Date Published: October 19, 2018
Publisher: Public Library of Science
Author(s): María de la Luz Martínez-Rodríguez, Luis A. Uribe-Noguez, Carla I. Arroyo-Anduiza, José Antonio Mata-Marin, Gamaliel Benitez-Arvizu, María L. Portillo-López, Alicia Ocaña-Mondragón, Yury E Khudyakov.
The circulatory system is the main mechanism for transmission of the Hepatitis C Virus (HCV). A new class of HCV infections, Occult HCV infection (OCI), is defined as the presence of HCV-RNA in hepatocytes with the absence of HCV in the serum/plasma utilizing current laboratory assays. Different groups have reported the prevalence of OCI; however, its associated risk factors have not been established. In Mexico, there are no reports about OCI, so the objective of our study was to determine the prevalence of OCI in total blood donors in Mexico City, as well as its associated risk factors.
Blood donors that were considered eligible for donation, according to NOM 253-SSA1-2012, were randomly selected. Demographic data was collected from 1,037 donors. Plasma and peripheral blood mononuclear cells were assessed for HCV-RNA. The presence of HCV-RNA was determined by nested PCR for the 5′-UTR region. Logistic regression was used to calculate the odds ratio (OR) and 95% confidence interval (95%CI) to determine the level of association.
The prevalence of OCI was 3.4% among blood donors. Homosexual relationships (OR = 5.52, 95%CI: 1.53–19.92, p<0.05) and acupuncture (OR = 3.56, 95%CI: 1.41–8.98, p<0.05) were significantly associated with OCI. There is a significant presence of OCI in the blood donor population in Mexico City. The main risk factors for OCI transmission are homosexual relationships and acupuncture. This study supports the increased use of sensitive and specific screening tests for blood bank testing.
Chronic Hepatitis C Virus infection (CHC) is a world health problem, affecting more than 71 million people and causing about 500,000 deaths each year. It is estimated that, in 2015, there were 1.75 million new Hepatitis C Virus (HCV) cases [1,2]. In Mexico, the prevalence of HCV infected persons is estimated to be 1.4% of the total population. Interestingly, blood transfusions are one of the most frequent risk factor for developing HCV infections [3,4].
Originally, 1,050 blood donors agreed to participate. Eleven donors were identified to have other comorbidities: 2 were positive for HIV by serology, 3 were positive for anti-HCV but were negative for NAT, 1 was positive for anti-HBV, anti-HIV, and anti-HCV, 2 were positive for T. cruzi, and 3 donors to T. pallidum. Thus, these blood samples were removed from the cohort, according to Mexican regulations. Two donors withdrew from the study for unspecified reasons. Of the remaining 1,037 samples, the prevalence of OCI for the study population was 3.4%. The demographic data of the cohort are shown in Table 1. Even though there were almost double the numbers of males (n = 707) than females (n = 330), there was no difference in the distribution of OCI positive cases. When the donors were stratified into age groups, there were no differences in the distribution of OCI positive cases. Interestingly, neither sex nor age was considered factors influencing OCI.
Hepatitis C is a global health problem and transfusion of contaminated blood products is one of the most important mechanisms for its transmission. In Mexico, voluntary donation is rare and more than 90% of the population that goes to a blood bank are family or replacement donors . One of the main objectives of a blood bank is to provide safe, pathogen-free blood. Even though NAT is a highly sensitive molecular technique used to detect plasma HCV-RNA, it is unable to detect the presence of HCV-RNA in PBMCs and consequently OCI. Here, we performed a search for HCV-RNA in plasma and PMBCs using highly sensitive molecular techniques, RT-PCR and nested PCR. With our system, we observed a sensitivity of about 50 genome equivalents (6 IU/mL) in about 70% of patients with OCI [23,24]. The remainder of patients had HCV genome equivalents less than 6 IU/mL, which would present a non-infectious state. Using these techniques, we identified 35 blood donors that were positive for OCI out of 1,037 blood donors that were negative for the detection of serum HCV-RNA or anti-HCV. Therefore, we presumed the OCI prevalence in Mexico City to be 3.4%, which is remarkably higher than the prevalence of HCV-infected persons (1.4%). The Mexican prevalence of OCI is noticeably high, considering that the study population is a random population of individuals, who believe themselves healthy. Our results are similar with reported prevalences in blood donor populations from Egypt (5.7%) , China (2.2%)  and Spain (2.1%) .
In Mexico, no previous studies have been conducted to establish the prevalence of OCI in blood donors. Based on our results, we can conclude that the prevalence of OCI in blood donors in Mexico City is high (3.4%) and is not being detected in blood banks by standard procedures. The main risk factors for OCI transmission are homosexual relationships and acupuncture. The detection of OCI in blood banks can significantly reduce the spread of HCV infections, thus significantly reducing medical costs for the care and treatment of patients with CHC. The detection of OCI is important, not only in blood banks but also in molecular biology laboratories, where the presence of HCV is monitored in liver transplant patients, dialysis patients, multi-transfused hemophiliacs, and in patients who, after having reached sustained viral response (SVR), have relapsed [31,32].