KHIN THANT SIN
A STUDY OF HEPATITIS B SURFACE ANTIGEN
INTRODUCTION
Hepatitis B is one of the major diseases of mankind with more than two billion individuals infected with this virus globally, of whom 30 million are chronically infected carriers. Myanmar is highly endemic for Hepatitis B infection with an approximately 10-15% HBsAg carrier rate and 35-40% infection rate.
OBJECTIVES
1. To study the prevalence of HBsAg in children under 14 years.
2. To study the factors influencing the prevalence of HBsAg in children.
MATERIALS AND METHODS
Sample Collection
Children of 600 in two areas of Yangon were studied for HBsAg. Children of 347 were from Thingangyun township, a periurban area of the city. The remaining 253 were from different wards of Lanmadaw township, the central part of Yangon city.
Methods
One ml of blood was drawn by venopuncture using disposable needles.
The demographic characteristic of each subject was recorded in the proforma. Risk factors, such as history of overt jaundice, history of close contact with hepatitis or jaundice patients, any history of taking injection, infusion or transfusion of blood, blood products within the past year were also collected.
All the serum samples separated were stored at -20 degree C. HBsAg was tested by reverse passive haemagglutination method (RPHA) at the Experimental Medicine Research Division of the Department of Medical Research (DMR) in Yangon.
RESULTS
I. Of 253 children studied in the urban area, 31 children were HBsAg positive (i.e., 12.2%) and 35 among 347 children from periurban area were HBsAg positive (i.e., 10.0%). The average prevalence was 11.0%.
****Table(1)
II. Age specific prevalence rate in two different locations
In urban area, the highest carrier rate was found to be in 11-14 years age group-25%. In periurban area, the high prevalence rate occurred in younger age group (one year and 2-5 years age group - 11.9% and 10.8% respectively). The difference was not statistically significant P<0.5.
The attack rate of Hepatitis B is not associated with age.
****Table(2)
III. Prevalence of HBsAg in children according to sex
It was found that 41 out of 304 male children and 25 out of 296 female children were HBsAg positive (15.64% and 8.4% respectively).
There were no statistically significant difference between male and female prevalence (P<0.1).
****Table(3)
IV. Correlation between past history suggestive of viral hepatitis and HBsAg positive cases
Thirty children out of 600 gave past history suggestive of viral hepatitis (5%) and only four out of 30 children were HBsAg positive (13.3%).
****Table(4)
V. Correlation between contact history and HBsAg positive cases
Table five shows the correlation between history of contact with Viral Hepatitis cases and HBsAg positive cases.
Only six cases out 30 (i.e., 20%). The result was not statistically significant (P<0.06).
****Table(5)
VI. Correlation between history of parenteral exposure and HBsAg positive cases.
There were 251 cases who gave history of parenteral exposure to injections (both intramuscular and intravenous) through blood and blood products transfusion. Among them 37 children (14.7%) were HBsAg positive. In the group where there was no history or parenteral exposure, only 29 (8.3%) were HBsAg positive
****Table(6)
VII. Correlation between both negative past history of hepatitis and contact and positive parenteral exposure
Table seven shows the correlation between negative risk factor group and parenteral; exposure. Among 545 cases from the group, 234 cases gave a history of parenteral exposure 35 cases were HBsAg positive (15%). In 311 cases out of 545, history of parenteral exposure was negative (57.1%) and the correlation was statistically significant.
****Table(7)
VIII. Correlation of HBsAg positive cases in different socio-economic groups
Table B shows the distribution of HBsAg positive rate in social class IV (44.7%), which is significantly higher (P<0.0005) compared with other three social classes.
When the social classes were divided into only two i.e., High (I and II) and Low (III and IV) there was significantly high rate of positivity in low socio-economic class (17%) compared with only (6.4%) positivity in high social class.
****Table(8)
DISCUSSION
In the study, the prevalence of HBsAg positive children was 12.21% in urban area and 10% in periurban area and the average of carrier state is less than 0.1% in low endemic areas such as Northern Europe, North America and Australia and 15% in high endemic area including China, SEA, the Pacific region and tropical Africa.
Prevalence of HBsAg in Asian countries is 9.6% in Hongkong, 15% in Thailand, 10-15% in Taiwan. In our country in the general population, the positivity rate is reported by Khin Mg Tin et al in 1981 is 10% which is quite similar prevalence with the present study.
Prevalence of HBsAg positive children according to specific age group
In this study, the peak incidence of positivity rate was in six -- ten years age group (34%) but not statistically significant. A similar finding in the Middle East which was not age-related was published by Ala.U Touhan in 1990.
Studied in Africa showed that the high rate of carriers began in early and middle childhood. In Africa, no one was HBsAg positive during their first year of life showing that horizontal spread was more common. In our study, the positivity rate during the first year of life was 9%, indicating that mother infant transmission plays a major role. This is in accordance with previous studies done in Myanmar.
Prevalence of HBsAg positive children according to sex
There was no significant sex difference of HBsAg antigenaemia in this study. In the study done in Sagaing and Bago in our country in 1989, overall HBsAg positivity rate was slightly higher in males than females and the prevalence of male preponderance increases with age.
Correlation between HBsAg positive cases and past history of jaundice and history of contact with jaundiced patients
In this study, there was no significant correlation between past history of liver disease evidenced by jaundice or contact history and HBsAg positive cases.
According to the study among family members in the Middle East, previous contact with a jaundiced person was an important risk factor associated with HBV carriers and infection. In most cases, person to person and non severe contact may be the major mode of transmission between a symptomatic HBV carriers and susceptible individuals. Chronic intrafamilial contacts, especially among children, are the major factors in maintaining the high HBV prevalence rates.
Prevalence of HBsAg positivity rate in different socio-ecomonic status
In the present study, there was significant association between HBsAg positivity and socio-economic status.
According to this study, among family members in the Middle East, it was found that socio-economic factors play an important role in prevalence of HBV carrier rates.
In the study done in our country in Sagaing and Bago, the HBsAg positivity rate was 11.6% in the lowest social class and 7.03% in the highest social class.
CONCLUSION AND RECOMMENDATIONS
This study of Hepatitis B surface antigen in Myanmar children was carried out as a cross-sectional study of 253 children from Lanmadaw Township (urban area) and 347 from Thingangyun Township (periurban area).
The prevalence of HBsAg positivity rate was not significantly different in urban and periurban areas and the average prevalence was 11%. There was no significant association between age groups and HBsAg positivity rate, and could be found in any age group. Also no significant correlation was found for sex difference and HBsAg positivity.
There was no significant correlation between past history suggestive of hepatitis and HBsAg positivity rate. The same result was obtained regarding contact history and HBsAg positivity.
It was found out that there was definite correlation between parenteral exposure (i.e., infections and infusions) and HBsAg positivity rate. So parenteral exposure is significantly a major risk factor for the spread of Hepatitis B and carriers. Even though there is no past history suggestive of hepatitis or contact history, there is definite chance to obtain the disease with parenteral exposure.
The correlation between different socio-economic groups and HBsAg positivity was also significant; the prevalence of HBsAg positivity rate was highest among the lower socio-economic state.
Based on the experiences gained from this study, the following recommendations may be made.
1. Liberal use of disposable needles, syringes and gloves should be planned to decrease the horizontal transmission rate.
2. If disposable needles, syringes and gloves cannot be used, the instruments should be sterilized very properly.
3. Traditional practices such as tattooing, ear piercing, or circumcision should be done by proper sterilization of instruments.
4. Sharing personal and household items such as razors, toothbrushes, combs, towels, etc., should be avoided.
5. Blood should be transfused only if absolutely necessary. According to WHO recommendation, only blood screened for HBsAg by a sensitive method should be used for the transfusion.
6. A high evidence of maternal-neonatal mode of HBV transmission was found in SEA. WHO has now recommended to induce the HB vaccince in UCI programme throughout the world.
7. High-risk groups for HBV infection such as medical personnel should by fully immunized.
COUNTRY PROFILE
DEMOGRAPHIC INDICATORS
1. Land Area 676,577.5 Sq. km
2. Population 43 millions
3. Population Density 63.56/sq. km
4. Population Distribution Urban : Rural
20 : 80
5. No. of states and Divisions 7 States and 7 divisions
6. No. of Districts 55
7. No. of Townships 320
8. No. of Village Tracts 13577
9. No. of Villages 61666
10. Dependency Ratio 58%(52%<15 yrs.,
6%>60 yrs.)
11. Adult Literacy Rate 86%
12. Gross National Product per capita US $ 300.00
HEALTH IMPACT INDICATORS
1. Crude Birth Rate 28 per 1000 population
2. Crude Death Rate 9 per 1000 population
3. Annual Growth Rate 1.88%
4. Life Expectancy at Birth - Female 63.1
- Male 58.9
- Both Sexes 60.9
5. Total Fatality Rate 3.5
6. Interval between Birth 2
7. IMR per 1000 LB 47.5
8. MMR per 1000 LB 1.2
- Urban 1
- Rural 1.8
HEALTH STATUS INDICATORS
1. Malaria
Clinically diagnosed malaria morbidity rate 24.5
Clinically diagnosed mortality rate 9.32
Case Fatality Rate% 3.8
2. Dangue Haemorrhagic Fever
Morbidity per 100000 children of < 15 yrs 82.21
Case Fatality Rate% children < 15 yrs 3.59
3. Tuberculosis
Sputum positives prevalence per 1000 1.0
4. PEM (Weight for age below [-] 2SD of NCHS 30.58
reference among < three yrs old children(%)
5. Iron deficiency anaemia in Pregnancy 58.06
(% anaemia women with Hb concentration
< 11gm% among pregnant women)
6. Iodine deficiency disorder (% Visible goiter 33.08
among five - 14 yrs age group
7. Vitamin A deficiency (%Bitot spot among < five yrs) 0.37
8. Percentage of Low birth weight babies (< 2500gm) 23.4
HEALTH FACILITIES
1. Government hospitals 689
2. Indigenous hospitals 2
3. Dispensaries 328
4. Primary and Secondary Health Centres 83
5. Maternal and Child Health Centres 358
6. Rural Health Centres 1455
7. School Health Teams 88
HEALTH MANPOWER
1. Doctors 13353
2. Health Assistants 1276
3. Lady Health Visitors 1616
4. Midwives 8407
5. Public Health Supervisor I 495
6. Public Health Supervisor II 940
7. Auxiliary Midwives 18856
8. Community Health Workers 36358
9. Trained Traditional Birth Attendants 15945
HEALTH CARE DELIVERY
1. Doctors per 10000 population 3
2. Basic Health Staff per 10000 population 7
Edited by Yoichi Sakakihara