Prevalence of hepatitis B virus markers in municipal ...

Occupational Medicine 2005;55:60–63 doi:10.1093/occmed/kqi007

Prevalence of hepatitis B virus markers in municipal solid waste workers in Keratsini (Greece) G. Dounias,1 E. Kypraiou,1 G. Rachiotis,1 E. Tsovili1 and S. Kostopoulos2 ............................................................................................................................................................

Aim

To evaluate the prevalence of hepatitis B virus (HBV) markers among municipal solid waste workers (MSWWs) in Keratsini (Greece).

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Methods

We assessed in a cross-sectional study the prevalence of biological markers of HBV infection (HbsAg, anti-Hbc, anti-Hbs) and their association with exposure to waste and other socio-demographic factors in 166 municipal employees in Keratsini (Greece).

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Results

The prevalence of anti-Hbc (þ) did differ significantly between exposed and non-exposed employees to waste. Older employees had a significantly higher prevalence of anti-Hbc (þ ). MSWWs who were anti-Hbc (þ) were less educated than non-exposed employees. Logistic regression analysis has shown that the exposure to waste and age were independently associated with the anti-Hbc positivity.

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Occupational exposure to waste is possibly associated with the acquisition of HBV infection. Immunization of MSWWs should be considered to reduce the risk of HBV infection.

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Key words

Cross-sectional study; hepatitis B infection; municipal solid waste workers; occupational exposure.

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Introduction

and has classified HBV as a class three biological agent [10,11]. The occupational risk for acquiring HBV in municipal solid waste workers (MSWWs) is not well established. In occupational settings transmission of HBV occur via accidental needle-sticks or other injuries from contaminated sharp instruments [12]. HBV is resistant on exposed surfaces for more than 7 days [13] and thus MSWWs risk infection from contaminated sharps instruments [14] (e.g. biomedical waste from private practitioners office or from intravenous drug users), which are improperly discarded. Some European countries (Italy, Greece) have recommended the immunization of these workers against HBV infection [15,16]. Our cross-sectional study investigates the prevalence of HBV markers in MSWWs and its association with socio-demographic factors.

Hepatitis B virus (HBV) infection is a serious worldwide public health problem. Over two billion people around the world have been infected and HBV is a leading cause of chronic hepatitis, cirrhosis and hepatocellular carcinoma. The annual mortality from HBV infection and its sequelae is estimated at 1 – 2 million people on a worldwide scale [1,2]. The endemicity of HBV infection varies greatly. Historically, Greece has had the highest burden of HBV infection in the European Union. In recent years, a decline has occurred and today Greece is an area of intermediate endemicity of HBV infection [3,4]. HBV is mainly a biological risk to health care workers (HCWs) although other occupational groups with increased risk include public safety workers, fire-fighters, military forces, butchers, barbers, embalmers and sewage workers [5–9]. The European Community states that all workers should be protected from biological agents

Methods From September 1999 to December 2001 we conducted a seroprevalence survey of municipal employees in Keratsini, a suburb of Piraeus port. Socio-demographic data were obtained from the occupational health records for 166 of 447 municipal employees of Keratsini. All employees were attending an annual medical with

1

Department of Occupational and Industrial Hygiene, National School Of Public Health, Athens, Greece. 2

Department of Occupational and Environmental Medicine, Elefsina General Hospital, Thriasion, Greece. Correspondence to: G. Dounias, National School of Public Health (NSPH), 196 Alexandras Av., 11521 Athens, Greece. e-mail: [email protected] Occupational Medicine, Vol. 55 No. 1 q Society of Occupational Medicine 2005; all rights reserved

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Conclusion

G. DOUNIAS ET AL.: HBV MARKERS IN MUNICIPAL SOLID WASTE WORKERS 61

software (version 8.0). A P value less than 0.05 was considered as statistically significant.

Results Table 1 illustrates the socio-demographic characteristics of municipal employees by occupational exposure status. MSWWs were less educated than their non-exposed colleagues. Sex, age, duration of employment and marital status did not differ by exposure group. HBsAg was detected in 12 employees of the total sample (7%). The prevalence of HBsAg was higher in MSWWs (11.3%) than in non-exposed (4.5%), but the difference was not statistically significant (x2, P ¼ 0.13), (Table 2). Anti-HBc was found in 17 out of 71 MSWWs (prevalence: 24%) while in non-exposed was found in 7 of 91 (prevalence: 8%). The difference in the prevalence of anti-HBc between the exposed and the non-exposed municipal employees was statistically significant (x2, P ¼ 0.007) (Table 2). Anti-HBc (þ) MSWWs reported significantly fewer years of education than non-exposed (P ¼ 0.01) (Table 3). There was no significant difference in mean age, duration of employment, sex or marital status between the exposed and the non-exposed employees who were anti-Hbc (þ ) (Table 3). Prevalence of anti-HBc increased with age. The mean age of workers who were anti-Hbc positive was significantly higher than who were anti-HBc negative (45.4 years, 6.2 SD versus 41.9, 8.8 SD, respectively, Student’s t-test, P ¼ 0.024). In the age group # 42 the prevalence of anti-HBc was 5% versus 21% in the age group # 42 and a statistically significant difference was recorded (x2, P ¼ 0.005) (Table 2). The prevalence of anti-HBc (þ ) did not differ significantly between municipal employees

Table 1. Socio-demographic characteristics of Keratsini municipal employees by occupational exposure status Characteristic

Exposed (n ¼ 71)

Non-exposed (n ¼ 88)

Sex Male Female Ageb Duration of employmentb Marital status Married Unmarried Educational status ,9 years $9 years

n (%) 58 (82%) 13 (18%) 41.6 years (8.4) 9.2 years (4.8)

n (%) 66 (75%) 22 (25%) 43.11 (8.8) 10.4 (6.7)

54 (76%) 17 (24%)

65 (74%) 23 (26%)

0.85a

64 (90% 7 (10%)

54 (61%) 34 (39%)

, 0.001a

a

x2 test.

b

Mean, standard deviation.

c

Student’s t-test.

P-value

0.34a 0.27c 0.18c


an occupational physician and gave their informed consent for participation in the study. Five employees reported previous vaccination against HBV. Their serum samples demonstrated titres of antiHbs . 100 miu/ml and therefore these employees were excluded from the study. Two employees (one exposed and one non-exposed to waste) who underwent seroconversion to HBsAg (þ ) after reported blood transfusion were also excluded from the study to avoid possible bias. The mean municipal employment duration was 9 –7 years (range: 1 –31 years; SD 6, 1). All serum samples were tested for HBsAg, anti-HBs, anti-HBc by enzymelinked immunosorbent assay. Municipal employees who were at risk of exposure to waste (MSWWs) comprised the study group (n ¼ 71) while the control group comprised office and manual employees without exposure to waste (n ¼ 88). Employees were also distributed into two groups according to sex (male, female), age (#42 years, .42 years based on the mean age of the sample), years of education (9 years or greater), marital status (married, unmarried) and duration of employment (#10 years, .10 years) based on the mean of the years of municipal employment. We did not investigate non-occupational risk factors for HBV infection such as sexual behavior, drug use, tattooing, acupuncture. Chi-square (x2) test was used as the univariate analysis for the comparison of the prevalence of HBV markers in subgroups. For quantitative data, normality was assessed and Student’s t-test was used for statistical analysis. In order to assess the potential risk factors with which antiHBc status was independently associated, a logistic regression model was used as the multivariate analysis. Positivity of anti-HBc was the dependent variable in the model. Sex, age, occupational exposure to waste and education group were the independent variables. Biostatistical analysis was performed by the use of SPSS

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Table 2. Prevalence of HBV markers and demographic variables in Keratsini municipal employees Number

HbsAg

N ¼ 159 124 35 N ¼ 159 61 98 N ¼ 159 71 88 N ¼ 159 118 41 N ¼ 159 120 39 N ¼ 159 121 38

Sex Male Female Age , 42 $ 42 years Occupation Exposed Non-exposed Education # 9 years . 9 years Marital status Married Unmarried Duration of employment # 10 years . 10 years

Anti-Hbc

Anti-Hbs

10 (8.1%) 2 (5.7%)

20 (16.1%) 4 (11.4%)

10 (8.1%) 2 (5.7%)

2 (3.3%) 10 (10.2%)

3 (4.9%) 21 (21.4%)p

1 (1.6%) 11 (11.2%)p

8 (11.3%) 4 (4.5%)

17 (23.9%)pp 7 (8%)

9 (12.7%)p 3 (3.4%)

8 (6.8%) 4 (9.8%)

19 (16.1%) 5 (12.2%)

11 (9.3%) 1 (2.4%)

7 (5.8%) 5 (12.8%)

16 (13.3%) 8 (20.5%)

10 (8.3%) 2 (5.1%)

7 (7.4%) 5 (8.1%)

14 (14.9%) 10 (16.1%)

6 (6.5%) 6 (9.7%)

p

P , 0.05.

pp

with # 10 years employment and those with . 10 years. Also the prevalence of anti-HBc (þ ) did not differ between the two educational groups (# 9 years of education, . 9 years) (Table 2). Moreover, no statistically significant difference in the prevalence of anti-HBc (þ ) was recorded between married and unmarried employees (x2, P ¼ 0.3). The prevalence of anti-Hbs differed significantly by occupation (x2, P ¼ 0.036) and age group (x2, P ¼ 0.03) (Table 2). Logistic regression analysis showed that occupational exposure to waste was independently associated with the likelihood of anti-HBc (þ ). MSWWs had a 4-fold Table 3. Socio-demographic characteristics of anti-Hbc (þ ) municipal employees Characteristic

Exposed (n ¼ 17)

Non-exposed (n ¼ 7)

Sex Male Female Ageb Duration of employmentb Marital status Married Unmarried Educational status , 9 years $ 9 years

n (%) 15 (88%) 2 (12%) 45.53 (6.6) 9.2 (3.4)

n (%) 5 (71%) 2 (29%) 45 (5.5) 11.9 (4.0)

13 (77%) 4 (24%)

3 (43%) 4 (57%)

0.16a

17 (100%)

2 (29%) 5 (71%)

,0.001a

a

x test.

b

Mean, standard deviation.

c

Student’s t-test.

2

P-value

0.55a 0.8c 0.15c

increased rate of positive anti-HBc than the non-exposed municipal employees (Table 2). Logistic regression analysis has showed an independent association between anti-HBc (þ ) and ageing. All the examined municipal employees were confidentially informed about the results of their blood tests for HBV markers. MSWWs with laboratory findings of chronic hepatitis had hepatological follow-up. All seronegative employees started a vaccination program against HBV (Table 4).

Discussion Beside the HBsAg, anti-HBc is an important indicator for the study of various epidemiological aspects of HBV infection [17]. In our results the univariate analysis showed a significantly higher prevalence of positive antiHBc in the group exposed to waste and the oldest group of municipal employees. The prevalence of anti-Hbs is related to past hepatitis B infection followed by immunity. Logistic regression analysis shows that the occupational exposure to waste and age are independently associated with the likelihood of anti-HBc (þ ), after adjustment for age, sex and educational status. The lack of association with duration of employment in logistic regression analysis suggests a confounding influence, probably by age, given the close correlation of the duration of employment with employee’s age. Published information about the occupational risk for HBV infection in MSWWs is sparse. Kanitz et al. [18] have studied HBV infection in solid waste collectors in Genoa. The results revealed a higher prevalence of HbsAg and anti-HBc than in the general population, but


P , 0.01.

G. DOUNIAS ET AL.: HBV MARKERS IN MUNICIPAL SOLID WASTE WORKERS 63

Table 4. Logistic regression analysis of anti-Hbc (þ ) Factor

Sex Female Male Age group , 42 years $ 42 years Occupation Non-exposed Exposed Education group , 9 years $ 9 years

Odds Ratio (OR)

Confidence Interval (CI)

1.00 (ref) 1.31

0.38 –4.45

1.0 (ref) 6.17

1.69 –22.5

1.0 (ref) 4.66

1.61 –13.48

1.0 (ref) 0.57

0.16 –1.99

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