·        

8.3 Central Nervous system diseases

 

Some viral infections can cause pathogenicity in the brain and spinal cord (central nervous system [CNS]). Viruses may be neuroinvasive (able to enter the CNS after crossing the blood brain barrier) and/or neurovirulent (can cause damage to the nerve cells). Mumps virus is highly neuroinvasive but not very neurovirulent while herpesviruses are more neurovirulent. Viruses can cause disease in a variety of ways including infection of a specific area of the brain or infect systemically to the CNS. Sometime their infection causes lysis of the neurons while other type of infections can cause demyelination of axons.

 

Meningitis - Virus infects the meningeal cells of the CNS. Symptoms include headache, fever, and neck stiffness with/or without vomiting. Mumps and Enteroviruses are most common agents.

 

Poliomyelitis - The disease involves demyelination of nerve cells and is most common in the countries where polio virus has not been eradicated.

 

Encephalitis - Symptoms include fever, headache, stiffness of the neck muscles, vomiting, and deviations from the normal state of consciousness. Patients are often lethargic and show signs of seizures. Sometimes paralysis may develop before coma and death. Recovered patience may show mental retardation, epilepsy, paralysis, deafness, and blindness. Many Arboviruses and Herpesviruses are associated with the severe form of encephalitis. Guillain-Barre syndrome is a condition caused by Epstein - Barr virus (EBV) infection. Similar kind of condition seen in the patients infected with influenza or chickenpox which are under aspirin treatment and are characterized by cerebral edema. The condition is often lethal and known as Reye's syndrome .

 

8.4 Urogenital system diseases

 

Herpes simplex virus and papillomaviruses are the major viruses infecting the genital area. Sexual transmission is the main way of acquiring these agents. Herpesvirus infection manifests as painful itching and ulcerated vesicular lesions occasionally accompanied by fever and malaise especially in woman. Recurrences are common although generally less severe than the initial infection. Certain types of HPV may progress over several years through stages of cervical neoplasia to invasive squamous cell carcinoma.