Abstract
BackgroundProgressive multifocal leukoencephalopathy (PML), a rare but fatal demyelinating disease caused by JC virus (JCV), occurs mainly in immunocompromised patients. As PML develops in individuals with various underlying disorders sporadically and infrequently, a nationwide survey of PML is difficult. This study was conducted to elucidate the characteristics of PML in Japan through an internet-assisted laboratory surveillance program.MethodsA diagnostic support system for PML was established using a real-time PCR assay of JCV DNA in cerebrospinal fluid (CSF), and requests for testing were received from clinicians via specialized websites. Medical histories of patients were collected through standardized questionnaires, and a database of CSF JCV loads and clinical information was created and analyzed.ResultsFor 4 years from April 2007 to March 2011, CSF specimens from 419 patients were tested. Forty-eight individuals were found positive for JCV DNA in their CSF and were diagnosed with PML. PML primarily occurred not only in HIV-positive patients (33.3%) but also in patients with hematologic disorders after receiving stem cell transplantation, chemotherapy, and/or immunosuppressive treatment (39.6%). The frequencies of PML cases among the subjects in these two categories were 20.3% and 23.5%, respectively. Although no significant features were observed with respect to CSF JCV loads in PML patients with an HIV infection or hematologic disorder, males were predominant in both groups (100% and 89.5%, respectively). The proportion of PML cases with autoimmune disorders (6.3%) or solid-organ transplants (2.1%) was smaller than those with HIV infection or hematologic disorders, probably due to the limited availability of therapeutic monoclonal antibodies and transplantation from brain dead donors.ConclusionsThe results suggest that the internet-assisted laboratory surveillance program might be a useful strategy for collecting precise real-time information on PML on a national level. The current database provides important background information for the diagnosis and treatment of patients with risk factors for PML.
Highlights
Progressive multifocal leukoencephalopathy (PML), a rare but fatal demyelinating disease caused by JC virus (JCV), occurs mainly in immunocompromised patients
Progressive multifocal leukoencephalopathy (PML) is a rare but fatal demyelinating disease caused by JC virus (JCV), a small DNA virus belonging to the family Polyomaviridae, genus Polyomavirus [1,2,3]
Detection of JCV DNA in cerebrospinal fluid (CSF) specimens from patients From April 2007 to the end of March 2011, 504 CSF specimens from 419 patients were submitted to the National Institute of Infectious Diseases (NIID) for testing by hospitals in 43 of Japan’s 47 prefectures (91.5%), with many requests received from the Tokyo metropolitan area and other regions with large populations (Figure 1A)
Summary
Progressive multifocal leukoencephalopathy (PML), a rare but fatal demyelinating disease caused by JC virus (JCV), occurs mainly in immunocompromised patients. Several other recent studies demonstrated the incidence of PML using national databases in the USA, such as the National Multiple Cause of Death Data system, the Nationwide Inpatient Sample, the US health insurance claims database, and the US Renal Data System [24,25,26,27]. While these database screening strategies are considered to be beneficial for the surveillance of PML, the amount of information available for each case is limited
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