Hepatitis C virus (HCV) is a major cause of liver-related morbidity and mortality worldwide, with an estimated global prevalence of 170 million chronic infections. HCV-induced liver disease is the most common indication for liver transplantation and it has emerged as a leading cause of death among hospitalized HIV-infected patients treated during the HAART era [1
]. Transmission of HCV is known to occur through contact with contaminated blood, most notably in the context of injection drug use, transfusion of blood products prior to 1992, chronic hemodialysis, occupational exposure to blood, and nosocomial and perinatal exposure. In addition, several studies have reported low levels of suspected sexual and household transmission of HCV [2
Although much is known about the routes of HCV transmission, nearly 15% of infected individuals report no identifiable source of exposure. Unexplained cases are particularly high among drug-users who have no history of injection risk and no other identifiable risk factors [3
]. One hypothesis that might account for the high number of unexplained HCV infections among noninjection drug-users was proposed by researchers at the US National Institutes of Health (NIH), who identified intranasal cocaine use as a significant risk factor for HCV among volunteer blood donors [4
]. They reasoned that HCV might be transmitted through contaminated implements, such as straws or spoons, that are commonly used to nasally inhale powdered drugs, including heroin, cocaine, and methamphetamines. Chronic nasal inhalation of these substances (including the adulterants they contain) can cause tissue deterioration and bleeding of nasal membranes. Implements inserted into an eroded nasal cavity may come into contact with HCV-infected mucus or blood, which may then be transmitted to an uninfected individual sharing the same implement. The debate regarding this potential mode of transmission intensified when the National Heart, Lung and Blood Institute (NHLBI) Retrovirus Epidemiology Donor Study (REDS) was unable to confirm intranasal drug inhalation as an independent risk factor for HCV [5
]. These conflicting reports prompted the American Association of Blood Banks (AABB) to add, and then shortly thereafter remove, intranasal cocaine use from their list of criteria used to screen potential blood donors. A subsequent review of the literature found serious methodological limitations with both the NIH and NHLBI/REDS studies [6
]. Although HCV has been detected in the saliva, semen, and other nonserological fluids of some plasma-positive patients [7
], no virological studies have been undertaken to determine whether HCV is present in the nasal secretions of intranasal drug users, a necessary precondition for internasal viral transmission. Here, we report preliminary findings on the detection of HCV RNA in the nasal secretions of plasma-positive chronic drug sniffers.