myanmar
and the interplay with the epidemic in surrounding southeast Asian countries.

Methods: Totals of 30 HIV-positive blood specimens were sampled in the
capital city, Yangon. HIV-1 env gene C2/V3 regions from PBMCs were amplified
with PCR and sequenced. Phylogenetic relationships and nucleotide sequence
variations were compared with the published sequences from Thailand. The additional 459 sera collected nationwide in 1995 were tested by V3-peptide enzyme
immunoassay (PEIA) for serologic determination of HIV-1 subtype B' (the "Thai-B"
or "Be" cluster within subtype B) and E.
Results: We have genetically identified two HIV-1 subtypes, B' and E in Yangon. B' was sole strain sequenced (21/21) among Yangon IDUs, while both B'
(6/9) and E (3/9) were detected among heterosexuals. The interperson nucleotide
sequence variations in env C2/V3 regions within B' and E were 6.7 ~ 2.1% and
7.1 ~ 0.7%, respectively, and were similar level to those observed in Thailand.
PEIA found that B' was major strain among both IDUs (43/47) and heterosexuals
(15/18) in Yangon. In contrast, E was predominantly distributed in the cities of
Tachelaik (25/26) and Kawthaung (20/23) near the border to Thailand, where the
heterosexual transmission is a major pathway of HIV-1 spread. In northeast and
central Myanmar, B' and E were detected in both IDUs and the heterosexuals,
without showing any significant segregation by risk groups.
Conclusions: Three patterns of HIV spreads emerged in Myanmar: (i) B' predominated in Yangon. (ii) E was dominantly distributed in Thai border. (iii) In upper
Myanmar, both B' and E occurred in a mixed distribution. Findings are consistent
with the view that HIV spread might have taken place at the time close to that
in Thailand and the multiple entries and exchanges of HIV-1 with neighboring
countries are important factors attributable to the current distribution of subtypes
in Myanmar.
S13131 Emerging HIV infections with two distinct subtypes of
HIV-1 among injecting drug users in southern China
Xiaofang Yu1, J. Chen2, Y. Shao3, C. Beyrey1, S. Lai4. 1Dept Molecular
Microbiology & Immunology, Jhons Hopskins University Baltimore MD;
University of Miami, Miami, USA; 2Guangxi Health & Anti-Epidemic Center
Guangxi; 3Chinese Academy Preventive Medicine Beijing, China
Objective: Over the past several years, there have been reports of increasing
prevalence of drug abuse, particularly injection drug use. in China. Over the
same period, HIV-1 appears to have spread rapidly in this population, though
detailed prevalence studies have been scarce. There is also some evidence that
HIV infections have been spread by drug traffickers, and along geographic routes
associated with heroin trading. Guangxi province has a rapidly growing population
of drug users; this is the first report of HIV infection rates, risks, and subtypes
among this population.
Methods: Between 1996 and 1997, 227 drug users from Guangxi province,
a southern province in China which borders Vietnam in the south and Yunnan
province in the west, were studied for prevalence and risk factors for HIV-1
infection. To investigate sources of transmission, viral env sequences of randomly selected samples from HIV-1 positive individuals were also determined for
subtypes of HIV-1.
Results: The overall HIV prevalence among drug users was 40%. Most had
used drugs for three years or less. Sharing of injection equipment and unprotected
sex were significantly associated with HIV-1 infection. Subtypes C and E HIV-1
were detected in infected drug users in Guangxi province. However, these two
subtypes of HIV-1 were sharply segregated in two geographic locations: only
subtype C was found in a border city with Yunnan province, while only subtype E
was found in a city bordering northern Vietnam. HIV-1 strains within each subtype
were remarkably homogenous, with a mean inter-subject DNA distance of 1.81%
for subtype E and 0.98% for subtype C, respectively.
Conclusion: HIV-1 infection among drug users in Guangxi province represents
two emerging epidemics which were presumably initiated from distinct sources.
Factors associated with HIV-1 infection were not restricted to injection: unprotected sexual behaviors are likely to increase the probability of HIV transmission
beyond this high risk population. Designing and implementing effective intervention strategies targeted toward both injecting and sexual risks are urgently needed
to further reduce HIV-1 spread in China.
S13132 Molecular epidemiology of HIV infection in China
Yiming Shao1, L. Su2, X.H. Sun3, H. Xing2, P.L. Pan2, H. Wolf4, J. Shen3. 127
Nan wei Avenue, Beijing 100050; 2National AIDS Reference Lab (NARL),
Beijing; 3 Ministry of Health, China, Beijing, PR China; 4University of
Regensburg, Regensburg, Germany
Objectives: To determine the HIV subtypes and to study their geographic and
risk distribution, correlations and transmission chains of various HIV strains in
China.
Design: Follow-up study combined with cross section study.
Methods: The HIV subtypes were determined by both serotyping with V3
peptides EIA and genotyping with HMA and sequencing of 500 bp around C2 to
V3 region of env. The genetic data was integrated with the epidemiological data
for overall analysis.

Results: In China's first HIV epidemic region bordering Myanmar, only subtype
B strains were found in the late 80s. The subtype E and C HIV-1 strains were
identified in the same region in the early and middle 90s respectively. From 1996
to 1997, a national wide molecular epidemiology survey was conducted in 24 of
China's 30 provinces. The genetic diversity among the HIV-1 strains of different
subtypes and regions were compared and analyzed with epidemiological data.
In more than 300 strains analyzed, three major HIV subtypes, subtype B' (50%),