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Research on Immunology
Research on Immunology
iConcept Press

Chapter 9

Research on Immunology

Infection with West Nile Virus: Opsoclonus-myoclonus Syndrome

by Victoria Birlutiu, Rares Mircea Birlutiu and Cristina Rezi

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West Nile virus (WNV) is a zoonotic arbovirus, from Flaviviridae family, belonging to the genus Flavivirus, which was form the first time identified in Uganda, in 1937, and which reappears in the specialist's attention in the nineties, being involved in neuroinvasive infections, with a mortality between 10-30% and possible neurologic sequels. WNV is described in epidemiological hot spots in the United States, Central America, Canada, Europe and Africa. According to a rapport of CDC (Centers for Disease Control and Prevention), which was published in 2014, the West Nile infection's incidence is over 1.00 at 100000 people. The most frequent way of transmission for West Nile virus is from birds, especially passerines, but there are described over 300 species of birds with risk of WNV infection, through mosquitoes, at humans or at other 30 species of vertebrates. There are also documented cases of vertically WNV transmission from mother to child during child birth or lactation, of cases of transmission through transfusions or organ donors, hemodialysis, by skin contamination or through aerosols in laboratories. The West Nile virus virion has a diameter of 45-50 nm, with an icosahedral symmetry and a structure which is similar with the one of Dengue fever virus. It owns a lipid envelope with spikes of surface M (membrane) and E (envelope) glycoproteins, monocatenar genom, linear RNA with positive sense, containing among 11000 and 12000 nucleotides which encodes seven nonstructural proteins and three structural proteins. The nucleocapsid is formed by 12 kDa proteins. The virus is multiplying in the tegument, at the Langerhans cells level, in lymph nodes, the viral load being present before the central nervous system invasion. The asymptomatic infections are 300 times more frequent, compared with the symptomatic ones, due to the peripheral clearance of the virus, without neural invasion. In the neural invasion, there are involved the Toll-like receptors 3, the CCR5 receptor and its ligand. The central nervous system lesions consist in local inflammation, brain edema and encephalitis, especially by affecting the hippocampi, thalamus and temporal region, black substance and cerebellum. 80% of the cases of WNV infection are asymptomatic. In the forms of disease without neurological involvement, can appear influenza-like syndrome, lymph nodes enlargements and digestive manifestations. Approximate one third to one half of the cases present punctuate exanthema, macula or papules. Exceptionally, there can be described hepatomegaly, splenomegaly, myocarditis and pancreatitis. The central nervous system involvement appears at less than 1% of cases and it consists in encephalitis, meningitis, Guillain-Barre syndrome, optic neuritis, poliomyelitis-like paralysis. Until now there have been described five cases of WNV encephalitis, manifested as Opsoclonus Myoclonus Syndrome (OMS). OMS represents a pluri-ethiological neurological disorder, produced in children, most of the times as a paraneoplastic syndrome associated with neuroblastoma in over 50% of the cases. In adults, OMS appears as a paraneoplastic manifestation associated with breast, pulmonary, renal, pancreatic or gallbladder cancer, associated with autoimmune diseases, post streptococcal infections, hydro-electrolytic imbalance, cerebral anoxia and cerebral hemorrhages, viral infections with Coxsackie virus (B2, B3), Epstein-Barr, herpes simplex virus, Saint Luis viral encephalitis, C virus hepatitis, rubella, mumps virus, cytomegalovirus, human immunodeficiency virus (HIV), in infections with Mycoplasma pneumoniae, Rickettsia or Borrelia burgdoferi. OMS in manifested by opsoclonus - rapid, multivectorial, conjugated movements of the eyes, which persist during sleep, without involving the alteration of the visual field, and by myoclonus - short involuntary movements of the body, members, and sometimes, but nor mandatory associated with ataxia or other cerebellums signs, sleep disorders

Author Details

Victoria Birlutiu
Faculty of Medicine, "Lucian Blaga" University of Sibiu, Romania
Rares Mircea Birlutiu
Faculty of Medicine, "Lucian Blaga" University of Sibiu, Romania
Cristina Rezi
Polisano Medical Clinic, Sibiu, Romania


Victoria Birlutiu, Rares Mircea Birlutiu and Cristina Rezi. Infection with West Nile Virus: Opsoclonus-myoclonus Syndrome. In Research on Immunology. ISBN:978-1-922227-91-1. iConcept Press. 2016.