Diagnostic accuracy and predictive value in differentiating the severity of dengue infection.

OBJECTIVE: To review the diagnostic test accuracy and predictive value of statistical models in differentiating the severity of dengue infection. METHODS: Electronic searches were conducted in the Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, MEDLINE (complete), PubMed and Scopus. Eligible studies to be included in this review were cohort studies with participants confirmed by laboratory test for dengue infection and comparison among the different severity of dengue infection by using statistical models. The methodological quality of the paper was assessed by independent reviewers using QUADAS-2. RESULTS: Twenty-six studies published from 1994 to 2017 were included. Most diagnostic models produced an accuracy of 75% to 80% except one with 86%. Two models predicting severe dengue according to the WHO 2009 classification have 86% accuracy. Both of these logistic regression models were applied during the first three days of illness, and their sensitivity and specificity were 91-100% and 79.3-86%, respectively. Another model which evaluated the 30-day mortality of dengue infection had an accuracy of 98.5%. CONCLUSION: Although there are several potential predictive or diagnostic models for dengue infection, their limitations could affect their validity. It is recommended that these models be revalidated in other clinical settings and their methods be improved and standardised in future.

OBJECTIF: Analyser la précision des tests de diagnostic et la valeur prédictive des modèles statistiques pour différencier la sévérité de l'infection par la dengue. MÉTHODES: Des recherches électroniques ont été effectuées dans la base de données de revues systématiques Cochrane, le registre central des essais contrôlés Cochrane, MEDLINE (complète), PUBMED et Scopus. Les études éligibles à inclure dans cette revue étaient des études de cohorte avec des participants confirmés par un test de laboratoire pour l'infection par la dengue et une comparaison entre les différentessévérités de l'infection par la dengue à l'aide de modèles statistiques. La qualité méthodologique des articles a été évaluée par des scientifiques indépendants à l'aide de QUADAS-2. RÉSULTATS: 26 études publiées de 1994 à 2017 ont été incluses. La plupart des modèles de diagnostic ont produit une précision de 75% à 80%, sauf un avec 86%. Selon la classification de l'OMS 2009, deux modèles prédisant la dengue sévère présentent une précision de 86%. Ces deux modèles de régression logistique ont été appliqués au cours des trois premiers jours de la maladie. Leur sensibilité et leur spécificité étaient respectivement de 91% à 100% et de 79,3% à 86%. Un autre modèle évaluant la mortalité à 30 jours de la dengue présentait une précision de 98,5%. CONCLUSION: Bien qu'il existe plusieurs modèles prédictifs ou diagnostiques potentiels de l'infection par la dengue, leurs limites pourraient affecter leur validité. Il est recommandé que ces modèles soient revalidées dans d'autres milieux cliniques et leurs méthodes améliorées et normalisées dans le futur.

Differentiation of Aedes aegypti and Aedes notoscriptus (Diptera: Culicidae) eggs using scanning electron microscopy.

Aedes notoscriptus and Aedes aegypti are both peri-domestic, invasive container-breeding mosquitoes. While the two potential arboviral vectors are bionomically similar, their sympatric distribution in Australia is limited. In this study, analyses of Ae. aegypti and Ae. notoscriptus eggs were enabled using scanning electron microscopy. Significant variations in egg length to width ratio and outer chorionic cell field morphology between Ae. aegypti and Ae. notoscriptus enabled distinction of the two species. Intraspecific variations in cell field morphology also enabled differentiation of the separate populations of both species, highlighting regional and global variation. Our study provides a comprehensive comparative analysis of inter- and intraspecific egg morphological and morphometric variation between two invasive container-breeding mosquitoes. The results indicate a high degree of intraspecific variation in Ae. notoscriptus egg morphology when compared to the eggs of Ae. aegypti. Comparative morphological analyses of Ae. aegypti and Ae. notoscriptus egg attributes using SEM allows differentiation of the species and may be helpful in understanding egg biology in relation to biotope of origin.

Intraspecific variation in desiccation survival time of Aedes aegypti (L.) mosquito eggs of Australian origin.

Aedes aegypti (L.) mosquitoes preferentially oviposit in natural and artificial receptacles where their eggs are able to withstand drying as water levels fluctuate. Desiccation-resistant eggs also increase the potential for establishment in non-native habitats while providing logistical impediments to control programs. Viability and mean survival times of eggs stored under three dryness conditions for up to 367 days were investigated among three field-derived colonies of Australian Ae. aegypti to understand variation in desiccation survival. Further investigations compared egg survival between an established colony and its wild counterpart. Our results confirmed that Ae. aegypti eggs can withstand desiccation for extended periods of time with approximately 2-15% egg viability recorded after one year and viability remaining above 88% under all conditions through 56 days. Intraspecific variations in egg survival times were recorded, suggesting local adaptation while each of the colonies demonstrated a consistent preference for higher humidity. Egg volume varied between the populations, suggesting a relationship between egg volume and survival time, with the marginally larger eggs (Charters Towers and Innisfail) having greater desiccation resistance over the range of conditions. The strong survivorship of Charters Towers eggs in dry, warm conditions demonstrates the adaptive significance of a desiccation-resistant egg.