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

632 Abstracts 33198-33202

12th World AIDS Conference

associated with use of NEPs (OR = 1.00, 0.80-1.26) or use of pharmacies (OR
= 0.79, 0.62-1.01) as a source of sterile needles.
Common reasons for not using a local NEP were: able to obtain needles
elsewhere (92%), fear of being identified (17%), and fear of being caught carrying
needles (13%).
Conclusion: Although needle-exchange programs existed in all three cities,
knowledge and use of local NEPs varied. Even when a local NEP is available,
pharmacies may be important sources of sterile needles to injecting drug users.
33198 1 Lack of PWA network in Africa
David Kiddie Kasente. c/o Re. Julius Mbogua, Youth Secretary PCEA, Box
42868, Nairobi, Kenya, Kenya
Project: PWAs from 13 African countries gathered in Mombasa, Kenya to discuss
their position in the AIDS crisis and the challenges in Africa.
The cardinal AIM was to form a Network:
- to enable PWAs to share Experiences, Information, Innovations, Exchange
visits
- to help AIDS Service organizations to reverse the high infection trend
- to form a united body to act as PWA spokesman/person and to fight against
Human Rights abuse.
Result: a Network for African people was formed
- increased participation in all spheres of AIDS
- openness in talking about AIDS
Challenges: - lack of management and organizational skills
- lack of accountability on the part of PWAs
- HIV/AIDS disability being a big liability
- personalization of NAP+ by those in office
- lack of financial and human resources
- lack of monitoring and evaluation system
What can be done? - capacity building
33199 Residual risk of transfusion-transmitted viral infections
(HIV and other viruses) in France
Josiane Pillonel1, A.M. Courouc2. 1 RNSP 14 Rue du val D'Osne 94415, Saint
Maurice Cedex; 21INTS, Retrovirus Study Group, Viral Hepaatitis Study, Paris,
France
Objectives: To compare the risk of HIV transmission by transfusion of blood
given when the donor was within the window period with the residual risk of other
transfusion-transmitted viral infections (HTLV, HBV, HCV) and to analyse their
evolution over 3 periods, 1992-1994, 1993-1995 and 1994-1996.
Method: A seroconversion incidence model developed by the Retrovirus Epidemiology Donor Study (REDS) in the USA was used. This method is based
on the following relation: Residual risk = Incidence rate among repeat donors x
Window period duration. Residual risks were calculated with data collected by
the blood transfusion centres belonging to the Retrovirus Study Group (RVG) and
the Viral Hepatitis Study Group (VHG) which collect 30% of blood donations in
France. The risks were calculated over 3 periods (1992-1994, 1993-1995 and
1994-1996). Incident cases were the donors who gave a seronegative donation followed by a seropositive donation during the study periods. A total HBV
incidence rate was estimated by multiplying the HBs Ag incidence rate by 2.78
(ratio derived from VHG data). The denominators, expressed as person-years
(P-Y), were calculated by summing time intervals between the first and the last
donation of each donor during the study periods. The window period estimates
were derived from the literature.
Results: RVG and VHG incidence data, incidence rates (per 100 000 P-Y),
window period estimates (in days) and residual risk (per million donations) for
each virus are presented, for the last period (1994-1996), in the following table:

blot (WB) assays, and an HIV-1 IFA to correctly classify HIV-1 Group O sera.
Design: Test well-characterized HIV-1 Group O sera by all assays.
Methods: 24 HIV-1 Group O samples originating from infected individuals in
Cameroon were included. All had been well-characterized by a synthetic peptide
EIA and/or an HIV-1 Group 0 immunoblot. Sera were tested by eight HIV-1/2
rapid assays (A/Q Rapid HIV, BiSpot HIV-1/2, Genie II, HIV-Spot, HIVCHEK
Sys.3, Serodia HIV-1/2, Multispot, Quix 1-2-0), 3 Western blots (BioRad, Genetic
Sys/Sanofi, Genelabs), and an HIV-1 IFA (Sanofi).
Results: Of the 24 samples, 4 samples were missed by not more than 1 test,
while another sample was missed by 3 tests. 4/5 of the samples which were
missed by any of the rapid assays produced indeterminate results by at least one
of the Western blots. The sensitivity of the 8 rapid tests in detecting HIV-1 Group
O samples varied from 89-100%. By the Western blot assays, 17/24 sera were
characterized as positive by all Western blots, 1/24 was considered indeterminate
by all blots, and 3 of the remaining 6 were positive by two of the blots. Of the
samples classified as indeterminate, most produced reactions to core and pol
products only, and only 2 sera showed reactions to gp160. All samples were
classified positive by the IFA.
Conclusions: The rapid HIV screening assays produced varying results when
testing Group O sera, with only 2 classifying all as positive. One of the samples
was problematic, being misclassified by more than one screening test and being
indeterminate by all 3 WB. The WB assays were 71-92% effective in correctly
classifying the samples, while the IFA detected all.
33201 Cost-effectiveness of pooling blood samples for HIV
screening among blood-donors
Alessandro Ghirardini1, Marcello Pagano2, R. Bellocco2, E. Litvak2,
M. Gonzales1, X. Xi Tu3. 1 Viale Regina Elena, 299 Istituto Superiore Di Sanita
L.E.B., Italy; 2Harvard School of Public Health, Boston; 3University of Pittsburgh,
Pittsburgh, US
Objectives: To evaluate the feasibility of pooling blood samples for HIV screening
in blood transfusion centers in Italy.
Methods: A simulation study was performed using data from the Italian Surveillance System of Blood Donations, which collects blood for donations and data
on HIV-screening. The pooling strategy was compared with individual screening,
with respect to accuracy and cost. The strategy used in this study was that of
pooling 15 blood samples: if the pool was positive, it was divided into two and
re-tested. If negative, it was re-tested and all samples were declared as negative
if the pool tested negative this second time.
Results: This strategy resulted in a reduction of false negative tests, from 16
to 10. The number of ELISA tests was 10% that of individual tests. The cost of
tests when pooling was also 10% of that of individual screening of the 2,000,000
of blood donations/year in Italy.
Conclusions: The proposed pooling strategy appears to improve the efficiency
of HIV screening, with a reduction of false negative tests and a potential savings
of $US 17,000,000 for Italy. This strategy could be useful in screening populations
with a low HIV prevalence, such as blood donors.
33202 Prevalence of HIV antibodies in replacement blood
donors in Delhi
Krishna Ray. D // 59 Andrewsganj New Delhi 110049, India
Objectives: - to determine the i) prevalence of HIV antibodies and HBsAg, ii)
HIV seropotivity according to socio-demographic parameters and iii) HIV serotype
prevalent in the blood donors.
Methods: - Sera obtained from 43685 replacement blood donors attending
four blood banks (A, B, C, D) of Delhi from April 1994 to March 1996 were
screened for HIV antibodies (1&2) and HBsAg by Enzyme Immuno Assay (EIA).
Of these, A was a Govt, hospital and the rest private. The socio demographic
data and previous history were collected. Repeat testing for HIV antibodies was
done in all the EIA reactive samples by a second EIA/lmmunocomb HIV 1 & 2
and the repeated reactives were considered as HIV positive.
Results: HIV seroprevalence per thousand & HBsAg % positivity were observed respectively as: 4.4 & 2.7 in A; 2.1 & 2.7, in B; 2.6 & 2.7 in C and 2.1 & 0.7
in D. A statistically significant difference (p < 0.01) was observed in the HIV seroprevalence of the donors at A and the other blood banks. However, the marginal
decrease in the overall HIV seroprevalence observed in the two years was not
statistically significant. Most of the donors were in the 21-30 yrs. age group
(51.9%) & 93.8% were males. A total of 73.0% were married and 49.5% had 1-4
family members. HIV seropositivity was highest (10.2/1000) in the teenagers and
more in males but no difference was detected with marital status. Most belonged
to service class and were skilled workers. The seropositivity rate increased with
the increase in the family size. The type of infection was predominantly HIV 1.
The study highlights the importance of mandatory transmissible disease screening of donated blood. A large number of blood bags had to be discarded because
of our policy of screening them for HIV only once. The significantly higher HIV
seropositivity in donors at the Govt. Blood Bank than that in the private ones

indicates that the initial donor selection process is not optimum at the former
and some of them are probably professional donors in the guise of replacement
donors.

Virus Incident
cases
HIV 14
HTLV 1
HBV 13
HCV 25

P-Y
845 758
845 758
982 359
930 965

Incidence rate/105
(95%CI)
1.66 (0.9-2.9)
0.12 (0.0-0.8)
3.67 (2.6-5.1)
2.69 (1.8-4.0)

Window period
(range)
22 (6-38)
51 (36-72)
56 (25-109)
66 (38-94)

Residual risk/106
(95% CI)
1.0 (0.1-3.4)
0.2 (0.0-1.6)
5.6 (1.8-15.2)
4.9 1 (1.9-10.3)

Over the first 3-year period (1992-1994), the residual risks were slightly higher
for HIV, HTLV and HBV: respectively, 1.7 (0.3-4.4), 0.5 (0.1-2.2) and 8.9 (3.0-23.0)
per million donations. The residual risk was stable for HCV.
Conclusion: The residual risk of HIV transmission by transfusion, associated
with the window period (the major source of risk), is currently low in France (1
in 1 million donations) and still decreasing. For HTLV this risk is even lower (1
in 5 million donations) due to a very low incidence rate. For HCV (1 in 200 000
donations) and for HBV (1 in 180 000 donations), the residual risks are higher
due to a longer window period and higher incidence rates.
33200 Detection of antibodies to HIV-1 group O by eight
screening and four confirmatory assays
Niel Constantine1, R.D. Saville1, L. Zekeng2, H.A. Anhary1, F. Ketema1,
L. Gurtler3. 1725 W Lombard St. Rm 515, Institute of Human Virology, University
of MD. Baltimore, MD. 21201, USA; 2AIDS Control Programme, Yaounde,
Cammeroon; 3Max Von Pettenkifer-lnstitut, Munchen, Germany
Objective: To determine the ability of a variety of rapid HIV tests, 3 HIV Western