Relationship of cliff swallows, ectoparasites, and an Alphavirus in west-central Oklahoma.

Approximately 250 isolates of a newly recognized virus, related to western equine encephalitis virus (family Togaviridae, genus Alphavirus), were obtained from cimicid bugs, Oeciacus vicarius; Cliff Swallows, Hirundo pyrrhonata; and House Sparrows, Passer domesticus in a study area in west-central Oklahoma at Buggy Creek and Caddo Canyons. Antigenicity of the virus strains varied slightly from isolate to isolate. This paper summarizes the ecology of the area by describing in general the flora and fauna there.

A new arbovirus from Aedes albopictus, an Asian mosquito established in the United States.

Ten strains of a new arbovirus belonging to the Bunyamwera group (Bunyaviridae) were recovered from field-collected Aedes albopictus mosquitoes in Potosi, Missouri. This evidence indicates that this species may serve as an arbovirus vector in the United States. The urban-suburban distribution, aggressive biting behavior, and broad viral susceptibility of Ae. albopictus may lead to the transmission of viruses of known public health importance and perhaps of viruses hitherto not transmitted to humans because of the feeding pattern of their usual vectors.

Bivens arm virus: a new rhabdovirus isolated from Culicoides insignis in Florida and related to Tibrogargan virus of Australia.

During field studies in 1981 on the transmission of bluetongue viruses in ruminants in Florida, a virus was isolated from Culicoides insignis collected near water buffalo (Bubalus bubalis) recently imported from Trinidad. Electron microscopy showed that this isolate, for which the name Bivens Arm virus is proposed, has rhabdovirus morphology. Serologic comparisons were made with recognized rhabdoviruses from terrestrial vertebrates and hematophagous arthropods. Indirect fluorescent antibody, complement fixation and neutralization tests indicated antigenic reactivity between Bivens Arm virus and two rhabdoviruses found only in Australia, Tibrogargan and Coastal Plains viruses. The Australian isolates cause subclinical infections in cattle and water buffalo and are believed to be transmitted by Culicoides. Initially, it was thought that Bivens Arm virus may have been introduced to Florida with the water buffalo from Trinidad, but a serologic survey of cattle serum, collected before the importation of the buffalo revealed antibody to the virus in cattle on farms located in diverse areas of Florida.

Brus Laguna virus, a Gamboa bunyavirus from Aedeomyia squamipennis collected in Honduras.

A virus isolate from Aedeomyia squamipennis collected in Honduras in 1967 was identified as a member of the Gamboa serogroup (family Bunyaviridae, genus Bunyavirus). This is the ninth Gamboa serogroup virus and the eighth shown to be a distinct serotype.

Human infections with Tensaw virus in south Florida: evidence that Tensaw virus subtypes stimulate the production of antibodies reactive with closely related Bunyamwera serogroup viruses.

Maguari virus, a member of the Bunyamwera serogroup (family Bunyaviridae, genus Bunyavirus) has not been isolated north of Trinidad. Anecdotal information from other investigators has indicated the presence of antibody to Maguari virus in human residents of south Florida. We attributed such antibody to either cross-reactivity with Tensaw virus, the only Bunyamwera serogroup virus known in south Florida, or to cross-reactivity to an antigenic subtype or variant of Tensaw virus. Five strains, identified as Tensaw virus when they were isolated from mosquitoes collected in south Florida more than 20 years ago, were retrieved from storage. They were compared by serum dilution-plaque reduction neutralization tests with Bunyamwera serogroup prototypes Tensaw, Maguari, Cache Valley, and Tlacotalpan viruses. The south Florida isolates were shown to be most closely related to prototype Tensaw virus and most distantly related to prototype Maguari virus. One isolate could not be distinguished from prototype Tensaw virus, and the other 4 appeared to be subtypes of prototype Tensaw virus. More than 300 serum samples from humans in south Florida were tested for neutralizing antibody to prototypes Tensaw and Maguari viruses and to 3 of the field isolates. Thirteen had antibody to prototype Tensaw virus only, 19 to prototype Maguari virus only, and 39 to both. Antibody to all but 6 of these 71 was attributed to infection with Tensaw virus, to a subtype of Tensaw virus, or to travel or birth outside the United States. It is likely that those with antibody to Maguari virus only had been infected with yet another subtype of Tensaw virus, although another, undiscovered, Bunyamwera serogroup virus may exist in south Florida.

Reevaluation of the western equine encephalitis antigenic complex of alphaviruses (family Togaviridae) as determined by neutralization tests.

Fourteen viruses closely related to the Fleming strain of western equine encephalitis (WEE) virus were cross-tested by serum dilution-plaque reduction neutralization. The results demonstrate that strains McMillan, R-43738, AG80-646, BeAr 102091, and Y62-33 are subtypes or varieties of western equine encephalitis virus strain Fleming. Ockelbo, Kyzylagach, and Babanki are subtypes of the prototype strain (EgAr 339) of Sindbis virus. Fort Morgan and Buggy Creek viruses are closely related to each other, whereas Highlands J and Aura viruses are distinct from other members of this antigenic complex. There appear to be parallels between geographic distribution and antigenic relatedness. We hypothesize that birds, the principal vertebrate hosts for these viruses, spread the progenitor viruses north and south and from continent to continent. Viruses of the WEE complex with lesser antigenic differences may develop in discrete ecologic conditions.

Investigation of a possible yellow fever epidemic and serosurvey for flavivirus infections in northern Cameroon, 1984.

A cluster of fatal hepatitis cases in northern Cameroon in 1984 stimulated a field investigation to rule out an epidemic of yellow fever. A serosurvey of villages in the extreme north of the country, in a Sudan savanna (SS) phytogeographical zone, disclosed no evidence of recent yellow fever infection. However, further south, in a Guinea savanna (GS) phytogeographical zone, serological evidence was found of endemic yellow fever virus transmission. The results indicate a potential for epidemic spread of yellow fever virus from the southern GS zone to the nothern SS zone of Cameroon, where immunity in the population was low.

A newly recognized vesiculovirus, Calchaqui virus, and subtypes of Melao and Maguari viruses from Argentina, with serologic evidence for infections of humans and horses.

In 1983, 17 virus strains were isolated from mosquitoes collected during an outbreak of western equine encephalitis in Santa Fe Province, Argentina. Strains of western equine encephalitis, Venezuelan equine encephalitis, St. Louis encephalitis, and Antequera viruses were isolated, as were several bunyaviruses of the California and Bunyamwera serogroups and a new vesiculovirus. Complement fixation and neutralization tests were used to identify the California serogroup virus as a subtype of Melao virus, the Bunyamwera serogroup virus as a subtype of both Maguari and Playas viruses, and the vesiculovirus as a newly recognized agent for which the name Calchaqui virus is proposed. A limited serosurvey of horses and humans in Santa Fe Province and horses from the adjacent Santiago del Estero Province was performed to determine the prevalence of neutralizing antibody to the subtypes of Melao and Maguari viruses and to Calchaqui virus. The high prevalence of antibodies to these three agents indicates the need for further studies of their disease potential in horses, because they are closely related to several other viruses that are known equine pathogens.

Epizootic vesicular stomatitis in Colorado, 1982: epidemiologic studies along the northern Colorado front range.

Epidemiologic evaluations were made of farm personnel on vesicular stomatitis-affected premises along the front range of the Rocky Mountains in Colorado during the 1982 epizootic. A similar antibody prevalence was noted to that of veterinarians and research and regulatory personnel who were involved with the same epizootic. Risk of infection resulted from intimate physical contact with infected horses or cows. Incidence and infection rates in horses were 45%; rates in cows were much lower, only 5%. Some epidemiologic clues were gained by a detailed study of an equine ranch. The pasture was incriminated as the area of highest risk, where 100% infection rates were noted. Horses in open pens and barns were at lower risk. Severe clinical disease in horses resulted in higher neutralizing antibody titers than inapparent or mild infection. Maternal antibody was detected in foals up to 4 months of age, and the level of antibody in the foal was a reflection of the dam's antibody level.

Distribution of Bunyamwera serogroup viruses in North America, 1956-1984.

We attempted to tabulate all Bunyamwera serogroup (family Bunyaviridae, genus Bunyavirus) isolates from North America. By summarizing information from the laboratories of the Centers for Disease Control, data generously shared by other laboratories, and the published literature, we were able to accumulate data regarding 1,372 Bunyamwera serogroup viruses. These were: Tensaw (664, including 8 from vertebrates), Cache Valley (396, including 6 from vertebrates), Main Drain (160, including 14 from vertebrates), Lokern (69, including 8 from vertebrates), Northway (13, including 5 from vertebrates), Tlacotalpan (7), Santa Rosa (2), Santa Cruz (1 from a horse), and 60 of undetermined serotype. Virus isolation rates by month of collection were correlated with collection efforts, but associations of viruses and arthropod vectors varied by location, vertebrate host, and arthropod distribution. Tensaw virus was isolated principally from Anopheles crucians mosquitoes (466/656 isolates from arthropods) in the southeastern United States; Cache Valley virus principally from An. quadrimaculatus (94), Coquillettidia perturbans (59), Culiseta inornata (45), Aedes sollicitans (30), Psorophora columbiae (23), An. punctipennis (18), and Ae. vexans and trivittatus (18 each) mosquitoes (total = 305/382 isolates from arthropods from all of the United States and Canada, except the southeastern United States); Main Drain virus from Culicoides variipennis (31), Culicoides (Selfia) sp. (65), and Psorophora (23) and Aedes (21) species mosquitoes in the western United States; Lokern virus from Culicoides species (55/61 isolates from arthropods) in the western United States. Relationships between vector and vertebrate host distributions are discussed briefly in regard to geographic distribution of the Bunyamwera serogroup viruses.

Arbovirus investigations in Argentina, 1977-1980. III. Identification and characterization of viruses isolated, including new subtypes of western and Venezuelan equine encephalitis viruses and four new bunyaviruses (Las Maloyas, Resistencia, Barranqueras, and Antequera).

Forty viruses isolated from mosquitoes between 1977 and 1980 in Argentina have been identified and characterized. Nineteen strains of VEE virus, identical by neutralization (N) tests, were shown by hemagglutination-inhibition tests with anti-E2 glycoprotein sera to represent a new subtype VI of the VEE complex. RNA oligonucleotide fingerprints of this virus were distinct from subtype I viruses. The virus was not lethal for English short-haired guinea pigs, indicating that it is probably not equine-virulent. Three strains of a member of the WEE virus complex were shown to differ by N tests in 1 direction from prototype WEE virus. The new WEE subtype was also found to be distinct by RNA oligonucleotide mapping. Its vector relationships indicate that it is an enzootic virus, and it has not been associated with equine disease. A new member of the Anopheles A serogroup was identified, shown to be most closely related to Lukuni and Col An 57389 viruses, and given the name Las Maloyas virus. A strain of Para virus (Bunyaviridae, Bunyavirus) was identified. Six isolates, representing 3 new viruses morphologically resembling bunyaviruses are described; the names Antequera, Barranqueras, and Resistencia are proposed for these agents, which were all isolated from Culex (Melanoconion) delpontei in Chaco Province. No serologic relationships between these viruses and other bunyaviruses were found. Since they are antigenically interrelated, they form a new (Antequera) serogroup. Eight Gamboa serogroup viruses and 2 strains of St. Louis encephalitis virus were also identified.

Antigenic relationships among Turlock serogroup Bunyaviruses as determined by neutralization tests.

Antigenic relationships between the five recognized Turlock serogroup viruses (family Bunyaviridae, genus Bunyavirus) were determined by serum dilution-plaque reduction neutralization tests. Results indicated that Turlock , Umbre , M' Poko and Lednice viruses are distinct from each other and that Yaba -1 virus is a subtype of M' Poko virus.

The effect of immune globulin on the response to trivalent oral poliovirus and yellow fever vaccinations.

To assess whether immune globulin may be administered concurrently with trivalent oral poliovirus vaccine (OPV) or yellow fever vaccine, antibody responses were studied in Peace Corps volunteers embarking for overseas duty in 1978. Of 200 volunteers who received OPV, 192 (96%) had pre-existing neutralizing antibody to at least 2 poliovirus types; of 160 yellow fever vaccinees, 24 (15%) had pre-existing 17D yellow fever antibody. Each volunteer received 5 ml of immune globulin, 0-7 days before, 3-5 days after, or 28-32 days after vaccination. This last group was designated the control group. Of the volunteers who received immune globulin 0-7 days before vaccination, 71% 72%, 49%, and 82% responded to poliovirus types 1, 2, and 3, and yellow fever, respectively (response was defined as a 4-fold or greater rise in serum neutralizing antibody titre between baseline (0-7 days before vaccination) and follow-up (15-40 days after vaccination)). These rates did not differ significantly from those in persons who received immune globulin 28-32 days after vaccination (61%, 60%, 51%, and 83%, respectively). Thus, among individuals who, for the most part, were immune to poliomyelitis but not to yellow fever, immune globulin did not decrease the antibody response to OPV or to yellow fever vaccine when given 0-7 days before vaccination.

Serodiagnosis of western equine encephalitis virus infections: relationships of antibody titer and test to observed onset of clinical illness.

Sera from horses and human beings with clinically diagnosed western equine encephalitis (WEE) virus infections were tested for hemagglutination-inhibition (HI), complement-fixation (CF), and neutralizing (N) antibody to WEE virus. These tests confirmed infection in 43.8% (HI), 56.3% (CF), and 80.4% (N) of horses and 54.5% (HI), 59.1% (CF), and 77.3% (N) of human beings. Use of the N test as an adjunct to the HI and CF tests increased the likelihood of serologic confirmation to 91.7%. In both horses and human beings, N antibody increased steeply at the end of the 1st week after onset. The results suggested that the presence of a high HI, CF, and/or N antibody titer in a single serum obtained from horses during the acute phase of illness caused by WEE virus can be used as presumptive evidence for infection with this virus.