Hepatitis E Virus infection and waste pickers: a case-control seroprevalence study

Whether waste pickers are a risk group for hepatitis E virus (HEV) infection is largely unknown. Therefore, this study aimed to determine the association between HEV exposure and: 1) the occupation of waste picker; and 2) the work characteristics of waste pickers. An age-and gender-matched case-control seroprevalence study of 86 waste pickers (mean age: 35.45 ± 17.15 years) and 86 control subjects of the general population was performed. We determined anti-HEV IgG antibodies in sera of cases and controls using a commercially available enzyme-linked immunoassay. The McNemar’s test was used to assess the association between HEV seropositivity and the occupation of waste picker. The association between HEV seropositivity and work characteristics of waste pickers was assessed by bivariate and regression analyses. Anti-HEV IgG antibodies were detected in 14 (16.3%) of the 86 waste pickers and in 8 (9.3%) of the 86 control subjects (McNemar’s pair test: OR = 13.0; 95% CI: 0.73-230.77; P=0.02). Ill waste pickers had a higher HEV seroprevalence than those who were apparently healthy (6/15: 40% vs 8/71: 11.3%, respectively: P=0.01). Waste pickers with reflexes impairment had a higher HEV seroprevalence than those without this impairment (5/10: 50% and 9/76: 11.8%, respectively; P=0.009). Logistic regression analysis of sociodemographic, work, and behavioral characteristics of waste pickers showed that HEV seropositivity was associated with increasing age (OR = 6.52; 95% CI: 1.95-21.78; P=0.002) and raising pigs (OR = 12.01; 95% CI: 1.48-97.26; P=0.02). This is the first age- and gender-matched case-control study on the association between HEV infection and the occupation of waste picker. Waste pickers represent a risk group for HEV infection. Factors associated with HEV seropositivity found in this study may help in the design of optimal planning to avoid HEV infection.


Introduction
between anti-HEV IgG antibodies seropositivity and: 1) the occupation of waste picker; and 82 2) the work characteristics of waste pickers.

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Study design and populations studied 86 Through a case-control study design 86 waste pickers (cases) and 86 age-and 87 gender matched control subjects without waste picker occupation (controls) were studied. 88 Inclusion criteria for enrollment of waste pickers were: 1) subjects with an occupation of 89 waste picker in Durango City, Mexico; 2) 14 years and older; and 3) who accepted to 90 participate in the study. Gender and socioeconomic level were not restrictive criteria for 91 enrollment of cases. Fifty-four (62.8%) of the waste pickers were females and 32 (37.2%) 92 were males. Cases were 14 to 76 (mean: 35.45 ± 17.15) years old. On the other hand, eating or drinking alcohol while working, and eating from the garbage. In addition, a 107 habitual washing hands before eating was recorded. With respect to behavioral data, the 108 characteristics drinking untreated water or unpasteurized milk, consumption of unwashed 109 raw vegetables or fruits, consumption of raw or undercooked meat, type of meat consumed 110 (pork, boar, rabbit, beef, goat, lamb, venison, squirrel, horse, rat, chicken, turkey, and fish), 111 consumption of sausages, ham, salami or chorizo, contact with animals, traveling, and 112 contact with soil (gardening or agriculture). As to housing characteristics, we used the 113 Bronfman's criteria [14]: number of rooms in the house, number of persons in the house, 114 availability of drinkable water, form of elimination of excreta, and type of flooring 115 (ceramic, wood, concrete, soil).

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Detection of anti-HEV IgG antibodies 118 We obtained a blood sample from each subject. Serum was obtained from the blood sample 119 by centrifugation. Serum samples were frozen at -20°C until analyzed. Detection of anti-120 HEV IgG antibodies in serum samples was performed by using a commercially available 121 enzyme immunoassay kit: "AccuDiag TM HEV IgG ELISA" (Diagnostic Automation Inc.,

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Woodland Hills, CA. USA). All assays were performed following the manufacturer's 123 instructions. housing, and behavioral characteristics of waste pickers with a P value < 0.05 obtained in 136 the bivariate analysis were selected for further analysis using regression analysis with the 137 Enter method. We calculated the odds ratio (OR) and 95% confidence interval (CI), and a P 138 value < 0.05 was considered as statistically significant.   Table 1). As to the 159 correlation of socio-demographic characteristics of waste pickers and HEV seropositivity, 160 bivariate analysis showed that HEV seroprevalence increased with age (P<0.001). Other 161 sociodemographic characteristics of waste pickers including gender, residence, socio-162 economic status or educational level did not show an association with HEV seroprevalence.

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A correlation between HEV seropositivity and sociodemographic characteristics of waste 164 pickers is shown in Table 2. Concerning clinical characteristics, waste pickers who referred 165 themselves as ill had a higher HEV seroprevalence than those who were apparently healthy 166 (6/15: 40% vs 8/71: 11.3%, respectively: P=0.01). HEV seroprevalence was comparable 167 (P=0.63) in waste pickers with a history of blood transfusion (2/9: 22.2%) than in those 168 without blood transfusion (12/77: 15.6%). Waste pickers with reflexes impairment had a 169 higher HEV seroprevalence than those without this impairment (5/10: 50% and 9/76: 170 11.8%, respectively; P=0.009). Impairments in memory, hearing and vision did not show 171 an association with HEV seropositivity. Of the work characteristics, HEV seroprevalence 172 increased with seniority (Table 3), whereas other work characteristics including history of 173 injuries with sharp material, wearing hand gloves and face masks, eating or drinking 174 alcohol while working, washing hands before eating, and eating from the garbage did not 175 show an association with HEV seropositivity. As to behavioral characteristics of waste pickers, bivariate analysis showed that raising pigs, consumption of venison, and squirrel 177 meat were associated (P<0.05) with HEV seropositivity (Table 4) showed that HEV seropositivity was associated with increasing age (OR = 6.52; 95% CI: 188 1.95-21.78; P=0.002) and raising pigs (OR = 12.01; 95% CI: 1.48-97.26; P=0.02) ( Table   189   5).

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The seroepidemiology of HEV infection in waste wickers has been poorly studied.

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There has been only one previous study on the seroprevalence of HEV in waste pickers. In 202 such study researchers reported the seroprevalence of HEV infection in waste pickers in a 203 central Brazilian city [13]. The design of their study was cross-sectional, and the 204 association between waste picker occupation and HEV seroprevalence was not determined. 205 Therefore, in the present study, using an age and gender-matched case-control design, we 206 aimed to determine the association between HEV seropositivity and the occupation of 207 waste picker. Using the McNemar´s pair test, we found that waste pickers had a 208 significantly higher HEV seroprevalence than controls. Thus, this result suggests that waste 209 picker occupation is associated with HEV infection. The HEV seroprevalence of waste 210 pickers was also associated with seniority in the activity by bivariate analysis. This result 211 further supports the association between HEV seropositivity and waste picker occupation.

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The fecal oral route of HEV infection has been described as predominant in developing