Feasibility of ultra-low-volume indoor space spraying for dengue control in Southern Thailand.

OBJECTIVES: To assess the feasibility of conducting standard indoor space spraying using ultra-low-volume (SID-ULV) in terms of willingness to pay (WTP) and ability to pay (ATP) and ability to conduct space spraying by local administrative organisations (LAO) in lower Southern Thailand. METHODS: Cross-sectional study. The executive leaders of each LAO were asked to state their WTP and ATP for SID-ULV. Willingness to pay was measured by the payment card and open-ended question methods. Ability to pay was calculated using the budget allocation for space spraying and estimated expenditure for SID-ULV. Ability to conduct the SID-ULV was assessed by interviewing the spraymen. Average WTP and ATP were calculated and uncertainties were estimated using a bootstrapping technique. RESULTS: Ninty-three percent of executive leaders were willing to pay for SID-ULV. The average WTP per case was USD 259 (95% confidence interval [CI] 217-303). Thirty-eight percent of all LAO had actual ATP and 60% had ideal ATP. The average annual budget allocated for space spraying was USD 2327 (95% CI: 1654-3138). The amount of money LAO were willing to pay did not vary significantly between their different types, but ATP did. Thirty-two percent of spraymen could not complete all nine procedures of SID-ULV. CONCLUSIONS: Although WTP for SID-ULV space spraying was high, ATP was low, which revealed the flexibility of budget allocation for SID-ULV in each LAO. The spraymen require training in SID-ULV space spraying.

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 m(2) were USD 705 (95% Confidence Interval CI, 539-888), 180 (95% CI, 150-212) and USD 23 (95% CI, 17-30). 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.

Assessing the spreading patterns of dengue infection and chikungunya fever outbreaks in lower southern Thailand using a geographic information system.

PURPOSE: The aims of this study were to assess the incidence of dengue infection (DEN) and chikungunya fever (CHIK) and determine the direction and speed of CHIK between August 2008 and June 2009 in lower southern Thailand. METHODS: The National Communicable Disease Surveillance System database and a geographic information system containing data on case locations were combined. R and ArcView were used for identifying incidence, direction, and speed of disease outbreaks. RESULTS: A total of 27,166 patients were identified, of which 3319 and 23,847 had DEN and CHIK, with incidences of 73 and 521 per 100,000, respectively. The direction of the CHIK outbreak moved from south to north with a median speed of 7.5 km per week. CHIK cases increased after 6 weeks of increasing cumulative rainfall with variation of average daily temperatures (23.7-30.7 degrees C) per week. There was no clear association of DEN with climate variables. CONCLUSIONS: The combination of surveillance and geographic information system data of DEN and CHIK can be used to determine the speed and direction of disease spread. DEN is endemic, but CHIK is an emerging disease. Because of the rapid spread of CHIK, strict and timely integrated vector control programs after case notification must be implemented.