Prevalence and genotyping of Toxoplasma gondii in questing Ixodes ricinus ticks from forest areas of Northern Poland

Abstract

Toxoplasma gondii occurs in a wide range of intermediate hosts whose blood may be a source of infection for ticks. There are few studies on the involvement of ticks in T. gondii life cycle and this one includes the largest number and all stages of Ixodes ricinus collected from the widest area, covering seven recreational localities within a forest biotope in Northern Poland. The aim of this study was to determine the prevalence of T. gondii DNA in collected 2144 questing ticks to establish if they may be involved in T. gondii transmission. The aim was also genotyping of detected T. gondii as knowledge about its genotypes occurring in European ticks is insufficient. The next goal was detection of ticks coinfection with T. gondii and Borreliaceae, as all ticks examined in this study have previously been tested for the presence of Borreliaceae DNA. Nested PCR and sequencing of the obtained B1 gene fragment were conducted. T. gondii DNA was detected in 0.9% of all ticks (1.1% of nymphs, 0.7% of larvae). The presence of T. gondii in unfed larvae and nymphs may indicate the possibility of its transovarial and transstadial transmission. Prevalence of T. gondii DNA in ticks collected from individual sites was focal (0-4.3%) and seems to be dependent on local conditions. Among all examined ticks, 0.3% were coinfected with T. gondii and Borreliella spp. vs. 0.6% of specimens with T. gondii single infection. The obtained B1 sequences showed the greatest similarity (99.71–100%) to the sequence representing type III.