Regional Health Forum WHO South-East Asia Region(Volume 6, Number 1)

Research

Prevalence of Hepatitis C in Healthy Population and Patients with Liver Ailments in Myanmar
Khin Pyone Kyi*, Myo Aye*, Khin May Oo*, Moh Moh Htun*,
San San Oo*, Khin Ohnmar Lwin* and Khin Maung Win**

Introduction

TRANSMISSION of hepatitis C virus (HCV) occurs through blood and blood products, although sexual transmission and intrafamilial transmission have also been reported.¹ HCV is responsible for most cases of post transfusion hepatitis, but there is epidemiological evidence to suggest that it is a cause of acute hepatitis without overt blood exposure and has been labelled community-acquired or sporadic HCV infection. The incidence of chronic sequelae is high and approximately 70% of patients with post transfusion hepatitis C will develop chronic hepatitis. A high percentage of these patients will progress onto cirrhosis and hepato-cellular carcinoma (HCC).²

In HCV infection, the antigenaemia is limited and the concentration of HCV antigens in serum are at the lower limit of detectability by existing immunoassay technology. ³ At present, the diagnosis of HCV infections are mostly carried out by viral antibody (anti-HCV) tests. A positive anti-HCV test indicates exposure to HCV and represents therefore, a surrogate marker of ongoing infection.⁴ A polymerase chain reaction (PCR) has been used to detect HCV RNA but is difficult both to interpret and perform.

A study conducted in 1991 at the Department of Medical Research (DMR), Myanmar reported that among the HCC cases, 35% were positive for anti-HCV, detected by using Anti-C₁₀₀-3 EIA test kits using Enzyme Linked Immunosorbent Assay test system (ELISA) from Orthodiagnostic Systems, USA.⁵ The present study was undertaken with an aim to determine the prevalence of HCV infection among apparently healthy subjects and patients with various liver diseases by using immunoblot assay system to detect the HCV antibody.

Materials and methods

Subjects

The study consisted of 741 subjects which included 362 apparently healthy subjects without liver disease who were enrolled for hepatitis B vaccination at the DMR. The remaining 379 subjects were patients with various types of liver diseases attending the out-patient department of the Liver Unit at the YangonGeneralHospital. These included patients with fatty liver, acute hepatitis, chronic hepatitis, cirrhosis and HCC already confirmed by standard tests. Blood was collected from the subjects, and after serum separation, the samples were stored at -80°C until ready to be tested for anti-HCV.

Test system

Chiron RIBA HCV Test System - Immunoblot Assay 3.0 from USA, a qualitative enzyme immunoassay nitrocellulose based confirmatory test for anti-HCV was used to detect the hepatitis C marker in the 741 serum samples.

Results

In the apparently healthy 362 subjects, the prevalence of anti-HCV was 9(2.5%) whereas in the 379 patients with various types of liver diseases, 95 patients (25%) were positive for the HCV marker.

Percentages of the HCV marker varied in patients with different types of liver diseases. In the 36 patients with fatty liver, anti-HCV was not detected. Only 10% were positive for anti-HCV in 30 acute hepatitis patients whereas 15(17.2%) were positive in 87 chronic hepatitis patients, 38.5% in the 117 cirrhosis patients and 29.3% in 109 hepatocellular carcinoma patients.

The detection of anti-HCV in the above-mentioned two groups of subjects according to sex was evident as follows. In the subjects without liver disease, 100% of 177 male subjects were negative for the HCV marker whilst in the 185 female subjects, 4.86% were positive. In the liver disease patients, 22.3% were positive in 242 male patients and 29.9% were positive in 137 female patients.

The prevalence rate of anti-HCV became higher according to age in both groups. In this study, anti-HCV was not detected below the age of 21 years. Between the ages of 21 to 50 years, the prevalence of the HCV marker was 1.1% to 2.8% in normal subjects whilst it was 10.6% to 24% in patients with liver diseases. Above the age of 50 years, the prevalence rate increased significantly, being 6.1% to 14.3% in normal subjects and 40.8% to 42.6% in liver disease patients.

In both groups of subjects, the HCV marker positive cases gave a previous history of blood transfusion and/or surgical operations at a higher rate than HCV marker negative cases. In healthy subjects, amongst the anti-HCV positive cases, 44.4% gave a previous history of blood transfusion and surgical operation, whereas the rate was 20.1% in anti-HCV negative cases. In patients with liver diseases, it was 88.4% in anti-HCV positive cases and 39.1% respectively in anti-HCV negative cases.

Discussion

HCV poses a serious worldwide health problem and an estimated 100 million individuals globally are chronically infected with it. The prevalence rate differs from country to country. In the present study, the detection of anti-HCV in apparently healthy subjects without liver disease was approximately 2.5%. This figure was higher than those reported from Western Europe, Japan, USA, Bangladesh or Indonesia and was comparable to that of Northern Italy and much less than in blood donors of Egypt.

In this study, the prevalence of HCV marker in the patients with liver disease was approximately ten times higher than those in the healthy subjects (25% to 2.5%). This higher prevalence was expected, as HCV infection was reported to be associated with a wide spectrum of liver diseases ranging from asymptomatic carriage to severe forms of chronic hepatitis, the major complication being development of cirrhosis and HCC. In Singapore, the positivity rate for anti-HCV was 1.7% in normal healthy population, 3% in chronic hepatitis B carriers and 20% in primary HCC cases.⁹ Our study also showed that the prevalence of anti-HCV became significantly higher in the more serious liver ailments, as it was not detected in fatty liver, 10% positivity in acute hepatitis cases, 17.2% in chronic hepatitis cases and 38.5% and 29.3% in cirrhosis and HCC cases respectively. A previous study in Myanmar showed that in HCC cases, 35% were positive for anti-HCV.⁵ A retrospective study on the serum of hepatitis B carriers in Myanmar, stored frozen in 1994, showed that 2.2% were positive for anti-HCV using HCV serum cassette tests, Fresno, USA.¹²

Esteban and group in 1991 reported that in their study among blood donors in Spain, there was no difference in prevalence with respect to sex (1.17% males, 1.08% females). However, the seroprevalence among male donors under 30 was three times higher than that among female donors in the same age group (1% vs 0.3%).¹³ Studies of HCV infection in the United States showed that males predominate slightly over females.^14,15 In the present study, Myanmar females showed a higher incidence in both the apparently normal group of subjects (4.9% to 0%) and patients with liver disease (29.9% to 22.3%).

The incidence of HCV infection was reported to vary by age. The analysis of the HCV carrier state in over 100 million Japanese blood donors showed no anti-HCV positivity in subjects between 6-15 years, 0.36% positivity in subjects between 16 to 20 years, gradually increasing to about 2.8% in those older than 50 years.¹¹ In USA, HCV seroprevalence among blood donors ranges from 0.5 per 1 000 in donors younger than 20 years, to 6.9 per 1 000 in donors of ages 30 to 39 years.¹⁶ Our study also showed that in control subjects as well as in patients with liver disease, there was no anti-HCV positivity below 20 years of age. From then on, the anti-HCV positivity increased gradually from 1.1% in healthy subjects and 11.6% in patients between 21 to 30 years group up to 14.3% and 42.6% respectively in those above 60 years of age.

The study in Spain also showed that a history of blood transfusion, intravenous drug abuse and tattooing was significantly more common among anti-HCV positive donors than in seronegative controls.¹³ This was in accordance with the findings in the present study, where a higher number of anti-HCV positive cases had a history of blood transfusion and surgical operations than in seronegative subjects. It was also reported from a study in USA that among recipients of blood transfusion and control subjects of untransfused hospital patients having similar diagnosis and undergoing generally similar operative procedures, 3.3% of the blood recipients and only 0.1% of the control subjects seroconverted to anti-HCV.¹⁷

This study showed that HCV infection is highly prevalent in Myanmar both in the apparently healthy population as well as in patients with end stage liver diseases such as cirrhosis and HCC. Since no vaccine is as yet available for HCV infection, the most effective control measure would be to prevent this potentially life-threatening viral disease. Preventive measures include the screening and testing of blood, plasma, organ, tissue and serum donors, virus inactivation of plasma-derived products, risk-reduction counselling and services, implementation and maintenance of infection control practices, identification, counselling and testing of persons at risk, medical management of infected persons, health education, surveillance and research.¹⁸ Since this is a preliminary report from a study in a limited group of subjects, further large scale surveys will be required to determine the prevalence of HCV infection throughout Myanmar.

Acknowledgement

This study was supported by a grant from the World Health Organization.

References

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* Department of Medical Research (Lower Myanmar), No. 5, Ziwaka Road, Dagon PO, 11191, Yangon, Union of Myanmar.
** Liver Unit, YangonGeneralHospital, Department of Health