Disease Information for West Nile fever/encephalitis: Definition

  • Viral encephalitis with bird vector and horse and cattle reservoir; presents with weak legs ascending paralysis with confusion, then encephalitis; CSF lymphocytes and PCR CSF positive; can be lethal; supportive treatment; Head MRI shows meningeal enhancement---------------------------------------------West Nile Encephalitis; Kunjin fever; West Nile Fever; West Nile encephalitis is an inflammation of the brain caused by the West Nile virus, which was first identified in Uganda in the 1930s and first found in the United States in 1999; The disease is spread to humans through the bite of mosquitoes who have fed upon infected birds; It is not spread from person to person, nor is it spread directly from other animals to people, although horses and some other animals are known to become ill from infection with West Nile virus; In humans, most cases are mild with flu-like symptoms, but the disease may occasionally be severe and may even be life-threatening---------[NORD 2005]----------------------

    Fever, malaise, stiff neck, sore throat, and nausea and vomiting, progressing to stupor, coma, and convulsions;

    Signs of an upper motor neuron lesion (exaggerated deep tendon reflexes, absent superficial reflexes, pathologic reflexes, and spastic paralysis); Cerebrospinal fluid protein and opening pressure often increased, with lymphocytic pleocytosis; The arboviruses are arthropod-borne agents that produce clinical manifestations in humans; The mosquito-borne agents include three alphaviruses (causing Western, Eastern, and Venezuelan equine encephalitis), five flaviviruses (causing West Nile fever, St. Louis encephalitis, Japanese B encephalitis, dengue, and yellow fever), bunyaviruses (the California serogroup of viruses [in particular, California encephalitis caused by the Lacrosse agent), and some causes of viral hemorrhagic fever (Rift Valley fever); The tick-borne causes of encephalitis include the flavivirus Powassan (northeastern United States and Canada) and tick-borne encephalitides of Europe; Infection with West Nile virus was first identified in the United States in the New York City area in 1999; The virus spread rapidly, with initial cases reported along the Atlantic seaboard;