The diagnosis of rabies is generally made at autopsy. It is very important to give the rabies vaccine before any clinical sign of disease. Arvoviruses are agents transmitted to humans by ticks and mosquitoes. These are a series of specific viruses including eastern equine encephalitis, western equine encephalitis, Venezuelan equine encephalitis, Japanese B encephalitis, Lacrosse St. Louis encephalitis, and LaCrosse virus that are restricted geographically and seasonally by their particular vectors. The arvoviruses cause sporadic and epidemic encephalitis throughout the world and their encephalitis is often complicated by seizures in particularly children.
Paralytic poliomyelitis involves viral infection of motor neurons selectively.
The most common cause is poliovirus although occasionally other enteroviruses can cause paralytic poliomyelitis. There is a prodrome of 1-4 days of sore throat, gastrointestinal upset, and fever with mild headache followed by increased fever, severe headache, vomiting, neck stiffness, asymmetric muscle weakness, and loss of reflexes. In addition to acute viral syndrome, there are also chronic viral syndromes. Mechanisms of viral persistence in the central nervous system include sequestration of viral or proviral DNA, noncytopathic infection, lytic infection of a rapidly replicating cell population which is most pertinent for congenital infection. A mutant or defective virus and immune mechanisms that allow persistent central nervous system infection.