occupational risk for hepatitis a and hepatitis e among health care professionals?

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94 Infection 30 2002 No.2 URBAN& VOGEL

Infection Brief Report

Occupational Risk for Hepatitis A and Hepatitis Eamong Health Care Professionals?

M. Nbling, F. Hofmann, F.-W. Tiller

Abstract

Background: Since transmission routes of hepatitis E virus(HEV) and hepatitis A virus (HAV) are believed to be similar,comparable risk factors and a correlation between the twoseroprevalence rates may be assumed.Materials and Methods: Anti-HAV and anti-HEV serologywas assessed in 511 German subjects from nursing, pediatricnursing and administration groups, none of whom had beenvaccinated against HAV. At the same time a standardizedquestionnaire on occupational and individual parameters wascompleted.Results: Overall seroprevalence for anti-HEV was 3.9%, foranti-HAV 28%. Multivariate analysis revealed that anti-HEVseroprevalence was significantly higher in persons workingin emergency admission or in surgery, while persons working

in childrens psychiatry were more likely to be anti-HAVpositive. Comparing the two serological results, nocontingency difference was found (2 = 0.42 (df = 1),p > 0.05).Conclusion: Specific departments of health care show higherprevalence of anti-HAV or anti-HEV. In the case of HEVfurther studies in the exposed working field are needed.Since no connection between the two serological results wasfound, transmission mechanisms might be (partly) different.

Key WordsHepatitis E Hepatitis A Occupational risk Health careworkers

Infection 2002;30: 9497

DOI 10.1007/s15010-002-2023-3

IntroductionHepatitis E is an acute,self-limiting disease caused by hep-atitis E virus (HEV) and is endemic in a number of devel-oping countries in Asia, Africa, the Middle East and Cen-tral America. HEV was first identified by immune electronmicroscopy in feces of patients with enterically transmittednon-A, non-B hepatitis [1, 2]. Case fatality is usually low(0.53%) [3],but is especially high among pregnant women(1530%, reason unknown). Seroprevalence of anti-HEV

can reach rates of up to 40% in endemic areas. In Central

Europe it is estimated to be around 14% among the nor-mal population; a study in Munich detected 4% in a rela-tively small sample [4].Transmission of HEV occurs mostlyby the fecal-oral pathway via contaminated drinking water[5]. Parenteral infections or contact transmissions in healthcare professionals have also been observed [6].The latterare of special interest for occupational medicine in the fieldof health care workers. In general, epidemiological knowl-edge about seroprevalence, occupational and individualrisk factors for hepatitis E is very limited and a lot of ques-tions remain open [7].

Hepatitis A virus (HAV) was first isolated in 1973.Transmission of HAV is mostly fecal-oral. Seroprevalenceis closely related to general socio-hygienic living standards

and to age [8-10]. In Europe the seroprevalence has de-creased rapidly during the last decades.Values of < 10% arecurrently observed in the younger generation.Tourists andother travelers to endemic regions [1114], food handlers[1517], sewage and (probably) sewage workers [1820],and some other smaller groups are considered as riskgroups. Health care workers and personnel of day care cen-ters are also at higher risk for infections with HAV [21, 22].

Since transmission routes and geographic spread of thetwo viruses are believed to be similar, it may be supposedthat anti-HAV positive persons are more likely to be anti-HEV reactive and vice versa.

The main objective of this study was to identify (andquantify) factors associated with significantly higher anti-

HAV and anti-HEV seroprevalence (risk factors). Theother objective was to check whether the risk groups forHAV infection were the same as the risk groups for HEV

M. Nbling (corresponding author), F.Hofmann

Dept. of Applied Physiology, Occupational Medicine and Infectiology, Uni-versity of Wuppertal,FB14 Safety Engineering,Gaustr. 20, D - 42097Wuppertal,Germany; Phone:(+49/761) 82526,Fax: -83432, e-mail:[email protected]. Tiller

Medical Immunological Laboratories Munich,Bayerstr.53, D-80336 Mu-nich, Germany

Received: February 15, 2001 Revision accepted: December 4, 2001


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M. Nbling et al. Hepatitis A and Hepatitis E Seroprevalence

Infection 30 2002 No.2 URBAN& VOGEL 95

infection, determined from a contingency table of the twosets of serological results.

Materials and MethodsThe study was performed as a cross-sectional study in three hos-pitals in southwestern Germany. Enrolment was standardized byage (range: 1950 years) and profession (control group working inadministration, nurses and pediatric nurses).

Serological results for anti-HAV and anti-HEV (IgG-ELISA)titers were combined with data collected by means of a standard-ized questionnaire on basic sociodemography, individual work his-tory and travel behavior (Table 1).

Both serological results and a questionnaire were availablefor 511 Germans (all born in Germany and not vaccinated againstHAV).

StatisticsStatistical analysis was carried out by means of crosstabs withPearsons 2 statistic, analysis of variance and logistic regressionanalysis.Since the study type is cross-sectional and the outcome isnot rare (at least in the case of anti-HAV),odds ratios (calculableas:OR = eb) would overestimate the relative risks (RR, as preva-

lence risk ratios) by far and were therefore not used as an ap-

proximation of the RR [23]. Instead, the b-coefficients and theirstandard errors are given. Following the suggestions ofHosmerandLemeshow [24], the likelihood ratio test (LR) was used insteadof the Wald statistic when performing logistic regression analysis.

Results and DiscussionAs can be seen from table 2, thanks to the age-standardizedenrolment, mean and SD for age were very similar in thethree professional groups.

The overall seroprevalence of anti-HEV was 3.9%(20/511) and 28% (143/511) for anti-HAV (which included102 positive and 41 borderline results). In the following re-sults borderliners for anti-HAV are presented in a singlegroup with the positives, since analysis revealed a close sim-

ilarity between the positive and the borderline group.

Risk factorsNone of the sociodemographic factors such as age, sex,number of children or number of brothers and sisters,wassignificantly related to anti-HEV seroprevalence in a mul-tivariate model.The same was shown for the general occu-pational parameters, profession and overall years of occu-pation.

From the more detailed parameters concerning travel-ling and occupational history, two travel zones (Latin/SouthAmerica and Far East/South East Asia) and two specific oc-cupational areas, emergency admission and surgery, weresignificantly associated with higher seroprevalence (Table 3).

In the multivariate model for anti-HAV positivity, themost important factor was a dummy buildup of age. Thisseparated the persons born and growing up under the poorhygienic conditions prevailing in the first years after WorldWar II (with a very high prevalence) from the subjects bornlater, during the German economic boom (showing a lowanti-HAV prevalence). Further factors related to a higherprobability of positive serological results were the param-eters a) family size: number of brothers and sisters andnumber of children,underlining the possibility of secondarytransmission and b) travel to the La-Plata states (Argentinaand Uruguay). Of the occupational factors, the workingtime in childrens psychiatry was positively related to theanti-HAV seroprevalence (Table 4).

Correlation of Anti-HEV and Anti-HAVSince HAV and HEV are mostly transmitted in a similarway (fecal-oral), a correlation between anti-HEV- and anti-HAV test results may be presumed. According to this hy-pothesis, persons with positive anti-HAV results would bemore likely to test positive for anti-HEV and vice versa.

However, as the results in the contingency table show(Table 5), our data do not substantiate this hypothesis.Sero-logical results of anti-HAV and anti-HEV testing are not re-lated to one another, they are statistically independent.Therate of anti-HEV positivity was 3.8% among the positives forHAV and, almost equally, 4.2% for the HAV negatives.

Variable Categories for analysis

Sociodemographic factorsAge (years) 1950 (in groups of 2 years)Age dummy (years) 1940, 4150

(born close to World War II)Sex Female, maleNo. of children 0 to 5No. of brothers and sisters 0 to 14

Work related factorsProfession Administration, nurse,

pediatric nurseYears of occupation < 5, 59, 1014, > 14Occupational history Area(s) and duration

of occupation(s) in months

Travel factorsTravel during last 10 years 12 geographic world zones:

travelling (yes/no)and lengthof stay in months

Table 1Contents of questionnaire.

No. Mean (years) SD

Administration 173 33.5 9.23

Nurses 178 32.8 9.17Pediatric nurses 160 33.5 9.21Total 511 33.3 9.20

ANOVA: F = 0.28 (df = 2), eta = 0.03, p > 0.05 (0.76)

Table 2Sample and mean of age by profession.


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A general risk for the whole work-

ing sector of health care professionalsfor HAV and/or HEV infections was notfound (in Germany).However,employ-ment in certain departments or units ofnursing and pediatric nursing was asso-ciated with higher anti-HEV or higheranti-HAV prevalence rates.This was alsotrue of travel to endemic regions andsome sociodemographic factors.

In the case of anti-HEV, furtherstudies, especially in the exposed work-ing fields (e. g. endoscopy), are neces-sary to control these findings and toprovide more detailed results.

Concerning a correlation presumedbetween anti-HEV and anti-HAV onthe basis of the similar transmissionroute, no such connection could bedemonstrated.

Whether or not transmission mech-anisms other than the fecal-oral routeare responsible for these findings is un-clear.

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Predictor b SE (b) Sig (LR) df

Occupation in surgery unit (yes no) 1.6141 0.6231 < 0.05 (0.022) 1

Occupation in emergency unit (months) 0.0202 0.0078 < 0.05 (0.011) 1

Travel to Latin/South America 0.0335 0.0207 < 0.01(0.0098) 1(excluding Argentina/Uruguay) (months)

Travel to Far East/South East Asia 0.0492 0.0238 < 0.10 (0.072) 1(excluding Japan) (months)

Constant 3.6802 0.2914

Model build and fit by logistic regression analysis. Sig(LR): likelihood ratio test; borders:

p(in) < 0.05, p(out) > 0.10; model parameters: n = 511; -2LL = 147; GOF = 526;Hosmer/Lemeshow C = 3.2, df = 2, p > 0.20; model2 = 21.7, df = 4, p < 0.001;cases correctly classified (cutoff = 0.5): 96.3%

Table 3Predictors and estimation model for anti-HEV.

Predictor b SE (b) Sig (LR) df

Occupation in childrens 0.0280 0.0155 < 0.05 (0.0473) 1psychiatry (months)

Travel to the La-Plata states 0.3057 0.1604 < 0.10 (0.05) 1(Argentina/Uruguay) (months)

No. of children 0.2231 0.1032 < 0.05 (0.031) 1

No. of brothers and sisters 0.1150 0.0614 < 0.10 (0.061) 1

Age (dummy: 40 years) 1.4271 0.2345 < 0.001 (< 0.0005) 1

Constant 1.9024 0.2053

Model build and fit by logistic regression analysis. Sig(LR): likelihood ratio test; borders:p(in) < 0.05, p(out) > 0.10; model parameters: n = 508 (3 missing values for number ofchildren/number of brothers and sisters), 2LL = 529; GOF = 500; Hosmer/LemeshowC = 9.9, df = 7, p > 0.15; model 2 = 71.0, df = 5, p < 0.001; cases correctly classified(cutoff = 0.5): 73.6%

Table 4Predictors and estimation model for anti-HAV.

Hepatitis E Not reactive Reactive TotalHepatitis A n (%) n (%) n (%)

Negative 354 (96.2) 14 (3.8) 368 (100)Positive/borderline 137 (95.8) 6 (4.2) 143 (100)Total 491 (96.1) 20 (3.9) 511 (100)

2 = 0.42 (df = 1), Phi = 0.01, p = n.s. (0.838)

Table 5Serological results concernig HEV and HAV.


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