California encephalitis virus
Encyclopedia
California encephalitis virus was discovered in Kern County, California and causes encephalitis
in humans. 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 virus belongs to the Bunyaviridae
family of viruses. The La Crosse Virus
is the most common form of encephalitis virus in the United States. Other related viruses include: California encephalitis, St. Louis Encephalitis
and West Nile Virus
.
The original California Encephalitis virus was isolated and put along side with fifteen other related viruses that are now categorized as the California serogroup. From 1996 to 1998, approximately three times as many reported human cases of arboviral encephalitis were caused by California serogroup viruses as were reported for
western equine encephalomyelitis
viruses, St. Louis encephalitis, and eastern equine encephalomyelitis viruses combined.
In the United States several factors influence the transmission and control of disease of arboviral encephalitis like those of the California Encephalitis virus. These factors include: the season, geographical location, patient age, and the regional climate condition such as spring or rainfall. There are approximately 75 cases reported per year. The highest occurrence of arboviral encephalitis in the United States is in the Midwestern states with most cases occurring in the late summer to early fall. Outdoor activities, especially in woodland areas, are associated with an increased risk of infection.
Mortality rates are less than 1% and most patients with encephalitis clinical symptoms recover completely; however, 20% of patients develop behavioral problems or recurrent seizures. Encephalitis disease in general occurs almost exclusively in children from 6 months to 16 years old.
After the virus enters your body via a mosquito bite, the virus undergoes local replication at the skin site where virus entered the body. A primary spread of virus occurs, with seeding of the reticuloendothelial system having to do with mainly the liver, spleen, and lymph nodes. With the ongoing replication of the virus a secondary spread occurs, with the seeding of the CNS. Not all the cases reach this stage depending on the efficiency of viral replication at the different stages, and the degree of virus spread. The California encephalitis virus invades the CNS through either the cerebral capillary
endothelial
cells or the choroid plexus
.
The encephalitis is characterized by fever, drowsiness, and lack of mental alertness and orientation. Seizures occur in 50% of children. Focal neurologic signs such as 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 patient is a carrier of the infection but experiences no symptoms or causes a gentle feverish illness.
To summarize the main physical aspects of this virus described in the previous paragraphs include: fever, lethargy, focal neurologic findings, focal motor abnormalities and paralysis.
Encephalitis
Encephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue...
in humans. 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
Arbovirus
Arbovirus is a term used to refer to a group of viruses that are transmitted by arthropod vectors. The word arbovirus is an acronym . Some arboviruses are able to cause emergent disease.-Transmission:...
(arthropod-borne virus).
California encephalitis virus belongs to the Bunyaviridae
Bunyaviridae
Bunyaviridae is a family of negative-stranded RNA viruses. Though generally found in arthropods or rodents, certain viruses in this family occasionally infect humans. Some of them also infect plants....
family of viruses. The La Crosse Virus
La Crosse Encephalitis
La Crosse encephalitis is an encephalitis caused by an arbovirus which has a mosquito vector .-History:...
is the most common form of encephalitis virus in the United States. Other related viruses include: California encephalitis, St. Louis Encephalitis
St. Louis Encephalitis
St. Louis Encephalitis is a disease caused by the Culex mosquito borne St. Louis Encephalitis virus. St. Louis encephalitis virus is related to Japanese encephalitis virus and is a member of the Flaviviridae subgroup. This disease mainly affects the United States...
and West Nile Virus
West Nile virus
West Nile virus is a virus of the family Flaviviridae. Part of the Japanese encephalitis antigenic complex of viruses, it is found in both tropical and temperate regions. It mainly infects birds, but is known to infect humans, horses, dogs, cats, bats, chipmunks, skunks, squirrels, domestic...
.
History
It was first discovered and isolated in 1943 from mosquitoes collected in Kern County, California. Two years later the first human cases of encephalitis were attributed to this new virus. Three reported cases in total and all three cases were in residents of Kern County in the Central Valley of California. In all three cases there was strong laboratory evidence confirming infection due to the presence of neutralizing antibodies linked to California encephalitis. Since then, most cases have been associated with the La Crosse virus and California encephalitis is a rare cause of disease in the Western World. This is due to the fact that, ever since these three original cases, no further cases of human disease caused by the prototype California encephalitis have been reported.The original California Encephalitis virus was isolated and put along side with fifteen other related viruses that are now categorized as the California serogroup. From 1996 to 1998, approximately three times as many reported human cases of arboviral encephalitis were caused by California serogroup viruses as were reported for
western equine encephalomyelitis
Western equine encephalitis virus
The Western equine encephalomyelitis virus is the causative agent of relatively uncommon viral disease Western equine encephalomyelitis . An Alphavirus of the family Togaviridae, the WEE virus is an arbovirus transmitted by mosquitoes of the genera Culex and Culiseta...
viruses, St. Louis encephalitis, and eastern equine encephalomyelitis viruses combined.
In the United States several factors influence the transmission and control of disease of arboviral encephalitis like those of the California Encephalitis virus. These factors include: the season, geographical location, patient age, and the regional climate condition such as spring or rainfall. There are approximately 75 cases reported per year. The highest occurrence of arboviral encephalitis in the United States is in the Midwestern states with most cases occurring in the late summer to early fall. Outdoor activities, especially in woodland areas, are associated with an increased risk of infection.
Mortality rates are less than 1% and most patients with encephalitis clinical symptoms recover completely; however, 20% of patients develop behavioral problems or recurrent seizures. Encephalitis disease in general occurs almost exclusively in children from 6 months to 16 years old.
Pathophysiology
Initial infection by the virus and primary spread of the virus causes the onset of non-specific symptoms such as headache and fever. Secondary spread and the multiplication of the virus in the CNS (central nervous system) causes symptoms such as stiff neck, lethargy and seizures. It then can result in encephalitis, when inflammation of the brain produced by infection of the virus damages nerve cells, which affects signaling of the brain to the body.After the virus enters your body via a mosquito bite, the virus undergoes local replication at the skin site where virus entered the body. A primary spread of virus occurs, with seeding of the reticuloendothelial system having to do with mainly the liver, spleen, and lymph nodes. With the ongoing replication of the virus a secondary spread occurs, with the seeding of the CNS. Not all the cases reach this stage depending on the efficiency of viral replication at the different stages, and the degree of virus spread. The California encephalitis virus invades the CNS through either the cerebral capillary
Capillary
Capillaries are the smallest of a body's blood vessels and are parts of the microcirculation. They are only 1 cell thick. These microvessels, measuring 5-10 μm in diameter, connect arterioles and venules, and enable the exchange of water, oxygen, carbon dioxide, and many other nutrient and waste...
endothelial
Endothelium
The endothelium is the thin layer of cells that lines the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. These cells are called endothelial cells. Endothelial cells line the entire circulatory system, from the heart...
cells or the choroid plexus
Choroid plexus
The choroid plexus is a structure in the ventricles of the brain where cerebrospinal fluid is produced...
.
Symptoms
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. This phase manifests as fever, chills, nausea, vomiting, headache, and abdominal pain.The encephalitis is characterized by fever, drowsiness, and lack of mental alertness and orientation. Seizures occur in 50% of children. Focal neurologic signs such as 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 patient is a carrier of the infection but experiences no symptoms or causes a gentle feverish illness.
To summarize the main physical aspects of this virus described in the previous paragraphs include: fever, lethargy, focal neurologic findings, focal motor abnormalities and paralysis.