In Papua New Guinea, the laboratory diagnosis of HIV infection is based on proof of HIV antibody in the patient's serum. Under the government scheme, the testing is done in 30 laboratories, including the Papua New Guinea HIV Reference Laboratory (NRL), the Red Cross Blood Transfusion Service in Port Moresby, and 19 provincial and 9 district laboratories. An alternative testing strategy was adopted in 1993 based on a WHO recommendation, replacing the classical testing strategy (enzyme immunoassay + Western blot). The alternative testing strategy uses several EIA, rapid or simple HIV antibody assays for the detection and confirmation of the HIV antibody. This approach is faster and cheaper, with the same sensitivity and specificity as the classical testing algorithm. Except for the NRL, the Serodia Fujirebio HIV-1 gelatin particle agglutination assay is used throughout the country as the screening test. The PNG National HIV Reference Laboratory is the only laboratory authorized to perform confirmatory testing and to release positive results. Therefore, all serum samples reactive in the screening assay are sent to the NRL for confirmation by the battery of EIA, rapid or simple assays in accordance with the alternative testing strategy adopted. The paper explains the alternative testing strategy and highlights the principle of each individual test that is employed. PIP: In Papua New Guinea, HIV antibody testing is performed in 19 provincial and 9 district laboratories, the HIV National Reference Laboratory, and the Port Moresby Red Cross Blood Transfusion Service. Before 1993, enzyme immunoassay and Western blot were used for HIV serotesting and positive findings were sent to Australia for confirmation. Since 1993, the Serodia Fujirebio HIV gelatin particle agglutination assay has been used as the first screening test, followed by the enzyme-linked immunosorbent assay; the third test used for repeatedly reactive samples is generally the Immunocomb. All repeatedly positive results are forwarded to the reference laboratory for confirmation. Results are available within 7 days. In Papua New Guinea, the specificity of the Serodia Fujirebio test is consistently greater than 99%.
AIDS Serodiagnosis - methods ; Blotting, Western - methods ; Enzyme-Linked Immunosorbent Assay - methods ; Fluorescent Antibody Technique ; HIV Infections - diagnosis ; Papua New Guinea ; Polymerase Chain Reaction - methods ; Sensitivity and Specificity

OBJECTIVETo Evaluate four kits for screening HIV antibody by comparing and analyzing the HIV antibody screening positive results and Western Blot (WB) test results.

METHODSFrom January 2004 to June 2009, three ELISA kits (Zhongshan, Biomérieux and Livzon) were used for initial screening HIV antibody. The reactive positive samples were reexamed by initial ELISA kit and a rapid kit (Abbot Determine HIV-1/2). All repeatedly reactive positive screening results were followed by WB test.

RESULTSA total of 193 (0.094%) WB confirmed positive results were obtained from 206 151 specimens. The sensitivities and predictive values of negative test result (PVN) of three ELISA kits were all 100% and those of Abbot Determine HIV-1/2 were 93.93%, and 91.67% respectively. All false negative results from Abbot were WB indeterminate. The specificities of Zhongshan, Biomérieux, Livzon and Abbot were 99.88%, 99.89%, 99.96% and 89.38%; the study predictive values of a positive test result (PVP) were 35.58%, 46.46%, 76.61% and 92.20%; the efficiencies were 99.88%, 99.89%, 99.96% and 91.98%; the areas under ROC curve of the three ELISA kits were 0.93, 0.99, and 0.95 respectively. PVP of Livzon was obviously higher than those of Zhongshan (chi(2) = 45.804, P = 0.000), Biomérieux (chi(2) = 25.231, P = 0.000) and Biomérieux was higher than Zhongshan (chi(2) = 2.488, P = 0.115). PVP of Abbot was highest (chi(2) = 18.633, P = 0.000, vs Livzon). There were some specimens with S/CO (optical density of sample/cut off) ratio < 6 or > or = 6 in all three groups with positive, indeterminate and negative WB results. The S/CO ratio from Zhongshan in confirmed positive group (14.29 + or - 2.63) was higher than in positive-negative group (2.80 + or - 3.25) (t = 17.652, P = 0.000). The S/CO ratio from Biomérieux in confirmed positive group(16.09 + or - 2.35) was higher than in positive-negative group (2.14 + or - 1.91) (t = 31.622, P = 0.000). The S/CO ratio from Livzon in confirmed positive group (11.54 + or - 1.95) was higher than in positive-indeterminate group (5.54 + or - 3.57) (t = 6.386, P = 0.000), positive-negative group (3.25 + or - 2.41) (t = 21.772, P = 0.000) and positive-indeterminate group was higher than positive-negative group (t = 2.301, P = 0.033).

CONCLUSIONThe performances of four HIV antibody screening kits are good but estimating WB confirming result in line with S/CO ratio is not available. All repeated screening positive results should be followed by confirmatory tests.

AIDS Serodiagnosis ; methods ; Blotting, Western ; methods ; Enzyme-Linked Immunosorbent Assay ; methods ; statistics & numerical data ; HIV Antibodies ; blood ; HIV Seropositivity ; diagnosis ; Humans ; Indicators and Reagents ; Mass Screening ; Reagent Kits, Diagnostic ; Sensitivity and Specificity

OBJECTIVETo estimate the human immunodeficiency virus (HIV-1) prevalence of injecting drug users (IDUs) in Chongqing city.

METHODSTo apply BED-capture enzyme immunoassay (CEIA) which was based on the principle of HIV-antibody varies as the disease progress, in order to estimate both the HIV incidence and prevalence of IDUs from two IDUs surveillance sites in Chongqing.

RESULTSDuring the research period, 4711 serum samples were tested by ELISA and 130 were HIV-1 positive, confirmed by Western blot. The prevalence of IDUs surveillance site A from 1999 to 2006 were 0.73%, 2.02%, 1.54%, 2.96% and 2.80%, and the incidence rates were 0.57%, 0.93%, 0,1.24% and 1.68% respectively. The prevalence of IDUs surveillance site B appeared to be 4.21%, 9.96%, 8.13%, and the incidence rates were 0.95%, 1.04% and 0.90% respectively, from 2004 to 2006.

CONCLUSIONMany of the IDUs HIV carriers in Chongqing had been infected for long time, and the incidence rates among them were steady, keeping at the same level for 1-2 years. Promotion on intervention for IDUs had produced certain effects but more attention still needs to be paid.

AIDS Serodiagnosis ; methods ; China ; epidemiology ; Drug Users ; HIV Antibodies ; blood ; HIV Infections ; blood ; epidemiology ; HIV Seroprevalence ; Humans ; Immunoenzyme Techniques ; Incidence ; Population Surveillance ; Prevalence ; Substance Abuse, Intravenous ; epidemiology ; virology ; Urban Population ; statistics & numerical data