Study to Determine the Hepatitis C Virus Infection Prevalence Among Patients Attended Primarily for Vasculitis and Other Potential Extrahepatic Manifestations

1. Introduction.

The prevalence of Hepatitis C determined by serological test to detect antibodies against the hepatitis C virus (HCV) is around 1.4% in Mexico, being slightly higher in the north (2.0%) than in the south (1.5%). ) and the entities of the center (1.1%) of the country. However, there are high risk groups where the prevalence is much higher, for example, among intravenous drug users such as heroin, it is estimated that prevalence of hepatitis C is as high as 11.7%, with an interval ranging from 2.7 to 39.1% .

Recently, the Global Prevalence study of HCV - Polaris Observatory at American Association for de the Study of Liver (AASLD), has documented that the prevalence in Mexico determined by viral load quantification (which is the most specific study) ranges from 0.0 to 0.6%, being higher in the North, than in the Center and in the South of the country.

Although it is classically considered that chronic hepatitis C infection (CHC) is usually asymptomatic, there are studies that show that up to two thirds of patients may present some type of extrahepatic manifestation. The most frequent extrahepatic manifestation is type II mixed cryoglobulinemia (MCG-II) and clinically the most common presentation is leukocytoclastic vasculitis (LCV) with palpable purpura that affects the lower extremities. It is estimated that up to 80% of MCG-II cases are due to CHC. The prevalence of CHC infection has been reported in higher numbers in patients with LCV than in the general population. A multinational study in 2009, found that the prevalence of anti-HCV antibodies specifically in patients consulting for "autoimmune diseases" was as high as 8.7%, compared to healthy subjects (general population) where it was 0.4%. In this study, the diagnosis of CHC with determination of viral load or genotype was not confirmed.

In another study, conducted in Brazil, which included 367 patients with rheumatological diseases, the prevalence of CHC, confirmed with viral load determination, was 1.9%, also higher than that reported in the open population in that country. The difference remarkable in the prevalences reported by serological tests and by viral load, particularly in patients with autoimmune diseases, can be explained because patients with autoimmune diseases have autoantibodies that can generate cross reactions and result in false positives, for this reason, in the presence of a positive result in these tests, must always be confirmed with the gold standard that is the quantification of viral load. 2. Research question.