Paediatric Virology and its interaction between basic science and clinical practice (Review)

Mammas, Ioannis N.; Greenough, Anne; Theodoridou, Maria; Kramvis, Anna; Rusan, Maria; Melidou, Angeliki; Korovessi, Paraskevi; Papaioannou, Georgia; Papatheodoropoulou, Alexia; Koutsaftiki, Chryssie; Liston, Maria; Sourvinos, George; Spandidos, Demetrios A.

Viral infections can invade the cNS of children, spreading into the peripheral nervous system (PNS) and more rarely into the CNS (88) . The CNS is protected by effective immune responses and multi-layer barriers; however, some viruses enter the CNS with efficiency via the bloodstream or by directly infecting nerves that innervate peripheral tissues, resulting in immune-mediated pathology (89) . Viral infections of the cNS more often cause meningitis, characterised by a high fever, headaches, vomiting, photophobia and neck stiffness and encephalitis, which appear with clinical evidence of neurological dysfunction, such as altered mental status, seizures, behavioral changes and focal neurologic signs (90) . Other clinical manifestations are myelitis, characterised by weakness, bladder dysfunction, flaccid paralysis and reduced or absent reflexes, radiculitis, which is characterised by weakness, shooting pain, dysesthesia and diminished reflexes and complex syndromes, such as meningoencephalitis and encephalomyelitis. Viruses affect different sites of the CNS; enteroviruses, herpes simplex virus 2 (HSV-2) and mumps virus (MuV) are responsible for >90% of cases of aseptic meningitis, whereas herpes simplex virus 1 (HSV-1) is the most common cause of encephalitis in developed countries. Other types of herpes viruses, such as Epstein-Barr virus (EBV), cMV, varicellazoster virus (VZV) and human herpes viruses 6 and 7 (HHV-6 and -7) can invade the brain and influence the neurological status of children. Additionally, there are viruses (Table III) , such as West Nile virus (WNV), Japanese encephalitis virus, Tick-borne encephalitis virus and Western and Eastern equine encephalitis virus, with certain geographic distribution and their differential diagnosis should be taken into account in cases of children, who have travelled in susceptible areas (91, 92) . According to the recent data from the Paediatric Intensive care Unit (PICU) of the 'Aglaia Kyriakou' Children's Hospital (88) in Athens, Greece, among 29 children with cNS infection admitted to the PIcU during the past 5 years, 17 patients (59%) had a viral infection; however, a certain aetiological factor was detected in only 6 of these patients (4 cases with influenza, 1 case with enterovirus and 1 case with HHV-7), whereas 2 patients suffered from autoimmune encephalitis.