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California encephalitis virus, a newly described agent.
Abstract: In three cases of encephalitis in humans that occurred in the area where the newly described California virus was isolated from mosquitoes, serological evidence seemed to indict the California virus as the etiological agent. In the case of an infant with very severe disease, the serological evidence was convincing; the evidence was almost as strong in the case of a seven-year-old boy; the results in an adult were equivocal. Inapparent infection in man is quite common as indicated by neutralization tests on the sera of nearly 600 residents of California, but encephalitic manifestations of infection are extremely rare. In Kern County, California, where the virus was discovered, approximately 11 per cent of the population has been infected. Infection rates are higher in adults than in very young children. Absence of neutralizing antibodies from 64 specimens of blood from persons in Japan, Washington, and other states supports the specificity of the neutralization test in man and suggests that this virus is absent or is not being similarly transmitted in some areas. Serological evidence from serial bleedings of two sick horses suggested, but did not definitely establish, that this virus leads to a naturally acquired encephalomyelitis in horses. Serological tests with the viruses of western equine and St. Louis encephalitis did not lead to any other etiological diagnosis in the sick animals studied. Results of neutralization tests on the sera of eight horses and three cows in Kern County suggested extremely high infection rates, and an immunity rate of 18 per cent was noted in rabbits and ground squirrels. In the natural biological cycle rabbits and ground squirrels are suspected as the possible counterpart of birds in the St. Louis and western equine virus cycles. There is no evidence from field or laboratory to indicate that birds become infected with the California virus. Sera from 33 mammals other than man were collected from Northern California and Washington. All were free from neutralizing antibodies, again supporting the specificity of positive findings from Kern County.
Publication Date: 1952-11-01 PubMed ID: 13009479PubMed Central: PMC1521486 The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Animal Health
- Diagnosis
- Disease Diagnosis
- Disease Etiology
- Disease Outbreaks
- Disease Prevalence
- Disease Surveillance
- Encephalitis
- Encephalomyelitis
- Epidemiology
- Equine Health
- Horses
- Infection
- Infectious Disease
- Mosquito-borne Diseases
- Public Health
- Serodiagnosis
- Serological Surveys
- Veterinary Medicine
- Veterinary Research
- Virus
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
The research paper documents the study of California encephalitis virus, a newly discovered virus originating from mosquitoes. The researchers analyze several human and animal infection cases, providing evidence for the virus’s prevalence and transmission mechanisms.
Study of Encephalitis Cases
- The authors commence with details of three human encephalitis cases potentially originated from the California virus. Convincing serological evidence was presented in two cases – a severely ill infant and a seven-year-old boy – while adult’s results remained ambiguous.
- The researchers assert that asymptomatic infection in humans is prevalent, based on neutralization tests performed on nearly 600 California residents. However, severe symptoms such as encephalitic manifestations are extremely rare.
Prevalence of the Virus in Kern County
- In Kern County, California’s region where the virus was first identified, around 11% of the populace carry the infection. The infection rates skew higher among adults compared to very young children.
- The lack of neutralizing antibodies in 64 blood specimens from Japan, Washington, and other states reinforces the test’s specificity and suggests the virus not being present or transmitted in the same manner in these locations.
Impact on Animals and Possible Transmission Route
- The researchers studied serial bleedings from two sick horses and found serological evidence suggesting the virus may cause encephalomyelitis in horses, but this outcome was not definitively established.
- Neutralizing tests results from the serum of eight horses and three cows found in Kern County implied high infection rates. Among rabbits and ground squirrels, an immunity rate of 18% was noted. This finding supports the hypothesis where similar to birds in the St. Louis and Western equine virus cycles, rabbits and small rodents could also play a role in transmission cycles.
- No evidence supporting bird infection with the California virus was found in both field and lab conditions.
Findings from Other Geographic Locations
- Serum samples from 33 mammals, excluding humans, from Northern California and Washington were analyzed. None of these specimens showed any neutralizing antibodies, adding credence to the specificity of the positive results previously gathered only from Kern County.
Cite This Article
APA
HAMMON WM, REEVES WC.
(1952).
California encephalitis virus, a newly described agent.
Calif Med, 77(5), 303-309.
Publication
Researcher Affiliations
MeSH Terms
- Adult
- Animals
- Birds
- California
- Child
- Culicidae
- Encephalitis
- Encephalitis Virus, California
- Encephalitis, Arbovirus
- Horses
- Humans
- Infant
- Japan
- Male
- Neutralization Tests
- Sciuridae
- Washington
References
This article includes 2 references
- Hammon WM, Reeves WC. Recent Advances in the Epidemiology of the Arthropod-borne Virus Encephalitides: Including Certain Exotic Types.. Am J Public Health Nations Health 1945 Oct;35(10):994-1004.
- Hammon WM. THE ETIOLOGY AND EPIDEMIOLOGY OF THE VIRUS GROUP OF ENCEPHALITIDES.. Calif Med 1947 Oct;67(4):217-20.
Citations
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