Increase of sexually transmitted hepatitis C virus in HIV+ men who have sex with men in Barcelona, Spain. A problem linked to HIV infection? by Manzanares-Laya, S, García de Olalla, P, Garriga, C, Quer, J, Gorrindo, P, Gómez, S, Rodríguez-Frias, F, Plasencia, V, Carcia-Cehic, D, Gregori, J, Solà, R, Barberà, M, Esteban, J, Caylà, J