Risk of perinatal transmission of hepatitis B virus in Jordan.

OBJECTIVES
To determine the risk of perinatal transmission of hepatitis B virus (HBV) in Jordan.


METHODS
Plasma samples from 1000 pregnant Jordanian women were screened by ELISA for HBV markers (HBsAg, HBeAg, anti-HBe, anti-HBc and anti-HBs).


RESULTS
HBsAg and HBeAg were detected in 4.3% and 0.1% of the pregnant women, respectively. The overall prevalence of antibodies was 6%, 11.1% and 7.5% for anti-HBe, anti-HBc and anti-HBs, respectively. Women were assigned to four groups according to the serological patterns of HBV markers: susceptible (85.9%), with acute infection (2.9%), with chronic infection (1.4%) and previously infected (9.8%). Most women were at the third trimester of pregnancy, therefore women with acute and chronic hepatitis at this gestational age were at risk of transmitting HBV infection to their newborns. Women who belonged to the low socio-economic class were at higher risk of HBV infection.


CONCLUSIONS
Based on the results, we recommend screening women for HBV during pregnancy in order to identify HBV carriers. All newborns born to carriers should be vaccinated immediately after birth, both passively and actively. Also vaccination of HBV seronegative pregnant women is recommended.

Perinatal transmission of hepatitis B virus (HBV) is an important route of infection. It occurs mainly in infants due to exposure to infected blood and genital secretions during delivery 1,2 and to in utero passage of HBV DNA 3 . In the absence of immunoprophylaxis, perinatal transmission occurs in 10-20% of women who are seropositive for hepatitis B surface antigen (HBsAg) and up to 90% in women who are seropositive for both HBsAg and hepatitis B e antigen (HBeAg) 4,5 . Newborns to HBsAg-positive mothers who do not become infected at birth remain at high risk of infection until the age of 5-6 years 4 . However, newborns of HBeAg positive women are carriers and at risk of long-term complications of hepatitis B infection including cirrhosis and hepatocellular carcinoma 6,7 . They may not eliminate the virus despite passive-active immunization 8 .
To prevent HBV infection, a universal strategy has been adopted by many countries 9 . The strategy is based on screening pregnant women for HBV markers and providing passive and active immunization to newborns of potentially infectious mothers.
In Jordan, hepatitis B vaccine has been integrated into the current childhood immunization program since 1995. But screening of pregnant or childbearing women for HBV markers is not a routine test. Therefore, the need to know the prevalence of HBV in pregnancy and the risk of perinatal transmission of HBV is vital in the planning of preventive measures. For this reason, the present study has been conducted to: (1) provide information on the prevalence of HBV markers among pregnant women in Jordan; (2) examine the relationship between HBV seropositivity and risk factors; and (3) evaluate the possibility of maternal transmission in view of seroprevalence of HBV markers in pregnant women.

Subjects
One thousand pregnant Jordanian women aged 15-44 years, attending the antenatal clinic in Amman and Al-Salt, were randomly studied. The implications of chronic HBV infection and the risks of transmission of the virus to the infant were explained to the participating women, and their consent to take part in the study was obtained. Each woman completed a questionnaire that included: age, history of hepatitis, blood transfusion, hemodialysis, surgery and dental procedure and socioeconomic status, which was determined based on family size and annual family income.

Serology
Five milliliters of blood was taken from each woman. The plasma was separated, aliquoted and stored at -20°C until assayed. Plasma samples were tested for antibody against hepatitis B core antigen (anti-HBc), HBsAg and its antibody (anti-HBs) and HBeAg and its antibody (anti-HBe) by commercially available ELISA kits (DiaSorin, Italy).

Biochemical tests
The levels of alanine transaminase (ALT) and aspartate aminotransferase (AST) in each plasma sample were measured by spectrophotometer using commercially available ALT and AST testing kits (Menagent, Italy) according to the manufacturer's instructions.

Statistical analysis
The data were analyzed statistically using the Chi-square test. P values of less than 0.05 were considered significant.

Prevalence of HBV serological markers
As shown in Table 1, HBsAg was found in 4.3% of plasma samples, indicating acute or chronic infection with HBV. Only one woman was found positive for HBeAg, indicating also acute or chronic infection. The overall prevalence of antibodies was 6%, 11.1% and 7.5% for anti-HBe, anti-HBc and anti-HBs, respectively. Presence of these antibodies indicates chronic infection or recovery from acute infection. There was no significant difference among age groups with respect to the prevalence of HBV antigens and antibodies.

Liver function tests
All women with the serological markers shown in Table 1 had transaminases within the normal range, indicating the absence of liver damage.

Hepatitis B status
The women were divided into four groups (I-IV) according to the serological patterns of HBV markers (    Table 3 Prevalence of HBV infection in pregnant Jordanian women, stratified by socio-economic status HBV infection is significantly higher in women of lower socio-economic status than in those of mid status (p < 0.01). Most HBsAg-positive women were of low status. Twenty-two HBsAgpositive women with acute hepatitis (group II) were of low socio-economic status compared with seven of mid status. Twelve HBsAg-positive women with chronic hepatitis (group III) were of low status while two were of mid status. Similarly, 71 women who had hepatitis prior to the study (group IV) were of low status while 27 were of mid status.
The majority of women (930) were unemployed; there was a higher prevalence of HBV infection among unemployed than employed women (Table 3). Sixty employed and 799 unemployed women, respectively, were susceptible to HBV infection (group I). Most HBsAgpositive women (24) with acute hepatitis (group II) and all HBsAg-positive women with chronic hepatitis (group III) were unemployed.

Prevalence of HBV infection in relation to risk factors
Data presented in Table 4 is based on the answers in the questionnaire. Only two women reported a history of hepatitis, 117 had a blood transfusion, five had hemodialysis, 776 had a dental procedure and 417 had undergone surgery. There were no significant differences between groups I-IV with respect to these risk factors (p = 0.5-0.9).

DISCUSSION
Maternal screening and treatment of newborns by passive and active immunization can control perinatal transmission of HBV. Screening of pregnant Jordanian women revealed that 4.3% were HBsAg positive with acute or chronic hepatitis. There was no significant difference in the prevalence of HBsAg in different age groups. Similar results were reported by other investigators 10 . In other parts of the world, the prevalence of HBsAg in pregnant women has been reported as 0.1-39.7% [10][11][12][13] . One out of the 1000 pregnant women was found positive for HBeAg. Higher prevalence has been reported in pregnant women: 4.6% in South Africa 14 , 6.2% in Turkey 13 and 43% in Taiwan 10 .
Presence of HBsAg or both HBsAg and HBeAg in pregnant Jordanian women indicates high risk of maternal-fetal transmission. Their newborns should receive hepatitis B immunoglobulin (HBIG) immediately after birth and vaccination within 12 hours of birth.
Screening of Jordanian women for HBV antibodies revealed that 6%, 11.1% and 7.5% were positive for anti-HBe, anti-HBc and anti-HBs, respectively. Presence of anti-HBe indicates a risk of perinatal transmission in those with chronic infection. Anti-HBs was found in most anti-HBc mothers who had hepatitis indicating that those women are immunized and there is no risk of maternal transmission. Anti-HBc was detected in most women with chronic infection and in all women who had hepatitis. Lower prevalence of  Table 4 Prevalence of HBV infection in pregnant Jordanian women in relation to risk factors anti-HBc was reported in Swiss (3.3%), Spanish (3.7%) and Portuguese (5.4%) women 12 . Higher prevalence was reported in ex-Yugoslavian (18.6%), Turkish (29.9%) and African (39.7%) women 12 . Of special interest is the group of 20 anti-HBc positive women with 'isolated anti-HBc'. They could either have recovered from acute HBV infection and cleared HBsAg but not yet developed anti-HBs, or infected for a long time and lost both anti-HBe and anti-HBs. In the former case, newborns -especially for mothers in the third trimester -could be at risk of in utero infection which might occur some time before delivery, as reported in pregnant Swiss women 12 .
To eliminate the risk of perinatal transmission in Jordan, we also recommend active and passive immunization of newborns of this group of women.
In the present study, 85.9% of women are susceptible to HBV infection and need vaccination and follow-up during pregnancy. Their infants require only vaccination 15 according to the immunization program in Jordan.
Most women, including those who have acute and chronic infection, are of low socioeconomic status. Intrafamilial transmission might occur due to sharing of facilities and overcrowding (median number of family members before marriage = 10; median number of children = 4). There was no statistical difference among the groups of women according to the risk factors (Table 4). We concluded that blood transfusion, hemodialysis, surgery and dental procedure are not major routes of HBV infection in the population studied.
In conclusion, we reinforce the potential value of the vaccination program targeted at Jordanian children in early life along with passive immunization of newborns of HBsAg-positive and HBeAg-positive mothers. Seroprevalence surveys of HBV infection in children must be carried out to determine the effectiveness of the HBV vaccination program in Jordan. We also recommend HBV screening during pregnancy and possibly vaccination of pregnant women.