PTH - Preemptive Treatment for Herpesviridae

Inclusion Criteria: * mechanical ventilation \> 96 hrs and expected duration of mechanical ventilation of at least 2 days * positive blood CMV PCR (500 IU/ml) OR positive oropharyngeal HSV PCR * age \> 18 years * informed consent * negative pregnancy test Exclusion Criteria: * \< 18 years * Receiving ganciclovir or aciclovir or another antiviral agent active against HSV/CMV * Had received antiviral agent active against HSV/CMV during the previous month * Hypersensitivity to aciclovir/ganciclovir * Pregnancy * Breast feeding * Bone marrow failure * Solid organ recipients * Bone marrow recipients * HIV positive patients * Receiving immunosuppressive agents * SAPS II \> 75 * Withdrawing/withholding * Neutropenia (\< 500 mm3) * Thrombocytopenia (\< 25 G/L) * ICU readmission