Infection by genotype 5a of HCV in a district of southeast Spain

TO THE EDITOR: Hepatitis C virus (HCV) is the most frequent cause of chronic liver disease in Western Europe. There are different viral genotypes of HCV; the most common are 1b, 1a, and 3, with the last type especially prevalent among i.v. drug abusers (1). The infection by genotype 5a is very infrequent in Western countries, and this viral type seems to be confined to South Africa (1–3). We noted in our district an unusually high rate of patients infected by this viral genotype. The district of L’Alcoià i el Comtat is located in the interior of the province of Alicante, in southeast Spain, with a population of 134,652 inhabitants and only one hospital. We have reviewed all HCV genotyping of patients in the district and evaluated clinical and epidemiological characteristics of patients with genotype 5a. HCV genotyping was carried out in all patients using a commercial single polymerase chain reaction (Amplicor, Roche Diagnostics, Basel, Switzerland) and a reverse hybridization system of the amplified product (Innolipa, Innogenetics, Zwijnaarde, Belgium). Both procedures were performed and interpreted according to the recommendations of the manufacturers. In three patients we carried out a phylogenetic analysis through sequentiation of genomic fragments in the NS5b region of HCV. HCV genotyping was carried out in 486 patients, between June, 1986 and September, 1999. Fifty of these patients were infected by genotype 5a (10.3%). The distribution of genotyping other than 5a was similar to that in other Spanish and European reports (4–6), with a clear predominance of genotype 1b (Table 1). The patients infected by genotype 5a had a mean age of 63.4 12.6 yr (range 26–89); 54% were male. Seventyeight percent of patients had chronic hepatitis and 22% were in the cirrhotic phase of their liver disease. Two patients had a hepatocellular carcinoma. The mechanism of infection was unknown in 80% of patients infected with genotype 5a, 16% acquired the infection by blood transfusion, and only one patient was an i.v. drug abuser. Eighty-four percent of the patients live in Alcoy, the largest city in the area, but this city has only 43% of the inhabitants of the district. Phylogenetic analysis of HCV genomic fragments in three patients revealed differences in genetic sequences, thus discarding the possibility of the existence of only one, recent source of infection. We have also evaluated HCV genotyping in other districts of the same province. This genotyping was performed in the same laboratory and with the same procedures described above. In 1084 HCV genotypings, only five patients were infected by genotype 5a (0.4%). Distribution of genotypes was similar to those reported in other Spanish and European articles (4–6). In summary, we have found a noteworthy rate of infection by this rare HCV genotype, clearly higher than the one found in adjacent districts. The majority of the cases have been seen in only one town, in a higher percentage than expected for its size. The infection was more prevalent between old people. A high percentage of genotype 5a infections were from unknown origin, more than expected in the general population, which fluctuates around 40% (7). Sequentiation of HCV genomic fragments in three patients discards a common and recent source of infection, but we cannot discard a common source of infection that occurred many years ago. An unexpectedly high prevalence of other HCV genotypes was reported in other regions of Europe (8, 9); however, to our knowledge a prevalence of genotype 5a that high is not known outside of South Africa. It is necessary to perform an epidemiological study to clarify the special characteristics of HCV infection in this area of southeast Spain.