Cost of standard indoor ultra-low-volume space spraying as a method to control adult dengue vectors.

Objectives To access the costs of standard indoor ultra-low-volume (SID-ULV) space spraying for controlling dengue vectors in Thailand. Methods Resources related to SID-ULV space spraying as a method to control dengue vectors between July and December 2009 were identified, measured and valued taking a societal perspective into consideration. Information on costs was collected from direct observations, interviews and bookkeeping records. Uncertainty of unit costs was investigated using a bootstrap technique. Results Costs of SID-ULV were calculated from 18 new dengue cases that covered 1492 surrounding houses. The average coverage of the SID-ULV was 64.4%. In the first round of spraying, 53% of target houses were sprayed and 44.6% in the second round, of which 69.2% and 54.7% received entire indoor space spraying. Unit costs per case, per 10 houses and per 100 m2 were USD 705 (95% Confidence Interval CI, 539888), 180 (95% CI, 150212) and USD 23 (95% CI, 1730). The majority of SID-ULV unit cost per case was attributed to productivity loss (83.9%) and recurrent costs (15.2%). The unit cost of the SID-ULV per case and per house in rural was 2.8 and 1.6 times lower than municipal area. The estimated annual cost of SID-ULV space spraying from 2005 to 2009 using healthcare perspective ranged from USD 5.3 to 10.3 million. Conclusions The majority of the cost of SID-ULV space spraying was attributed to productivity loss. Potential productivity loss influences the achievement of high coverage, so well-planned SID-ULV space spraying strategies are needed to reduce costs.