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Biomedical subjects

C H Calisher

Publications and source records attributed to C H Calisher.

At least 163 records · Page 9Linked to original sources
PubMed1979

A comparison of La Crosse virus isolated obtained from different ecological niches and an analysis of the structural components of California encephalitis serogroup viruses and other bunyaviruses.

Analyses of the oligonucleotide fingerprints of the three genome ribonucleic acid (RNA) species of 11 isolates of La Crosse (LAC) virus, obtained from various ecological niches in the northern United States and compared to those of prototype LAC virus, showed that in each place from which these isolates were obtained LAC variants and varieties were present with related, but distinguishable, nucleotide sequences for their large, medium, or small RNA species. The RNA genomes of prototypes trivittatus (TVT), snowshoe hare (SSH), Tahyna (TAH), and Lumbo (a variety of TAH) viruses of the California encephalitis (CE) serogroup, and Guaroa of the Bunyamwera serogroup also consist of three RNA species, each with unique and distinguishable nucleotide sequences which bear little resemblance to those of the LAC virus isolates. The virions of CE group viruses (CE, Jamestown Canyon, Keystone, LAC, Melao, SSH, TVT, TAH viruses and South River, an unregistered virus) have three major viral polypeptides, designated G1, G2, and N.

Arboviruses↗
PubMed1979

Relationships of bunyamwera group viruses by neutralization.

A standardized serum dilution plaque reduction neutralization test was used for cross-neutralization studies of 23 strains of Bunyamwera serogroup viruses. Antigenic relationships were determined by inspection of the neutralization tests results as well as by numerical taxonomic analysis. Based on these analyses five complexes, containing 1-11 viruses, were distinguished. Little or no cross-reactivity was observed between viruses of different complexes. Three of the viruses tested were indistinguishable from prototypes and probably represent strains or varieties of those prototypes. A tentative classification scheme for the Bunyamwera group is presented.

Antigens, Viral↗
PubMed1978

Eastern equine encephalitis in Massachusetts, 1957-1976. A prospective study centered upon analyses of mosquitoes.

Reappearance of eastern equine encephalitis (EEE) in Massachusetts residents in the 1970's provided an opportunity to assess the predictive value of data on rainfall, EEE in horses, and carriage of EEE virus (EEEV) by mosquitoes, factors which had been studied annually since the last EEE outbreak in 1955-1956. The cycle of multiple cases during 1973-1975 started in a second consecutive year of rainfall that exceeded the annual mean by more than 20 cm, conditions recapitulating the 1955-1956 experience. In 1973, widespread EEE fatalities in horses presaged human cases, another recapitulation of the 1955-1956 experience. However, in 1974, when horses were immunized extensively, no equine cases were seen even though three human fatalities occurred. An unseasonably early appearance of EEEV in mosquitoes was the only basis upon which the threat to humans could have been recognized. These changes in the recognition and distribution of EEEV activity from season to season illustrate the difficulty in making rational decisions regarding widespread aerial insecticide applications for mosquito control.

Animals↗
PubMed1978

Emergence of a new arbovirus disease in Brazil. I. Isolation and characterization of the etiologic agent, Rocio virus.

In April, 1975, an epidemic of human encephalitis was detected in several counties in the State of São Paulo, Brazil; the epidemic continued into 1976. A virus was isolated from central nervous system (CNS) tissues of a 39-year-old male who died on December 8, 1975; the virus was found to be a new flavivirus for which the name Rocio virus is proposed. Nine further isolations of Rocio virus were obtained from CNS tissues of 17 patients who died with clinical symptoms of encephalitis. Isolations of virus and serologic evidence of Rocio virus infection in a significant proportion of the encephalitis patients suggested that Rocio virus was the etiologic agent of the epidemic. Rocio virus was isolated only from patients who died within 5 days of onset of illness. The virus was isolated from two sentinel mice exposed in the epidemic zone and from a rufous collared sparrow (Zonotrichia capensis) collected in the area.

Adolescent↗
PubMed1978

St. Louis encephalitis in Memphis-Shelby County, Tennessee, 1975: epidemiologic aspects of human cases.

An epidemic of St. Louis encephalitis (SLE) occurred in Memphis-Shelby County, Tennessee, in the summer of 1975, as part of an outbreak involving large portions of the Eastern United States. A total of 187 suspected cases were reported, of which 62 were laboratory-confirmed or presumptive SLE. The overall attack rate was 8.1/100,000; rates were higher in lower socioeconomic districts. The case fatality rate was 19.4%. Climatologic data and related factors favoring the occurrence of this outbreak are discussed.

Acute Disease↗
PubMed1978

New Minto virus: a new rhabdovirus from ticks in Alaska.

Three strains of a virus were isolated from Haemaphysalis leporis-palustris (Packard) ticks removed from snowshoe hares (Lepus americanus Erxleben) in east central Alaska. We suggest that the virus be named New Minto for the location in which the ticks were collected. Prototype New Minto virus is sensitive to the action of sodium deoxycholate and kills suckling mice by the intracerebral but not intraperitoneal route; weaned mice do not die after intracerebral, intraperitoneal, or subcutaneous inoculation. The virus produces plaque in serially propagated Vero but not in primary Pekin duck embryo cells. By complement-fixation and neutralization tests New Minto is related to Sawgrass Virus, a hitherto ungrouped virus from Florida. The establishment of a Sawgrass group is suggested. In addition, Sawgrass virus was found by electron microscopy to belong to the Family Rhabdoviridae.

Alaska↗
PubMed1977

Isolation of Bhanja virus from ticks in Yugoslavia.

Two strains of Bhanja (BHA) virus, an ungrouped arbovirus, were isolated from Haemaphysalis punctata ticks collected from sheep on the island of Brac in the Yugoslavian Adriatic. Serologic testing gave evidence of the endemicity of BHA virus on the island, and antibody prevalence rates were high for both man (35.8%--ranging locally to 61.3%) and sheep (100%). No antibody was found in 82 small mammals tested. Evidence of a natural cycle involving ticks and sheep, the potential significance of this virus for man and for animals of agricultural importance, and factors related to its epidemiology are discussed.

Animals↗
PubMed1977

Rio Grande--a new phlebotomus fever group virus from south Texas.

Three strains of a new Phlebotomus fever group virus were isolated from pack rats (Neotoma micropus) collected in south Texas during 1973--1974; the name Rio Grande was proposed for this virus. The virus is pH 3.0 labile, sensitive to the action of sodium deoxycholate and heat (56 degrees C) labile. The results of a serosurvey indicated that pack rats are probably the principal vertebrate host for Rio Grande virus and that year-round transmission of the virus may occur. Because no isolations of this virus were made from hematophagous insects, the vector, if any, remains undetermined.

Animals↗
PubMed1976

Virological and serological studies of Venezuelan equine encephalomyelitis in humans.

During the 1971 epidemic of Venezuelan equine encephalomyelitis (VEE) in south Texas, 203 suspect VEE cases were evaluated by the Center for Disease Control. Sixty-seven were confirmed as cases of VEE. Laboratory confirmation was accomplished by isolation of VEE virus from a serum specimen taken during the acute illness in 50 (75%) of the confirmed cases. Serological confirmation was obtained in 17 cases (25%). Virus isolations were most often obtained from sera collected during the first 3 days of illness. Peak serum virus titers (algebraic mean, 10(5-7) suckling mouse intracranial 50% lethal doses [SMICLD50] per ml) occurred on day 2 of illness. One-half of the sera from which virus was isolated contained at least 10(5) SMICLD50/ml, which has been shown to be sufficient to infect some vector mosquitoes. Blood from 13 virus-positive VEE cases was obtained 1 and 11 months after illness. Hemagglutination-inhibiting, complement-fixing, and neutralizing antibodies were formed by all 13 patients 1 month after illness. Hemagglutination-inhibiting antibody titers were essentially unchanged 11 months after illness. Complement-fixing antibody was undetectable 11 months after illness in 23% of cases and was detectable at dilutions of 1:8 or 1:6 in 77%. Neutralizing antibody (measured by log neutralization index) was not detectable 1 year after illness in one person (8%); titers had declined from 1.0 to 2.0 in 46%, were unchanged in 39%, and were not tested in one person (8%). No evidence of intrafamilial spread of VEE virus was obtained in either of two illness and antibody surveys. A randomized household illness and antibody survey of 681 Port Isabel residents revealed an inapparent infection ratio of 1:11 and an overall antibody prevalence of 3.2%.

Adolescent↗
PubMed1976

Serum dilution neutralization test for California group virus identification and serology.

The serum dilution neutralization test was evaluated for serological diagnosis of California group arbovirus infections and identification of virus isolates. The technical advantages and the degree of subtype specificity of the serum dilution neutralization test over the hemagglutination inhibition test and the complement fixation test were demonstrated with paired specimens from human cases, single human survey sera, and sentinel rabbit sera. Twenty-one virus isolates from various geographical areas of the United States were also used to evaluate the efficacy of the serum dilution neutralization test for specific virus identification.

Adolescent↗
PubMed1975

Epidemic Venezuelan equine encephalitis in North America in 1971: vector studies.

A major epidemic of Venezuelan equine encephalitis occurred in south Texas in the summer of 1971. More than 1500 equines died of VEE in Texas, and 110 human cases with no deaths were reported. Vector studies in south Texas and northern Tamaulipas revealed that the overall mosquito infection rates during the peak of the epidemic were about 1:100, one of the highest rates observed for a major epidemic. Mosquito infection rates of this magnitude could easily explain the intensity of VEE outbreaks in both equines and man. A total of 943 VEE virus isolations were made from mosquitoes. Eight of the 12 mosquito species found infected were implicated in the epidemic cycle of VEE for the first time. Sufficient laboratory and field evidence is available to prove that Psorophora confinnis was one of the primary vectors of VEE. The lack of laboratory evidence necessitates the use of the term "probable" primary vectors for other species apparently equally as involved on the basis of field infections; these include Aedes sollicitans, Aedes thelcter and Psorophora discolor. Eight other species from which less than 10 VEE virus isolations were made were considered auxiliary vectors. Mosquitoes of some species were tested individually; such tests showed 2-4% of the probable primary vectors to be infected. The first isolation of VEE virus of the epidemic was made from P. confinnis on June 28, 1971. Highest mosquito infection rates occurred during the week of July 5. Mosquito infection rates declined precipitously in the last 3 weeks of July 1971, signaling the end of the epidemic in the study area. One explanation for the decline was that equines, the principal epidemic hosts, were eliminated as a source of virus by death or by acquisition of natural or induced immunity. Mosquito control appeared to be effective in reducing the infected mosquito population while the immunization of equines with TC 83 VEE vaccine was accomplished. Quarantines appeared to be effective in restricting the VEE virus activity to south Texas. Undoubtedly all of the control measures contributed to stopping the epidemic. Continued VEE surveillance by various government and other agencies failed to reveal any further epidemic VEE activity in the US in 1972. Other arboviruses isolated during the VEE studies in south Texas included St. Louis encephalitis virus, and San Angelo subtype of the California Group. A virus of the Bunyamwera Group was also isolated from Palo Blanco, Tamaulipas.

Animals↗
PubMed1975

Arbovirus vector ecology studies in Mexico during the 1972 Venezuelan equine encephalitis outbreak.

Virus vector studies were conducted in the States of Durango, Chihuahua, and Tamaulipas, Mexico, in June and July 1972. Apparently only a low level of Venzuelan equine encephalitis (VEE) virus transmission to equines occured at the time of the study, and the infection was restricted to areas which had not experienced overt activity during the preceding year. The low level of infection was associated with a scarcity of mosquitoes. The IB (epidemic) strain of VEE virus was isolated from two pools of Anopheles pseudopunctipennis (Theo.) and the blood of one symptomatic equine. The low mosquito population, the relatively few equine cases observed, and the absence of reports of VEE human disease from the outbreak area suggested VEE virus persistence through a low-level mosquito-equine transmission cycle. Other studies have already indicated that wild vertebrates play no more than a minor role in outbreaks of epidemic VEE. Mosquito collections made in areas of the states of Durango, Chihuahua, and Tamaulipas, where considerable epidemic activity of VEE had occurred in 1971, failed to reveal evidence of VEE virus persistence. Twenty-nine ioslations of other arboviruses were also made in these studies: including 22 of St. Louis encephalitis virus (SLE), 2 of Flanders virus, 1 of Turlock virus, 1 of Trivittatus virus of the California Group, 1 of western equine encephalitis virus (VEE), and 2 (from Santa Rose) which possibly represent a hitherto unknown virus in the Bunyamwera Group. These are the first reports of SLE virus isolations from mosquitoes in Mexico, and the first demonstration of Trivittatus, VEE Turlock and Flanders viruses in Mexico from any source.

Animals↗
PubMed1975

Laboratory studies of a lymphocytic choriomeningitis virus outbreak in man and laboratory animals.

Investigation of an outbreak of prolonged febrile illness in medical center personnel at the University of Rochester School of Medicine and Dentistry revealed lymphocytic choriomeningitis (LCM) virus to be the causative agent. Syrian or golden hamsters (Mesocricetus auratus) were found to be the only animals involved in maintaining the virus and were the source of human infections. Isolations of LCM virus were made from autopsy specimens of 13 of 46 (28%) golden hamsters. Virus isolations were made from 22 of 28 (79%) frozen specimens of 11 tumor lines transplanted repeatedly in golden hamster cheek pouches. No virus isolations were made from 86 autopsied laboratory mice, laboratory rats, Chinese hamsters (Cricetulus griseus), or laboratory rabbits or from 10 tumor cell lines transplanted in laboratory mice. Complement-fixation testing of 301 animal sera from the vivarium also revealed involvement primarily of golden hamsters. The probable source of virus introduction into the Rochester facilities was found to be two LCM-contaminated tumor lines sent from a biological supplier to Rochester in 1969.

Animals↗
PubMed1975

Laboratory studies of Venezuelan equine encephalitis virus in equines, Texas, 1971.

During the summer and fall of 1971, epizootic and epidemic Venezuelan equine encephalitis was detected in Texas. Isolates of epizootic (IB) and vaccine (TC-83) strains were distinguished by virulence of the former for guinea pigs. Vaccine virus was isolated from 1 to 14 days after vaccination and neutralization tests demonstrated the appearance of antibody about a week after vaccination. Viremia titers of subtype IB in horses ranged from 2.2 to 8.3 log10 suckling mouse intracranial 50% lethal doses per ml. Of 101 equines from which Venezuelan equine encephalitis virus (IB or TC-83) strains were isolated, 87 had no neutralizing antibody against Venezuelan, eastern or western equine encephalitis viruses.

Animals↗