J. Bravo

Bio: J. Bravo is an academic researcher. The author has contributed to research in topics: Dengue fever & 2009 Bolivian dengue fever epidemic. The author has an hindex of 15, co-authored 20 publications receiving 1617 citations.

Dengue haemorrhagic fever/dengue shock syndrome: lessons from the Cuban epidemic, 1981.

Abstract: Dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS) is one of the principal causes of hospitalization and death among children in several south-east Asian countries. Also, in the Region of the Americas, there has been an increase in the frequency of dengue fever epidemics and in the number of cases of DHF/DSS. In 1981 an epidemic of dengue haemorrhagic fever occurred in Cuba and this suggests that there is a high risk that such epidemics could recur in the region. The article summarizes the main clinical, virological, and epidemiological data obtained during the outbreak, some of which are reported for the first time.

Dengue hemorrhagic fever in Cuba, 1981: a retrospective seroepidemiologic study.

Abstract: In Cuba, 2 epidemics of dengue virus occurred: 1 caused by DEN-1 in 1977 and 1 caused by DEN-2 in 1981. The latter was associated with cases of dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). To study viral risk factors for DHF/DSS, a retrospective seroepidemiological survey was conducted in Cerro, a densely populated district in Havana City. The prevalence of plaque reduction neutralizing antibodies to DEN-1 and DEN-2 viruses was measured in 1,295 individuals (children and adults). Of these, 43.7% were immune to DEN-1 virus and 23.6% to DEN-2 virus. Of those individuals who were immune, 26.1% were immune to DEN-1 virus only, 6% to DEN-2 virus only, and 17.6% to both viruses. The DEN-2 virus infection rate in DEN-1 immune individuals was 3.8 times higher than in non-immune individuals. The 5 DHF/DSS cases in the sample had evidence of DEN-1 virus plus DEN-2 virus infections. Three were children and 2 were young adults. No cases were found in individuals infected with DEN-1 virus or DEN-2 virus only. Children infected by DEN-1 virus followed by DEN-2 virus had a high risk of acquiring DHF/DSS. Blacks and whites were equally infected with DEN-1 and DEN-2 viruses.

Why dengue haemorrhagic fever in Cuba? I. Individual risk factors for dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS)

Abstract: During the dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS) epidemic in Cuba in 1981, we identified some individual risk factors for the development of the severe clinical picture or for the fatal outcome of the disease. The percentage of secondary infection in 3 groups of patients with DHF/DSS was between 95 and 98·3 and it is concluded that secondary infection is an important, but not the only, condition for the development of DHF/DSS. An analysis of these 3 groups of patients and a fourth group of fatal cases showed that chronic diseases such as bronchial asthma, diabetes mellitus and sickle cell anaemia were additional risk factors contributing significantly to the development of DHF/DSS. The study also revealed that race was an individual risk factor, since DHF/DSS was more prevalent in white than in black persons.

Why dengue haemorrhagic fever in Cuba? 2. An integral analysis

Abstract: The epidemiological factors present in Cuba in 1981, when the dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS) epidemic occurred, were exceptional when compared to those of other countries in the region. Evidence is presented which demonstrates that virulence of the circulating strain is an important element in the analysis of an epidemic. Although the two current hypotheses to explain the occurrence of DHF/DSS epidemics are valid in well defined but different epidemiological situations, neither Halstead's hypothesis of secondary-type infection or Rosen's hypothesis of the role played by the virulence of the circulating strain can explain all cases. An integrated, multifactorial and unifying hypothesis is presented, which could be applied in different epidemiological situations. It is based mainly on an in-depth analysis of the literature and of the Cuban experience.

Dengue and Dengue Hemorrhagic Fever

Abstract: Dengue fever, a very old disease, has reemerged in the past 20 years with an expanded geographic distribution of both the viruses and the mosquito vectors, increased epidemic activity, the development of hyperendemicity (the cocirculation of multiple serotypes), and the emergence of dengue hemorrhagic fever in new geographic regions. In 1998 this mosquito-borne disease is the most important tropical infectious disease after malaria, with an estimated 100 million cases of dengue fever, 500,000 cases of dengue hemorrhagic fever, and 25,000 deaths annually. The reasons for this resurgence and emergence of dengue hemorrhagic fever in the waning years of the 20th century are complex and not fully understood, but demographic, societal, and public health infrastructure changes in the past 30 years have contributed greatly. This paper reviews the changing epidemiology of dengue and dengue hemorrhagic fever by geographic region, the natural history and transmission cycles, clinical diagnosis of both dengue fever and dengue hemorrhagic fever, serologic and virologic laboratory diagnoses, pathogenesis, surveillance, prevention, and control. A major challenge for public health officials in all tropical areas of the world is to devleop and implement sustainable prevention and control programs that will reverse the trend of emergent dengue hemorrhagic fever.

Dengue: a continuing global threat

Abstract: Dengue fever and dengue haemorrhagic fever are important arthropod-borne viral diseases. Each year, there are ∼50 million dengue infections and ∼500,000 individuals are hospitalized with dengue haemorrhagic fever, mainly in Southeast Asia, the Pacific and the Americas. Illness is produced by any of the four dengue virus serotypes. A global strategy aimed at increasing the capacity for surveillance and outbreak response, changing behaviours and reducing the disease burden using integrated vector management in conjunction with early and accurate diagnosis has been advocated. Antiviral drugs and vaccines that are currently under development could also make an important contribution to dengue control in the future.

Pathogenesis of dengue: challenges to molecular biology

Abstract: Dengue viruses occur as four antigenically related but distinct serotypes transmitted to humans by Aedes aegypti mosquitoes. These viruses generally cause a benign syndrome, dengue fever, in the American and African tropics, and a severe syndrome, dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS), in Southeast Asian children. This severe syndrome, which recently has also been identified in children infected with the virus in Puerto Rico, is characterized by increased vascular permeability and abnormal hemostasis. It occurs in infants less than 1 year of age born to dengue-immune mothers and in children 1 year and older who are immune to one serotype of dengue virus and are experiencing infection with a second serotype. Dengue viruses replicate in cells of mononuclear phagocyte lineage, and subneutralizing concentrations of dengue antibody enhance dengue virus infection in these cells. This antibody-dependent enhancement of infection regulates dengue disease in human beings, although disease severity may also be controlled genetically, possibly by permitting and restricting the growth of virus in monocytes. Monoclonal antibodies show heterogeneous distribution of antigenic epitopes on dengue viruses. These epitopes serve to regulate disease: when antibodies to shared antigens partially neutralize heterotypic virus, infection and disease are dampened; enhancing antibodies alone result in heightened disease response. Further knowledge of the structure of dengue genomes should permit rapid advances in understanding the pathogenetic mechanisms of dengue.