In this analytical, population-based study, adults over 15 years old in urban and rural areas of Chaharmahal and Bakhtiari comprise the sample population. With confidence interval 95%, relative error 25%, and 800000-individual population of the area under study, 3000 individuals were enrolled. The method of sampling was clustered, consisting of 50 60-individual clusters (32 urban, 18 rural). The inclusion criteria were 15 years and older, and consent to participate. The written consent to enter into the study was obtained from the participants to fill out the questionnaire, to take blood sample, and generally to observe research ethics. This study has ethics code of 90-2-6/1 of Ethics Committee of the University. Notably, the sample considered in the present study is similar to another study simultaneously approved with similar protocol and ethics code [23].

Three separate teams were formed for interview, blood sample taking, and laboratory to implement the study. Firstly, interview team referred houses, explained the purpose of the research project, and questioned the presence of qualified individual(s) in the house. If the answer was yes and the individual was consent to participate, the researchers asked him/her to fill out the questionnaire. For seroprevalence of hepatitis, two consecutive tests, HCV Ab and western blotting were used. By this way, to confirm the test, positive HCV Ab samples were further investigated by western blotting and the confirmed samples by western blotting were considered as hepatitis C-positive. HCV-Elisa was run with Dia-Pro kit (Italy) and western blotting with MP kit.

Having entered the data into SPSS19 software, we did data analysis using descriptive parameters, and chi-square and Fisher’s exact test, and then significant factors in univariate analysis were entered into logistic regression model to eliminate probable confounding factors. The level of significance was considered 0.05.

Mean age of the participants was 38.4±16.3 (range: 15-90) years old. 63% were female and 75% married. Initially, 40 of 3000 were HCVAb-positive and after running western blotting, HCVAb-positive cases declined to 27. Therefore, the prevalence of HCVAb was obtained 1.4% (95% CI, 0.95-1.7) and positive hepatitis C prevalence by western blotting was 0.9% (95% CI, 0.65-1.3).

The highest prevalence was obtained in Kiar and Ardal Counties (respectively 2.08% and 1.66%) and no positive western blotting was derived in Lordegan and Farsan [Table/Fig-1]. The prevalence in men was obtained 1.2%, two times higher than the prevalence in women. The highest prevalence (2.12%) was obtained in 35-44 years old population followed by 25-34 years old (0.9%) and 45-54 years old (0.8%) populations. The prevalence in married individuals was obtained 1.22%, two times higher than the prevalence in single individuals. The prevalence in Fars ethnicity (1%), civil servants (1.9%), non public occupations (1.58%), and the jobless (1.07%) was higher than others. The prevalence in cities (0.8%) and villages (0.7%) was approximately similar. For education, the highest prevalence was obtained in those able to read and the illiterate (1%) and as the education grew higher, the prevalence decreased [Table/Fig-1].

Chi-square indicated that out of the risk factors and the factors contributing to the transmission, history of hospital stay and jaundice, first degree relatives infected with HCV, and history of blood transfusion, tattoo, outpatient surgery, contact with hepatitis-infected individuals, imprisonment, intravenous (IV) drug abuse, and smoking were significantly associated with the disease prevalence. The highest odds ratio was obtained for history of IV drug abusers (OR=38.2, 95% CI, 14.06-103.9) followed by imprisonment (OR=8.9, 95%CI, 2.97-26.6) [Table/Fig-2]. However, by logistic regression (enter model), out of the above factors, only history of IV drug abuse was obtained as significant (p< 0.05).

In this study, the prevalence of HCV Ab was obtained 1.4% and that of positive hepatitis C by western blotting was obtained 0.9% in Chaharmahal and Bakhtiari. The prevalence of hepatitis C has been already studied in high risk populations, but few studies have been conducted as population-based. A population-based study investigated prevalence of hepatitis C in three provinces in northern, central, and southern Iran; the general prevalence was reported 0.5%, and the prevalence in Golestan 1%, in Tehran 0.3%, and in Hormozgan 1.6% [20]. In a population-based study in Amol (Mazandaran province), the prevalence of hepatitis C was obtained 0.05% [21], and in another study in Zahedan 0.5% [22].

By the findings of a study, the prevalence of hepatitis C, similar to hepatitis B, was heterogenous and varied depending on cultural, ethnicity-related conditions and lifestyle among provinces [24]. Although the population-based prevalence of hepatitis B in Chaharmahal and Bakhtiari has been already obtained 1.3% [24], which is lower than national prevalence, but hepatitis C prevalence was higher than the general, national prevalence obtained in Merat et al., study [20]. Therefore, it seems that hepatitis C is being replaced as and turned into the most prevalent chronic, viral hepatic disease, which highlights greater emphasis on and necessity of appropriate planning for preventing, treating, and controlling it. This has been already confirmed by some studies in Iran and other countries [8,20].

In the present study, the prevalence was twice higher in men than women, which is consistent with most studies in Iran and other countries, and possibly attributable to more risk factors in men. The highest prevalence was obtained in 35-44 years old population followed by 25-34 years old and 45-54 years old populations. In similar studies, the prevalence was higher in older populations, as well [8–12]. The prevalence was obtained higher in married individuals than single, and lower in Turk and Lor populations than Fars. This could be due to different lifestyle and less frequent high risk behaviors. Study of the association between ethnicity and hepatocellular carcinoma could be helpful in this regard.

The occupations most involved were non-public, civil servants, and jobless. The prevalence was not much different between cities and villages. In a study in Pakistan, the prevalence was obtained higher in 20-49 years old population and was not different between men and women. The prevalence has been already reported higher in married individuals, the individuals with public and outside home occupations and low socioeconomic status [13], consistent with the present study. The prevalence was higher in the individuals with the education level lower than diploma. In other similar investigations, consistent with the present study, the prevalence was less in the individuals with higher education [8–13], which is due to enhanced knowledge, attitude, and practice in these individuals.

Out of the risk factors and the factors contributing to the transmission, hospital stay history, first degree relatives infected with HCV, and history of blood transfusion, tattoo, outpatient surgery, contact with hepatitis-infected individuals, imprisonment, IV drug abuse, and smoking were significantly associated with disease prevalence, which is consistent with other studies [5–20]. However, by logistic regression, only history of IV drug abuse was yielded as significant. Probably, imprisonment and smoking were not significant in the model due to association with IV drug abuse. In study of Iran’s three provinces, imprisonment and IV drug abuse were the main factors in the model [18]. In study of Amol, Mazandaran province, unsterile puncture and infection in first degree relatives were obtained as the main risk factors in the model [19], but in study of Zahedan, none of the risk factors were obtained as significant in multivariate analysis [20]. In this province, the highest odds ratio was obtained for IV drug abuse, so IV drug abuse seems to be the main factor. But, difference in ethnicity and probable effect of lifestyle should be considered, as well.

It seems that hepatitis C is growing as the most prevalent chronic, viral hepatic disease. Further consideration of risk factors and routes of infection transmission is crucial for appropriate planning for, and preventing, treating, and controlling hepatitis C. IV drug abusers as the most important group need special consideration and surveillance in order to cut infection chain and decrease the disease incidence.