Protective and enhancing HLA alleles, HLA-DRB1*0901 and HLA-A*24, for severe forms of dengue virus infection, dengue hemorrhagic fever and dengue shock syndrome.

BACKGROUND: Dengue virus (DV) infection is one of the most important mosquito-borne diseases in the tropics. Recently, the severe forms, dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), have become the leading cause of death among children in Southern Vietnam. Protective and/or pathogenic T cell immunity is supposed to be important in the pathogenesis of DHF and DSS. METHODOLOGY/PRINCIPAL FINDINGS: To identify HLA alleles controlling T cell immunity against dengue virus (DV), we performed a hospital-based case control study at Children's Hospital No.2, Ho Chi Minh City (HCMC), and Vinh Long Province Hospital (VL) in Southern Vietnam from 2002 to 2005. A total of 211 and 418 patients with DHF and DSS, respectively, diagnosed according to the World Health Organization (WHO) criteria, were analyzed for their characteristic HLA-A, -B and -DRB1 alleles. Four hundred fifty healthy children (250 from HCMC and 200 from VL) of the same Kinh ethnicity were also analyzed as population background. In HLA class I, frequency of the HLA-A*24 showed increased tendency in both DHF and DSS patients, which reproduced a previous study. The frequency of A*24 with histidine at codon 70 (A*2402/03/10), based on main anchor binding site specificity analysis in DSS and DHF patients, was significantly higher than that in the population background groups (HCMC 02-03 DSS: OR = 1.89, P = 0.008, DHF: OR = 1.75, P = 0.033; VL 02-03 DSS: OR = 1.70, P = 0.03, DHF: OR = 1.46, P = 0.38; VL 04-05 DSS: OR = 2.09, P = 0.0075, DHF: OR = 2.02, P = 0.038). In HLA class II, the HLA-DRB1*0901 frequency was significantly decreased in secondary infection of DSS in VL 04-05 (OR = 0.35, P = 0.0025, Pc = 0.03). Moreover, the frequency of HLA-DRB1*0901 in particular was significantly decreased in DSS when compared with DHF in DEN-2 infection (P = 0.02). CONCLUSION: This study improves our understanding of the risk of HLA-class I for severe outcome of DV infection in the light of peptide anchor binding site and provides novel evidence that HLA-class II may control disease severity (DHF to DSS) in DV infection.

Prevalence of and factors associated with reproductive tract infections among pregnant women in ten communes in Nghe An Province, Vietnam.

BACKGROUND: A community-based survey was conducted to investigate reproductive tract infections (RTIs) among pregnant women in Vietnam, where epidemiologic data on these infections are scarce. METHODS: The focus of the study were: candidiasis, bacterial vaginosis, group B streptococcal infection,trichomoniasis, gonorrhea, syphilis, and hepatitis B. In addition to their prevalence, a generalized estimating equation was used to analyze infection-associated factors and diagnostic test analysis to examine the accuracy of currently performed presumptive clinical diagnoses. RESULTS: Among 505 pregnant women in 10 communes, 182 (36%) had at least one infection with a wide regional variation in prevalence. The most prevalent infection was candidiasis (17%); sexually transmitted infections were rare except hepatitis B (10%); and the prevalence of bacterial vaginosis and group B streptococcal infections was 7% and 4%, respectively. Two factors were associated with the decreased risk of endogenous infections: a higher household assets score (odds ratio [OR] = 0.67) and condom use (OR = 0.15). Not living with a husband (OR = 1.55) was associated with an increased risk. For hepatitis B, three factors were associated with a decreased risk: employment by the government (OR = 0.26), higher education (OR = 0.18), and being older at the time of first sexual intercourse (OR = 0.58). Women's self-reported symptoms and clinical findings had low positive predictive values. Only clinical findings from the vaginal wall showed both a sensitivity and specificity over 50%. CONCLUSIONS: Suggested recommendations are: extensive application of microscopic diagnosis, prevention of hepatitis B transmission, and addressing the issues of regional differences in the prevalence of RTI and of less wealthy people.