Prevalence of the hepatitis B surface antigen in a population of workers in Cameroon

doi:10.4236/ojgas.2013.38057

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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

Email: #[email protected]

Received 30 September 2013; revised 29 October 2013; accepted 15 November 2013

tion License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly

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

OPEN ACCESS

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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