A 44-year-old male patient was admitted in the Radiotherapy Unit, in February 2012, due to a nasopharyngeal carcinoma. Subsequently, due to the occurrence of severe respiratory failure and epileptic manifestations (seizures), the patient was admitted to the Intensive Care Unit of the same hospital. The patient required prolonged mechanical ventilation and shown persistent elevated temperature (38-39°) and a continuous worsening of clinical symptom during the entire hospitalization. The patient did not present any significant cardiovascular or respiratory pathology in the anamnesis, but the only relevant data was the periodic manifestation of herpetic lesions from HSV-1, with a recurrence of one episode per year. During the entire stay in ICU, there was any kind of sign or typical herpetic macroscopic lesion. Blood tests showed the presence of 12,600 WBC (cells / mm3-93% neutrophils, 4% lymphocytes, 3% monocytes), 3,610,000 RBC / mm3, 138,000 platelets. A useful laboratory test was the monitoring of procalcitonin: lower values  under the cut-off supported the hypothesis that the diagnosed bronchopulmonary infection was of viral etiology. The clinical evaluation of the patient was integrated performing 3 chest RX within a week: the first two RX showed unilateral opacities with ground glass and diffuse areas of consolidation; moreover, a modest pleural effusion was found. The third radiogram reported slight improvements.

An encephalic RMN was also performed: the images showed several areas of "edemigenic encephalitic suffering", such as the mesial cortical-subcortical region of the temporal lobes, the hippocampal area, the anterior frontal region (across the cortical region), the ethmoidal cavity and the anterior frontal-basal white matter. All these radiological findings were confirmed by TC (Figures 1-4).

The diagnostic investigation concerning the presence of HSV-1 continued by the examination of different samples of BAL and CSF, analyzed at the Clinical Virology laboratory of the same hospital as (Figure 5) shows.

BAL and CSF were negative for bacteria, mycobacteria and fungi. The patient's general condition progressively worsened until exitus, which occurred 18 days after hospitalization.

We reported the clinical case of a 44-year-old patient who presented, during his hospitalization, severe respiratory failure associated with epileptic manifestations. Through the analysis of several samples of BAL and CSF, our clinical investigation reported an infection of the lower airways supported by HSV-1; in addition, the virus was found in CSF samples [13-15]. The presence of viral DNA was collected in different regions and supported the hypothesis of a disseminated infection. CNS dissemination can be explained by two different theories: the first is represented by the viral distribution through the blood stream [16]. The second one could involve the reactivation of a latent infection and consider the neurotropism of herpesviridae and their transneuronal directional diffusion capacity through the synapses, interesting the sympathetic and parasympathetic nerve system [8]. On the basis of our results, in this case we consider the first hypothesis more plausible, that is the one that suggests the dissemination of the virus, from the lungs to the CNS, through the circulatory stream. By using PCR, the detection of HSV-1 in peripheral blood may be associated with either a primary infection or an exogenous or endogenous reinfection in a severely immunosuppressed patient. The clinical manifestations that can occur when HSV-1 is found in the blood are symptoms of CNS, as an alteration of mental status. As reported by Berrington, et al. [17], in 46% of patients presenting mental state alterations, the presence of HSV-1 was identified in the cephalic-rachidian liquor, after a finding in the blood stream. 

In the clinical case described, the patient, positive for HSV-1, belonged to the category of subjects with a risk of exitus of 40% [5], due to the immunosuppression and severity of the underlying disease: factors that could favor an endogenous reactivation of the virus. Furthermore, the fact that the patient has been supported to prolonged mechanical ventilation increases the probability of the occurrence of respiratory infection by HSV-1, in agreement with what has been stated by several Authors: a prospective study demonstrates the presence of HSV-1 in the lower airways 64% of critically ill patients enrolled [12]. A hypothesis that we believe is plausible by comparing a study of Deback, et al. [18] is that the oral cavity represents an important reservoir of HSV-1: in this way, following a state of immunosuppression of the patient, the virus can reactivate and spread from the oropharynx to the lower airways. In immunocompromised patients subjected to mechanical ventilation, the diagnosis of HSV-1 pneumonia can be considered both as a possible triggering factor of important neurological sequelae and as an indication of worsening of the patient's clinical condition: both correlate with bad outcome. The finding of different positivity for HSV-1, in the various samples of BAL and CSF examined, allowed the start of a specific treatment by Acyclovir, despite which, the patient's condition worsened until the exitus: the reasons for the failure therapeutic may be due to resistance to acycovir [19]. The final considerations require a careful reflection on some concepts, hoping for further study, investigation and analysis.

The intensive care units apply daily numerous microbial screening protocols, especially bacterial and mycotic; viral ones also assume primary importance, but not for all pathogens belonging to this category, such as herpesviridae. HSV-1 assumes a primary role in many respiratory and neurological diseases: it mainly involves immunosuppressed subjects and in which numerous pathologies coexist; critically ill patients in intensive care units and subjected to long period mechanical ventilation. We wonder if it is not appropriate to update "our" clinical research, with the development of modern and adequate research protocols for HSV-1. Not only would the diagnostic techniques be refined for numerous pathologies that still require further investigation but would significantly increase the level of clinical-diagnostic surveillance. It would increase an early and appropriate therapy administration, reducing the rate of complications and the risk of mortality. Management of critical patients, as well as their outcome, will be affected by considerable improvement.