For pregnant women infected with Zika virus, the newborn child may have microcephaly.Other potential complications following viral encephalitis include:
Encephalopathy
Flaccid paralysis
Impaired intelligence
Low blood sodium level
Mononeuropathy
Mood and behavioral changes
Residual neurological deficits

Epidemiology
While the etiology of many cases of encephalitis is unknown, viruses account for about 70% of confirmed encephalitis cases, with the herpes simplex virus being the most common cause at about 50% of encephalitis cases. The incidence of viral encephalitis is about 3.5 to 7.5 per 100,000 people, with the highest incidence among the young and the elderly. Viral encephalitis caused by some viruses, such as the measles virus and the mumps virus, has become less common due to widespread vaccination. For others, such as Epstein-Barr virus and cytomegalovirus, incidence has increased due to the increased prevalence of AIDS, organ transplantation, and chemotherapy, which have increased the number of immunocompromised people who have weakened immune systems or who are susceptible to opportunistic infections. Time of the year, geography, and animal, including insect, exposure are also important. For example, arbovirus infections are seasonal and cause viral encephalitis at the highest rate during the summer and early fall when mosquitos are most active. Similarly, those who live in warm, humid climates where there are more mosquitos are more likely to experience viral encephalitis. Prevention
As many encephalitic viruses are transmitted by mosquitos, many prevention efforts revolve around preventing mosquito bites. In areas where such arboviruses are widespread, people should use protective clothing and should sleep under a mosquito net. Removing containers of stagnant water and spraying insecticides can be beneficial.
Additional testing, such as serology for various arboviruses and HIV testing, may also be performed based on the individuals history and symptoms. Brain biopsy and body fluid specimen cultures and PCR may also be useful in some cases. Electroencephalography (EEG) is abnormal in more than 80% of viral encephalitis cases, including those who are experiencing seizures, and may need to be monitored continuously to identify non-convulsive status. Lack of testing resources may prevent accurate diagnosis.Test results specific to certain viruses include:
For herpes simplex virus encephalitis, a CT scan may show low-density lesions in the temporal lobe. These lesions usually appear 3 to 5 days after the start of the infection. Japanese encephalitis often has distinct EEG patterns, including diffuse delta activity with spikes, diffuse continuous delta activity, and alpha coma activity. Differential diagnosis
A broad differential diagnosis can be performed that looks at many potential causes of the encephalitis, infectious and noninfectious. Potential alternatives to viral encephalitis include malignancy, autoimmune or paraneoplastic diseases such as anti-NMDA receptor encephalitis, a brain abscess, tuberculosis or drug-induced delirium, exposure to certain drugs or toxins, neurosyphilis, vascular disease, metabolic disease, or encephalitis from infection caused by a bacterium, fungus, protozoan, or parasitic worm. In children, differential diagnosis may not be able to distinguish between viral encephalitis and immune-mediated inflammatory CNS diseases, such as acute disseminated encephalomyelitis, as well as immune-mediated encephalitis, so other diagnostic methods may need to be used.