Showing papers by "Gustavo Kourí published in 2011"

Virus Role During Intraepidemic Increase in Dengue Disease Severity

Abstract: Dengue epidemics in Cuba have repeatedly demonstrated a month-to-month increase in clinical severity during secondary infections. The dengue 2 outbreak that occurred in Santiago de Cuba in 1997 was accompanied by the most severe intraepidemic increase in disease severity reported to date. It was initially proposed that the appearance of neutralization escape mutants during the course of the epidemic might explain this phenomenon. Recent studies have revealed that during the course of this epidemic, nucleotide substitutions appeared only in nonstructural (NS) genes, most of which were silent, except for one change in the NS1 gene. To study whether or not variation in the NS1 gene might be associated with increased disease severity during the epidemic, this gene was partially sequenced from 15 isolates obtained at different times during the 1997 epidemic. Early epidemic isolates differed from those obtained later by replacement only of threonine with serine at position 164 in the NS1 protein, an amino acid rarely found in any genotype of dengue 2 virus. All viruses isolated from patients located in Health Districts, where dengue 2 transmissions occurred late in the epidemic, contained Serine at position 164, indicating that this change was fixed within a few months. Here we argue that this single mutation contributes to viral survival or replication efficiency, resulting in enhanced infection in the presence of enhancing antibodies, a phenomenon that we term increased virus "fitness" in contrast to "virulence," an intrinsic property of the virus.

Prevalence of febrile syndromes in dengue surveillance, havana city, 2007.

Abstract: OBJECTIVE Determine point prevalence of febrile syndromes and compare with prevalence reported by habitual clinical and seroepidemiologic dengue surveillance system in Havana City METHODS In October 2007, a descriptive, cross-sectional study was carried out in a representative sample, calculating prevalences of febrile syndromes and undifferentiated febrile syndromes Chi-square analysis was used for rate comparisons RESULTS Point prevalences of febrile syndromes and undifferentiated febrile syndromes were 3526 and 1442 times greater, respectively, than those reported by the habitual clinical and seroepidemiologic dengue surveillance system; these differences were statistically significant (p < 0001) CONCLUSIONS Point prevalence of febrile syndromes was far greater than prevalence reported by the habitual clinical and seroepidemiologic dengue surveillance system, an indication of underreporting