Which is the real genotype distribution of hepatitis C virus infection in Mexico?

Few years ago the distribution of hepatitis C virus (HCV) genotypes in Mexico was unknown. An important exception is the study written by Alvarado-Esquivel et al in 1998. That study reported results of 516 blood donors from 21 states obtained in two referrals blood-banks, and 235 patients with liver disease from the States of Mexico, Jalisco, Michoacan and Oaxaca. 1 In the last year four studies on this topic were published in different journals, even one in Annals of Hepatology. 2 These new studies intended to obtain «national representativeness». The genotypic variability of HCV has implications that included differences in pathogenecity, 3,4 sensitivity of diagnostic techniques, 5 response to treatment, and vaccine efficacy. 6 For this reason it's important to review the methodology used in each study, and their findings (consistencies and inconsistencies). Afterwards, it will be possible to define a better picture of the genotype distribution of HCV in Mexico. In this sense, it is important to remember that, in addition to clinical objectives for each infected patient, from a public health perspective the occurrence recognition of a disease is one important step to identify and promote preventive strategies, and define cost-effectiveness treatments. In this letter we want to analyze briefly the methodology used in these papers, and propose a national distribution of HCV genotypes. The first study was written by Chiquete & Panduro. 7 In this study they carried out a systematic review of studies indexed in Medline, Imbiomed, MedicLatina, Artemisa and Medigraphic databases. The authors found three articles with information on genotype distribution in Mexico, two of them were multicenter studies. One of these two latter studies is also an abstract from the Dehesa-Violante et al study. To obtain a unique estimator to each genotype we calculated the mean of these three observations since the homogeneity of data included. Sánchez-Avila et al included in their study patients infected with HCV (n = 1 390) from different regions of the country (2003-2006), previous to receive antiviral treatment. The biological samples were analyzed in the 2 The study by Dehesa-Violante et al, reported the genotype distribution of patients from 22 hospitals of some Mexican cities 10 reported the findings of a new systematic review. The search was realized in PubMed, MedicLatina, Imbiomed, Medigraphic, and Scielo databases. Data were extracted from 11 studies with asymp-tomatic and high-risk subjects. Given the relative homo-geneity of data, we summarized the information with the …