Hughes virus from Trinidadian ticks and terns

Fifteen strains of Hughes virus were isolated from Soldado Rock, Trinidad, between 1962 and 1965. Seven isolates came from ticks of the Ornithodoros capensis complex and 8 from nestling birds, Sterna fuscata.(AU)

Arbovirus studies in Bush Bush Forest, Trinidad, W.I., September 1959-December 1964. VI. Rodent-associated viruses (VEE and agents of groups C and Guama): isolations and further studies

Details are given on isolations of seven virus types from material collected in Bush Bush Forest during the study period: 262 of Venezuelan equine encephalitis (VEE), 71 of Caraparu-like, three of Oriboca, two of Restan, 63 of Bimiti, 56 of Catu, and 87 of Guama. Data from experimental-infection studies are presented, as well as results of serologic studies with hemagglutinating antigens of VEE and Caraparu-like viruses and some 1,200 sera of Bush Bush rodents. It was found that the natural transmission cycles of five of these virus types in Bush Bush are similar and include a period of multiplication and viremia in forest-floor rodents and a period of multiplication in mosquitoes among which Culex (Melanoconion) protesi, at least, is capable of subsequent transmission. Similar cycles are inferred for the remaining two virus types, Oriboca and Restan. In 1964 a severe reduction of the rodent population took place, Culex portesi continued abundant, and only Bimiti of the seven virus types was isolated. It is concluded that an alternate host population of sufficient size was not then available to these viruses in Bush Bush. Very little evidence was found to implicate mosquito species other than C.portesi as essential vectors during epizootic or inter-epizootic periods. (AU)

Arbovirus studies in Bush Bush Forest, Trinidad, W. I., September 1959-December 1964. IV. Vertebrate populations

An introduction has been given to the principal vertebrates of Bush Bush Forest, which include 59 species of mammal (32 of bat), 171 species of bird , 27 species of reptile, 7 species of amphibian, and an undetermined number of fish. Special attention was paid to the population dynamics, longevity, and range of small forest rodents. During the study years the populations of small rodents declined almost to the point of disappearence. (AU)

Arbovirus studies in Bush Bush Forest, Trinidad, W.I., September 1959-December 1964. III. Entomologic studies

Bush Bush Forest entomologic investigations were concered mainly with mosquitoes, the most conspicuous element of the bloodsucking arthropod fauna. More than 92 species were demonstrated, but only about two dozen were common. Mosquitoes were studied in relation to thier physical environment, seasonal activity, diel activity, horizontal stratifaction in the forest, food preferences, and larval habitats. Large numbers were collected for virus studies. Other groups investigated were phlebotomine flies (10 species), Culicoides flies (10 species), horseflies (18 species), Cuterebridae (one species), sucking lice (four species), fleas (one species), ticks (nine species), and various mites including 15 species of trombiculid. (AU)

Arbovirus studies in Bush Bush Forest, Trinidad, W.I., September 1959-December 1964. II. Field program and techniques

The field program of the Trinidad Regional Virus Laboratory in Bush Bush Forest included studies in which arboviruses (their prevalence and epidemiology) were the chief interest and also studies on the biology of the arthropods and vertebrates possibly associated with arbovirus cycles. The techniques used included the exposure of sentinel animals, trapping and bleeding of small mammals and reptiles, netting and bleeding of birds, collection of bloodsucking arthropods, and observations on the diel- and seasonal-activity patterns, food sources, and habitat preferences of the more abundant species of mosquitoes.(AU)

Arbovirus studies in Bush Bush Forest, Trinidad, W.I., September 1959-December 1964. I. Description of the study area

Bush Bush Island and the surrounding Nariva Swamp, eastern Trinidad, are described in terms of their topography, flora, and fauna as an introduction to a series of papers reporting the results of 5 years of arbovirus studies in this area. (AU)

Laboratory studies with wild rodents and viruses native to Trinidad. II. Studies with the Trinidad Caraparu-like agent TRVL 34053-1

Trinidad virus TRVL 34053-1, belonging in group C and closely related to Caraparu virus, was shown to circulate in the blood of naturally and experimentally infected Oryzomys laticeps velutinus. All seven experimental animals circulated virus; the maximum virus level observed in their serum was 5.8 dex LD50 for adult mice inoculated intracerebrally with 0.03 ml. Studies with 80 experimentally infected animals, 40 Oryzomys and 40 Zygodontomys b. brevicauda, showed that hemagglutination-inhibiting (HI), complement-fixing and neutralizing antibodies persisted for about 2 months after birth and neutralising antibodies persisted for about 1 month longer. (Summary)

Preliminary interpretation of virus activity in the Nariva Swamp study area of Trinidad

The virus isolations made in 1960 and 1961 in the Nariva swamp study area of Trinidad appear to have three recognizable patterns: (1) They occur almost exclusively in the rainy season (2) Infection of sentinel mice takes place mainly during the night. (3) Differences in virus density consistently occur in various areas of the swamp (AU)

Virus studies in Trinidadian swamps

Some generalizations are presented about the historical associations of swamps with mosquitoes and fevers. It is pointed out that in years past malaria tended to obscure disease patterns and that with the decrease in malaria, a backlog of fever cases still remains to be elucidated. Work in the Caroni Swamp in Western Trinidad is described. This area is coastal, estuarine mangrove swamp in a region with an annual rainfall of 30 to 40 inches. Minimal evidence of activity of arthropod-transmitted viruses has been obtained, on examination of resident vertebrates and mosquitoes. Work in the region of the Nariva Swamp in Eastern Trinidad is described This is also a coastal swamp but with more vegetation, extending into swamp forests, and dry ground forests bordering swampy regions. Rainfall is about 80-90 inches per year. There are good populations of animals, birds and biting insects in the forests. The virus yield from the Nariva Swamp area has been heavy, with 90 virus isolations in 1960 and 105 in 1961. These viruses are of at least 12 different types and include viruses of real or potential importance to the public health, such as Venezuelan equine encephalitis, St. Louis, Oropouche and yellow fever. It is felt that high rainfall tropical forest bordering on fresh-water herbaceous swamp areas represent a favourable environment for the maintenance of cycles of arthropod-transmitted viruses. Such an area in Trinidad has been much more productive of viruses than a mangrove swamp area with which its compared (AU)

Eastern equine encephalitis virus infection of birds in the Caribbean

EEE virus was not recovered from any birds in the Caribbean and the immune rate was very low. Thus there is as yet no positive evidence that migrating birds participate in the spread of the virus (AU)