title: Infections and mixed infections with the selected species of Borrelia burgdorferi sensu lato complex in Ixodes ricinus ticks collected in eastern Poland: a significant increase in the course of 5 years.
abstract: In the years 2008-2009 and 2013-2014, 1620 and 1500 questing Ixodes ricinus ticks, respectively, were examined on the territory of the Lublin province (eastern Poland). The presence of three pathogenic species causing Lyme disease was investigated: Borrelia burgdorferi sensu stricto, B. afzelii and B. garinii. The proportion of I. ricinus ticks infected with B. burgdorferi sensu lato showed a highly significant increase between 2008-2009 and 2013-2014, from 6.0 to 15.3%. A significant increase was noted with regard to all types of infections with individual species: single (4.7-7.8%), dual (1.2-6.6%), and triple (0.1-0.9%). When expressed as the percent of all infections, the frequency of mixed infections increased from 21.4 to 49.2%. Statistical analysis performed with two methods (by calculating of odds ratios and by Fisher's exact test) showed that the frequencies of mixed infections in most cases proved to be significantly greater than expected. The strongest associations were found between B. burgdorferi s. s. and B. afzelii, and between B. burgdorferi s. s. and B. garinii. They appeared to be highly significant (P < 0.0001) when assessed by two methods for 2013-2014, and for the sum of findings for both time periods. The proportions of the individual species detected in the mixed infections in 2008-2009 and 2013-2014 revealed highly significant increases for B. burgdorferi s. s. and B. garinii (from 33.9 to 71.1% and from 18.2 to 82.9%, respectively), and an insignificant decrease for B. afzelii (from 51.4 to 41.6%). The proportions of the species B. burgdorferi s. s., B. afzelii and B. garinii (with combined single and mixed infections) for 2008-2009 and 2013-2014 were: 51.2/44.0 %, 30.6/24.9% and 18.2/31.1%, respectively. In conclusion, our results seem to indicate the detrimental trend of the increasing infection rate of I. ricinus ticks with B. burgdorferi s. l. in eastern Poland, and dramatic enhancement of mixed infections with individual species, which may result in mixed infections of humans and exacerbation of the clinical course of Lyme disease cases on the studied area.
authors.affiliation: Department of Health Biohazards and Parasitology, Institute of Rural Health, Jaczewskiego 2, 20-090, Lublin, Poland. afatla@poczta.onet.pl.
authors.forename: Angelina
authors.initials: A
authors.lastname: Wójcik-Fatla
authors.affiliation: Department of Health Biohazards and Parasitology, Institute of Rural Health, Jaczewskiego 2, 20-090, Lublin, Poland.
authors.forename: Violetta
authors.initials: V
authors.lastname: Zając
authors.affiliation: Department of Health Biohazards and Parasitology, Institute of Rural Health, Jaczewskiego 2, 20-090, Lublin, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Sawczyn
authors.affiliation: Department of Health Biohazards and Parasitology, Institute of Rural Health, Jaczewskiego 2, 20-090, Lublin, Poland.|Department of Parasitology and Invasive Diseases, National Veterinary Research Institute, Pulawy, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Sroka
authors.affiliation: Department of Health Biohazards and Parasitology, Institute of Rural Health, Jaczewskiego 2, 20-090, Lublin, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Cisak
authors.affiliation: Department of Health Biohazards and Parasitology, Institute of Rural Health, Jaczewskiego 2, 20-090, Lublin, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Dutkiewicz
mesh_terms: D000818:Animals; D001898:Borrelia / Q000302:isolation & purification*; D025065:Borrelia burgdorferi / Q000302:isolation & purification; D005260:Female; D018884:Ixodes / Q000382:microbiology*; D008297:Male; D011044:Poland; D013045:Species Specificity; D013997:Time Factors
keywords: Borrelia afzelii; Borrelia burgdorferi sensu lato; Borrelia burgdorferi sensu stricto; Borrelia garinii; Eastern Poland; Ixodes ricinus; Mixed infections