Open AccessLarval Indices of Vector Mosquitoes as Predictors of Dengue Epidemics: An Approach to Manage Dengue Outbreaks Based on Entomological Parameters in the Districts of Colombo and Kandy, Sri Lanka
Author(s) -
N.W.B.A.L. Udayanga,
Subashinie Aryaprema,
Nayana Gunathilaka,
M. C. M. Iqbal,
Thilan Fernando,
W. Abeyewickreme
Publication year - 2020
Publication title -
biomed research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 126
eISSN - 2314-6141
pISSN - 2314-6133
DOI - 10.1155/2020/6386952
Subject(s) - dengue fever , outbreak , aedes aegypti , sri lanka , aedes albopictus , vector (molecular biology) , veterinary medicine , dengue virus , risk assessment , larva , environmental health , geography , biology , medicine , virology , ecology , environmental planning , tanzania , recombinant dna , biochemistry , computer security , gene , computer science
Background Early detection of dengue epidemics is a vital aspect in control programmes. Predictions based on larval indices of disease vectors are widely used in dengue control, with defined threshold values. However, there is no set threshold in Sri Lanka at the national or regional levels for Aedes larval indices. Therefore, the current study aimed at developing threshold values for vector indices in two dengue high-risk districts in Sri Lanka.Methods Monthly vector indices (House Index [HI], Container Index [CI], Breteau Index for Aedes aegypti [BI agp ], and Ae. albopictus [BI alb ]), of ten selected dengue high-risk Medical Officer of Health (MOH) areas located in Colombo and Kandy districts, were collected from January 2010 to June 2019, along with monthly reported dengue cases. Receiver Operating Characteristic (ROC) curve analysis in SPSS (version 23) was used to assess the discriminative power of the larval indices in identifying dengue epidemics and to develop thresholds for the dengue epidemic management.Results Only HI and BI agp denoted significant associations with dengue epidemics at lag periods of one and two months. Based on Ae. aegypti , average threshold values were defined for Colombo as Low Risk (2.4 ≤ BI agp < 3.8), Moderate Risk (3.8 ≤ BI agp < 5), High Risk (BI agp ≥ 5), along with BI agp 2.9 ≤ BI agp < 4.2 (Low Risk), 4.2 ≤ BI agp < 5.3 (Moderate Risk), and BI agp ≥ 5.3 (High Risk) for Kandy. Further, 5.5 ≤ HI < 8.9, 8.9 ≤ HI < 11.9, and HI ≥ 11.9 were defined as Low Risk, Moderate Risk, and High Risk average thresholds for HI in Colombo, while 6.9 ≤ HI < 9.1 (Low Risk), 8.9 ≥ HI < 11.8 (Moderate Risk), and HI ≥ 11.8 (High Risk) were defined for Kandy.Conclusions The defined threshold values for Ae. aegypti and HI could be recommended as indicators for early detection of dengue epidemics and to drive vector management activities, with the objective of managing dengue epidemics with optimal usage of financial, technical, and human resources in Sri Lanka.