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Background: Prevention of transfusion transmissible HIV and other infections relies on selection of low risk donors and screening donors with sensitive assays. Selection of donors at low risk in developing countries with major heterosexual epidemics of HIV has been difficult. However, the prevalence of HIV among blood donors reflects the control of infection in the community and the self exclusion in part of donors who have previously tested positive. Methods: We evaluated the trends in HIV prevalence among 175,251 blood donors in Chiang Mai, Thailand, between 1990 and 1998. This area has had an explosive HIV epidemic beginning in 1988-1998. These data were useful to monitor the safety of the blood supply and the evolution of the epidemic. Results: The overall HIV prevalence was 3.0% in men and 0.96% in women; prevalence was higher in first time than repeat donors. The HIV prevalence peaked at 4.04% in 1991, leveled off at about 3.5% between 1992 and 1994, then declined to 0.68% in 1998. In 1998 HIV prevalence was similar in men and women and volunteer and repeat donors. Conclusions: There has been a substantial decline in the HIV prevalence among blood donors in N. Thailand in the past few years. This decline probably reflects widespread testing for HIV and a decreased HIV incidence due to an effective public health program to prevent incident infections from exposure during commercial sex the, "100% condom program. More effective exclusion of high risk donors may have contributed to the decline. This is an example of improvement in the safety of blood in a developing country experiencing a major AIDS epidemic. [ABSTRACT FROM AUTHOR]

Background: Thailand's epidemic of HIV infection, which began in 1988, has primarily involved heterosexual transmission of the virus. This study describes changes in prevalence of HIV and other infectious diseases among blood donors in northern Thailand from 1990 through 2001., Study Design and Methods: Serologic screening results and demographic data were analyzed from 276,066 donors screened at two blood collection facilities in Chiang Mai, Thailand, from 1990 through 2001., Results: The HIV prevalence peaked in 1991 to 1993 at 4.04 percent and then declined to 0.38 percent in 2001. The overall prevalence of HIV infection was 2.16 percent; HIV prevalence was higher among male (2.24%) than among female (0.64%) donors, in first-time donors, and in replacement volunteer donors. The majority of the donors were men and first-time donors throughout this study. The prevalence of antibodies to syphilis decreased significantly in both men and women. However, the prevalence of antibodies to HCV and HBsAg were stable., Conclusions: The declining HIV prevalence from 1990 through 2001 among blood donors in two large blood banks in northern Thailand indicates significant progress toward recruitment of a safer donor population in a developing country despite a major HIV and AIDS epidemic involving the general population.

HIV-1 coreceptors CCR5 and CXCR4 play an important role in viral entry and pathogenesis. To better understand the role of viral tropism in HIV-1 transmission, we examined the coreceptor utilization of viral isolates obtained from men enrolled in a study of heterosexual transmission in northern Thailand. Viral isolates were obtained from HIV-1-positive males who had either HIV-1-infected spouses (RM; n = 5) or HIV-1-uninfected spouses (HM; n = 10). Viral isolates from 1 of the 5 RM males and 2 of the 10 HM males were CCR5 tropic, whereas isolates from 3 RM males and 6 of the HM male isolates were CXCR4 tropic. Of the nine X4-tropic isolates, seven also used at least one of the following coreceptors: CCR8, CCR1, CCR2b, or CX3CR1, and none employed CCR5 as an additional coreceptor. More importantly, three isolates, RM-15, HM-13, and HM-16 (one from a transmitter and two from nontransmitter), did not infect GHOST4.cl.34 cells expressing any of the known coreceptors. Further analysis using MAGI-plaque assays, which allow visualization of infected cells, revealed that RM-15 had low numbers of infected cells in MAGI-R5 and MAGI-X4 cultures, whereas HM-13 and HM-16 had high levels of plaques in MAGI-X4 cultures. Replication kinetics using activated lymphocytes revealed that these three isolates replicated in CCR5(+/+) as well as CCR5(-/-) peripheral blood mononuclear cells, suggesting that these isolates did not have an absolute requirement of CCR5 for viral entry. All three isolates were sensitive to the X4-antagonistic compounds T-22 and AMD3100. Analysis of the C2V3 region did not reveal any significant structural differences between any of the Thai subtype E isolates. Thus, there was no association between the pattern of coreceptor usage and transmissibility among these subtype E HIV-1 isolates.

Objective: To describe risks for HIV transmission from male blood donors to their regular female sex partners in Chiang Mai, Thailand., Design: Cross-sectional study., Methods: From March 1992 through September 1995, 405 HIV-seropositive male blood donors (index cases) and their regular female partners were enrolled in the study. Women with risk factors for HIV infection other than sexual contact with the index male were excluded. Couples were interviewed and examined; specimens were collected for laboratory analysis., Results: Overall, 46% of the 405 women enrolled were HIV-positive. Ninety-eight per cent of male index cases had a history of sex with a female prostitute; 1.5% reported always using condoms with their regular partner. History of sexually transmitted disease (STD) and swollen inguinal lymph nodes in the female partner were associated with an increased risk of HIV infection in the female. History in the female of genital herpes [odds ratio (OR), 3.46; 95% confidence interval (CI), 1.50-8.78], gonorrhea or chlamydia infection (OR, 2.71; 95% CI, 1.39-5.53), and stable relationship of longer than 24 months (OR, 2.28; 95% CI, 1.02-5.09) were associated with an increased risk of HIV infection in the female. Consistent condom use in the past 2 years (OR, 0.10; 95% CI, 0.01-0.79) was associated with a decreased risk of HIV infection in the female., Conclusions: Married women in northern Thailand who appear otherwise to be at low risk for HIV infection may be exposed to this virus by their husbands. High rates of sex with commercial sex workers among men and low use of condoms within stable relationships may be important factors promoting the transmission of HIV in married couples. Programs to increase the regular use of condoms among married couples could be an important public health intervention to prevent transmission of HIV and other types of STD in northern Thailand.

We investigated the distribution of HLA-A and B locus, gene frequency (GF), antigen frequency (AF), haplotype frequency (HF) and non detectable antigens in Northern Thais. Of 289 native northern Thai people residing in Chiang Mai province for many generations were tested using lymphocytotoxicity test and 146 unrelated subjects were selected for analysis. The common alleles were A2, A11 and A24 for A locus with GF of 36.4%, 35.4% and 15.6%, respectively and B46, B40 and B13 for B locus with GF of 21.1%, 15.7% and 8.6%, respectively. The frequent linkage disequilibrium haplotypes were A2,B46; A33,B17 with HF of 15.9%; 5.0% and LD of 8.3%; 4.6%, respectively (p < 0.0001). The undetectable antigens (blanks) occurred with GF = 11.64% at A locus and GF = 4.92% at B locus. Comparing the GFs to other Thai ethnic groups, showed that the Northern Thais shared several alleles such as A2, A11, B46, and B62 in common with Dai Lue (Thai-speaking people who lived in the southern part of China), (p > 0.05), more than Thais, Thai/Chinese or present-day Thais (p < 0.001). Especially, HLA-B46 with the GF of 21.1% is considered to be a very typical antigen for Southern Mongoloids. These similarities will support the root of migration and origin of Northern Thais.