Dengue type 3 virus isolated from an Antiguan patient during the 1963-64 Caribbean epidemic

A strain of dengue type 3 virus was isolated from the blood of an Antiguan patient in cell cultures of African green-monkey kidney during studies on a dengue outbreak that occured in the Caribbean region in 1963 and 1964. The virus was adapted to mice by blind intracerebral passage. Illness appeared in mice at the 11th mouse-brain passage. Four other agents, presumed to be dengue type 3 strains, were isolated from Antiguan patients. Serologic studies on serum from patients of five Caribbean territories showed that the outbreak was due to a group B arbovirus. (AU)

A comparitive study of virulences, plaque morphologies and antigenic characteristics of Venezuelan encephalitis virus strains

Virulences of VE virus strains from tropical regions of the North and South American continents were studied in adult Syrian hamsters, Swiss albino mice and cotton rats. Virulence profiles were based on frequency and time of illness and death following subcutaneous inoculation of small doses of virus as collected in nature or after only a few passages in laboratory hosts. Forty-one strains from Mexico, USA-Florida, Panama, Colombia, and Venezuela uniformity killed hamsters inoculated s.c. with 4-1000 PFU; incubation periods were usually 3-6 days, but some Panamanian and USA-Florida strains had incubation periods 1-2 days longer than strains from other countries. All of 37 strains from these countries regularly produced illness in adult mice, but killed only 71-82 percent; in adult cotton rats, signs of illness were not recognized, but death occurred in 18-30 percent. Variations in virulence profiles for mice and cotton rats among 28 Mexican strains were ogten as great as those seen among 9 strains from USA-Florida, Panama, Colombia and Venezuela. Virus strains from the Bush Bush areas of Trinidad, however, had distinctive virulence profiles. All 5 of these strains killed hamsters only after prolonged incubation periods of more than 5 days, and killed only 1 of 25 mice; neither of two strains killed cotton rats. Young and Johnson reported (Amer. J. Epid., 1969, 89 286-307) that these Trinidad strains should antigenically be classified as Mucambo rather than VE virus. The TC 83 attenuated strain of VE virus in a dose of 500 PFU given s.c. killed no hamsters, mice or cotton rats, but in some experiments employing larger doses, up to 20 percent hamsters became ill and 5-10 percent died without apparent relationship to dose. Plaque sizes and morophologies of 19 VE and 5 Trinidad Mucambo virus strains in primary chicken embryonic cell cultures did not correlate with virulence for hamsters, mice, cotton rats or man, nor with geographic, host or tissue source or year of collection. In sera of cotton rats and mice 3-4 weeks after s.c. inoculation, titers of VE virus HI antibody measured with hemagglutinin from a Mexican virus strain were similar for strains from Mexico, Colombia and Venezuela. However they were lower with USA-Florida and TC 83 virus strains and with Trinidad Mucambo virus strains, suggesting that these viruses differ antigenically from Mexican, Colombian and Venezuelan strains. Nevertheless the attenuated TC 83 vaccine virus protected adult mice against s.c. challenge by 28 Mexican and 8 other VE virus strains from USA-Florida, Panama, Colombia and Venezuela, suggesting that immunologically distinct types of VE virus based on cross-protection do not exist in these countries. (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. 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)

A further account of the Trinidad outbreak of acute rabic myelitis: histology of the experimental disease

Experimental work proving that the cause of the Trinidad outbreak of acute myelitis in man, and of the so-called botulism in cattle, is the virus of the rabies detailed. The vector has not been determined with certainty but the evidence available suggests that it is the vampire bat. The histology of spontaneous cases and of the disease in the monkey and rabbit is described (Summary)