A disease or disorder that occurs due to an exposure to risk factors arising from work activities is considered an occupational disease [1]. If ignored, these diseases can cause irreparable damage to humans [2]. Butchers who are in close contact with livestock and raw meat are at particular risk of zoonotic parasitic infections such as toxoplasmosis and hydatidosis [4, 5].
This study observed a significant higher anti-T. gondii IgG seroprevalence in the case (52.8%) than control (32%) group (p = 0.001), but seropositivity for anti-T. gondii IgM in the case group was insignificant, as compared to the control group (p = 0.098). A possible reason for the high prevalence of anti-T. gondii IgG could be the butchers’ lack of knowledge about the nature of parasitic infections and occupational diseases and the route of their transmission.
In the present study, two of several important risk factors for toxoplasmosis in butchers were age and work experience. Owing to the longer period of exposure to risk factor, raise in the probability of toxoplasmosis among butchers was not unpredictable with increasing age and work experience. In our study, butchers had a constant and easy access to meat and their preference was to eat half-cooked meat; therefore, these two factors became significant risk factors in the occurrence of toxoplasmosis in butchers. Other risk factors for toxoplasmosis in our study include butchers’ education level, their contact with cats as one of the most important sources of toxoplasmosis, consumption of unboiled milk, and contact with soil. Other seroepidemiological studies have suggested similar findings in people occupationally exposed to livestock. A study from Portugal has reported an anti-T. gondii IgG seroprevalence of 75.8% for butchers and slaughterhouse workers compared to 60.1% in the control group. Similar to our study, researchers have identified that the aging of butchers is a reason for this high prevalence of toxoplasmosis [19]. This observation has also been found in the Central India, with an anti-T. gondii IgG seroprevalence of 48.4% in slaughterhouse workers and butchers vs. 6.6% of the general population. Some major reasons for the high prevalence of toxoplasmosis among butchers aged > 30 years are cat contact, wearing gloves, and contact with soil [20]. In another similar research, Alvarado-Esquivel and colleagues introduced the years spent as a butcher as a potential risk factor for toxoplasmosis [21]. In additional similar study conducted among the butchers of Sanandaj City, the west of Iran, eating while working and wearing gloves were the most significant risk factors for toxoplasmosis in butchers [5]. A study in the Northeast of Iran in Mashhad City among slaughterhouse workers demonstrated increasing age of workers and work duration as the potential risk factors for toxoplasmosis [4]. In a comparable study conducted in Khuzestan, the southwest of Iran, on butchers, Mardani et al. presented 48.8% anti-T. gondii IgG in butchers vs. 28.8% in the control group, and attributed this high prevalence to the work experience of the butchers, which was in line with our results [22]. The common point of our study and all the mentioned studies is the high prevalence of anti-T. gondii IgG antibodies among butchers compared to controls. Although our results are in conformity with various studies, some researchers have shown different conclusions. In a study conducted by Thiong’o et al. in Kenya, no significant differences were found in the seropositivity of T. gondii IgG antibody among slaughterhouse workers and butchers compared to the general population [23], likely due to applying methods with variable sensitivities. Despite all the aforesaid interpretations, the relative importance of the risk factors varies between cities and countries due to differences in cultural patterns and environmental factors. In general, the prevalence of the infection varies depending on the epidemic area, socio-cultural behaviors, and geographical and climatic factors.
To our knowledge, this is the first case-control study reporting the prevalence of anti-hydatidosis IgG in butcher in the northwest of Iran. In this study, we indicated significantly higher anti-hydatidosis IgG antibody seroprevalence in butchers (10/8%) of Tabriz City compared to the controls (0/0%). Among risk factors investigated herein, education level, age, contact with dogs, contact with soil, and consuming unwashed vegetables were statistically significant factors for hydatidosis seroprevalence in butchers of the stated city. This outcome was predictable given that with increasing the age of butchers, the risk of hydatidosis raises because of the slow development of hydatid cyst in intermediate hosts and humans. In addition, the lower level of education in butchers, the lower awareness of contacting parasitic and infectious diseases and the higher exposure to the infections. A number of studies have confirmed our results. In a study conducted in Pakistan, Alvi et al. found that 9.61% of the samples were seropositive for anti-IgG hydatidosis in butchers. They have also observed that contact with dog, age > 30 years, formal education levels, and work experience for > 10 are the main reasons for the high prevalence of hydatidosis in butchers [16]. A similar investigation among slaughterhouse workers revealed a 5.5% anti-IgG hydatidosis seroprevalence in Mashhad [4]. In another study in India, the prevalence of hydatidosis among butchers who were arguably at the potential risk of being infected with the disease was reported as 15.4% [24]. Asadi’s investigation in Urmia, the northwest of Iran, the same as our study, showed that the consumption of unwashed vegetables is the main risk factor for hydatidosis [18]. The study by Sakhaei et al. in Jolfa County, the Northwestern Iran, displayed that consumption of unwashed vegetables and contact with dogs were more seropositive for hydatidosis [15]. Results of our study displayed that occupation remains a significant factor in the epidemiology of hydatidosis and suggested butchers as one of the main occupational risk groups for hydatidosis. Of note, anti-hydatidosis IgG seroprevalence in the control group of this study (0/0%) was lower than that of some other studies [15, 25], mainly due to enhancing knowledge of people about zoonotic diseases and prevention measures, or it is likely related to the large number of their samples.
Butchers were positive and negative for both parasitic infections, and no significant relationship was observed between toxoplasmosis and hydatidosis positivity. This result of our study is consistent with those of Yousefi et al.’s investigation in Mashhad that reported 3 (3.3%) and 36 (39.6%) slaughterhouse workers were respectively positive and negative for both infections, and there was no significant relation between toxoplasmosis and cystic echinococcosis positivity [4]. Butchers are among at-risk occupations regarding parasitic infections, including toxoplasmosis and hydatidosis. This group is in close contact with meat and livestock as a source of contamination. Therefore, butchers should be given the necessary equipment and training to change the process of preparing meat for sale from manual and traditional to industrial and automatic methods, which will reduce the exposure to raw meat. Owing to financial and time limitations, we performed limited sensitivity tests to confirm positive cases. Additional studies with more sensitivity tests could manage this concern.