Genotype 3(G3) infection is the predominant type in South East Asia (Bangladesh, Pakistan, India and Sri Lanka). In addition, because of the "promiscuous exposure" to hepatitis C amongst injection drug users, it is not unusual for the latter to be infected with G3 as well. There are several subtypes of G3. Viral genotype has long been recognized as a major factor influencing the response to interferon-based therapy. Patients infected with G2 and G3 respond much better to current therapy with peginterferon and ribavirin than those infected with G1 and G4. Most studies have grouped patients with G2 and G3 together, with few published comparisons of rates of viral clearance between these two favourable genotypes.