Anti-HIV antibody titer: an alternative supplementary test for diagnosis of HIV-1 infection.

The diagnosis of HIV infection is based on screening of HIV antibodies and confirmed by a more specific supplementary test. The most common confirmation test is Western blot, which is expensive, time consuming and subject to technical skill. The present study was carried out to evaluate whether the anti-HIV-1 antibody titer is valid as a supplementary test for diagnosis of HIV-1 infection. Anti-HIV-1 antibody titers of 2,414 anti-HIV-1 positive sera determined by the particle agglutination (PA) method were analysed in comparison with the Western blot analysis. The Western blot negative result was found in 11 of 2,414 (0.46%) anti-HIV-1 positive sera, these sera also gave negative anti-HIV by ELISA. The PA titers of these sera were found in the range of 16 to 64. Seventeen samples (0.70%) with anti-HIV-1 in the titer range of 16 to 256 showed indeterminate Western blot analysis. The rest, 2,386 of these 2,414 sera (98.84%), were shown to be positive by Western blot. However, all of the 2,356 sera with antibody titers > or = 512 (97.6%) demonstrated positive Western blot results. Five cases among the 17 (29.4%) indeterminate sera were examples of early seroconversion of HIV infection, which were confirmed in follow up specimens. The results suggest that only the samples with antibody titers < 512 are required to be confirmed for HIV infection by Western blot. It is possible that early seroconversion may be inferred from anti-HIV titers. Therefore, in order to reduce time and cost, the PA anti-HIV titer can be used as an alternative supplementary test for diagnosis of HIV-1 infection in most positive screened anti-HIV samples. Western blot is needed for testing in only a few cases.

DNA typing of the HLA-A, -B and -C genes: possible MHC class I haplotypes in the northeastern-Thais.

The phenotype and gene frequencies of HLA class I were studied in the Northeastern Thai population. Blood samples were collected from 100 unrelated healthy northeastern-Thais. HLA-A, -B and -Cw alleles were determined using the polymerase chain reaction- amplification refractory mutation system (PCR-ARMS). 12 HLA-A, 20 HLA-B and 14 HLA-Cw alleles were found. Linkage disequilibrium analysis indicated the existence of 7 HLA-A-B and 19 HLA-B-Cw haplotypes. A*0207-Cw*01-B*4601 was the most common possible haplotype in this population. These results provide regional basic information for further studies in anthropology, organ transplantation and MHC disease associations in the northeastern-Thais.

Association of HCV and Treponema pallidum infection in HIV infected northeastern Thai male blood donors.

The study was performed to determine the association of seroprevalence of hepatitis C virus (HCV) and Treponema pallidum (T. pallidum) infection among HIV infected first time male blood donors (HIV group) in comparison with the HIV seronegative blood donors (control group) in the Northeast of Thailand (NET). Serum samples were collected from 10,321 first blood donation voluntary male donors. All samples were screened for anti-HIV and anti-HCV by particle agglutination test, and syphilis antibody by RPR. The anti-HIV positive sera were repeated by EIA and confirmed by western blot. The reactive anti-HCV samples were confirmed by EIA whereas reactive syphilis antibody samples were confirmed by TPPA. Fisher's exact test was used for statistical analysis. The prevalence of anti-HIV in first time male donors was 0.70 per cent (72/10,321). The age of HIV group and 10,018 male control group ranged from 17-50 years old. The prevalence of HIV among 21-40 years old age group was significantly higher than the 17-20 years old (p = 0.00003). The 17-20 years old HIV group showed significantly higher sero-prevalence of TPPA (p = 0.003). The 21-30 years old HIV group gave significantly higher sero-prevalence of anti-HCV (p = 0.0008) and TPPA (p = 0.045), but the seroprevalence of anti-HCV and TPPA among the 31-50 year old group were nonsignificantly different (p > 0.05). The concurrence of anti-HCV and TPPA in HIV groups was not found. This result indicated that HIV infection among NET voluntary male blood donors was significantly associated with T. pallidum infection in young adults and the HCV infection in mature adults.

Seroepidemiology of HTLV-I infection in northeast Thailand: a four year surveillance.

The human T-lymphotropic virus type I (HTLV-I) can be transmitted through blood transfusion, sexual contact, perinataly and by breast feeding. We carried out a four years seroepidemiology surveillance study of HTLV-I infection among northeast Thai population by screening for antibodies to HTLV-I (anti-HTLV-I) in 1992, 1993, 1995 and 1997. A total of 8,323 blood samples were collected from 6,228 blood donors, 832 pregnancies, 219 multitransfused patients, 53 HIV positive intravenous drug users and 1,000 northeast-Thai workers at different periods of time. The serum samples were tested for anti-HTLV-I by particle agglutination (PA) technique and confirmed by Western blot. One sample from a multitransfused patient collected in 1992 and one sample from a blood donor collected in 1995 demonstrated positive anti-HTLV-I screening by PA but negative by Western blot. This finding indicates that at present HTLV-I is not a public health problem in the northeast of Thailand but surveillance should be continually conducted.

Reducing the risk of HIV transmission through blood transfusion by donor self-deferral.

A cross sectional study was conducted to evaluate the validity of implementing a blood donor self-deferral form for reducing the risk of HIV transmission through blood transfusion. The self-deferral form which was given to all blood donors, included questions about HIV risk factors in the three month period prior to blood donation. Donors were asked to declare confidentially whether their blood was safe for transfusion or not. Blood was collected and examined for HIV antigen, anti-HIV antibodies, HBsAg and syphilis antibodies. All of the serological markers detected among high risk donors and general donors were compared and analysed by Yates corrected X2 test and one-tailed Fisher's exact test with a significance level of 0.05. There were 401 self-deferred high risk donors and 15,523 general donors. The HIV antigen was found as a single marker in only one male high risk individual. The prevalence of anti-HIV antibodies, HBsAg and syphilis antibodies among the general donors was 0.61%, 5.29% and 1.17%, respectively. The anti-HIV, HBsAg and syphilis antibodies in the high risk donors were 1.99%, 7.98% and 1.25%, respectively. In comparison with the general donors, the high risk donors demonstrated statistically significant higher prevalence rates of HIV antigen (p < 0.05), anti-HIV (p < 0.005) and HBsAg (p < 0.05). In conclusion, donor self-deferral is valid for reducing the risk of HIV transmission through blood transfusion and its implementation should be encouraged when recruiting blood donors.

Different cell volume with high target cell population between liver disease and homozygous hemoglobin E.

Blood samples with increased percentage of target cells were collected from liver disease, thalassemia, homozygous hemoglobin E (E/E), and nonidentified cases. Normal cases who had no history of liver disease and normal hemoglobin typing were also included in the study for control. Patients with liver disease had increased target cell percentage with normal MCV, whereas, the other three groups had increased target cell percentage and reduced MCV. The difference was more obvious when compared with liver disease and homozygous Hb E cases. These two groups had comparable target cell percentage (14.36 +/- 4.77 in liver disease, and 14.22 +/- 1.59 in homozygous Hb E) and comparable degree of anemia (Hb level in liver disease = 11.19 +/- 0.39, and 11.30 +/- 0.16 in homozygous Hb E) but they showed a statistical significance (p less than 0.0001) between MCV (79.66 +/- 2.18 fL in liver disease, and 60.40 +/- 0.75 fL in homozygous Hb E).