Encephalitis: Viral

Description

Symptoms

Early Signs of Infection. In most of the relatively common US arbovirus infections, including West Nile virus, less than 1% of infections cause any noticeable symptoms. Symptoms that do occur are usually those of a mild flu. The symptoms and severity of the condition depend on the age of the patient at time of the infection, the type of virus, and the part or parts of the brain affected.

Early Symptoms of Encephalitis. Symptoms of encephalitis usually appear within four days to two weeks of exposure to the arbovirus. Early symptoms of arbovirus encephalitis are also similar to those of a flu and usually include fever, headache, nausea and vomiting, muscle aches, and lethargy. West Nile virus specifically may produce a non-itchy rash on the chest, back, and arms (lasting about a week).

Because encephalitis involves one or more parts of the brain, however, other symptoms may develop that distinguish it from the flu. They include personality changes, confusion, or other disturbing mental symptoms as well as poor muscle control and sensory impairment.

In most cases, early symptoms of arbovirus encephalitis last three to five days and resolve without becoming serious.

Symptoms of Full-Blown Encephalitis. The standard symptoms of severe arbovirus encephalitis include:

• Behavioral and personality changes.
• Sensitivity to light.
• Vomiting.
• Lethargy and reduced consciousness.
• Seizures (uncommon with West Nile Virus).
• Memory loss.
• Stiff neck and back. (Stiff neck with fever and headache would indicate meningitis--infection in the membranes covering the brain and spinal column.)
• Confusion.
• Coma.

Motor Disorders in Arbovirus-Related Encephalitis. In addition to the standard symptoms of encephalitis noted above, motor disorders are likely in arbovirus-related encephalitis. They include severe general weakness, an inability to coordinate voluntary muscle movements (ataxia), tremor, partial paralysis, difficulty in hearing, seeing, or speaking (Brocas aphasia), or difficulty in swallowing (dysphagia).

Symptoms of Herpes Simplex (HSV) Encephalitis

Early Symptoms. Early symptoms of encephalitis in herpes simplex (HSV) patients include fever and headache.

Symptoms of Full-Blown Encephalitis. Symptoms of herpesvirus encephalitis may evolve slowly, but most often they appear abruptly. The standard symptoms include:

• Stiff neck.
• Seizures.
• Partial paralysis.
• Stupor.
• Coma.

Other symptoms can include:

• Odd mental states.
• Smell and taste disturbances.
• Loss of speech or comprehension.
• Memory loss.
• Emotional volatility.
• Bizarre or psychotic behavior.
• Confusion.
• Heart rhythm disturbances.

Because of the local nature of the infection, herpes simplex may produce symptoms that differ from other forms of viral encephalitis. They may include loss of feeling or paralysis on one side of the body, or other specific symptoms that are isolated to one side. About 50% of patients have such symptoms. In severe cases without treatment, respiratory arrest can occur within the first 24 to 72 hours.

Symptoms in Infants. Infants with herpesvirus encephalitis may develop lesions in the mouth, in the eye, or on the skin within one to 45 days. Other symptoms include lethargy (unusual lack of activity), seizures, and changes in temperature. Their fontanels, the soft spots on their head where the skull has not yet closed, may bulge outward.