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Background: Little is known about the prevalence of hepatitis B virus (HBV) DNA and the genotype distribution among patients with liver diseases in Nepal, where obstruction of the hepatic portion of the inferior vena cava (IVCO) is common. The aim of the present paper was to assess the roles of HBV infection and IVCO in liver cirrhosis (LC) and hepatocellular carcinoma (HCC) in Nepal., Methods: Serum samples from 121 patients (89 male, 32 female; age, 55.0 +/- 13.6 years) with or without IVCO consisting of 70 LC patients and 51 HCC patients in Nepal, were tested for HBV-DNA., Results: The HBV-DNA was detected in 68 patients (56%) including 20 hepatitis B surface antigen (HBsAg)-negative patients: 33 LC patients (47%) and 35 HCC patients (69%) had detectable HBV-DNA (P = 0.0303). Among the 89 patients with IVCO, HBV-DNA was detected in HCC patients significantly more frequently than in LC patients (80%vs 43%, P = 0.0005). The frequency of HBV viremia was significantly higher among HCC patients with IVCO than those without (80%vs 44%, P = 0.0236), and that of HBV viremia with IVCO was significantly higher among HCC patients than among LC patients (55%vs 27%, P = 0.0153). The HBV genotypes A and D were predominant, and genotype A was significantly more frequent among HCC patients than among LC patients (22%vs 6%, P = 0.0090). Among HCC patients, those with genotype A HBV were significantly younger than those with genotype D (43 +/- 13 vs 57 +/- 12 years, P = 0.0252)., Conclusion: Hepatitis B virus alone (especially genotype A) or in concert with IVCO may be responsible for development of HCC in Nepal.

To investigate the genetic changes in hepatitis E virus (HEV) strains in the Kathmandu valley of Nepal, we compared the 412 nt sequence within open reading frame 2 of HEV among HEV isolates recovered from 16 patients in 1999, 14 patients in 2000 and 38 patients in 2002, and additional isolates recovered from 48 patients in 1997 whose nucleotide sequences have been previously published. All 116 HEV-viraemic samples were genotyped as 1 and subtyped further as 1a (n=85, 73 %), 1c (n=29, 25 %) and mixed infection of 1a and 1c (n=2, 2 %): subtype 1c was detected only in 1997. Among the 1a isolates, nucleotide sequence identity with the representative 1a isolate of Ne131-1997 was 96.4+/-2.4 % (mean+/-SD) in 1997, 93.9+/-1.7 % in 1999, 92.2+/-1.0 % in 2000 and 91.7+/-0.5 % in 2002, indicating gradual diversification of HEV sequences. When phylogenetic analysis of the 87 subtype 1a isolates was performed, they further segregated into five clusters, with two predominant clusters of 1a-2 and 1a-3: the annual frequency of cluster 1a-2 isolates decreased from 63 % in 1997, to 50 % in 1999, to 7 % in 2000 and no cases in 2002; cluster 1a-3 isolates were observed in all four years and its annual frequency increased from 5 % in 1997 to 95 % in 2002. Of the remaining three clusters, cluster 1a-1 was detectable only in 1997 and clusters 1a-4 and 1a-5 emerged in 2000 and 2002, respectively. These results indicate that genetic changes and take over of HEV strains may contribute to the genetic variability of HEV in the community.

One hundred fifty-four consecutive patients with sporadic acute hepatitis, who were seen at a city hospital in the Kathmandu valley of Nepal in 1997, were studied. IgM antibodies to hepatitis A virus were detected in four patients (3%), IgM antibodies to hepatitis B core in four patients (3%), hepatitis B surface antigen in 20 (13%), and hepatitis C virus RNA in four patients (3%). IgM antibodies to hepatitis E virus (HEV) (anti-HEV IgM) and HEV RNA were detected in 77 (50%) and 48 (31%), respectively. Consequently, 86 patients (56%) including nine HEV-viremic patients without anti-HEV IgM, were diagnosed with hepatitis E. The cause of hepatitis was not known in 53 patients (34%). All 48 HEV RNA-positive samples were genotyped as 1, and subtyped further as 1a in 17 (35%), 1c in 29 (60%), and mixed infection of 1a and 1c in 2 (4%). A seasonal difference in the prevalence of HEV subtypes was recognized. Before the rainy season (January to July), both 1a and 1c isolates were found: the intrasubtypic difference was up to 9.0% and 1.7%, respectively, in the 412-nucleotide sequence of open reading frame 2. During the rainy season (August), only 1c isolates (n = 17) with 99.5-100% identity were found; 13 of 17 isolates had the same sequence, being identical to the 3 isolates that emerged at the end of July. These results suggest that a particular HEV 1c strain spread widely during the rainy season and was implicated in a small epidemic in the Kathmandu valley in August 1997.

Tibetans have been living in Nepal since 1959. Study of the prevalence of viral hepatitis among them showed that they have a high prevalence of hepatitis B virus (HBV) infection. Prevalence of total HBV infection and Hepatitis B surface antigen (HBsAg) among them was 61% and 16% compared to 10.0% and 0.7% respectively among the Nepalese. The predominant HBsAg subtype among the Tibetans was 'ayw'. Perinatal and childhood transmission was found important in the spread of HBV infection among the Tibetans.

Prevalence of hepatitis C virus (HCV) infection in Nepal was studied by assaying sera from different population groups for anti-HCV by the second generation enzyme immunoassay method and for HCV RNA by polymerase chain reaction. The anti-HCV was positive in 0.6% of 2,860 healthy adults. HCV infection was responsible for 1.3% of acute viral hepatitis. Only drug addicts (DA) are known to have a very high incidence of the infection. The number of intravenous drug abusers (IDA) in Nepal have increased considerably since 1991 when buprenorphine (tidigesic) was introduced in the local market. About 72% of the drug addicts were found to be IDA and 94% of the IDA were anti-HCV positive. It is concluded that though the prevalence of HCV infection in the community is low, and at present it accounts for only a small number of acute and chronic liver diseases, the presence of a large number of DA in the country with high incidence of HCV infection may result in the emergence of HCV as an important cause of chronic liver disease in Nepal in future.

Infection with GB virus C (GBV-C) and hepatitis C virus (HCV) was surveyed in various populations in Kathmandu, Nepal. GBV-C RNA and HCV RNA were detected in four (2%) and none, respectively, of 181 normal controls. Viral RNAs were detected significantly more frequently (P < 0.001) in 32 (44%) and 43 (60%), respectively, of 72 users of illicit intravenous drug, and in three (14%) and one (5%) of 22 patients on maintenance hemodialysis. The three hemodialysis patients with GBV-C RNA had been transfused with more blood units than the 19 without GBV-C RNA (51 +/- 21 vs. 5 +/- 3 units, P < 0.01), and one was co-infected with HCV. Of 145 patients with chronic liver disease, GBV-C RNA was detected in four (3%) and HCV RNA in 12 (8%); only one patient with GBV-C RNA was without markers of HCV or hepatitis B virus infection. In the 32 drug addicts infected with GBV-C, genotypes were G1 in two (6%), G2 in 26 (81%), G3 in three (9%), and the remaining one (3%) was coinfected with G2 and G3. GBV-C genotypes in the 13 individuals in the populations other than drug addicts were G2 in 11 (85%) and G3 in two (15%). HCV genotypes in the 43 drug addicts with viremia were l/1a in 21 (49%), V/3a in 19 (44%) and l/1a plus V/3a in two (5%); these genotypes were not prevalent in normal controls and patients with chronic liver disease in Nepal. These results indicate that GBV-C infection is prevalent in healthy subjects in Nepal at a frequency (2%) comparable with those in the other countries and that GBV-C transmits efficiently by intravenous drug abuse among drug addicts and by transfusion in hemodialysis patients.

Prevalence of hepatitis B and C virus infection amongst intravenous drug users (IDU) in Nepal is not known. To estimate such prevalence 72 IDU individuals were tested for HBV and HCV markers. About 80% of the drug abusers are both anti-HBc (59/72) and anti-HCV (58/72) sero-positive. However persistent infection with hepatitis B, as indicated by positive HBsAg, was detected in only 5.5% (n = 4). Active hepatitis C infection, as indicated by HCV RNA positivity, was documented in 74% (42/58) of those who were anti-HCV positive. Importance of awareness of this observation among the healthcare workers in the prevention of hepatitis C in the community is stressed.

A total of 145 patients with chronic liver disease, including 20 with chronic hepatitis, 63 with cirrhosis and 62 with primary hepatocellular carcinoma from Nepal were tested for markers of hepatitis B virus or hepatitis C virus infection. HBsAg was detected in 57 (39%) and hepatitis C virus RNA in 12 (8%); the cause of liver disease was not known in the remaining 76 (52%). HBsAg was found in 5 (1.3%) of 379 normal controls, whereas hepatitis C virus-associated antibodies were detected in 13 (3.4%), none of whom was positive for serum hepatitis C virus RNA. Subtypes of 102 HBsAg samples, from patients and asymptomatic carriers, were adw in 35 (34%), adr in 4 (4%) and ayw in 48 (47%); the remaining 15 (15%) were of atypical subtypes such as ad, ay and a. Of 12 hepatitis C virus RNA samples, genotype I was detected in 1, genotype II in 5 and genotype V in 1; the remaining five samples were not to be classified by polymerase chain reaction with primers specific for genotypes I to V deduced from hepatitis C virus core sequences, despite high hepatitis C virus RNA titers in all of them. Sequences of 192 amino acids in the entire E1 region of unclassifiable hepatitis C virus isolates from five patients differed from each other in 17% to 23%, and varied from reported isolates of defined genotypes in 13% to 44%. These results indicate that atypical subtypes of hepatitis B virus and novel genotypes of hepatitis C virus would prevail in Nepal.

Hepatitis Delta Virus (HDV) infection is very rare in Nepal. Anti-HDV antibody was detected in none of the 110 HBsAg sero-positive persons with different profile of HBV infection. It was however detected in only one patient of liver cirrhosis and hepatocellular carcinoma who were sero-negative for HBsAg but had serological evidence of past infection with HBV and HCV.