California encephalitis orthobunyavirus type strain California encephalitis virus was discovered in Kern County, California, and causes encephalitis in humans.[1] Encephalitis is an acute inflammation of the brain that can cause minor symptoms, such as headaches, to more severe symptoms such as seizures. Mosquitoes serve as its carrier and for this reason this virus is known as an arbovirus (arthropod-borne virus).
California encephalitis orthobunyavirus belongs to the Bunyavirales order of viruses. The La Crosse Virus from the same genus is also a common cause of encephalitis in the United States. Other viruses with similar disease symptoms but genetically unrelated include: Saint Louis encephalitis and West Nile virus.
The incubation period of California encephalitis is usually 3–7 days. An early symptoms phase of 1–4 days commonly precedes the onset of encephalitis, manifesting as fever, chills, nausea, vomiting, headache, lethargy and abdominal pain.[2]
The encephalitis is characterized by fever, drowsiness, and lack of mental alertness and orientation. Seizures occur in 50% of children. Focal neurologic findings, like focal motor abnormalities and paralysis, irregular and abnormal reflexes develop in 20% of children. 10% of patients develop coma.
The total duration of illness rarely exceeds 10–14 days. Recurrent unprovoked seizures occur even after the illness has passed develops in 20% of patients, especially those who had seizures during the acute illness. In adults, infection is asymptomatic, which means that the patient is a carrier of the infection, but experiences no symptoms or only mild feverish illness.[2]
The mortality rate is less than 1% and most patients with encephalitis clinical symptoms recover completely. Up to 20% of patients develop behavioral problems or recurrent seizures.[2]