Showing papers by "Gustavo Kourí published in 1996"

Advances in dengue diagnosis.

Abstract: Despite improvements in health, epidemics of infectious diseases continue to occur, and new diseases emerge and old diseases reemerge (113). Mosquito-borne flavivirus diseases are currently considered reemerging infections because of the increase in the incidences of yellow fever and, mainly, dengue fever and dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) observed in the last few years (30, 86). The dengue syndrome is an acute febrile viral exanthem, accompanied by headache, myalgia, anorexia, gastrointestinal disturbances, and postration, caused by viruses transmitted by mosquitoes (43). DHF is a severe febrile disease characterized by abnormalities of hemostasis and increased vascular permeability. DSS is the result of a hypovolemic shock observed in some DHF cases. DHF/DSS represents the severe form of dengue fever (52). The disease is caused by any one of the four distinct serotypes (1 to 4) of the dengue virus (52, 114). These viruses are members of the family Flaviviridae; they have a common morphology and genomic structure, and all members share common antigenic determinants. The four dengue virus serotypes are classified as a complex on the basis of clinical, biological, and immunological criteria. Dengue virus complex-specific antigenic determinants have been demonstrated by using neutralization assays, which also can differentiate the dengue virus complex into four antigenically distinct dengue virus serotypes, since each serotype presents a type-specific determinant (49, 52). The flaviviruses are transmitted by mosquitoes of the Stegomia family, mainly Aedes aegypti, a domestic, day-biting mosquito that prefers to feed on humans (52, 99). This is a highly urbanized mosquito, breeding in water stored for domestic use or collected rainwater. A jungle cycle has been proposed to exist in Southeast Asia, since there is a high rate of dengue transmission among different species of monkeys (52, 105). The genomic RNA of dengue viruses is single stranded and approximately 11 kb in length. The RNA is infectious and, as in the rest of the flaviviruses, it has a single open reading frame (103). The order of proteins encoded in the long open reading frame is 59-C-prM(M)-E-NS1-NS2A-NS2B-NS3-NS4A-NS4BNS5-39. The mature virion contains three structural proteins: C, the nucleocapside or core protein of 13.5 kDa; M, a membrane-associated protein of 8 kDa; and the E (envelope) protein of 51 kDa. The E protein has the sites for viral attachment to and transport through host cell plasma membranes. Functional domains responsible for the neutralization and hemagglutination of goose erythrocytes are associated with the E protein. It contains epitopes specific for serotype, dengue complex, and group (6, 48, 103, 115). Considering the technology currently used for the diagnosis of dengue viruses, a case definition in which laboratory confirmation is emphasized has been proposed. The laboratory criteria for confirmation of the infection and the disease include the isolation of dengue virus from serum and/or autopsy samples, the demonstration of a fourfold or greater increase in the titer of immunoglobulin G (IgG) or IgM antibody to one or more dengue virus antigens in paired serum samples, or the demonstration of dengue virus antigen in autopsy tissue or serum samples by immunohistochemistry, by immunofluorescence, or by the detection of the viral nucleic acid (98).

[Dengue in Nicaragua, 1994: reintroduction of serotype 3 in the Americas].

Abstract: The principal aim of this work was to report the reintroduction of dengue virus serotype 3 in the Americas after an absence of 17 years. In addition, it describes the most common symptoms associated with classical dengue and hemorrhagic dengue and presents data on the distribution of the epidemic in the various comprehensive local health care systems of Nicaragua. The study group consisted of 39 patients hospitalized in Managua and Leon for dengue with hemorrhagic manifestations and hemorrhagic dengue. Of these patients, 34 were classified as probable or confirmed cases of dengue. The most frequent symptoms were fever, headache, vomiting, and muscle and joint pains. The tourniquet test was positive and thrombocytopenia was confirmed in 56% and 44% of the patients, respectively. Epistaxis (67%) was the most common hemorrhagic sign. Of the 356 serum samples received through the dengue surveillance systems in October 1994, IgM antibodies were detected in 43%. The virus was isolated from 5 of 24 samples tested (serotype 3 from 3 and serotype 1 from 2). The reintroduction of serotype 3 of dengue into the Region was demonstrated, along with its ability to produce epidemics of hemorrhagic dengue. The countries are warned that if they do not quickly take the measures described in the guidelines for the prevention and control of dengue and dengue hemorrhagic fever, new epidemics may occur in the Americas, given the large number of persons susceptible to this serotype and the high density of the mosquito vector in most of the countries of the Region.

Relaciones genéticas del virus dengue 3 aislado en la epidemia de FHD en Nicaragua, 1994

Abstract: It is reported the isolation of 2 dengue strains, 3 in samples from Nicaraguan patients suffering from dengue with hemorrhagic manifestations, which showed the reintroduction of this serotype in the region after being 17 years out of circulation. It is also reported the genetic characterization of the isolated strain, which, according to its classification, belongs to the group of dengue 2 strains isolated in Southeast Asi and which have been associated to hemorrhagic dengue. These results suggest the origin of this strain.

Direct sequencing of an amplified product from a serum sample

Abstract: It is reported the nucleotide and amino acidic sequence of a great variability region in the dengue 2 virus genome, starting from the RNA of the original virus with no passage in the isolation systems. It is compared with the first strain of dengue 2 isolated during the 1981 epidemic with 4 passages in lactating mouse. Results show that the nucleotide sequence of serum and of strain A15 are the same.