[Venezuelan equine encephalitis. 1995 outbreak: clinical profile of the case with neurologic involvement]. / Encefalitis equina venezolana. Epidemia de 1995: perfil clínico de los casos con compromiso neurológico.

INTRODUCTION: Venezuelan equine encephalitis virus has caused periodic epidemics and epizootics in the American continent since the 1920s. Such events have been profusely documented from the epidemiologic point of view, however, reports concerning the clinical features of this disease are rather scarce. OBJECTIVE: To analyze the clinical characteristics evidenced by Venezuelan equine encephalitis patients from Zulia state (western Venezuela) studied during the outbreak that occurred in Colombia and Venezuela in 1995. These cases, classified as complicated, were hospitalized at the Hospital Universitario de Maracaibo, state of Zulia, Venezuela. PATIENTS AND METHODS: The clinical charts of 313 Venezuelan equine encephalitis patients hospitalized during the period January 1st 1995-March 31st 1996 were reviewed. These cases accounted for 2.82% of 11,072 patients that were medically assisted during the outbreak. The following variables were analyzed: age, gender, signs and symptoms, contact history, complications and evolution. RESULTS: Intracranial hypertension signs became eloquent in 55.9% of these patients. Neurologic complications were represented by two cases of cerebellitis, two cases of meningoencephalitis and one case of encephalomyelitis. The mortality rate was 1.7%. CONCLUSION: Our results corroborate the benign evolutionary profile that is typical of this entity.

Strong Amerind/white sex bias and a possible Sephardic contribution among the founders of a population in northwest Colombia.

Historical and genetic evidences suggest that the recently founded population of Antioquia (Colombia) is potentially useful for the genetic mapping of complex traits. This population was established in the 16th-17th centuries through the admixture of Amerinds, Europeans, and Africans and grew in relative isolation until the late 19th century. To examine the origin of the founders of Antioquia, we typed 11 markers on the nonrecombining portion of the Y chromosome and four markers on mtDNA in a sample of individuals with confirmed Antioquian ancestry. The polymorphisms on the Y chromosome (five biallelic markers and six microsatellites) allow an approximation to the origin of founder men, and those on mtDNA identify the four major founder Native American lineages. These data indicate that approximately 94% of the Y chromosomes are European, 5% are African, and 1% are Amerind. Y-chromosome data are consistent with an origin of founders predominantly in southern Spain but also suggest that a fraction came from northern Iberia and that some possibly had a Sephardic origin. In stark contrast with the Y-chromosome, approximately 90% of the mtDNA gene pool of Antioquia is Amerind, with the frequency of the four Amerind founder lineages being closest to Native Americans currently living in the area. These results indicate a highly asymmetric pattern of mating in early Antioquia, involving mostly immigrant men and local native women. The discordance of our data with blood-group estimates of admixture suggests that the number of founder men was larger than that of women.

Autosomal, mtDNA, and Y-chromosome diversity in Amerinds: pre- and post-Columbian patterns of gene flow in South America.

To evaluate sex-specific differences in gene flow between Native American populations from South America and between those populations and recent immigrants to the New World, we examined the genetic diversity at uni- and biparental genetic markers of five Native American populations from Colombia and in published surveys from native South Americans. The Colombian populations were typed for five polymorphisms in mtDNA, five restriction sites in the beta-globin gene cluster, the DQA1 gene, and nine autosomal microsatellites. Elsewhere, we published results for seven Y-chromosome microsatellites in the same populations. Autosomal polymorphisms showed a mean G(ST) of 6.8%, in agreement with extensive classical marker studies of South American populations. MtDNA and Y-chromosome markers resulted in G(ST) values of 0.18 and 0.165, respectively. When only Y chromosomes of confirmed Amerind origin were used in the calculations (as defined by the presence of allele T at locus DYS199), G(ST) increased to 0.22. G(ST) values calculated from published data for other South American natives were 0.3 and 0.29 for mtDNA and Amerind Y chromosomes, respectively. The concordance of these estimates does not support an important difference in migration rates between the sexes throughout the history of South Amerinds. Admixture analysis of the Colombian populations suggests an asymmetric pattern of mating involving mostly immigrant men and native women.