Open Journal of Gastroenterology, 2013, 3, 323-327 OJGas
http://dx.doi.org/10.4236/ojgas.2013.38057 Published Online December 2013 (http://www.scirp.org/journal/ojgas/)
Prevalence of the hepatitis B surface antigen in a
population of workers in Cameroon*
Firmin Ankouane Andoulo1, Michèle Tagni-Sartre2, Dominique Noah Noah3#, Roger Djapa1,
Elie Claude Ndjitoyap Ndam3
1University Hospital of Yaounde, Department of Internal Medicine and Specialties, Faculty of Medicine and Biomedical Sciences,
University of Yaounde I, Yaounde, Cameroon
2Medical Center “La Cathédrale”, Yaounde, Cameroon
3Yaounde General Hospital, Department of Internal Medicine and Specialties, Faculty of Medicine and Biomedical Sciences, Uni-
versity of Yaounde I, Yaounde, Cameroon
Received 30 September 2013; revised 29 October 2013; accepted 15 November 2013
Copyright © 2013 Firmin Ankouane Andoulo et al. This is an open access article distributed under the Creative Commons Attribu-
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ABSTRACT
Hepatitis B surface antigen prevalence in populations
of blood donors in Cameroon is estimated at 6% -
16%. As such, the Objective of this study was to de-
termine the prevalence of Hepatitis B surface antigen
in a population of bank employees, who represent a
sample closer to the general population. In tests car-
ried out both Yaounde and Douala in December 2011,
we detected the hepatitis B surface antigen among
267 workers, including 151 men and 116 women of a
median age of 37 years. The Results obtained revealed
that the overall prevalence stood at 7.1%, with a
9.9% prevalence ratio in men, three times higher
than that in women (3.4%). Subjects aged 20 - 29
years and senior staffs were more affected (each of
them recording 8.1%). Potential nosocomial risks
were detected mostly at the level of dental care
(52.8%). Among the other risks of exposure, scarifi-
cation (53.6%) was more frequent. A univariate ana-
lysis revealed an insignificant relationship with tat-
toos (OR 2.6, 95% CI 0.5 - 10.8, p = 0.2). These re-
sults led to the Conclusion that Hepatitis B surface
antigen carrier prevalence in a population of workers
in Cameroon is not different from that of blood do-
nors. It is mainly due to early vertical and horizontal
contamination.
Keywords: Hepatitis B Virus; HBs Antigen; Chronic
Carrier; Prevalence; Cameroon
1. INTRODUCTION
The hepatitis B virus (HBV) can cause liver infection,
cirrhosis, liver cancer, liver failure and death [1,2]. Ac-
cording to the World Health Organization (WHO), ap-
proximately two billion people have been infected by
HBV worldwide [3]. More than 350 million of these
people ar e chronic carri ers and can transmit th e virus for
years, and nearly 25% of these chronic carriers develop
liver diseases such as chronic hepatitis, cirrhosis and
hepatocellular carcinoma (HCC) [4]. It is estimated that
over 600,000 people die yearly of HBV infection-related
complications, particularly in Sub-Saharan Africa and
Pacific Asia [3,5]. In developing countries, the effective
management of HBV infection is a public health concern.
This is due, partly, to the lack of reliable data on the
prevalence of infections in the general population [6].
Existing data in Cameroon report prevalence between 6
and 16% in the population of blood donors in public
hospitals [7,8]. Blood donors in Africa, in general, and in
Cameroon, in particular, are mostly unemployed and
underprivileged youth from poor socio-economic back-
grounds which are often exposed to sexually transmitted
infections [9]. As concerns public health, data on the
prevalence of HBV infection in this population of blood
donors sh ould be validated for use within the framework
of the Expanded Program on Immunization for children
(EPI), including the hepatitis B vaccine, developed in our
country on the recommendation of WHO since 2005 [3]. *Conflicts of interest: none.
#Corresponding author. The aim of our study was to estimate HB antigen

F. A. Andoulo et al. / Open Journal of Gastroenterology 3 (2013) 323-327 324
(HBsAg) carrier prevalence in a population of workers
and to analyze the determinants associated with HBV
infection in our context.
2. MATERIALS AND METHODS
We conducted a cross-sectional study in a population of
adult workers in Cameroon, specifically in Yaounde and
Douala, during voluntary screening within the context of
occupational medicine in December 2011. Yaounde and
Douala were selected because they are cosmopolitan
cities.
The variables recorded were: age, sex, social class
(worker, employee, and senior staff), personal and family
history, as well as the hepatitis B infection risk factors
available from books.
The tests were performed on workers whose hepatitis
B-infection status was not known, after filling out a
questionnaire on demographic data, risk factors, risk be-
haviors and health history. Workers were recruited
through the medical work and none had objected to the
publication of results. Workers who did not give their
consent as well as absentees and known hepatitis B car-
riers were exclud ed.
The screening tests were performed on a sample of 4
milliliters of venous blood taken at the elbow groove.
The serum collected was sent to two different laborato-
ries in each city, which is four laboratories in total, so
that the results could be compared. The search for
HBsAg was performed done using a 3rd generation
ELISA test, a commercial kit (DIA-HBV®, DiaProph.
Med, Ukraine, Russia). The results would be positive if
the optical density (OD) of the test sample was greater
than the threshold OD. The test would be negative if the
threshold OD was greater than the OD test sample.
Laboratory results which did not tally were excluded in
view of the final analysis.
The data was entered and analyzed using the French
version of the Epi Info 6.04 software and Excel 2007. As
concerns the quantitative variables, the median and in-
terquartile (IQR) were calculated. The proportions were
established for the qualitative variables with their confi-
dence intervals (CI) at 95%.
To examine the relationship between two discrete vari-
ables, we used the Pearson χ2 test with Yates’ modifica-
tion and Fisher’s exact test for reduced populations, an
accepted significance level of 5%.
3. RESULTS
3.1. Study Population and HBsAg Carrier
Prevalence
The testing involved 288 workers. Ten workers were
absent, 05 refused to participate in the screening, 01 was
hepatitis B positive and was under antiviral treatment.
Two hundred and seventy-two workers (94.4%) were
screened for HBsAg. Five results were excluded for the
following reasons: Conflicting resu lts (n = 3), No results
(n = 1), insufficient serum (n = 1). Two hundred and
sixty-seven (92.7%) workers were retained of which 49
(18.4%) in Douala and 218 (81.6%) in Yaounde. Subjects
aged 30 - 39 years made up the majority (44.9%). There
were 151 men (56.6%) and 116 women (43.4%) giving a
sex ratio of 1.3. Among them, there were 60 senior staff
(22.4%), 104 employees (39%) and 103 workers (38.6%).
The median age was 37 years (IQ R [32 years, 44 years]).
The overall prevalence was 7.1% (19/267), with six
(12.2%) cases in Douala and 13 (6%) cases in Yaounde.
Four women (3.4%) and 15 men (9.9 %) (p = 0.004) were
tested positive. The prevalence was significant in sub-
jects aged 20 - 29 years with 8.1% (3/37) (p = 0.02).
Among social classes, the highest prevalence rate was
recorded in senior staff with 8.1% (5/60) (p = 0.2) (Table
1).
3.2. HBV Infection Risk Factors
Many risk factors were identified. They are shown in
Table 2.
In terms of potential nosocomial risk, the main expo-
sure was at the level of dental care, reported 141 times
(52.8%). Among other exposure factors, we observed
that scarification was reported 143 times (53.6%).
Table 1. Demographics and HBsAg prevalence amongst 267
workers.
n (%)HBsAg positive n (%)95% CI
Age, years
(median/IQR)a 37 (31.44)
Gender:
Men 15156.615 (9.9) 7.1 to 23.1
Women 11643.44 (3.4) 2.8 to 7.1
Age group, years
20 - 29 3713.93 (8.1) 7 to 16.9
30 - 39 12044.99 (7.5 ) 2.8 to 12.3
40 - 49 8230.75 (6.1) 2.9 to 11.3
50 and + 2810.52 (7.1) 2.4 to 16.7
Social class
Senior staff 6022.45 (8.3) 1. 3 t o 1 5 .3
Employees 104398 (7.7) 2.6 to 12.8
Workers 10338.66 (5.8) 1.3 to 10.4
n = number, % = percentage, aIQR interquartile range, 95% confidence
interval 96%.

F. A. Andoulo et al. / Open Journal of Gastroenterology 3 (2013) 323-327 325
Table 2. Risk factors for HBV infection.
Risk Factors No. of cases %
Maternal histor y 6 2.2
Personal history of jaundice 26 9.7
Scarification 143. 53.6
Tattoo 20 7.5
Piercing 103 38.6
Surgery 65 24.3
Dental care 141 52.8
Gastrointestinal endoscopy 28 10
Blood transfusion or related 32 12
All workers acknowledged that they were heterosexual
(100%) and none admitted using intrav enous drugs.
Concerning sexuality, 70 questionnaires were filled
out. Of these responses, 40% reported a number of part-
ners greater than or equal to five, mostly in singles and
senior staff. Only six cases (2.2%) of a history of mater-
nal liver diseases were reported. All workers had at least
one known risk factor, and some subjects had several risk
factors.
3.3. The Relative Risk of HBV Infection
Table 3 shows th e known HBsAg risk facto rs. Male sub-
jects were significantly associated with HBsAg carriage
(OR 3.09, 95% CI 2 - 11.5, p = 0.04). A relationship was
found between the other factors, maternal medical his-
tory (OR 2.7, 95% CI: 0.33 to 22.3) and tattoos (OR 2.6,
95% CI: 0.52 - 10.80).
4. DISCUSSION
We believe this study is the first conducted on HBsAg
carrier prevalence in the general population in Cameroon.
Previous prevalence studies have been conducted on
populations which only imperfectly reflect the general
population. It is true that it excludes the youth below 20,
who (according to the last population census in 2010),
represent more than 43.6% of the country’s 20 million
inhabitants [10], due to the wo rking age and the majority
set at 21 years. However, the study seems to come closer
to the general population because its subjects were not
selected on the basis of known risk factors, but presume-
bly healthy subjects.
A prevalence of 7.1% was found in this range. These
lower figures, as compared to WHO estimate of 8% -
20% which makes Cameroon a highly endemic area, can
be explained partly by the exclusion of sexually active
people below 20 years, whose vertical and horizontal
Table 3. Relative risk of HBsAg carrier (univariate analysis).
Risk Factors OR (95%) p
Female 1 - -
Male 3.09 (2 to 11.50) 0.04
Maternal history 2.70 (0.3 to 22.30) 0.5
Scarification 0.96 (0.3 to 2.70) 0.9
Tattoo 2.6 (0.5 to 10.80) 0.2
Piercing 0.55 (0.2 to 1.71) 0.25
Gastrointestinal endoscopy 1 (0.0 to 4.99) 0.6
Blood transfusion 0.39 (0.1 to 2.97) 0.3
Surgery 0.56 (0.1 to 2.17) 0.27
Dental care 0.79 (0.3 to 2.21) 0.6
OR odds ratio, CI confidence interval, p p-value.
modes of contamination are well documented [11,12],
but also due to the selection of underprivileged individu-
als presumably less exposed to sexually transmitted in-
fections and certain customary rites [13,14]. Previous
studies in our country and in some sub-Saharan African
countries of the same endemic area revealed higher pre-
valence in the 20 - 29 years age group and among socio-
economically underprivileged patients [7,8,11,12,15].
The exclusion people below 20 years could have been a
selection bias, if there was kno wn high prevalence in that
age group. In this range, we would have expected to find
a lower prevalence among workers, if one were to con-
sider that some companies restrict access to employment
where HBsAg are detected in a pre-recruitment medical
examination. This result can be explained by the fact that
recruitment reports are not systematic. Only one worker
knew their HIV status. Most refused to undergo testing
because they feared the results, on the one hand, and the
possibility of being screened for HIV without their con-
sent, on the other hand. However, if the prerecruitment
examination were effective, it would have meant that the
contamination factors in this range are the same as those
known among Western workers, that is nosocomial ex-
posure and drug addiction [13], or those associated in
sub-Saharan Africa to poor hygiene conditions existing
especially during treatment, often neglected during ex-
amination [12], and finally, contamination during sexual
intercourse. It is important to compare this with a survey
conducted in France in 2003-2004 with a population of
18 - 80 years [13]. The said study brings out the differ-
ences in prevalence of HBsAg according to the conti-
nents where the subjects were born. Thus, those origi-
nating from sub-Saharan Africa recorded the highest
prevalence (5.25%), as compared to subjects from the
Indian Subcontinent (2.68%) and North Africa (0.24%).

F. A. Andoulo et al. / Open Journal of Gastroenterology 3 (2013) 323-327 326
Specific risk factors such as nosocomial exposure, cer-
tain rituals (scarification, tattoos...), sex with multiple
sexual partners and the socio-economic class were dis-
cussed in the study. All things being equal, the persis-
tence of a high prevalence among subjects from sub-
Saharan Africa, compared to other groups, shows that the
neo- and perinatal infection is very high in the sub-Sa-
haran Africa region [15-18]. This neo- and perinatal in-
fection is emphasized in the study carried out by Bigot et
al. in Benin [11], in which eight children from 40 HBV
seropositive mothers (20%) tested positive for HBsAg,
and in the study carried out by Lohouès-Kouacou et al.
in Côte d’Ivoire [19], where the incidence of perinatal
transmission was estimated at 32.8%.
One of the most important observations in our study
was the fact that all workers admitted that they were het-
erosexual. The fact that subjects do not admit to risky
sexual behavior, if any, is well-documented [20,21].
In Sub-Saharan Africa, the prevalence is generally
high. Senegal (17%) [22], Ivory Coast (18.2%) [15],
Madagascar (23%) [18] and Mali (24.9%) [5] are coun-
tries with a high level of HBV infection prevalence.
Cameroon’s prevalence rate is similar to that of countries
such as Benin (8.26%) [11] and the Democratic Republic
of Congo (DRC) (9.2%) [9]. Reunion has a low preva-
lence rate of 0.7%, which is close to that of Metropolitan
France, probably due to a better economy and better
health condition s [12,13 ].
Men were three times more likely to be HBsAg carri-
ers than women. This result tallies with that of other
studies conducted in Cameroon [7 ,8] and in the literature
[2,9,13,15].
The majority of workers with HBsAg were in the 20 -
29 year s age group. This age-related result is iden tical to
the previous study by Koanga Mogtomo et al. conducted
in our country [7]. Conversely, in mainland France [13],
as well as in DRC [9] and among United States immi-
grants [23], the 30 - 39 year age group that is that most
affected. The difference with the study conducted in the
DRC is at the level of the selection of the sample. The
difference with that carried out in mainland France is
explained by the means of contamination.
The relationship between HBsAg prevalence and low
socio-economic levels has been treated by other authors
[11,13-15]. Our results did not tally with theirs. This is
probably due to the social ascension of individuals from
underprivileged backgrounds and the fact that senior
staff had several sex partners.
The difference in the prevalence rate between Douala
(12.2%) and Yaounde (6%) supports th e idea that there is
a huge difference in infection patterns according to re-
gion, according to socio-economic status, and according
to hygiene, in the same city. This result is similar to that
obtained in the study by Mbendi Nlombi et al. in eastern
Kinshasa in DRC [9].
5. CONCLUSION
Our study shows a significant HBsAg carrier prevalence
in a population of workers close to the general popula-
tion in Cameroon, particularly among young people un-
der 30 years, in men and in Douala. It is not different
from that of the population of blood donors, which tends
to confirm the hypothesis of the existence of neo-Peri-
natal infection in our country. This result clearly high-
ghts the importance of strategies for vaccinating new-
borns and those for the treatment of pregnant women
who are chronic carriers of HBsAg in controlling the
risks of HBV c ont amination.
6. ACKNOWLEDGEMENTS
Hoffmann-La Roche Ltd. Cameroon Branch. Avenue De Gaulle, Rue
Noury. P.O. Box 8 71 Do ua la-Bonapriso, Cameroon.
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