BACKGROUND: Ixodes ricinus, a competent vector of several pathogens, is the tick 
species most frequently reported to bite humans in Europe. The majority of human 
cases of Lyme borreliosis (LB) and tick-borne encephalitis (TBE) occur in the 
north-eastern region of Italy. The aims of this study were to detect the 
occurrence of endemic and emergent pathogens in north-eastern Italy using adult 
tick screening, and to identify areas at risk of pathogen transmission. Based on 
our results, different strategies for tick collection and pathogen screening and 
their relative costs were evaluated and discussed.
METHODS: From 2006 to 2008 adult ticks were collected in 31 sites and 
molecularly screened for the detection of pathogens previously reported in the 
same area (i.e., LB agents, TBE virus, Anaplasma phagocytophilum, Rickettsia 
spp., Babesia spp., "Candidatus Neoehrlichia mikurensis"). Based on the results 
of this survey, three sampling strategies were evaluated a-posteriori, and the 
impact of each strategy on the final results and the overall cost reductions 
were analyzed. The strategies were as follows: tick collection throughout the 
year and testing of female ticks only (strategy A); collection from April to 
June and testing of all adult ticks (strategy B); collection from April to June 
and testing of female ticks only (strategy C).
RESULTS: Eleven pathogens were detected in 77 out of 193 ticks collected in 14 
sites. The most common microorganisms detected were Borrelia burgdorferi sensu 
lato (17.6%), Rickettsia helvetica (13.1%), and "Ca. N. mikurensis" (10.5%). 
Within the B. burgdorferi complex, four genotypes (i.e., B. valaisiana, B. 
garinii, B. afzelii, and B. burgdorferi sensu stricto) were found. Less 
prevalent pathogens included R. monacensis (3.7%), TBE virus (2.1%), A. 
phagocytophilum (1.5%), Bartonella spp. (1%), and Babesia EU1 (0.5%). 
Co-infections by more than one pathogen were diagnosed in 22% of infected ticks. 
The prevalences of infection assessed using the three alternative strategies 
were in accordance with the initial results, with 13, 11, and 10 out of 14 sites 
showing occurrence of at least one pathogen, respectively. The strategies A, B, 
and C proposed herein would allow to reduce the original costs of sampling and 
laboratory analyses by one third, half, and two thirds, respectively. Strategy B 
was demonstrated to represent the most cost-effective choice, offering a 
substantial reduction of costs, as well as reliable results.
CONCLUSIONS: Monitoring of tick-borne diseases is expensive, particularly in 
areas where several zoonotic pathogens co-occur. Cost-effectiveness studies can 
support the choice of the best monitoring strategy, which should take into 
account the ecology of the area under investigation, as well as the available 
budget.