California Encephalitis
California Encephalitis
A recent case of California encephalitis, a rare mosquito-borne viral disease, represents only the fourth ever reported and the first since the initial three cases in 1945. This case was diagnosed retrospectively on the basis of a rise in antibody titer between acute- and convalescent-phase serum samples.
The arbovirus California encephalitis virus was first isolated in 1943 from mosquitoes collected in Kern County, California. Two years later, three human cases of encephalitis were attributed to this new virus; all three cases were in residents of Kern County in the Central Valley of California. The best-documented case occurred in a 2-month-old Hispanic boy who had encephalitis and resultant developmental delay. There was strong laboratory evidence confirming infection from the presence of neutralizing antibodies to California encephalitis, but not to St. Louis encephalitis virus or western equine encephalomyelitis virus. Serum from a 7-year-old boy hospitalized with encephalitis also had neutralizing antibodies to California encephalitis. Serologic tests were inconclusive in a third possible case in a 22-year-old agricultural worker with mild encephalitis; neutralizing antibodies against both California encephalitis and St. Louis encephalitis were detected.
Since the original virus was isolated, other viruses have been isolated that are closely related to California encephalitis. This group of related viruses is now classified as the California serogroup, one of 16 serogroups within the genus Bunyavirus, family Bunyaviridae. Several other human pathogens (e.g., Jamestown Canyon virus, La Crosse virus, and Tahyna virus) also belong to the California serogroup. Little human disease was associated with these viruses until 1960, but now California serogroup virus infections are the most commonly reported cause of arboviral encephalitis in the United States. 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 virus, St. Louis encephalitis, and eastern equine encephalomyelitis viruses combined. However, since the three original cases from California, no further cases of human disease caused by the prototype California encephalitis had been reported. Campbell et al. summarized results of surveys for human antibodies to California serogroup viruses in California.
A recent case of California encephalitis, a rare mosquito-borne viral disease, represents only the fourth ever reported and the first since the initial three cases in 1945. This case was diagnosed retrospectively on the basis of a rise in antibody titer between acute- and convalescent-phase serum samples.
The arbovirus California encephalitis virus was first isolated in 1943 from mosquitoes collected in Kern County, California. Two years later, three human cases of encephalitis were attributed to this new virus; all three cases were in residents of Kern County in the Central Valley of California. The best-documented case occurred in a 2-month-old Hispanic boy who had encephalitis and resultant developmental delay. There was strong laboratory evidence confirming infection from the presence of neutralizing antibodies to California encephalitis, but not to St. Louis encephalitis virus or western equine encephalomyelitis virus. Serum from a 7-year-old boy hospitalized with encephalitis also had neutralizing antibodies to California encephalitis. Serologic tests were inconclusive in a third possible case in a 22-year-old agricultural worker with mild encephalitis; neutralizing antibodies against both California encephalitis and St. Louis encephalitis were detected.
Since the original virus was isolated, other viruses have been isolated that are closely related to California encephalitis. This group of related viruses is now classified as the California serogroup, one of 16 serogroups within the genus Bunyavirus, family Bunyaviridae. Several other human pathogens (e.g., Jamestown Canyon virus, La Crosse virus, and Tahyna virus) also belong to the California serogroup. Little human disease was associated with these viruses until 1960, but now California serogroup virus infections are the most commonly reported cause of arboviral encephalitis in the United States. 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 virus, St. Louis encephalitis, and eastern equine encephalomyelitis viruses combined. However, since the three original cases from California, no further cases of human disease caused by the prototype California encephalitis had been reported. Campbell et al. summarized results of surveys for human antibodies to California serogroup viruses in California.
Source...