Long-Term Survival, Morbidity, Social Functioning and Risk of Disability in Patients with a Herpes Simplex Virus Type 1 or Type 2 Central Nervous System Infection, Denmark, 2000-2016

Background: The long-term prognosis following herpes simplex virus (HSV) central nervous system (CNS) infection is still debated. Patients and Methods: We examined outcomes in all Danish residents who, during 2000-2016, tested PCR positive for HSV-1 (n=208) or HSV-2 (n=283) in the cerebrospinal fluid, compared to comparison cohorts from the general population (n=2080 and n=2830). Results: One-year mortality was increased among HSV-1 patients (difference 19.3%; 95% CI: 13.6% to 25.0%) and HSV-2 patients (difference 5.3%; 95% CI: 2.5% to 8.1%), but thereafter mortality was not increased. After exclusion of persons diagnosed with cancer prior to study inclusion, one-year mortality difference for HSV-2 patients was 1.7% (-0.1% to 3.5%). After five years, HSV-1 patients had lower employment (difference -19.8%; 95% CI: -34.7% to -4.8%) and higher disability pension rates (difference 22.2%; 95% CI: 8.4% to 36.0%) than the comparison cohort, but similar number of inpatient days, outpatient visits, and sick leave. HSV-2 patients had employment and disability pension rates comparable to the comparison cohort, but more inpatient days (difference 1.5/year; 95% CI: -0.2 to 3.2), outpatient visits (difference 1.3/year; 95% CI: 0.3 to 3.2), and sick leave days (difference 9.1/year; 95% CI: 7.9 to 10.4). Conclusion: HSV-1 and HSV-2 CNS infections differ substantially with respect to prognosis. HSV-1 CNS infection is followed by increased short-term mortality and long-term risk of disability. HSV-2 CNS infection has no substantial impact on mortality or working capability but is associated with increased morbidity.