Study of ixodid ticks in recreational areas of large cities in 2017–2022

Abstract

Background. Ixodes ticks are generalist ticks, which can easily adapt to new conditions, and therefore are widespread in urban areas. They are central components for understanding tick-borne disease epidemiology in large cities. Materials and methods. The main methods of collecting ticks were flagging, which was most often used; ticks were also collected manually by removing them from human and animal bodies. Ticks were examined in the laboratory by dark-field microscopy using optoelectronic systems IMAGLAV-SEO, Leica DM 500 (204), Olimpus, ZEISS Axio Lab A1, and MIKMED-1. PCR studies were performed in real time on a ROTOR Gene 6000 amplifier. Results. According to the results of field and laboratory studies in the parks of Ternopil during 2018–2019 by the Ternopil Regional Center for Disease Control and Prevention (TRCDCP) of the Ministry of Health of Ukraine, 524 ticks were collected, 515 of which were examined using dark-field microscopy (DFM) and polymerase chain reaction (PCR). Among the collected specimens, 63 (12.23 %) were the carriers of infectious pathogens, including 24 (4.66 %) carriers of Borrelia burgdorferi s.l. (Johnson et al., 1984). Besides, 7654 ticks removed from humans were examined in the laboratory of the TRCDCP and in the laboratory of the I. Horbachevsky Ternopil National Medical University. Of these, 1280 (16.72 %) specimens were carriers of infectious agents. The Lviv CDC collected 1314 ticks in recreational areas of Lviv during 2017-2022, of which 139 (10.58 %) were vectors. Of the 1136 ticks collected from humans, 295 (25.96 %) were carriers of B. burgdorferi s.l. Out of 540 ticks collected in parks by the Chernivtsi Regional Center for Tick Control in Chernivtsi, 164 (30.37 %) were infected with B. burgdorferi s.l. Out of 454 ticks collected from people in the city, 130 (28.63 %) were infected with B. burgdorferi s.l. In the parks of Khmelnytskyi, researchers of the Khmelnytskyi Regional Center for Tick Control collected 5068 tick species, of which 102 (2.01 %) were carriers of B. burgdorferi s.l. Spirochetes of B. burgdorferi s.l. were detected in 694 (34.87 %) species out of 1990 examined ticks removed from humans. Conclusions. The dominant tick species in the recreational areas of Lviv, Ternopil, Chernivtsi and Khmelnytsky regions are Ixodes ricinus and Dermacentor reticulatus. The proportion of ticks collected in city parks that carry infectious agents ranges from 10.58 % to 30.37 %, with the exception of Khmelnytsky, where the tick infestation rate is only 2.01 %. The infection rate of ticks removed from humans with B. burgdorferi s.l. and other pathogens ranges from 16.72 % to 34.87 %.

Keywords

• ixodes ticks
• dark-field microscopy
• pcr studies