Molecular Detection and Genetic Identification of Rickettsia Infection in Ixodes granulatus Ticks, an Incriminated Vector for Geographical Transmission in Taiwan

Tick-borne Rickettsia pathogens have become an emerging source of zoonotic infections and have a major impact on human health worldwide. In this study, the prevalence and genetic identity of Rickettsia infections in Ixodes granulatus ticks was firstly determined in Kinmen Island of Taiwan. A total of 247 I. granulatus ticks were examined for Rickettsia infection by nested-PCR assay targeting the citrate synthase (gltA) gene of Rickettsia. The Rickettsia infection was detected with a general infection rate of 4.86%, and was detected in nymph, male and female stages with an infection rate of 3.81%, 0% and 6.84%, respectively. Phylogenetic relationships were analyzed by comparing the gltA sequences obtained from four Taiwan strains and 19 other strains representing 13 genospecies of Rickettsia. Phylogenetic analyses reveal that all Taiwan strains were genetically affiliated to the genospecies of spotted fever (R. parkeri) and transitional (R. felis) groups of Rickettsia. Our findings reveal the first detection of R. parkeri-like and R. felis in I. granulatus ticks from Kinmen Island. As a tourist island between Taiwan and mainland China, these results demonstrate the epidemiological significance of diverse Rickettsia species existed in I. granulatus ticks and highlight the potential threat of geographical transmission among humans in the Taiwan area.

Retrospective Survey of Borrelia spp. From Rodents and Ticks in Thailand

Borrelia is a genus of spirochetal bacteria with several species known to cause disease in humans. The distribution of Borrelia has rarely been studied in Thailand. In this study, a retrospective survey of Borrelia was conducted in ticks and wild rodents to better characterize the prevalence, diversity, and distribution of Borrelia across Thailand. Several pools of DNA from tick samples were positive for Borrelia spp. (36/258, 13.9%). Borrelia theileri/B. lonestari was found in 17 tick samples (16 pools of Haemaphysalis bandicota and 1 pool of Rhipicephalus sp.), and Borrelia yangtzensis was found in 8 tick samples (2 pools of H. bandicota and 6 pools of Ixodes granulatus). Borrelia spp. were detected at low prevalence levels in rodent tissue samples (24/2001, 1.2%), with 19 identified as B. theileri or B. lonestari and 5 identified as B. miyamotoi. Several geographic and species-specific infection trends were apparent, with Ixodes ticks infected with B. yangtzensis and Haemaphysalis and Rhipicephalus ticks infected with both B. yangtzensis and B. theileri/B. lonestari. Notably, B. yangtzensis showed a similar geographic distribution to B. miyamotoi, which was identified in new areas of Thailand in this study. The flagellin gene sequence from B. miyamotoi was more similar to European (99.3–99.9%) than Japanese (96.9–97.6%) genotypes. This study greatly expands the knowledge of Borrelia in Thailand and identified several Borrelia species for the first time. It also found several ticks and rodents infected with the pathogen that were not previously known to carry Borrelia.

Detection of Borrelia burgdorferi Sensu Lato and Relapsing Fever Borrelia in Feeding Ixodes Ticks and Rodents in Sarawak, Malaysia: New Geographical Records of Borrelia yangtzensis and Borrelia miyamotoi

Members of the Borrelia burgdorferi sensu lato (Bbsl) complex are etiological agents of Lyme disease (LD), and Borrelia miyamotoi is one of the relapsing fever Borrelia (RFB). Despite the serological evidence of LD in Malaysia, there has been no report from Sarawak, Malaysian Borneo. Thus, this study aimed to detect and characterize Borrelia in rodents and Ixodes ticks from primary forests and an oil palm (OP) plantation in Sarawak. Borrelia yangtzensis (a member of the Bbsl complex) was detected in 43.8% (14/32) of Ixodes granulatus; most of the positive ticks were from the OP plantation (13/14). Out of 56 rodents, B. yangtzensis was detected in four Rattus spp. from the OP plantation and B. miyamotoi was detected in one rodent, Sundamys muelleri, from the primary forest. Further, the positive samples of B. yangtzensis were randomly selected for multilocus sequence analysis (MLSA). The MLSA results of successfully amplified tick samples revealed a clustering with the sequences isolated from Japan and China. This study is the first evidence of B. miyamotoi, a known human pathogen in Malaysia, and B. yangtzensis, which is circulating in ticks and rodents in Sarawak, Malaysian Borneo, and presenting a new geographical record of the Borrelia spp.

Prevalence of on-host ticks (Acari: Ixodidae) in small mammals collected from forest near to human vicinity in Selangor, Malaysia

Ticks are important vectors that transmit a variety of pathogenic microorganisms known to be medically important worldwide. Many vertebrate groups have become host to this organism, and their presence and abundance are an indicator of the condition of both host and its habitat. This study was conducted to determine tick’s infestation and its prevalence on small mammal’s residing in the recreational forests (RF) and semi-urban (SU) residential areas which have encountered Leptospirosis outbreak and cases in Hulu Langat, Selangor Malaysia. Trapping of the small mammals involved deploying two hundred cage traps in a systematic one-hectare plot (100 m x 100 m), as well as along the stream and forest trails at random. Ticks were extracted from the captured individual hosts. Identification of the tick species was performed based on morphological features and molecular approach using 16S rDNA and COI (cytochrome oxidase subunit I) genes. A total of 278 individuals of small mammals belonging to 15 species (13 Rodentia, 1 Scandentia and 1 Insectivora) were captured in the study areas. From these, 34 individuals from eight small mammal species were infested with ticks. The most infested host species was Muller’s giant Sunda rat (Sundamys muelleri) with 5.80% (n=16). Ticks prevalence was slightly higher in RF with 6.40% (n=18) compared to SU with 5.80% (n=16). A total of 107 adult ticks (103 female and 4 male) were collected from the infested host. Ixodes granulatus was the most dominant tick species encountered (70.40%, n=85), followed by Dermacentor sp. (18.60%, n=20), while Amblyomma sp. was the least abundant (2%, n=2). This study provides information on tick species present and tick burden on small mammal hosts within the study areas. Our findings suggest that the visitors to the recreational forests and the residents of the semi-urban area were not only exposed to Leptospirosis bacteria but also tick bites and potentially tick-borne disease, therefore, precaution should be taken to avoid contact with small mammal hosts.

Paenibacillus lautus, an opportunistic bacterial pathogen, isolated from Ixodes granulatus Supino (Acari: Ixodidae) collected from a Müller’s giant Sunda rat (Sundamys muelleri)

Wild rodents are carriers of ectoparasites such as ticks that are vectors of infectious diseases with human and veterinary significances. Due to their close association with human dwellings, synanthropic wild rodents may aid the spread and transmission of tick-borne pathogens. In light of this, an effort was initiated to study the cultivable bacteria within ticks collected from wild rodents trapped in Sungai Congkak Recreational Forest, Selangor. Ticks collected from four different rodent species; Sundamys muelleri, Maxomys whiteheadi, Maxomys rajah and Rattus rattus, were sterilely homogenized and cultured. One unique bacterial isolate originating from an engorged adult female Ixodes granulatus Supino collected off a Sundamys muelleri rat was identified as Paenibacilus lautus via 16S rDNA, ctpA sequencing and biochemical tests. Antimicrobial susceptibility testing revealed that the P. lautus isolate was resistant to ampicillin, penicillin, clindamycin, chloramphenicol, rifampicin and trimethoprim-sulfamethoxazole, mirroring the antimicrobial susceptibility profiles of clinical strains. Recovery of this opportunistic bacterial pathogen from the tick suggests that it may be transmitted to humans or other hosts through tick bites and cause disease once it enters the bloodstream. Therefore, it is important to remain vigilant due to its pathogenic potential and improve our waste disposal practices to avoid attracting rodents.