March 1997, Volume 47, Issue 3

Short Reports

Prevalence of Hepatitis B Surface Antigenaemia in Healthy Children

K.A. Abbas  ( Departments of Paediatncs, Children\'s Hospital, Pakistan Institute of Medical Sciences, Islamabad. )
Ashok. K. Tanwani  ( Departments of Pathology, Children\'s Hospital, Pakistan Institute of Medical Sciences, Islamabad. )

Introduction

The information about HBsAg carriage rate in children is scanty worldwide. There are few reports which suggest that chronic vimemia may be high in the developing countries1-4. The majority ofHBV carriers acquire infection before the age of 6 years and 25-30% of them will eventually die of chronic liverdisease orlivercancer. Data on the status of HBV carriage rate in Pakistani children is scarce though its status in adults and pregnant females is well documented5-8. Various methods are available for testing Hepatitis 13 surface antigen (HBsAg) in blood, the commonly usedbeing Serodia and Elisa methods. This study was done to determine the prevalence of HB sAg in healthy children and to compare the sensitivity of Serodia technique with Elisa technique.

Subjects, Methods and Results

Six hundred and sixty-four apparently healthy children between the ages of 0 to 12 years were studied between Febmafy, 1995 to January, 1996. Five hundred and nineteen were apparently healthy children attending hospital for minor complaints but without any history of liver disease, blood transfusion of serious illness and 145(6 to 12 years) were from one of the model schools of Isla.mabad city. A vethal consent was obtained from the parents and, the study design was clearedby the Ethical Committee of the hospital. Sera obtained from venous blood samples were stored at -20°C and later analyzed for HBsAg by Elisa technique. The positive results with Elisa technique were rechecked by reverse passive hemagglutination technique (RPHA) to find the sensitivity of the latertechnique. The data was entered inEPI-INFO. 5.1 and statistical analysis by chi-square test was performed. Of 664 children studied, 481(72%) were male and 183 (28%) female. Their mean age was 5.04±3.71 years. The overall positivity rate for HBsAg detected by Elisa technique was 3.6% (24 out of 664). The positivity rate was also checked in three age groups of 0-<1, 1- <5 and 5-<13 years (Figure).


‘Age and sex had no significant effect on the frequency of HBs antigenaemia. The results of school children were compared with those of hospital children. HBs Antigenaemia was detected in 4.8% (7/145) of school and 4.3% (7/164) of hospital children of the same age (5-<13 years). Twenty-four samples found positive for HBsAg by Elisa technique, were rechecked by Semdia technique. There were 17 positive, 4 non-specific and 3 negative results. The sensitivity of the Serodia method was 71%. The false negative results were due to the fact that the antigen is detectable at a concentration of >2.5 ng/ml with Serodia and 0.5 ng/ml with Elisa technique. Non-specific results may be due to the presence of cross reacting or non-specific proteins which are interfering in the reactions occurring in the Serodia technique.

Comments

HBs àntigenaemia was detected in 3.6% of 664 apparently healthy children. Prevalence in Pakistan is therefore higherthan 0.8-2.5% reported fromboth developed and developing countries. This figure is also more than 2%, which according to WHO is significant from the point of vaccination programme10. If our data is considered representative of national situationthe total number of carriers in Pakistani children can be estimated to be about 2.2 million. This study confirmed that the HBsAg carrier rate is high in childhood population in Pakistan. The reason for this high endemicity may be the younger age at which infection occurs, resulting in an inability to clear virus or in developing active immunity. Over-crowding, repeated use of unstenlised syringes and needles for injections and vaccinations, lack of mandatoiy testing of HBsAg for blood transfusion must have significantly contributed to the uninhibited transmission of HEy infection. It is concluded that as in adults, HBsAg carnage rate is high in Pakistani children and for testing HBsAg, Elisa technique seems to be more reliable than Serodia technique.

Acknowledgements

We sincerely thank Dr. S.J. Zuberi, Chairperson, PMRC for her encouragement and advice to undertake this work. We are also very grateful to Dr. Muhammad Khalif Bille, WHO Advisor on Pnmaiy Health for his valuable guidance and critical appreciation of the study, Dr. Essam Mahmood for collection of blood samples, Principal of Model School for giving pennission to collect blood samples from school children and the parents and children for their cooperation. This study would not have been possible without generous support of JICA Alumni Association of Pakistan, who provided financial support. Their help is gratefully acknowledged.

References

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