CO2 flagging - an improved method for the collection of questing ticks.

Background: Most epidemiological studies on tick-borne pathogens involve collection of ticks from the environment. An efficient collection method is essential for large sample pools. Our main aim was to evaluate the efficacy of a new method, where traditional flagging was enhanced by the use of CO2 dispersed into the white flannel. The CO2 was spread through a rubber hose network inserted into the flag blanket. The research was conducted in spring, in March-April 2011 in two locations from Cluj County, Romania.

Methods: The research was conducted in March-April 2011 in two locations from Cluj County, Romania. The flag to be tested contained a fine silicone rubber hose network which dispersed the CO2 in the shaft. On each collection site n=30 samplings were performed. Each sampling consisted in the simultaneous use of both flags (with and without CO2) by two persons. The CO2 concentration level on the flag canvas surface was measured. The efficacy of the method was determined by counting comparatively the total number of ticks and separate developmental stage count.

Results: Using the CO2 improved flag, 2411 (59%) Ixodes ricinus and 100 (53.8%) Dermacentor marginatus ticks were captured, while the CO2-free flag accounted for the collection of 1670 I. ricinus (41%) and 86 (46.2%) D. marginatus ticks. The addition of CO2 prompted a concentration difference on the surface of the flag ranging between 756.5 and 1135.0 ppm with a mean value of 848.9 ppm.

Conclusion: The study showed that the CO2 enhanced sweep flag increased the ability of I. ricinus (p<0001) but not of D. marginatus to be attracted to the flag blanket.