Sero-survey of Hepatitis B surface antigen amongst pregnant women attending Infectious Disease Hospital Bayara , Bauchi State , Nigeria

Hepatitis B virus (HBV) continues to cause serious health problems in developing countries. Neonatal infection with HBV, which is often acquired during delivery, carries a high risk resulting in persistent infection. This research aims to detect the prevalence of Hepatitis B surface Antigen (HBsAg) among pregnant women in our location of study. One hundred and eighty (180) sera samples were screened among pregnant women aged 13-49, using standard enzyme-linked immunosorbent assay (ELISA) method. Structured questionnaire were administered to the subjects to obtain demographic and other relevant data. Overall result showed that 31 (17.2%) were found to be positive for HBsAg among the total subjects screened. The highest prevalence was found among those aged 20-29 with 11 (6.1%) seropositivity (c2=7.902; P=0.048). Conside ring occupational distribution of volunteer subjects, a high prevalence of 12 (6.7%); P<0.05 was recorded among house wives, which shows a measure of significance compared to other women screened. Furthermore, based on various risk factors subjects with history of surgery and use of unsterilized sharp instruments recorded 15 (8.3%) prevalence (P=0.233; P>0.05). How ever, women in their second trimester of pregnancy recorded a higher prevalence of 23 (12.8%):(P=0.080; P<0.05). This study therefore emphasizes the public health importance of HBV among pregnant women and equally suggests that children born to women with Hepatitis B Virus, be closely monitored for infection beyond the one and the half years of age, this also calls for a proper enlightenment on the dangers posed by the virus, while a well designed vaccination schedule is advocated among the general population.


Introduction
Hepatitis B virus (HBV) occurs worldwide and constitutes a serious public health problem.Globally, it is estimated that more than 2 billion people have been infected with HBV; of these, about 350 million developed chronic infection and became carriers of the virus, while about 1.5 million deaths occurred from HBV related liver diseases, including end stage cirrhosis and hepatocellular carcinoma each year. 1,2HBV infection is spread through three major routes: perinatal, horizontal, and sexual transmission. 3In developing countries, the main routes of transmission are: neonatal with HBV carrier mother infecting her infant usually during birth or soon after birth following close contact, transmission of HBV via cuts, from reuse of unsterile sharp objects, sexual transmission, transfusion of infected blood or blood products, needle stick injury, re-use of HBV contaminated needles, syringes, lancets and instruments including those used in tribal body markings. 2Neonates who contract Hepatitis will have almost the a 90% risk of developing chronic HBsAg carriage and chronic liver disease.Infants may also spread the disease to siblings and to a community 4 about 80-90% of chronic infections have been found amongst infected neonates born to HBAg positive carrier mothers, followed by children uninfected before 6-months of age (30%).
Nigeria is classified among the group of countries endemic for HBV infection.Currently about 18 million Nigerians are infected.Many of these people may not be   There is a common belief that transmission of Hepatitis B virus from carrier mothers to their babies can occur during the prenatal period.Vertical transmission from infected mother to infant is thought to be partially responsible for high prevalent of infection in certain among high risk group individuals. 5ence it is recommended that high risk pregnant women should be tested for hepatitis B surface antigen (HBsAg) early in each pregnancy. 6he aim of this paper is to ascertain the prevalence of Hepatitis B surface Antigen among pregnant women in Bayara-Bauchi metropolis and to determine the possible risk it poses to foetus at birth, as this will help the identification of newborns who will require prophylaxis against perinatal infection (infants born to mothers positive for hepatitis B surface antigen have a 70-90% chance of acquiring perinatal HBV infection).Hence the in-utero transmission of HBV from infected mother to their off spring has been well documented.

Materials and Methods
This study was carried out at the Infectious

Discussion
In this study a prevalence of 17.2% was recorded.The result obtained is significant if compared with a related study in Maiduguri which showed that prevalence increased from 11.6% in 1994 to 15.8% in 1999. 7,8Furthermore, the results obtained in this study are equally higher than those obtained by Pennap et al., 9 who recorded a prevalence of of 6.67% among pregnant women attending antenatal clinic in Federal Medical Center Keffi, the works by Ndams et al., 10 recorded 12.3% prevalence in a study conducted among pregnant women in Minna, and the ones carried out by Onwuliri et al. 11 where a prevalence of 16.6% was recorded in a study among pregnant women in Vom.
Lower reports include 2.19% in Benin City, 12 4.3% in Port Harcourt in 2005, 13 2.89% in 2006, 14 and 5.7% in Ilorin. 15Within the same continent, the result of this study is higher than the 6.3% reported in pregnant women in Tanzania and 3.7% in Ethiopia. 16he reported prevalence in this study is a cause for alarm because it is high enough to warrant the initiation of routine antenatal screening for HBV infection.This is because HBV positive pregnant women represent a major reservoir of the virus in a community and this can be passed on to the children either vertically or even horizontally Onwuliri et al. 11 In this study women aged 20-29 recorded 6.1% prevalence compared to other age group with the lowest prevalence of 2.8% recorded among subjects aged 40-49, this is however contrary to the report of Pennap et al., 9 who recorded a high prevalence of 12.5% among pregnant women aged 40-44.The resultant high prevalence among this age group in our study is attributed to the fact that these women fall within the sexually active age bracket according to Zali et al. 17 Age is an important factor in epidemiology studies hence the age of acquiring infection was found to be a major determinant of the incidence of HBV.Most of the women studied were in the 2 nd trimester of gestation, this group also had the highest HBsAg seropositivity of 12.8%, the result obtained in this study is lower than those of Ndams et al. 10 who obtained a prevalence of 13.4% at the 2 nd trimester of pregnancy.Analysis showed that out of the 106 respondents, (58.8%) were housewives out of which about 12 (6.7%)tested positive for HBsAg as compared to civil servants who recorded 5.0% positivity, Although HBV  infection is considered one of the most important occupational infectious hazards in developed countries 18 results from this study did reveal statistical but not Clinical significance between HBV Seropositivity and the different occupations of the pregnant women studied.Women with a history of blood transfusions recorded a prevalence of 4.4%, while those with history of surgery recorded 8.3% similarly those with history of use of unsterilized/sharp instruments also recorded 8.3% prevalence which was statistically higher than other groups.This implies that the infections in this class of women possibly resulted from wounds obtained from exchange or re-use of sharp instruments.Although WHO recommended that hepatitis B vaccine be incorporated into routine infant and childhood immunization program for all countries by 1997, only 130 of 216 countries introduced hepatitis B immunization into their national infant and childhood immunization programme by the beginning of 2001.The major hurdle to universal hepatitis B immunization is the cost of hepatitis B vaccine, especially for developing countries the cost of three doses of hepatitis B vaccine remains higher than the cost of other vaccines included in routine infant immunization programmes. 19

Conclusion
This study reported a relatively high prevalence of HBsAg in the study area despite the high prevalence all the risk factors studied were not statistically significant as predisposing factors to HBV infection, Thus screening of all pregnant women should be made part of the antenatal care irrespective of risk factors.Likewise the administration of prophylaxis for babies of HBsAg positive mothers will greatly assist in reducing maternal transmission of HBV.
aware of the infection and hence fail to seek appropriate medical attention.

Figure 1 .
Figure 1.Overall distribution of hepatitis B surface antigen among pregnant women.

Figure 2 .
Figure 2. Age distribution as seroprevalence of hepatitis B surface antigen among pregnant women.

Figure 3 .
Figure 3. Occupational distribution of hepatitis B surface antigen among pregnant women.

Figure 4 .
Figure 4. Distribution of hepatitis B surface antigen among pregnant women with respect to trimester.

Table 3 . Distribution of Hepatitis B virus based on demographic factors. Occupation No. Tested Positive (%) Negative (%) P value
P<0.05.

Table 5 . Distribution based on trimesters.
P <0.05 is significant