Rapid and simple screening and supplemental testing for HIV-1 and HIV-2 infections in west Africa.

OBJECTIVE: To evaluate a combination of rapid tests as a strategy for screening and supplemental testing of serum for HIV-1 and/or HIV-2 antibodies. DESIGN: Cross-sectional evaluation. SETTING: Projet RETRO-CI, an AIDS research project in Abidjan, Côte d'Ivoire. METHODS: Serum specimens were collected from 1000 consecutive women giving birth in an Abidjan maternal and child health centre and from 185 hospitalized patients. All serum specimens were tested for HIV-1 and HIV-2 antibodies by whole-virus enzyme immunoassay; repeatedly reactive specimens were further tested by virus-specific Western blot and synthetic peptide-based tests. This was the reference strategy against which the algorithm under evaluation was compared. All specimens were subsequently tested by a mixed (HIV-1 and HIV-2) recombinant antigen-based test (Abbott Testpack), followed, if positive, by a rapid synthetic peptide-based test (Genetic Systems Genie) as a supplemental test. RESULTS: According to the reference strategy the prevalence of HIV-1 and/or HIV-2 infection was 13% among the pregnant women and 78% among the hospitalized patients. Compared with the reference strategy, the combination of rapid tests was associated with a sensitivity of 99.6%, a specificity of 99.9%, and positive and negative predictive values of 99.6 and 99.9%, respectively. Four per cent of HIV-2-positive and 1% of HIV-1-positive specimens were considered dually reactive by the rapid test combination. CONCLUSIONS: Synthetic peptide-based tests provide an alternative to Western blots for supplemental testing for HIV-1 and HIV-2. This combination of rapid tests offers performance characteristics comparable to an enzyme immunoassay and Western blot-based strategy, without requiring running water, electricity, or a well-developed laboratory. High-quality serodiagnosis of HIV-1 and HIV-2 infections is possible at the most peripheral levels of the health-care system in developing countries, the limiting factors being the costs of tests and training of staff.

PIP: Researchers from an AIDS research project took blood samples from 1000 consecutive women during childbirth at a maternal and child health center in Abidjan, Cote d'Ivoire, and from 185 hospitalized patients to compare the results of a combination of synthetic peptide-based rapid tests (product names, Testpack and Genie), which check for HIV-1 and HIV-2 antibodies, with those of the Western Blot-based test. They also wanted to see whether the rapid test-based strategy could replace the Western Blot-based test as a supplemental test. The Western Blot indicated the HIV-1 and/or HIV-2 prevalence to be 13% among the new mothers and 78% among the hospitalized patients for an overall prevalence of 23%. 3.3% of all people were positive for both HIV-1 and HIV-2. 17.4% tested positive for just HIV-1. 2.1% were positive for HIV-2. The rapid tests had a sensitivity of 99.6% and a specificity of 99.9%. The positive predictive value was 99.6% and the negative predictive value was 99.9%. The rapid tests identified 4% of the HIV-2 positive samples and 1% of the HIV-1 samples to be dually reactive. These findings demonstrated that rapid synthetic peptide-based assays reliably detect HIV-1 and HIV-2 antibodies and can be supplemental tests. High quality HIV serology can be performed in a setting without running water and electricity which was the case in this study. A further advantage of this strategy is that each test takes only 10 minutes. These tests would have significant effects on HIV testing and counseling, diagnosis, and screening of blood for transfusion in rural areas of developing countries.

Dual seroreactivity to HIV-1 and HIV-2 in female sex workers in Abidjan, Côte d'Ivoire.

OBJECTIVE: To determine the absolute and proportional prevalence of dual seroreactivity to HIV-1 and HIV-2 in female sex workers in Abidjan, to determine risk determinants for this serologic profile, and to describe the associated clinical and immunological characteristics. DESIGN: Cross-sectional study. SETTING: Confidential clinic for female sex workers in Abidjan. PARTICIPANTS: Female sex workers. MAIN OUTCOME MEASURES: HIV serostatus, CD4+ counts, women with AIDS, behavioural and sociodemographic characteristics. RESULTS: Among 1209 women tested, the overall HIV seroprevalence was 80%, while the prevalence of dual seroreactivity was 30%. Dual seroreactivity accounted for 38% of all HIV infections. Compared with women reacting to HIV-1 only, dually seroreactive women were significantly more likely to have been in sex work for a longer period, to be aged > or = 20 years, and to charge less money for intercourse. No difference in mean CD4+ count was noted between women with dual seroreactivity (561 x 10(6)/l) and HIV-1-seropositive women (558 x 10(6)/l). CONCLUSIONS: Female sex workers in Abidjan had the highest absolute (30%) and proportional rate (38%) of dual seroreactivity yet described in any population. Increased sexual exposure is associated with an increased risk of dual seroreactivity. Although better molecular diagnostic techniques are required, a substantial proportion of female sex workers in Abidjan is likely to be infected with both HIV-1 and HIV-2.

Evaluation of an HIV saliva test for the detection of HIV-1 and HIV-2 antibodies in high-risk populations in Abidjan, Côte d'Ivoire.

To evaluate saliva testing in a West African field situation where both HIV-1 and HIV-2 are present, a cross-sectional study was conducted among female sex workers (FSWs) and their stable male partners (SMPs) at a STD/HIV clinic in Abidjan, Côte d'Ivoire. Saliva samples were collected with the Omni-SAL device and tested for antibodies to HIV-1 or HIV-2 by GACELISA. The HIV seroprevalence was 71% among 468 FSWs and 61% among 31 SMPs. Salivary HIV antibodies were detected in all 227 HIV-1-seropositive, in all 6 HIV-2-seropositive and in 115 of 117 dually seroreactive participants, while no salivary HIV antibodies were detected in 148 of 149 seronegative participants. The sensitivity and specificity of the saliva test were 99.4% and 99.3% respectively, and the positive and negative predictive values were 99.7% and 98.7% respectively. In this West African field situation saliva testing has a high validity compared to serum testing. The Omni-SAL and GACELISA combination is an alternative strategy to serological testing because of its high sensitivity and specificity, the ease and safety of sample collection and its relatively low cost.