California encephalitis virus
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Anthony Gallo, B.S. [2]
Overview
Historical Perspective
California encephalitis virus was first discovered in 1943 in Kern County, California. In 1945, the first human cases of encephalitis were attributed to this new virus. Three cases in total were reported, and all three cases were Kern County residents. In all three cases there was strong laboratory evidence confirming infection, due to the presence of neutralizing antibodies linked to California encephalitis.[1]
Classification
There is no classification system established for California encephalitis virus. California encephalitis virus belongs to the Group V negative-sense ssRNA virus within the Bunyaviridae family of viruses, and the genus Orthobunyavirus. California encephalitis virus is also known as an arbovirus, or an arthropod-borne virus.[2] The California encephalitis serogroup, which contains genetically similar viruses such as La Crosse encephalitis, shares its name with the virus.
Pathophysiology
California encephalitis virus is usually transmitted via mosquitos to the human host.[2] California encephalitis virus contains negative-sense viral RNA; this RNA is complementary to mRNA and thus must be converted to positive-sense RNA by an RNA polymerase before translation. California encephalitis virus is made up of an enveloped virion with a helically symmetrical capsid. The envelope contains G1 glycoproteins. Neutralizing antibodies against these proteins block fusion of the virus with host cells and inhibit hemagglutination. The virus genome is over 12000 nucleotides in length and consists of three segments of various sized single-stranded RNA (negative sense and ambi-sense).
Causes
California encephalitis virus causes encephalitis in humans.
Differentiating California Encephalitis Virus from other Diseases
California encephalitis virus must be differentiated from other diseases that cause fever, headache, seizures, and altered mental status, such as:[2][3][4]
| Disease | Findings |
|---|---|
| La Crosse encephalitis | Presents with acute inflammation of the brain, caused by a viral infection; it may complicate into severe brain damage. Other findings include nausea, headache, vomiting in milder cases and seizures, coma, paralysis and permanent brain damage in severe cases. |
| Vector-borne encephalitis | Presents with acute inflammation of the brain, caused by a bacterial infection; it may complicate into severe brain damage as the inflamed brain pushes against the skull, potentially leading to mortality. |
| Viral encephalitis | Presents with acute inflammation of the brain, caused by a viral infection; it may complicate into severe brain damage as the inflamed brain pushes against the skull, potentially leading to mortality. |
| Encephalopathy | Presents with steady depression, generalized seizures. Generally absent are fever, headache, leukocytosis, and pleocytosis; MRI often appears normal. |
| Meningitis | Presents with headache, altered mental status, and inflammation of the meninges, which may develop in the setting of an infection, physical injury, cancer, or certain drugs; it may have an indolent evolution, resolving on its own, or may present as an rapidly evolving inflammation, causing neurologic damage and possible mortality. |
| Brain abscess | Presents with an abscess in the brain caused by the inflammation and accumulation of infected material from local or remote infectious areas of the body; the infectious agent may also be introduced as a result of head trauma or neurological procedures. |
| Acute disseminated encephalomyelitis (ADEM) | Presents with scattered foci of demyelination and perivenular inflammation; it can cause focal neurological signs and decreased ability to focus. |
Epidemiology and Demographics
Incidence
There are approximately 70-115 cases of California encephalitis virus per year in the United States.[5]
Age
California encephalitis virus commonly affects individuals between 6 months old and 15 years of age.[5]
Seasonal
The majority of California encephalitis virus cases are reported between in the summer months between July and September, and peaks in August.[5]
Geographic Location
The majority of California encephalitis virus cases are reported in the Midwestern United States, especially those living in rural and suburban settings surrounded by deciduous forests.[5]
Risk Factors
Common risk factors in the development of California encephalitis virus include:
- Young age
- Residing or working in rural and suburban settings
- Mosquito contact
- Summer season
- Outdoor activities such as camping or hunting
Natural History, Complications, and Prognosis
Natural History
California encephalitis virus usually clears in 1 to 2 weeks and rarely recurs. Less than 1% of cases result in mortality.[6] However, approximately 20% of patients have residual seizures.
Complications
Common complications of California encephalitis virus include:
- Recurring seizures
- Coma
- Loss of basic motor skills
- Loss of coordination
Prognosis
Prognosis for California encephalitis virus is generally good, with most individuals returning to full health in 2-3 weeks.
Diagnosis
History and Symptoms
If possible, a detailed and thorough history from the patient is necessary. In rare cases, California encephalitis virus presents with symptoms mimicking herpes simplex encephalitis.[7] Common symptoms of California encephalitis virus include:[8][2]
Physical Examination
Common physical examination findings of California encephalitis virus include:[6]
- Fever
- Ataxia
- Seizures
- Acute flaccid myelitis
- Somnolence
- Obtundation
- Acute flaccid paralysis
- Myalgia
Laboratory Findings
Laboratory findings consistent with the diagnosis of California encephalitis virus include:[6]
- Serologic cross-reactivity
- Presence IgM antibodies.
- Persistence of IgG and neutralizing antibodies
- Confirmation of arboviral-specific neutralizing antibodies in Enzyme linked immunosorbent assay (ELISA),
commonly include enzyme-linked immunosorbent assay (ELISA), immunofluorescence assay (IFA), and plaque reduction neutralization test (PRNT)
CT
MRI
Treatment
Medical Therapy
Prevention
References
- ↑ Eldridge BF, Glaser C, Pedrin RE, Chiles RE (2001). "The first reported case of California encephalitis in more than 50 years". Emerg Infect Dis. 7 (3): 451–2. doi:10.3201/eid0703.010316. PMC 2631795. PMID 11384526.
- ↑ 2.0 2.1 2.2 2.3 M.D. JE, Dolin R, Blaser MJ. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Expert Consult Premium Edition. Saunders; 2014.
- ↑ Kennedy PG (2004). "Viral encephalitis: causes, differential diagnosis, and management". J Neurol Neurosurg Psychiatry. 75 Suppl 1: i10–5. PMC 1765650. PMID 14978145.
- ↑ Arboviral Infections (arthropod-borne encephalitis, eastern equine encephalitis, St. Louis encephalitis, California encephalitis, Powassan encephalitis, West Nile encephalitis). New York State Department of Health (2006). https://www.health.ny.gov/diseases/communicable/arboviral/fact_sheet.htm Accessed on February 23, 2016
- ↑ 5.0 5.1 5.2 5.3 Goldman L, Schafer AI. Goldman's Cecil Medicine. Elsevier Health Sciences; 2011.
- ↑ 6.0 6.1 6.2 La Crosse Encephalitis. Ohio Department of Health. http://www.odh.ohio.gov/pdf/idcm/lac.pdf Accessed on February 25, 2016.
- ↑ Sokol DK, Kleiman MB, Garg BP (2001). "LaCrosse viral encephalitis mimics herpes simplex viral encephalitis". Pediatr Neurol. 25 (5): 413–5. PMID 11744319.
- ↑ Richie MB, Josephson SA (2015). "A Practical Approach to Meningitis and Encephalitis". Semin Neurol. 35 (6): 611–20. doi:10.1055/s-0035-1564686. PMID 26595861.
Initial infection by the virus and primary viremia causes the onset of non-specific symptoms such as headache and fever. Secondary viremia and the multiplication of the virus in the CNS causes symptoms such as stiff neck, lethargy and seizures. It can also cause encephalitis, when inflammation of the brain produced by infection of the virus damages nerve cells, which affects signalling of the brain to the body.
CEV is closely related to La Crosse Virus.
References