HIGH RATE OF HEPATITIS B VIRUS MOTHER-TO-CHILD TRANSMISSION IN LAO PEOPLE'S DEMOCRATIC REPUBLIC.

Hepatitis B virus infection is endemic in Lao People's Democratic Republic (PDR). Among 3,000 pregnant women attending an antenatal clinic at Mother and Child Hospital in Vientiane, Lao PDR, 5.8% were HBsAg positive by a rapid test. Among serum samples of 47 infants aged 9-12 months born to HBsAg-positive mothers, 38% were anti-HBs negative. Percent anti-HBs negative children is significantly higher in those born to HBeAg positive mothers than in those born to HBeAg negative mothers (60% vs 25%, p < 0.05). Out of 47 HBsAg-positive mothers, 10 had infants who were HBsAg positive. None of the infants born to HBsAg negative mothers became HBsAg positive but 10/19 (52.6%) of infants born to HBeAg positive mothers became HBsAg positive. This high rate of mother-to-child transmission of HBV in an endemic country is of concern and indicates that routine vaccination program for Lao infants needs strengthening.

A high variability of mixed infections and recent recombinations of hepatitis B virus in Laos.

In Lao PDR, where more than 8% of the population are chronic carriers of HBsAg, multiple genotypes and subgenotypes co-circulate and are prone to generate recombinant viruses. Phylogenetic analyses of multiple clones per donor revealed mixed infections of subgenotypes B1, B2, B4, C1, C5, I1 and I2 in almost 6% of HBsAg positive rejected blood donors. Recombination analyses and distance calculations furthermore showed that about 65% (17/26) of the mixed infected donors showed recombinations in the S-gene alone, involving the predominant genotypes B and C. These results suggest that, at least in Laos, hepatitis B virus (HBV) mixed infections lead to frequent recombinations. In many donors with recombinant strains, the recombinant fragment and a non-recombinant strain of the same genotype co-existed (127/185 analysed recombinant fragments). For a large proportion of these (60/127), the most closely related known virus was found, although not always exclusively, in the same donor. Recombinant virus strains are largely distinct. This is reflected in an unexpected diversity in recombination breakpoints and the relatively rare recombinations with identical recombination patterns of the same genotypes in different donors. Recent recombination events would explain the limited spread of each of the recombinants. Using a published mutation rate of 4.2 × 10(-5) mutations per site and year, the observed minimum genetic distances of 0-0.60% between parent strain and recombinant fragment would correspond to 0-71 years of evolution from a most recent common ancestor (MRCA). Thus several lines of evidence are suggestive of recent independent recombination events, a proportion of these even occurring within the same donors. In conclusion, our analyses revealed a high variability of mixed infections as a very probable breeding ground of multiple variable recombination events in Laos that so far have not led to new dominant strains.

Relationship among human papillomavirus infection, p16(INK4a), p53 and NF-κB activation in penile cancer from northern Thailand.

Human papillomavirus (HPV) E6 and E7 oncoproteins are essential factors for HPV oncogenesis. These E6 and E7 gene products play a central role in the induction of malignant transformation by interacting with several cellular regulatory proteins such as p16(INK4a), p53 and nuclear factor κB (NF-κB). In the present study, conducted in northern Thailand, HPV-DNA was detected in penile cancer cases using an in situ hybridization procedure and p16(INK4a), p53 and NF-κB were detected by immunohistochemistry. Using the cell cycle regulatory proteins p16(INK4a) (61.5%) and p53 (71.8%), it was found that of the 51 cases, 39 (76.5%) were HPV-DNA-positive in penile cancer. On the other hand, 25% p16(INK4a) and 75% p53, respectively, were found in HPV-negative cases. Prevalence of HPV infection (76.5%) was shown in penile cancer cases in northern Thailand. No difference was found between HPV-positive and HPV-negative cases with respect to the presence of the cell cycle regulatory protein p53. On the other hand, p16(INK4a) was found to be different between HPV-positive and HPV-negative cases. Inactivation of tumor suppressor genes, such as p16(INK4a) and p53, to genetic instability, cell immortalization, accumulation of mutations and cancer formation, with or without HPV and irrespective of HPV infection, is therefore suggested. Of the 39 HPV-positive cases, 35 (89.7%) were NF-κB-positive in the nucleus, 29 (74.4%) in the cytoplasm and 37 (94.9%) in the nucleus and/or cytoplasm. NF-κB was detected in 4 (33.3%) of the 12 HPV-negative cases. Therefore, we propose that penile cancer cases with HPV infection are more likely to activate NF-κB than those without HPV infection.

Genotypic distribution of hepatitis C virus in voluntary blood donors of northern Thailand.

The purpose of this study was to determine the prevalence and distribution of HCV genotypes among voluntary blood donors in northern Thailand. From 1998 to 2000, 167 serum samples which tested positive for anti-HCV antibodies in the screening of voluntary blood donors from 5 provinces in northern Thailand were selected for genotyping. Viral RNA was extracted from the sera. The core-E1 region of the HCV-RNA genome was amplified using a OneStep RT-PCR kit. The core-E1 amplicon was sequenced and the HCV genotype was assigned by comparing with the reference sequences available in the GenBank database. Of 167 anti-HCV positive serum samples, 126 (75.4%) contained HCV RNA as detected by PCR. HCV genotype 3 was the most predominant genotype (39.6%), of which 33.3% belonged to genotype 3a and 6.3% to 3b. Genotype 6 was detected in 31%, and genotype 1 was detected in 27.8%. Of the genotype 1 isolates, 14.3% were la, 12.7% were 1b, and 0.8% were 1c. Two HCV isolates detected in the present study were untypeable. About 75% of anti-HCV positive blood donors had chronic HCV infection. In northern Thailand, genotype 3a was the most predominant genotype, while genotype 6, 1a and 1b were also commonly found. The genotypic distribution of HCV isolates from various regions of Thailand were more or less similar. Nevertheless, in this study, the prevalence of HCV genotype 6 (31%) was higher than previously reported by others (8-18%). Phylogenetic analysis of the HCV isolates detected in the present study was also performed.

Possible new hepatitis B virus genotype, southeast Asia.

We conducted a phylogenetic analysis of 19 hepatitis B virus strains from Laos that belonged to 2 subgenotypes of a new genotype I. This emerging new genotype likely developed outside Southeast Asia and is now found in mixed infections and in recombinations with local strains in a geographically confined region.

Genotypes of hepatitis B virus among children in Chiang Mai, Thailand.

In sub-Saharan Africa, the Pacific, and particularly Asia, hepatitis B virus (HBV) infection is highly endemic, the most common route of transmission is perinatal. To minimize the number of horizontal transmissions, we determined the prevalence of HBV genotypes among children in northern Thailand. From a survey of 1,231 schoolchildren in Chiang Mai during 1998 to 2000, 55 (4.5%) were found positive for HBsAg. Fifty-three HBsAg-positive samples were available for this study. These came from 28 girls (52.8%) and 25 boys (47.2%), age 5-16 years, with a mean age of 12.8 (+/-2.6) years. The laboratory method was based on a multiplex-PCR for the detection of 6 HBV genotypes (A-F). Among 53 HBsAg positive cases, 48 (90.6%) were genotype C, followed by 4 cases of genotype B (7.5%), and 1 case (1.9%) with mixed infection with genotypes B and C. The high prevalence of HBV genotype C follow by genotype B is similar to that found among blood donors in northern Thailand and the nationwide epidemiological survey conducted in 2004. Perinatal transmission may play an important role in the spread of the virus in this area, as in other Asian countries, where genotypes C and B are highly prevalent.

Seroprevalence of hepatitis B and C virus infections among Lao blood donors.

There have been no previous reports of the prevalence of hepatatis B virus (HBV) and hepatitis C virus (HCV) infections in Lao PDR. From 2003 to 2005, 13,897 first-time blood donors were screened for the presence of hepatitis B surface antigen (HBsAg) and hepatitis C virus antibody (anti-HCV). The seroprevalence of HBsAg positive blood donors was 8.7%. The prevalence among males (9.7%) was higher than in females (6.2%). The prevalence of anti-HCV positive blood donors was 1.1%, with no significant differences between males (1.1%) and females (1.0%). Annual positive rates for HBsAg and anti-HCV during the years 2003 to 2005 did not differ significantly. Lao PDR has a high endemicity of HBV carriers (8.7%). Dual infection with HBV and HCV was 0.12%. For preventing HBV infection, the country introduced DPT-Hepatitis B vaccines into the National Immunization Program in 2001. The large reservoir of HBV and HCV infections will cause an enormous burden of patients with cirrhosis and hepatocellular carcinoma in the future.

The prevalence of human papillomavirus genotypes in penile cancers from northern Thailand.

The highest frequency of penile cancer occurs in Asia, Africa, and Latin America, and there have been a few reports concerning the association of penile cancer with human papillomavirus (HPV) infection in these areas. The objective of this study was to determine the relation between penile cancer and the prevalence of HPV genotypes in northern Thailand. Eighty-eight specimens of penile tissue (65 malignant, 1 pre-malignant, and 22 benign cases) were examined to determine the association of HPV infection. An in situ hybridization (ISH) method was used to detect and localize HPV-DNA. Sensitive HPV polymerase chain reaction (PCR) procedure was used for detection of HPV-DNA, and DNA sequencing was used to identify the HPV genotype. HPV-DNA was detected in 53.8% and 81.5% of cases of penile cancer, using ISH and PCR, respectively. The high-risk HPV-16, most commonly associated with penile cancer in previous reports, was found in only one case in this study. The most prevalent genotype was the high-risk HPV-18, found in 55.4% of the cases (32.3% single and 23.1% multiple infection) followed by the low-risk HPV-6, found in 43.1% of the cases (24.6% single and 18.5% multiple infection). In this study, penile cancer was found to be highly correlated with HPV-DNA. Specifically, infection with both the low-risk HPV-6 and the high-risk HPV-18 is the characteristic prevalence of HPV genotypes in penile cancer in this area.

Genotypes of hepatitis B virus among voluntary blood donors in northern Thailand.

There are distinct ethnogeographic variations for the distribution of various hepatitis B virus (HBV) genotypes, and pathogenic and therapeutic differences are also observed. In general, genotype B infection has a relatively better prognosis than genotype C. In Thailand, genotypes C and B were reported as the major genotypes; however, there were no previous reports of HBV genotyping in the north of the country. From 1998 to 2000, 216 HBsAg-positive serum samples (164 males and 52 females, aged 16-52 years), were screened and collected from voluntary blood donors in four provinces of northern Thailand. The method of Naito et al. was employed in this study, with the multiplex-PCR approach and genotype-specific primers to identify genotypes A-F. We found that the HBV genotype C was highly predominant in northern Thailand (89.3%), when compared with the previous reports of genotype C distribution among voluntary blood donors from other areas in the country (50-65%), followed by genotype B (7.4%), mixed infection of genotype B and C (1.9%) and genotype A (0.5%). Four samples (1.9%) were unclassifiable. There was no significant difference of genotype distribution among four northern Thai provinces or each age group.

Evaluation of a hepatitis B vaccination program in Chiang Mai, Thailand.

Chiang Mai is a province in northern Thailand that started a vaccination program for hepatitis B virus (HBV) infection in 1989. In this paper, we report the long-term efficacy of this program. Of children aged 4-9 years, 65.7% had a complete course and 3.8% had an incomplete vaccination course. Urban schoolchildren had higher percentage of HB vaccination than rural schoolchildren (89.1% vs 46.9% for the complete course, p < 0.001). The overall prevalence rate of HBsAg in Chiang Mai schoolchildren was 1.2%, with no significant differences between gender (p = 0.496) and school areas (p = 0.477). Anti-HBc antibodies were detected in 6.9% of children. Overall, 26.2% of children had protective levels of anti-HBs antibodies (> 10.0 mlU/ml), and 11.2% had low levels of these antibodies (1.0-9.9 mlU/ml). Compared to previous reports, our results show a lower percentage of anti-HBs antibodies, 33.8% of children age 4 years had protective anti-HBs antibodies, dropping to 18.4% by age 9 years. Among those anti-HBs seropositive, 9.1% were anti-HBc positive, indicating a natural infection with HBV. We found a small number of children, despite adequate immunization, developed HBV infection.

Clinicopathologic study of hepatic Penicillium marneffei in Northern Thailand.

CONTEXT: Penicillium marneffei, an opportunistic fungus, is endemic in Southeast Asia, especially in human immunodeficiency virus-infected individuals living in northern Thailand. OBJECTIVE: We present the results of a clinicopathologic study of hepatic penicilliosis among human immunodeficiency virus/acquired immunodeficiency syndrome patients. DESIGN: A search of liver biopsies in one institution from 1998 to 1999 identified 30 cases of penicilliosis. RESULTS: Histologically, hepatic lesions could be classified into 1 of 3 patterns: diffuse, granulomatous, and mixed. The diffuse pattern showed a diffuse infiltration of foamy macrophages that contained numerous P marneffei. The granulomatous pattern showed a formation of multiple granulomata with various degrees of inflammatory cell infiltration. The mixed pattern showed features intermediate between the diffuse and granulomatous patterns. Liver function tests of the 3 pathologic pattern groups were evaluated, but there were no statistically significant differences in aspartate aminotransferase, alanine aminotransferase, or alkaline phosphatase levels among the various histologic groups. CONCLUSION: To our knowledge, this is the largest series to date that documents the liver pathology that results from this pathogen. We hypothesize that the histologic patterns seen on biopsy reflect the level of the host's immunity. Hence, in addition to a diagnosis of penicilliosis, a liver biopsy may also provide an assessment of the host's immune status, whereas liver function tests do not.

Present epidemiological pattern of antibody to hepatitis a virus among Chiang Mai children, Northern Thailand.

Hepatitis A virus (HAV) infection is common in Southeast Asia, and most of the inhabitants acquire a lifelong immunity as a result of natural infection during childhood. However, the age-specific seroprevalence is changing with development of socioeconomic and hygiene status in this area and the infection is predicted to shift to adulthood with more severe clinical manifestations in the future. In this study, we report the present epidemiological pattern of antibody to HAV (anti-HAV) among schoolchildren in Chiang Mai, Northern Thailand. The overall prevalence rate of anti-HAV was 9.6% (11.4% in female and 7.5% in male children, and 10.8% in urban and 8.9% in rural schoolchildren, respectively). Our study, comparing with previous reports from other parts in Thailand, indicates a steady decline of anti-HAV prevalence among schoolchildren in Chiang Mai area, and discussed a possibility of an outbreak of HAV infection among urban schoolchildren.