The effectiveness of inspections on reported mosquito larval habitats in households: A case-control study

• Published in: PLoS neglected tropical diseases Vol. 13; no. 6; p. e0007492
• Main Authors: Aik, Joel, Neo, Zhi Wei, Rajarethinam, Jayanthi, Chio, Kaiyun, Lam, Wing Mun, Ng, Lee-Ching
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01-06-2019; Public Library of Science (PLoS)
• Subjects: Animals; Apartments; Aquatic insects; Biology and Life Sciences; Care and treatment; Confidence intervals; Containers; Dengue; Dengue fever; Dengue vaccines; Dependence; Disease control; Earth Sciences; Ecology and Environmental Sciences; Economic aspects; Economics; Ecosystem; Family Characteristics; Habitats; Health Services Research; Households; Housing; Human diseases; Humans; Immunization; Inspection; Inspection frequency; Larva - growth & development; Larvae; Medicine and Health Sciences; Mosquito Control - methods; Mosquito Vectors - growth & development; Mosquitoes; Multivariable control; Observational studies; People and Places; Programmes; Regression analysis; Risk factors; Safety and security measures; Singapore; Social Sciences; Statistical analysis; Systematic review; Tropical diseases; Vaccines; Vector-borne diseases; Viral diseases; Singapore; Cuba; Asia
• ISSN: 1935-2735; 1935-2727; 1935-2735
• DOI: 10.1371/journal.pntd.0007492

Dengue is an arboviral disease that imposes substantial health and economic burdens across the globe. Vector control remains a key strategy in settings where Dengvaxia (a dengue vaccine) has not been licenced due to safety concerns and where mass immunization programmes are not cost-effective. Though inspections are used as part of arboviral disease control programmes, evidence of their impact on the entomological activity in households is sparse.
We analysed nationally representative household inspection data collected from Singapore over a 3-year period, to determine the effect of inspections on reported mosquito larval habitats in households. A case was a household with a positive report of a mosquito larval habitat in its most recent inspection in 2017. A control was a household that was reported free of mosquito larvae in its most recent inspection in 2017. Using multivariable logistic regression, we analysed 3,205 cases and 557,044 controls. Households averaging three inspections per annum were associated with reduced odds of mosquito larval habitat reports [Adjusted Odds Ratio (AOR): 0.49, 95% Confidence Interval (95% CI): 0.38 to 0.63]. The effect of inspections declined with decreasing inspection frequencies but remained protective at lower levels. Longer intervals (30 to 36 months) between the most recent two successive inspections were associated with increased odds of mosquito larval habitat reports (AOR: 1.28, 95% CI: 1.06 to 1.56) compared to those carried out less than 6 months apart. Mosquito larval habitat reports exhibited a dependence on spatial and household-level characteristics such as the location of the community district, housing type and housing floor level. We observed a four-fold increase in the odds of mosquito larval habitat reports in households with an immediate previous report of larval activity compared to those that did not have one (AOR: 4.52, 95% CI: 3.67 to 5.56).
Our study confirms the protective effect of inspections on reported mosquito larval habitat reporting in households. Spatial, temporal and household-level characteristics should be accounted for in prioritizing vector control resources. Alternative strategies may help address recurrent entomological activity in households.