Size heterogeneity in the 3' noncoding region of South American isolates of yellow fever virus

The 3' noncoding region (3' NCR) of flaviviruses contains secondary and tertiary structures essential for virus replication. Previous studies of yellow fever virus (YFV) and dengue virus have found that modifications to the 3' NCR are sometimes associated with attenuation in vertebrate and/or mosquito hosts. The 3' NCRs of 117 isolates of South American YFV have been examined, and major deletions and/or duplications of conserved RNA structures have been identified in several wild-type isolates. Nineteen isolates (designated YF-XL isolates) from Brazil, Trinidad, and Venezuela, dating from 1973 to 2001, exhibited a 216-nucleotide (nt) duplication, yielding a tandem repeat of conserved hairpin, stem-loop, dumbbell, and pseudoknot structures. YF-XL isolates were found exclusively within one subclade of South American genotype I YFV. One Brazilian isolate exhibited, in addition to the 216-nt duplication, a deletion of a 40-nt repeated hairpin (RYF) motif (YF-XL-DeltaRYF). To investigate the biological significance of these 3' NCR rearrangements, YF-XL-DeltaRYF and YF-XL isolates, as well as other South American YFV isolates, were evaluated for three phenotypes: growth kinetics in cell culture, neuroinvasiveness in suckling mice, and ability to replicate and produce disseminated infections in Aedes aegypti mosquitoes. YF-XL-DeltaRYF and YF-XL isolates showed growth kinetics and neuroinvasive characteristics comparable to those of typical South American YFV isolates, and mosquito infectivity trials demonstrated that both types of 3' NCR variants were capable of replication and dissemination in a laboratory-adapted colony of A. aegypti.

The prevalence of hypertension and the state of cardiovascular health in Venezuela and surrounding nations

This review summarizes the prevalence of hypertension and the state of cardiovascular health in Venezuela and surrounding nations. First, the review discusses the fact that cardiovascular disease (CVD) is the main cause of death in Venezuela, Colombia, Brazil, and Trinidad and Tobago, accounting for 20 percent to 35 percent of all deaths. These data are similar to data from the developed world. Second, prevalence of hypertension in this region varies from 8 percent to 40 percent in the adult population, and, on average, 22 percent of the adult population of this region has an elevated blood pressure. However, prevalence rates very considerably from country to country and within regions of the same country. Although mortality from hypertension as the main cause of death accounts for 1 percent to 4 percent of all deaths, indicating a failure in the treatment of hypertension. In most Latin American countries, the degree of awareness, treatment and control of hypertension is low, necessitating the establishment of programs to prevent, detect and effectively treat hypertension and decrease CVD risk factors.(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)

Endemic goitre in South Trinidad (abstract only)

There is a preliminary report based on an analysis of 206 cases of surgical goitre seen at the San Fernando General Hospital between January 1954 and December 1959, and includes a personal series of 56 cases. Trinidad being the only island in the Caribbean geologically related to the mainland of South America, shows a pattern of endemic goitre distribution very similar to the goitre distribution around the upper reaches of the Orinoco Basin and the northern range of Venezuela. This potentially goitrous belt follows the anticlinal fold which flanks the geosynclinal basin of South Trinidad along the north and north west. Only 17 of the 205 cases were outside this belt. Male to female ratio among 153 simple goitres was 11 to 142. The incidence in women was closely related to multiparity. Age distribution was as follows : Under 20 years (17 cases); 21 to 40 years (94 cases); above 41 years (42 cases). Twenty eight cases in the total of 205 developed secondary thyrotoxicosis (AU)