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At least 613 records · Page 34Linked to original sources
PubMed2001

Epitopes on the dengue 1 virus envelope protein recognized by neutralizing IgM monoclonal antibodies.

Three of 41 IgM monoclonal antibodies derived from dengue 1 virus immunized mice neutralized dengue 1 infection in vitro. All three neutralizing monoclonal antibodies reacted with spatially related epitopes on the E protein of dengue 1 which were also recognized by antibodies in sera from dengue patients. Two neutralization-resistant populations of dengue 1 virus, D1-M10 and D1-M17, were selected by sequential passage of virus in C6/36 cells in the presence of neutralizing IgM monoclonal antibodies M10 and M17, respectively. Single nucleotide changes occurred in the E protein gene of each of these virus populations resulting in single amino acid substitutions at E279 (Phe-Ser) in D1-M10 and at E293 (Thr-Ile) in D1-M17. Both neutralization-resistant populations of virus were more sensitive to elevated temperature than was the wild-type dengue 1 virus and the infectivity and haemagglutinating ability of the neutralization-resistant populations decreased more slowly than that of wild-type virus when exposed to pH in the range 5.8 to 7.0. These are the first epitopes involved in neutralization to have been identified in dengue 1 virus and the first outside domain III of the E protein on any dengue virus.

Amino Acid Substitution↗
PubMed1993

Use of NS3 consensus primers for the polymerase chain reaction amplification and sequencing of dengue viruses and other flaviviruses.

Consensus primers for the polymerase chain reaction were designed based on conserved motifs within the serine protease and RNA helicase domains encoded by the NS 3 genes of dengue and other flaviviruses. Target fragments of 470 bp were amplified on cDNA templates synthesized from RNAs of dengue types 1, 2, 3, and 4, Japanese encephalitis, Kunjin, and yellow fever viruses using random or specific downstream primers. PCR of oligo(dT)-primed cDNAs from Japanese encephalitis and Kunjin viral RNAs did not yield target bands. As few as 10(3) copies of dengue viral RNA could be detected. Direct DNA sequencing of PCR products of reference strains of dengue 2 (NGC), Kunjin (MRM 61C) and yellow fever (17 D) viruses demonstrated complete concurrence with published data. However, 2 nucleotide differences were observed between our data for dengue 3 H87 strain and the published sequence, resulting in a single amino acid disparity. Differences at 21, 16, and 11 nucleotide positions were noted between dengue 1 Hawaii and S 275/90; dengue 4 H 241 and 814669; Japanese encephalitis Nakayama and JaOArS 982 viral strains, culminating in only 4, 1 and 1 amino acid residue differences, respectively. These amino acid disparities occurred outside putative active sites of the enzymatic domains, emphasizing the important role of the NS3 protein in flaviviral replication. This RNA-PCR consensus primer strategy coupled with DNA sequencing represents a valuable tool for the molecular diagnosis and epidemiology of dengue and other flaviviral infections.

Aedes↗
PubMed1982

Antiviral effects if ribavirin and 6-mercapto-9-tetrahydro-2-furylpurine against dengue viruses in vitro.

The antiviral effects of ribavirin (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide) and 6-mercapto-9-tetrahydro-2-furylpurine (6-MPTF) against dengue viruses were examined in vitro. Ribavirin significantly reduced the growth of dengue virus types 1-4 in LLC-MK2 cells at concentrations well below cytotoxic levels (cell viability was determined by trypan blue dye exclusion) Addition of guanosine to ribavirin-treated dengue virus-infected cell cultures completely reversed the antiviral effect of the drug. In contrast, ribavirin had no effect on dengue virus replication in human peripheral blood leukocytes (PBL). 6-MPIF, a specific inhibitor of hypoxanthine-guanine phosphoribosyltransferase, did not significantly reduce the growth of dengue viruses in either LIC-MK2 cells or human PBL. However, synergistic effects of 6-MPTF and ribavirin were observed, as combined treatment of the drugs markedly suppressed the replication of dengue viruses in human PBL. The successful demonstration that dengue virus replication in mononuclear leukocytes is markedly suppressed by the combined treatment of ribavirin and 6-MPTF signals a need to evaluate the efficacy of this treatment against dengue virus infections in vivo.

Animals↗
PubMed2005

Distinguishing dengue fever from other infections on the basis of simple clinical and laboratory features: application of logistic regression analysis.

BACKGROUND: Dengue fever is a frequent cause of admission to hospital in South East Asia, however many of the clinical characteristics and abnormalities on laboratory investigations at presentation are found in other common infections. OBJECTIVES: To describe the clinical and laboratory features of dengue fever and other common febrile illnesses in Singapore. STUDY DESIGN: We performed a prospective study of consecutive adult admissions to an infectious diseases hospital. Logistic regression analysis was used to identify symptoms, physical signs and laboratory features that differentiated dengue fever from other febrile illnesses within the first 2 days of admission. RESULTS: Of the 381 patients studied, 148 had serologically confirmed dengue fever. Most of these had uncomplicated dengue fever, and only 9% had dengue haemorrhagic fever. A model based on clinical features alone (including a variety of cutaneous signs, pulse rate and the presence of pharyngeal injection) was able to differentiate dengue fever from other infections with a sensitivity of 74% and specificity of 79%. A model based on clinical features (rash) and laboratory parameters (white cell count, haemoglobin, prothrombin time, creatinine and bilirubin levels), achieved a sensitivity of 84% and specificity of 85%. CONCLUSIONS: A combination of simple clinical and laboratory parameters are potentially able to predict dengue fever with a high level of accuracy in adults presenting to hospital with febrile illnesses in Singapore.

Adult↗
PubMedDate not supplied

Epidemic dengue transmission in southern Sumatra, Indonesia.

An outbreak of dengue fever (DF), dengue haemorrhagic fever (DHF), and dengue shock syndrome (DSS) in the city of Palembang, south Sumatra, Indonesia was investigated to (i) validate epidemic occurrence, (ii) confirm dengue virus aetiology and associated serotype(s), (iii) provide a demonstrable measure of community impact, and (iv) identify causative relationship (if any) with climatic El Niño Southern Oscillation (ENSO) influences. Trend analysis based on a 6-year retrospective review of hospital records demonstrates a 3-fold increase in clinical cases for the outbreak period (January-April 1998), relative to historical records. In the 2 hospitals surveyed, the monthly mean number of outbreak-related dengue cases over 4 months was 833 (range 650-995 cases/month); the mean monthly value for the previous 72 months was 107 (range 14-779 cases/month). An apparent trend in epidemic transmission was observed, evolving from a 5-year cyclic phenomenon to an annual occurrence, often indistinguishable from one year to the next. The proportional distribution of clinical outbreak cases into DF, DHF and DSS diagnostic categories was 24%, 66%, and 10%, respectively. The population aged 10-19 years accounted for the largest (35%) proportion of hospitalized DHF cases, followed by children aged 5-9 years (25%) and children aged 4 years (16%). Serum samples obtained during acute illness from 221 hospitalized patients were examined using serology, RT-PCR, and virus isolation in cell culture: 59% of samples had laboratory evidence of a dengue infection. All 4 dengue virus serotypes (DEN 1-4) were identified in epidemic circulation, with DEN 3 predominating (43%). DEN 1 was the principal serotype associated with less severe dengue illness, suggesting that virulence may be, in part, a function of infecting serotype. The climatic influence of ENSO on rainfall and temperature in the months leading up to and during the outbreak was dramatic, and is likely to contribute to favourable outbreak conditions.

Adolescent↗
PubMed1998

The 1993 dengue 2 epidemic in Charters Towers, North Queensland: clinical features and public health impact.

In 1993 an epidemic caused by dengue virus type 2 occurred in several North Queensland population centres. Charters Towers, estimated population 10,000, had 155 officially notified cases. An analysis of symptoms was undertaken using a random sample of 1000 residents to determine specificity of symptoms, the subclinical infection rate, and to establish the true extent of the epidemic. Retrospective diagnoses of dengue fever were based on the presence of both serum dengue 2 neutralizing antibody and presence of symptoms. An estimated 20% of the population had dengue fever. The rate of subclinical infections in this epidemic was 14.6%. There were no symptoms that were specific for dengue fever. Bleeding occurred more frequently in people who recalled a previous dengue infection during a dengue 1 epidemic 12 years earlier (55.6% vs. 16.8%, P = 0.003). Surveillance for future epidemics should be based on serological and virological confirmation of dengue virus infection amongst symptomatic patient.

Adolescent↗
PubMed1998

Determination of dengue virus serotypes in individual Aedes aegypti mosquitoes in Colombia.

Adult Aedes aegypti mosquitoes were collected in Puerto Triunfo, central Colombia, where dengue is endemic, during a six month period. Viral infection within the head of each individual mosquito was identified by an immunofluorescent assay (IFA) using a flavivirus-specific monoclonal antibody. The dengue virus serotype, present in each flavivirus-positive specimen, was then determined in portions of the remaining thorax using IFAs with serotype-specific monoclonal antibodies. Among 2065 female Aedes aegypti collected and tested, twenty-four flavivirus-positive individuals were found (minimum infection rate 11.6%), three identified as dengue type-1 and twenty-one as dengue type-2 virus. This was consistent with the isolation of only these two serotypes of dengue virus from dengue fever patients within this town. No vertical transmission of dengue virus could be detected in 1552 male Aedes aegypti collected. This method is inexpensive, simple, rapid to perform and suitable for use in developing countries to identify and distinguish different serotypes of dengue virus in their vectors during eco-epidemiological investigations.

Aedes↗
PubMed2001

Characterisation of lymphocyte response and cytokine patterns in patients with dengue fever.

It is believed that the pathogenesis of dengue is generated by a deregulation of the immunological response. Dengue virus-infected monocytes/macrophages are likely to secrete monokines, which play a role in clinical features observed in patients with dengue haemorrhagic fever or dengue shock syndrome. This is a report on a study on 45 individuals presenting clinical and laboratory characteristics of dengue virus infection. During the acute phase of infection, immunophenotyping of peripheral mononuclear leukocytes was carried out in 19 patients and demonstrated a reduced frequency of CD2+ lymphocytes and their CD4+ and CD8+ subsets. Normal ratios were recovered during convalescence. Also, during the acute phase, mononuclear cells proliferated poorly in response to mitogens and dengue antigens as detected by incorporation of radiolabeled thymidine. During convalescence the lymphoproliferative response was re-established. In addition, the presence of circulating cytokines was investigated in the plasma of the same 45 patients. Concentrations of tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin-10 (IL-10) and soluble tumor necrosis factor receptor (sTNF-Rp75) were found to be significantly elevated in patients when compared to normal controls. The increase in TNF-alpha was correlated with haemorrhagic manifestations and the increase in IL-10 with platelet decay. The data demonstrate that during the acute phase of dengue infection subsets of T lymphocytes are depressed in terms of both rate and function and provide evidence that circulating pro-inflammatory cytokines, such as TNF-alpha, are important in the pathogenesis and severity of dengue. IL-10 may be downregulating lymphocyte and platelet function.

Adult↗
PubMed2004

Use of simple laboratory features to distinguish the early stage of severe acute respiratory syndrome from dengue fever.

BACKGROUND: The diagnosis of severe acute respiratory syndrome (SARS) is difficult early in the illness, because its presentation resembles that of other nonspecific viral fevers, such as dengue. Dengue fever is endemic in many of the countries in which the large SARS outbreaks occurred in early 2003. Misdiagnosis may have serious public health consequences. We aimed to determine simple laboratory features to differentiate SARS from dengue. METHODS: We compared the laboratory features of 55 adult patients with SARS at presentation (who were all admitted before radiological changes had occurred) and 147 patients with dengue. Features independently predictive of dengue were modeled by multivariate logistic regression to create a diagnostic tool with 100% specificity for dengue. RESULTS: Multivariate analysis identified 3 laboratory features that together are highly predictive of a diagnosis of dengue and able to rule out the possibility of SARS: platelet count of <140 x 10(9) platelets/L, white blood cell count of <5x10(9) cells/L, and aspartate aminotransferase level of >34 IU/L. A combination of these parameters has a sensitivity of 75% and a specificity of 100%. CONCLUSIONS: Simple laboratory data may be helpful for the diagnosis of disease in adults admitted because of fever in areas in which dengue is endemic when the diagnosis of SARS needs to be excluded. Application of this information may help to optimize the use of isolation rooms for patients presenting with nonspecific fever.

Aspartate Aminotransferases↗
PubMed1993

Neuraminidase augments Fc gamma receptor II-mediated antibody-dependent enhancement of dengue virus infection.

Antibody-dependent enhancement (ADE) of dengue virus infection occurs when neutralizing antibodies at sub-neutralizing concentrations or non-neutralizing antibodies form complexes with the virus. These virus-antibody complexes can then attach to a Fc gamma receptor-bearing cell, via the Fc portion of the immunoglobulin, resulting in an increased number of infected cells. ADE may be responsible in part for the most severe clinical manifestations of dengue virus infection which include haemorrhage and shock. Three classes of human Fc gamma receptors exist, Fc gamma RI, Fc gamma RII and Fc gamma RIII. In this study, we examined the effects of neuraminidase on ADE of dengue virus infection mediated by the low-affinity Fc gamma RII. K562 cells, which express only Fc gamma RII, treated with neuraminidase resulted in augmentation of ADE of dengue virus infection by human anti-dengue antibodies. This augmented ADE of infection could be blocked by anti-Fc gamma RII monoclonal antibody IV.3. Incubation of neuraminidase-treated K562 cells with IgG-coated human red blood cells resulted in an increase in the percentage of rosette formations compared with the untreated K562 cells. A bispecific antibody directed against Fc gamma RII and dengue virus (IV.3 x 2H2) enhanced virus infection. Neuraminidase also augmented ADE mediated by this antibody, but to a much lesser degree (by 50%) compared with that seen using conventional human anti-dengue antibody (by 200 to 300%). Fluorescence-activated cell sorting analysis of neuraminidase-treated K562 cells showed that the number of Fc gamma RII-specific antibodies that bind to Fc gamma RII increases by 15 to 20% after treatment with neuraminidase. These results indicate that neuraminidase augments ADE of dengue virus infection and that the augmented ADE is mediated through Fc gamma RII.

Antibodies, Monoclonal↗
PubMed1982

Dengue virus multiplication in cultures of mouse peritoneal macrophages: effects of macrophage activators.

Dengue-2 virus multiplied in cultures of methylcellulose-induced peritoneal macrophages of BALB/c mice. The in vitro-cultivated macrophages from dengue-1 virus-immune mice produced larger amounts of dengue-2 virus than did those from nonimmune controls. The effect of macrophage activators was examined by using nonimmune macrophages. Enhanced virus production was demonstrated in cultures of macrophagges pretreated with phytohemagglutinin (PHA) or bacterial lipopolysaccharide (LPS). The number of virus-infected cells in the pretreated cultures was estimated to be about 0.01% or less of the total macrophages. Continuous treatment of macrophages with PHA before and after virus inoculation brought about the most marked enhancement of dengue-2 virus multiplication. On the other hand, treatment with concanavalin A or pokeweed mitogen showed little effect on the multiplication of the same virus. Treatment with carrageenan, a specific macrophage blocking agent, markedly suppressed dengue-2 virus production in both dengue-1 virus-immune macrophages and LPS-treated macrophages. The indirect fluorescent-antibody (FA) technique revealed dengue-2 viral antigen in the cytoplasm of infected macrophages, and the FA-positive macrophages were more numerous in PHA-treated cultures than in untreated controls. The results obtained are discussed in relation to a possible role of activated monocytes/macrophages in the pathogenesis of dengue hemorrhagic fever.

Animals↗
PubMed1999

Dengue virus structural differences that correlate with pathogenesis.

The understanding of dengue virus pathogenesis has been hampered by the lack of in vitro and in vivo models of disease. The study of viral factors involved in the production of severe dengue, dengue hemorrhagic fever (DHF), versus the more common dengue fever (DF), have been limited to indirect clinical and epidemiologic associations. In an effort to identify viral determinants of DHF, we have developed a method for comparing dengue type 2 genomes (reverse transcriptase PCR in six fragments) directly from patient plasma. Samples for comparison were selected from two previously described dengue type 2 genotypes which had been shown to be the cause of DF or DHF. When full genome sequences of 11 dengue viruses were analyzed, several structural differences were seen consistently between those associated with DF only and those with the potential to cause DHF: a total of six encoded amino acid charge differences were seen in the prM, E, NS4b, and NS5 genes, while sequence differences observed within the 5' nontranslated region (NTR) and 3' NTR were predicted to change RNA secondary structures. We hypothesize that the primary determinants of DHF reside in (i) amino acid 390 of the E protein, which purportedly alters virion binding to host cells; (ii) in the downstream loop (nucleotides 68 to 80) of the 5' NTR, which may be involved in translation initiation; and (iii) in the upstream 300 nucleotides of the 3' NTR, which may regulate viral replication via the formation of replicative intermediates. The significance of four amino acid differences in the nonstructural proteins NS4b and NS5, a presumed transport protein and the viral RNA polymerase, respectively, remains unknown. This new approach to the study of dengue virus genome differences should better reflect the true composition of viral RNA populations in the natural host and permit their association with pathogenesis.

3' Untranslated Regions↗
PubMed2006

[Early indicators of dengue infection in children].

OBJECTIVE: To identify clinical manifestations and laboratory findings useful for the early diagnosis of dengue in children. MATERIALS AND METHODS: We prospectively evaluated 125 children (aged 5 to 12 years old) with acute febrile syndrome with no apparent etiology. Paired serologic tests and/or viral culture were performed and dengue infection was confirmed in 40 patients and ruled out in 68 (17 indefinite cases). Early clinical manifestations (within the first 4 days of the disease) in the groups with dengue and other causes of febrile syndrome were compared. Independent indicators of dengue were determined in a multivariate logistic regression analysis. RESULTS: When clinical manifestations and complete blood count were considered, the independent indicators of dengue were: absence of nasal discharge, facial flushing, and leukocyte count < or = 4,500/.l. With at least two of these findings, a sensitivity of 67 % and a specificity of 72 % for the diagnosis of dengue were obtained. When coagulation tests were considered, a model for diagnosis was composed of: absence of nasal discharge, leukocyte count < or = 4500/.l, prothrombin time > 14 seconds, and partial thromboplastin time > 29 seconds. Two of these findings suggested a diagnosis of dengue with a sensitivity of 90 % and a specificity of 52.9 %. With at least 3 findings, specificity increased to 89.7 % and sensitivity decreased to 50 %. The presence of the four components of this latter model shows a specificity of 100 %. CONCLUSIONS: Some clinical manifestations and simple laboratory tests could aid the early detection of dengue infection in children.

Child↗
PubMed2004

Can hematocrit and platelet determination on admission predict shock in hospitalized children with dengue hemorrhagic fever? A clinical observation from a small outbreak.

Dengue infection is a major public health problem, affecting children in the Southeast Asia region. In Thailand, the dengue hemorrhagic fever is still a major infectious disease among the children with up to two to three epidemics per year. Hemoconcentration accompanied by platelet depletion are the predominant laboratory signs of dengue hemorrhagic fever. Findings from 23 hospitalized patients with dengue hemorrhafic fever in a small outbreak in a provincial hospital in Thailand are reported. The question if hematocrit and platelet determination on admission can predict shock in hospitalized children with dengue hemorrhagic fever was studied. The data from the discharge summary of these patients were studied, focusing on the admission hematology laboratory data. Regression analysis was used to test the correlation between the admission hematology laboratory data (hematocrit, white blood cell count, and platelet) and the focused outcome (shock or no shock). Of these 23 patients, shock did not develop in 19, and shock developed in four. There was no significant difference in admission hematology laboratory data between both groups (p < 0.05). The regression analysis revealed no significant correlation between the studied hematology laboratory data and the focused outcome (p > 0.05). It means that the three studied investigations on admission cannot predict shock in our hospitalized dengue hemorrhagic cases. From this study, it can imply that closed monitoring of dengue hemorrhagic patients is necessary. The general practitioner cannot rely on the admission hematology laboratory data to predict shock in these patients. Additionally, it might confirm that, although dengue infection can be fatal, with proper supportive treatment, especially hospitalization and hydration for severe cases, the outcome is very good.

Adolescent↗
PubMed2006

[Association between dengue incidence and climatic factors].

OBJECTIVE: To describe the occurrence of autochthonous dengue cases according to sex, age, suspected infection site and its relation with climatic variables. METHODS: Autochthonous dengue cases reported in São Sebastião, Southern Brazil, from 2001 to 2002 and confirmed in laboratory were studied. Larval density was verified by three indexes: building, recipients and Breteau. The relationship between rainfall, temperature and number of cases was analyzed through Spearman's correlation using time lag. RESULTS: The annual incidence coefficients for 2001 and 2002 were 80.3 and 211.1 per 10,000 inhabitants, respectively. Most dengue cases (n=1,091; 65%) were reported in the district's central area. Females (n=969; 60%) and the age groups 20 to 29 and 30 to 39 years old of both sexes were mostly affected. Significant associations were not observed between climatic variables and the number of dengue cases in the first month; however, this association became evident in the second month throughout the fourth month. CONCLUSIONS: The association between the number of dengue cases and abiotic factors identified the time lag in which rain and temperature favored the occurrence of new cases. These aspects, associated to tourist vulnerability in the coastal area, promoted conditions for dengue occurrence. The urbanization without sanitary infrastructure possibly affected mosquito density and dengue incidence. Such factors may have contributed to mosquito dispersion and dissemination of different dengue serotypes.

Adolescent↗
PubMed2005

Attenuation and immunogenicity of recombinant yellow fever 17D-dengue type 2 virus for rhesus monkeys.

A chimeric yellow fever (YF)-dengue serotype 2 (dengue 2) virus was constructed by replacing the premembrane and envelope genes of the YF 17D virus with those from dengue 2 virus strains of Southeast Asian genotype. The virus grew to high titers in Vero cells and, after passage 2, was used for immunogenicity and attenuation studies in rhesus monkeys. Subcutaneous immunization of naive rhesus monkeys with the 17D-D2 chimeric virus induced a neutralizing antibody response associated with the protection of 6 of 7 monkeys against viremia by wild-type dengue 2 virus. Neutralizing antibody titers to dengue 2 were significantly lower in YF-immune animals than in YF-naive monkeys and protection against challenge with wild-type dengue 2 virus was observed in only 2 of 11 YF-immune monkeys. An anamnestic response to dengue 2, indicated by a sharp increase of neutralizing antibody titers, was observed in the majority of the monkeys after challenge with wild-type virus. Virus attenuation was demonstrated using the standard monkey neurovirulence test. The 17D-D2 chimera caused significantly fewer histological lesions than the YF 17DD virus. The attenuated phenotype could also be inferred from the limited viremias compared to the YF 17DD vaccine. Overall, these results provide further support for the use of chimeric viruses for the development of a new live tetravalent dengue vaccine.

Amino Acid Sequence↗
PubMed2002

Enhanced severity of secondary dengue-2 infections: death rates in 1981 and 1997 Cuban outbreaks.

OBJECTIVE: To understand the possible effect that length of time has on disease severity with sequential dengue infections. METHODS: Death and hospitalization rates for dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) per 10,000 secondary dengue-2 infections were compared in the same age group for two dengue-2 (DEN-2) epidemics in Cuba. The first DEN-2 epidemic affected all of Cuba in 1981; the second one, in 1997, impacted only the city of Santiago de Cuba. The sensitizing infection for DHF/DSS for each of the DEN-2 epidemics was dengue-1 (DEN-1) serotype virus, which was transmitted in 1977-1979, that is, 4 years and 20 years before the two DEN-2 epidemics. Using published seroepidemiological data from the cities of Havana and Santiago de Cuba, we estimated the rates at which persons aged 15-39 years old and those 40 years and older were hospitalized or died of DHF/DSS in Havana and in all of Cuba in 1981 and in just Santiago de Cuba in 1997. RESULTS: Among adults 15-39 years old the death rate per 10,000 secondary DEN-2 infections was 38.5 times as high in Santiago de Cuba in 1997 as in Havana in 1981. As a further indication of the increased severity coming with a longer period between the initial DEN-1 infection and the secondary DEN-2 infection, the case fatality rate for that same age group was 4.7 times as high in Santiago in 1997 as it was in Havana in 1981. CONCLUSION: We found a marked increase in severity with the longer of the two intervals (20 years) between an initial DEN-1 infection and a secondary DEN-2 infection. Such a difference may be due to subtle shifts in causative dengue strains or to changes with the passage of time in the circulating population of human dengue antibodies. These observations have important implications for dengue control, pathogenic mechanisms, and vaccine development.

Adolescent↗
PubMed2004

[Evaluation of an educational module on dengue and Aedes aegypti for schoolchildren in Honduras].

OBJECTIVE: To evaluate the effectiveness of a special course on environmental health and dengue, given to primary school students and intended to promote behavioral changes in the mothers of those students that would lead to the safe handling of water, adequate disposal of trash, and control of household breeding sites of Aedes aegypti, the mosquito vector for dengue. METHODS: In the period from April to November 2002 a community field trial was carried out that included four public schools in the city of Comayaguela, Honduras. Two of the schools formed the intervention group, and the two others made up the comparison or control group. The data collection activities before and after the intervention included knowledge tests for the schoolchildren and the teachers; surveys of the knowledge, attitudes, and practices of the students' mothers; entomological surveys (systematic checking in order to find water containers, to search for mosquito larvae) in the homes of the schoolchildren; in-depth interviews with the students' mothers; observation in the classrooms; and postintervention focus group with the teachers. RESULTS: During the intervention period the largest epidemic of classical dengue ever in the history of Tegucigalpa, the capital of Honduras, occurred. That event prompted the Secretariat of Health to undertake large-scale control activities. In the two intervention schools there was a significant increase in the students' knowledge of the following three variables: dengue caused by a virus, life cycle of the vector, and reduction of breeding sites, which is the most effective measure for controlling the vector (P < 0.0001 for all those increases in knowledge). There were also significant increases in the knowledge of the same variables among the teachers in the intervention schools: dengue caused by a virus (P = 0.03), life cycle of the vector (P = 0.01), and reduction of breeding sites (P = 0.004). Reducing the number of breeding sites as being the best measure for controlling Aedes aegypti was the knowledge variable that showed the greatest change among the mothers in the intervention group (P = 0.02). The values for two of the entomological indices (the House index and the Breteau index) were better in the intervention group than in the control group, but the difference was not statistically significant. However, there was a statistically significant difference in the Breteau index values between the two control group schools and the one intervention school where the education course was implemented more adequately than in the other intervention school. CONCLUSIONS: The application of educational interventions directed to schoolchildren, as a part of a comprehensive plan for controlling Aedes aegypti, is an effective way to raise the awareness of teachers and parents with respect to the problem of dengue, and it also helps in encouraging family members to be involved in reducing breeding sites in the home. In moving to control the dengue vector, this strategy should take into consideration the involvement not only of families but also of civic and public institutions in the community. Given our results, it appears that this approach of using a special course for schoolchildren can constitute a fundamental pillar in the strategy for integrated dengue control.

Adult↗