Niger J Paed 2015; 42 (4):303 – 308
ORIGINAL
Sadoh AE
Risk factors and clinical correlates
Ofili AN
of hepatitits B seroprevalence in
Nigerian children
DOI:http://dx.doi.org/10.4314/njp.v42i4.4
Accepted: 24th February 2015
Abstract : Introduction: Estab-
was carried out. Blood samples
lishing risk factors for a disease
were assayed for HBsAg.
Sadoh AE
(
)
enables early identification of
Results: Of the 150 children re-
Department of Child Health
those with the disease (through
cruited 84(56%) were male. The
University of Benin Teaching Hospital
Benin City, Nigeria
screening) as well as targeted pre-
mean (SD) age of the children was
Email: ayebosadoh@yahoo.com
vention and control measures. The
33.0(39.1) months. HBsAg sero-
significance and relative impor-
positivity was 13.9%. Circumci-
Ojili AN
tance of such risk factors may
sion, scarification, ear piercing,
Department of Community Health
differ based on geographic loca-
history of blood transfusion, re-
University of Benin Teaching Hospital
tion and they may change over
ceipt of unsafe injections, present/
Benin City, Nigeria
time with the institution of control
past history of jaundice and malnu-
measures. In this study we exam-
trition were not significantly asso-
ined the association between
ciated with being seropositive
HBsAg seropositivity, some risk
(p>0.05).
factors and clinical features.
Conclusion: This study did not
Methodology: Consecutive chil-
identify any pathognomonic clini-
dren aged 2 months to 16 years
cal feature of hepatitis b seropreva-
who were admitted to a Chil-
lence. The lack of association be-
dren’s Emergency Room were
tween HBsAg seropositivity and
recruited. Data on the presence /
the studied risk factors may repre-
absence of risk factors such as
sent a real improvement in infec-
previous blood transfusion, scari-
tion control measures. Further re-
fications, receipt of unsafe injec-
search is required to ascertain if
tions and previous surgery were
there are still some unidentified
obtained. History to ascertain pre-
risk factors for hepatitis B trans-
vious or present history of jaun-
mission in Nigerian children.
dice and pale coloured stool was
obtained. Examination to detect
Keywords: Hepatitis B virus, in-
hepatomegaly and spenomegaly
fection, risk factors
Introduction
one geographic region to another. For example perinatal
transmission is the main route of acquisition of hepatitis
B virus infection in South East Asia. In the United
6
For many disease conditions there are identifiable risk
factors which enable targeted prevention and control
States of America, certain population groups have been
measures. Also in the health care setting these risk fac-
identified to be at increased risk such as injection drug
tors enables heightening the index of suspicion for the
users, HIV positive persons, Men who have sex with
diagnosis of a given disease. Hepatitis B virus infection
men, household and sexual contacts of persons with
chronic hepatitis B infection.
1
is a global health problem. The hepatitis B virus is trans-
mitted by percutaneous or mucous membrane exposure
The relative significance of some of these risk factors
to infectious blood or body fluids. In developing coun-
1
may also change over time as different interventions are
tries, common modes of transmission are perinatal
instituted for the control of such risk factors. For exam-
(mother to child), early child infections ( inapparent
ple, in the United States of America, since 1972 the
infections through close interpersonal contact with in-
blood supply has been screened for hepatitis B making
fected household contacts), unsafe injection practices,
the risk of transfusion transmitted hepatitis B extremely
rare.
7
unsafe blood transfusion and unprotected sexual con-
tact. Other frequently listed risk factors include proce-
2
dures during which sharp objects which may be con-
In Nigeria, the major route of acquisition is thought to
taminated are used such as tattoos, ear piercing and cir-
be horizontal during childhood and various studies have
cumcision.
3-5
suggested different risk factors including blood transfu-
The relative importance of these risk factors varies from
sion, children with sickle cell anaemia, circumcision.
304
Many of these studies were carried out before the wide-
Results
spread adoption of some control measures such as
screening of blood before transfusion, creating aware-
One hundred and fifty (150) children were recruited for
ness on transmission routes of blood borne diseases such
the study of whom 84(56%) were males. The mean age
as Human Immunodeficiency virus. Also some clinical
(SD) of the children was 33.0(39.1) months with a range
features such as jaundice, tender hepatomegaly are asoo-
of 2-180 months (2months -15 years). Majority of the
ciated with hepatitis b infection. Their presence in a pa-
children 124 (82.7%) were aged below 5 years (Table
tient may heighten the suspicion of hepatitis B infection.
1). Infants (younger than 12months) were 53(35.3%)
The aim of this study was to evaluate the association of
while those older than 10 years (120months) were 8
some of these aforementioned risk factors and clinical
(5.3%).
features with hepatitis b seroprevalence in Nigerian chil-
Age was available for 146 and 136 mothers and fathers
dren.
respectively. The mean age (SD) of mothers was 31.9
(5.9) years with a range of 19-50 years while the mean
age (SD) of fathers was 38.9(7.2) years with a range of
23-63 years.
Methodology
Majority of the mothers 59(39.9%) had tertiary educa-
tion. Only 4(2.7%) mothers did not attempt or complete
The study was carried out at the Children’s emergency
primary education. Majority of the children 98(72.6%)
room (CHER) of the University of Benin Teaching hos-
were from families of high socioeconomic status.
pital. The University of Benin Teaching Hospital
(UBTH) is a 700 bedded hospital. It is a tertiary health
Table 1: Sociodemographic characteristics of 150 children
facility. It takes care of patients from Edo state and those
Characteristic
n
(%)
referred from the neighbouring states of Ondo, Delta,
Gender
Ekiti, Enugu and Imo. The Children’s emergency room
Male
84
56.0
is one of four wards that cater for children in the Univer-
Female
66
44.0
sity of Benin Teaching Hospital. Most children beyond
Age group
the neonatal period who present with an acute illness
<12months
53
35.3
and who require admission are first admitted in the
12-59months
71
47.3
emergency room.
60-119months
18
12.0
≥ 120months
8
5.3
Maternal Age
Ethical clearance for the study was obtained from the
≤24
11
7.5
UBTH ethical review committee. Verbal consent was
25-29
48
32.9
obtained from parents of subjects after the objectives
30-34
39
26.7
and procedure of the study had been explained to them.
35-39
31
21.2
40-44
12
8.2
Consecutive patients aged 2 months to 16 years admitted
≥45
5
3.4
to CHER were recruited. Information on bio data such
Maternal LOE
as age, sex, maternal and paternal educational level and
I
59
39.9
11
9
6.1
occupation was obtained using a proforma. The pro-
111
35
23.6
forma was pretested at the Institute of Child Health Im-
IV
41
27.7
munization clinic. The instrument was administered by
V
4
2.7
the researcher. Immunization history was obtained for
Socioeconomic Status
each child.
f
The association between immunization
High
98
72.6
status and HBsAg seroprevalence has been reported
Low
37
27.4
elsewhere. History to ascertain previous or present his-
8
Number of persons in HH
tory of jaundice and pale coloured stool was obtained.
≤5
84
57.1
Physical examination to detect pallor, jaundice, lympha-
>5
63
42.9
denopathy, hepatomegaly,splenomegaly and spider nevi
I-university degree or equivalent, II- School certificate
was carried out. The presence or absence of risk factors
(Ordinary level GCE) plus teaching or other professional
such as previous blood transfusion, scarification marks,
training III- School certificate or grade II teachers’ certificate
or equivalents IV- modern three, primary six certificate V- Did
previous injections and surgery was ascertained. Injec-
not complete primary school,illiterate
tions that were received outside of health care facilities
LOE – Level of education
were considered to be unsafe.
HH -Household
The weight of each child younger than 12 months was
Risk factors for HBsAg seropositivity
measured using an infant weighing scale while a me-
chanical floor scale was used for children older than 12
Of the 150 children studied 21(13.9%) were positive for
months. Infants were weighed nude while older children
HBsAg. Table 2 shows the relationship between proce-
were weighed lightly clothed. Weight was recorded in
dures which involves the use of sharps and HBsAg sero-
kilograms to the nearest 0.05 kilogram
positivity. Of the 105 children who had been circum-
cised, 15(14.3%) were positive for HBsAg while 6
(14.3%) of those who had not been circumcised were
305
positive. There was no significant association between
associated with being HBsAg seropositive p=0.59. Past
circumcision and HBsAg status p=1.000.
history of pale stools, presence of pallor, hepatomegaly,
Circumcision was carried out by traditional healers,
splenomegaly and lymphadenopathy were not signifi-
health care personnel (at home) and health care person-
cantly associated with being seropositive.
nel (at health care facilities) in 12(11.4%), 18(17.1%)
There were 32 moderately/severely malnourished chil-
and 72(68.6%) children respectively. The person who
dren. Of these 8(25%) were HBsAg seropositive com-
carried out the circumcision was not known in 3(2.9%)
pared to 12(11.3%) of those who were not malnour-
children. Of those circumcised by traditional healers 2
ished. Nutritional status was not significantly associated
(16.7%) were seropositive compared to 2(11.1%) of
with being seropositive P=0.08.
those circumcised by health care personnel at home and
10(13.9%) of those circumcised by health personnel at
Table 3: Association between hepatitis B serostatus and some
health facilities. The place where circumcision was car-
clinical features
ried out was not significantly associated with HBsAg
Clinical features
HBsAg Serostatus
seropositivity p=0.91.
Positive
Negative
**pvalue
Of the 58 children whose ears were pierced, 32(55.2%)
n
%
n
%
were done at home using sterile pin ear rings while 21
History of pale stools
(36.2%) were done in health facilities using sterile pin
Yes
2
28.3
4
66.7
ear rings. One child had the ears pierced at home using a
No
18
13.4
116
86.6
0.20
Total
20
120
sewing needle. HBsAg was positive in 4(12.5%) of
Past History of jaundice
those whose ears was pierced at home and this was not
Yes
4
18.2
18
81.8
significantly different from the 5(23.8%) among those
No
17
13.5
109
86.5
0.52
whose ears were pierced in a health facility p=0.46.
Total
21
127
Previous blood transfusion, receipt of unsafe injections,
Jaundice
previous surgery, and having had scarifications were not
Yes
0
0
7
100
significantly associated with being positive for HBsAg
No
20
14.6
117
85.4
0.59
(p>0.05).
Total
20
124
Pallor
Yes
3
11.1
24
88.9
Table 2: Association between HBsAg serostatus and some risk
No
17
13.8
106
86.2
0.73
factors
Total
20
130
Risk factor
HBsAg serostatus
Hepatomegaly
Positive
Negative
p-value
Yes
9
20.0
36
80.0
n
%
n
%
No
11
11.3
86
88.7
0.20
Scarifications
Total
20
124
Yes
3
15.0
17
85.0
Splenomegaly
No
18
14.3
108
85.7
1.00
Yes
1
6.3
15
93.7
Total
21
125
No
19
15.1
107
84.9
0.47
Unsafe injections
Total
20
122
Yes
4
21.1
15
78.9
Lymphadenopathy
No
17
13.5
109
86.5
0.48
Yes
0
0
4
100.0
Total
21
124
No
20
14.5
118
85.5
1.00
Blood transfusion
Total
20
122
Yes
2
18.2
9
81.8
Nutritional status
No
19
14.2
115
85.8
0.66
Moderately/severe*
8
25.0
24
75.0
Total
21
124
Normal
12
11.3
94
88.7
0.08
Surgery
Total
20
118
Yes
1
50.0
1
50.0
No
20
14.0
123
86.0
0.27
*moderately/severe underweight **All comparisons were by Fishers
Total
21
124
Exact Test
Circumcision
Yes
15
14.3
90
85.7
The commonest provisional diagnosis was Pneumonia
No
6
14.3
36
85.7
1.00
Total
21
126
33(22.3%), closely followed by malaria 31(21.0%).and
Ear Piercing
then gastroenteritis 18(12.2%). Other diagnoses are as
Yes
9
15.5
49
84.5
shown in table 4. These diagnoses were similar to those
No
12
13.0
80
87.0
0.81
of children who were HBsAg positive. Table 5.
Total
21
129
Table 5: Provisional diagnosis of children who were HBsAg seroposi-
Comparison was by Fishers Exact test
tive
Provisional diagnosis
n
%
Clinical features and HBsAg seropositivity
Bronchopneumonia
8
38.1
Malaria
4
9.5
Of the 22 children who had a past history of jaundice 4
Gastroenteritis
3
14.3
(18.2%) were HBsAg positive and this was not signifi-
Accidental poisoning
2
9.5
cantly different from 17(13.5%) of those who did not
Tuberculosis
1
4.8
have a past history of jaundice.(Table 3) Similarly the
Septicaemia
1
4.8
Shigellosis
1
4.8
presence of jaundice in the patients was not significantly
Nephrotic syndrome
1
4.8
306
Table 4: Provisional diagnosis of the studied children
Scarification marks were not significantly associated
Provisional diagnosis
n
%
with hepatitis B status. This is similar to findings from
studies in Eastern Nigeria. In one study it was noted
12
Bronchopneumonia
33
22.3
that traditional healers request new blades from their
Malaria
31
21.0
clients to carry out scarifications. The current drive to
12
Gastroenteritis
18
12.2
Meningitis
14
9.5
raise awareness on the transmission routes of Human
Tonsilitis
8
5.4
immunodeficiency virus (HIV) which has similar routes
Septicaemia
7
4.7
of transmission as the hepatitis B virus may also have
Soft tissue infections
6
4.1
contributed to such improved practices.
Asthma
3
2.0
Unsafe injections were not associated with an increased
Seizures
3
2.0
risk of being positive for the hepatitis B surface antigen
Malignancy
3
2.0
in this study. This is in keeping with a study from
Accidental poisoning
3
2.0
Ilorin in which none of the children seropositive for
Bronchiolitis
2
1.4
HBsAg had a history of use of unsterile needles. The
3
Head injury
2
1.4
Acquired Immunodeficiency syndrome
2
1.4
finding in this study was however in contrast with find-
Tuberculosis
2
1.4
ings in Abakaliki in which unsafe injections was report-
edly the commonest route of hepatitis B infection.
13
Viral encephalitis
1
0.7
Intracranial space occupying lesion
1
0.7
Also in Pakistan HBsAg seropositivity was higher in
Chronic liver disease
1
0.7
children who had received therapeutic injections and this
Pertussis
1
0.7
was attributed to recycling of needles. It is also possi-
14
Tetanus
1
0.7
ble that
the same awareness drive on transmission
Chronic renal failure
1
0.7
routes for HIV may have resulted in improved practices
Nephrotic syndrome
1
0.7
Haemophiliac
1
0.7
among those who administer injections outside of health
Congenital heart disease
1
0.7
care settings resulting in the lack of association between
Shigellosis
1
0.7
HBsAg seropositivity and unsafe injections in this study.
Improved practices with sharps were also observed with
ear piercing in this study as most of the ear piercing was
done with sterile pin ear rings. Thus ear piercing was not
significantly associated with a higher prevalence of
Discussion
hepatitis B surface antigen. This was similar to findings
in Pakistan.
14
None of the risk factors examined in this study was sig-
nificantly associated with being seropositive for HBsAg.
Circumcision was not significantly associated with be-
Historically the first recorded cases of Hepatitis B
ing positive for hepatitis B surface antigen. Most of the
(formerly called serum hepatitis) are thought to be those
circumcisions (85.7%) were carried out by health care
that followed the administration of smallpox vaccines
personnel at home or in health facilities. That these
containing human lymph administered to shipyard work-
health workers are unlikely to use contaminated instru-
ers in Germany in 1883. In the early and middle parts
9
ments for the procedure may explain the lack of associa-
of the 20 century serum hepatitis was repeatedly ob-
th
tion of circumcision with being seropositive for HBsAg.
served following the use of contaminated needles and
This assertion is corroborated by findings in a study
syringes while the role of blood as a vehicle for trans-
from northern Nigeria where those who had traditional
mission was further emphasized in 1943 by Beeson
circumcision were more likely to be seropositive for
when he described jaundice that had occurred in seven
hepatitis B virus infection compared to those who had
circumcision done in health facilities.
4
recipients of blood transfusion . However the screening
9
of blood before transfusion has all but eliminated trans-
The finding that blood transfusion, ear piercing, scarifi-
fusion of blood/blood products as a source of hepatitis B
cation marks, and use of contaminated sharps were unas-
infection in some developed countries.
7
sociated with being seropositive is contrary to findings
in many studies in Nigerian adults.
15-17
These differences
Although some previous studies have reported blood
may be due to the fact that these adults most likely ac-
transfusion to be a risk factor for hepatitis b infection in
quired their infection years ago in their childhood before
children, in this study blood transfusion was not sig-
3,4
the advent of control measures for blood borne infec-
nificantly associated with hepatitis B infection. This is
tions became widely adopted in Nigeria both at health
in keeping with some other studies in Nigerian chil-
facility and at community levels.
dren.
10
The lack of association between seropositivity
and blood transfusion may be due to improved screening
A history of jaundice in the past or the presence of jaun-
of blood before transfusion that has been adopted in the
dice in the current illness was not significantly associ-
national guidelines on blood transfusion. However, the
11
ated with being positive for hepatitis B surface antigen.
differing results obtained between studies may be due to
This is similar to findings in Ilorin where none of the
differential implementation of the national guidelines on
children who were seropositive had a history of jaun-
dice. Similarly, the clinical features of hepatomegaly,
3
blood transfusion, but may also reflect earlier horizontal
transmission which is thought to be the major route of
splenomegaly and lymphadenopathy which may be pre-
transmission in Nigerian children.
sent either in acute or chronic hepatitis B infection were
307
not significantly associated with hepatitis B surface anti-
The lack of association of HBsAg seroprevalence with
gen status in this study. This suggests that these clinical
the studied risk factors may represent a real improve-
features are not specific and sensitive enough to discern
ment in infection control measures such as improved
hepatitis B infection. Moreover these are features that
blood screening, observance of standard precautions and
are present in more common conditions of children such
an informed population on prevention of blood borne
as malaria and septicaemia. Also children with acute
diseases at community level. Research is required to
hepatitis are more likely to be asymptomatic. The find-
ascertain if there are still as yet some unidentified risk
ing in this study is however in contrast to that in Port
factors for hepatitis B transmission in children in
Harcourt where hepatomegaly and jaundice were the
Nigeria.
commonest features in children who were seropositive.
18
That study may have been biased in that the children
Health care workers have been identified as being occu-
pationally at risk for hepatitis B infection. This risk is
23
evaluated were those in whom hepatitis B was highly
suspected.
determined by the prevalence of hepatitis B in the
The provisional diagnoses of the children showed that
patient population and by their rate of exposure to proce-
these were similar in both those who were hepatitis B
dures during which exposure to blood or blood products
seronegative and those who were seropositive. Most of
is likely. The prevalence of HBsAg among the children
the diagnoses were not referable to the liver. The one
studied is high therefore there is a need to adopt meas-
child who had a diagnosis of chronic liver disease was
ures to protect health care workers in this setting. Con-
not even seropositive for hepatitis B. Thus it is advisable
tinued observance of standard precaution is mandatory
that health care workers should observe standard precau-
as hitherto identified risk factors were not predictive of
tions when handling any patient or clinical specimen.
seropositivity in this study. A higher index of suspicion
will be required for diagnosis of hepatitis B in children
A significant proportion of the children studied (23.2%)
more especially as hepatitis B infection in children is
were either moderately or severely underweight. This is
mostly asymptomatic. Immunization of health care
comparable to the findings of 28.3% for moderately or
workers will be a worthy strategy to protect health care
severely underweight in the Nigerian Multiple Indicator
workers while universal infant immunization will reduce
Cluster Survey in 2011. Malnutrition is known to be a
19
HBsAg seroprevalence at community level.
risk factor for many infectious diseases.
20,21
Few studies
have evaluated this factor as a possible risk factor for
Author’s contribution
hepatitis B. In this study malnutrition was not signifi-
AES conceptualized the study, was involved in data
cantly associated with being seropositive. This is in
collection, analysis and interpretation, wrote the initial
keeping with findings from a study on Turkish children
draft and approved the final draft
with chronic hepatitis B infection in whom no signifi-
ANO contributed to the concept, was involved in data
cant difference was found in levels of alanine amino
analysis and interpretation and approved the final draft.
transferase, histological activity and HBV DNA
Conflict of interest: None
levels between those who were malnourished and those
Funding: None
who were not.
22
References
1.
Centre for Disease Control and
5.
Ali M, Idrees M, Hussain A, Reh-
9.
Vazigi NA, Balistreri WF. Acute
Prevention. Recommendation for
man IU, Saleem S, Afzal S, Butt S.
and chronic viral hepatitis (chapter
identification and public health
Hepatitis B virus in Pakistan: A
17) in: Liver diseases in children.
management of persons with
systematic review of prevalence,
Suchy FJ, Sokol RJ, Balistreri WF
chronic hepatitis B virus infection.
risk factors, awareness Tatus and
eds. Publisher Lippincort Williams
MMWR 2008;57(RR-8)1-20
genotypes. Virology J 2011;8:102
and Wilkins 2001.pg 370
2.
World Health Organization. Hepa-
Available at http://www.virology.
10. Angyo IA, Yakubu AM. Lack of
titis B fact sheet N ⁰ 204 Available
com/content/8/1/102
association between some risk
at http://www.who.int/
6.
Hou J, Liu Z, Gu F. Epidemiology
factors and hepatitis B surface
mediacentre/factsheet/fs204/en/#
and prevention of hepatitis B virus
antigenaemia in children with
3.
Agbede OO, Iseniyi JO, Kolawole
infection. Int J Med Sci 2005;2:50-
sickle cell anaemia. West Afr F
MO, Ojuawo A. Risk factors and
57
Med 2001;20(3):214-8
seroprevalence of hepatitis B sur-
7.
Centre for Disease Control and
11. National Blood Transfusion ser-
face antigenaemis in mothers and
Prevention. Diseases and Organ-
vice, Federal Ministry of Health.
their preschool age children in
isms. Available at http://
Nigerian National Blood Policy,
Ilorin, Nigeria. Therapy 2007;4:67
www.cdc.gov/bloodsafety/bbp/
Revised 2005
-72
diseases_organisms.html Accessed
12. Chukwuka JO, Ezechukwu CC,
4.
Ndako JA, Echeonwu GON,
28th February 2013
Egbuonu I. Cultural influences on
Olabode AO, Nwankiti OO, Ai-
8.
Sadoh AE, Ofili A. Hepatitis B
hepatitis B surface antigen sero-
makhu SO, Onoroh EM, Chuk-
infection among Nigerian children
positivity in primary school chil-
wuekezie J, Bonda JM, Paul GA.
admitted to a children’s emergency
dren in Nnewi. Nig J Paed
Seroprevalence of hepatitis B sur-
room. Afr Hlth Sci 2014;14:377-
2003;30(4):140-142
face antigen (HBsAg) among chil-
383
dren of primary school age in a com-
munity in North Central, Nigeria. Si-
erra Leone J Biomed Res 2010;2-32-37
308
13. Ugwuja E, Ugwu N. Seropreva-
16. Sule WF, Okonko IO, Ynunsa IP,
20. Berman S. Epidemiology of acute
lence of hepatitis B surface antigen
Odu NN, Frank-Peterside N.
respiratory infectons in children of
and liver function tests among
Hepatitis B surface antigenaemia
developing countries. Rev Infect
adolescents in Abakaliki, south
(HBsAg) and risk factors of trans-
Dis 1991;13:5454-5462
eastern Nigeria. Int J Trop Med
mission among patients attending
21. Huppertz H, Salman N, Giaquinto
21;6(2)
Universal Hospital Ankpa, Kogi
C, Risk factors for severe rotavirus
14. Jafri W, Jafri N, Yakoob J. Islam
state, Nigeria. Nature and Science
gastroenteritis Ped Infect Dis J
M, Farhan S, Jafar T et al. Hepati-
2011;9:37-44
2008;27:511-519
tis B and C; prevalence and risk
17. Nwokediuko SC.Risk factors for
22. Bekem SO, Targan S, Diniz G,
factors associated with seropositiv-
hepatitis B virus transmission in
Ortac R. Nutritional status of chil-
ity among children in Karachi,
Nigerians: a case control study.
dren with chronic hepatitis B in a
Pakistan. BMC infect dis 2006;
The internet J Gastroenterol-
population with low socioeco-
6:101
ogy.2010;10. DOI: 10.5580/1fdc
nomic status. Eur J Gaatroenterol
15. Yakasai IA, Ayyuba R, Abubakar
18. Alikor EA, Erhabor ON. Sero-
Hepatol 2009;21:1252-5
IS, Ibrahim SA. Seroprevalence of
prevalence of hepatitis B surface
doi:10.1097/
hepatitis B virus infection and its
antigenaemia in children in a terti-
MEG.0b013e32832a4ec3
risk factors among pregnant
ary health institution in the Niger
23. Ciorlia LAS, Zanetta DMT. Hepa-
women attending antenatal clinic
Delta of Nigeria. Niger J Med
titis B in health care workers:
at Aminu Kano Teaching hospital
2007;16(3):250-1
prevalence, vaccination and rela-
Kano, Nigeria. J Basic and clinical
19. National Bureau of Statistics. Ni-
tion to occupational factors. Braz J
reproductive sciences 2012;1:49-
geria: Multiple indicator cluster
Infect Dis 2005;9:384-9
55
survey 2011, Final report.