Risk of dengue virus infection according to serostatus in individuals from dengue endemic areas of Mexico.

The variability in the host immune response directed against dengue virus (DENV) has demonstrated the need to understand the immune response associated with protection in incident infection. The objective was to estimate the association between serostatus and the risk of incident DENV infection. We used a prospective study from 2014 to 2016 in the localities of Axochiapan and Tepalcingo, Morelos, Mexico. We recruited 966 participants, of which, according to their infection history registered were categorized in four groups. To accomplish the objectives of this study, we selected to 400 participants older than 5 years of age were followed for 2.5 years. Blood samples were taken every 6 months to measure serological status and infection by ELISA. In individuals with at least two previous infections the risk of new infection was lower compared to a seronegative group (hazard ratio adjusted 0.49, 95% CI 0.24-0.98), adjusted for age and locality. Therefore, individuals who have been exposed two times or more to a DENV infection have a lower risk of re-infection, thus showing the role of cross-immunity and its association with protection.

Spatiotemporal dynamics of human leptospirosis and its relationship with rainfall anomalies in Colombia.

Background: In Colombia, human leptospirosis (HL) is a disease that has had a mandatory notification rule since 2007. Humans usually acquire the infection through water contaminated with animal urine that comes into direct contact with cutaneous lesions, eyes or mucous membranes. Objectives: To analyze the spatiotemporal variability in the occurrence of HL cases in Colombia between 2007 and 2016, and its relation with the El Niño Southern Oscillation (ENSO) cycle and the consequent anomalies in rainfall in spatiotemporal clusters. Methods: An ecological study of the HL cases, aggregated by municipality, and reported between 2007 and 2016, is presented. Findings: During the period of study, 9928 cases of HL were reported, and 58.9% of the municipalities reported at least one case of leptospirosis. Six spatiotemporal clusters were identified-five were in the Andean region and one was in the Caribbean region. The assessment of the ENSO cycle and rainfall anomalies suggests the importance of La Niña episodes, and excess rainfall periods in the occurrence of cases of HL. Conclusions: Our results demonstrate the importance of the ENSO cycle, rainfall periods and periods with excess rainfall in the occurrence of cases and outbreaks of HL in Colombia, and suggest the importance of the topography of valleys and flood zones as zones in which the risk of infection is elevated.

[Early indicators of dengue infection in children]. / Indicadores tempranos de infección por dengue en niños.

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.

Early predictors of haemorrhage in acute febrile syndrome patients from Bucaramanga, Colombia: a dengue endemic area.

INTRODUCTION: Spontaneous haemorrhage is an important cause of hospitalisation in dengue patients. Early predictors of these complications could help to make opportune decisions. METHODS: We prospectively evaluated 51 febrile patients (without previous spontaneous haemorrhage), including 32 cases of dengue fever. Initial evaluation was performed during the first 96 hours after the onset of fever and included complete blood cell count and coagulation tests. Participants were followed-up daily until the seventh day of the disease. RESULTS: Overall, 15 patients developed spontaneous haemorrhage during the follow-up. Tourniquet test and dengue infection were not associated with haemorrhage (p-value is greater than 0.2). In a logistic regression analysis, platelet count (odds-ratio [OR] 0.78; 95 percent confidence interval [CI] 0.65-0.94) and partial thromboplastin time (OR 1.78; 95 percent CI 1.06-2.99) were independently associated with spontaneous haemorrhage. CONCLUSION: Early alterations in platelet count and coagulation test could predict spontaneous bleeding in the acute febrile syndrome.