Monitoring of Nesting Songbirds Detects Established Population of Blacklegged Ticks and Associated Lyme Disease Endemic Area in Canada

Historical Summary of Tick and Animal Surveillance Studies for Lyme Disease in Canada, 1975-2023: A Scoping Review

INTRODUCTION

Lyme disease (LD) is caused by infection with the bacteria Borrelia burgdorferi sensu lato (Bb) through the bite of an infected Ixodes spp. tick. LD has emerged as a public and animal health issue in Canada, with human incidence increasing in part due to the expansion of Ixodes scapularis ticks and their vertebrate hosts. We sought to provide the first comprehensive summary of published tick and animal surveillance literature regarding LD in Canada to describe changes in LD over time.

METHODS

We conducted a review to identify peer-reviewed LD-focused tick, mammal, and bird surveillance articles in three online databases between 1975 and 2023. Data on study characteristics, data collection years, and surveillance methods and findings were extracted. Descriptive statistics were reported.

RESULTS

In total, 115 studies were included for review. Results showed an increase in published surveillance literature and changes in study approaches and their provincial distribution over time, coinciding with increased LD cases in Canada. Seventy-four studies were published after 2014 when Canada's Federal Framework on Lyme Disease Act was introduced, and two-thirds of these studies focused on tick surveillance only. Overall, 58% of studies involved surveillance in Ontario but increases in all other provinces were observed after 2009.

CONCLUSIONS

Observed changes in five decades of LD-related tick and animal surveillance literature helps document the historical rapid spread of Ixodes and Bb across provinces. This can provide lessons for other regions that may transition from emerging to endemic status for LD in the coming years.

Detection of Anaplasma phagocytophilum, Babesia odocoilei, Babesia sp., Borrelia burgdorferi Sensu Lato, and Hepatozoon canis in Ixodes scapularis Ticks Collected in Eastern Canada

Tick-borne pathogens cause infectious diseases that inflict much societal and financial hardship worldwide. Blacklegged ticks, Ixodes scapularis, are primary vectors of several epizootic and zoonotic pathogens. The aim was to find varius pathogens of I. scapularis and to determine their prevalence. In Ontario and Quebec, 113 I. scapularis ticks were collected from songbirds, mammals, including humans, and by flagging. PCR and DNA sequencing detected five different microorganisms: Anaplasma phagocytophilum, 1 (0.9%); Babesia odocoilei, 17 (15.3%); Babesia microti-like sp., 1 (0.9%); Borrelia burgdorferi sensu lato (Bbsl), 29 (26.1%); and Hepatozoon canis, 1 (0.9%). Five coinfections of Bbsl and Babesia odocoilei occurred. Notably, H. canis was documented for the first time in Canada and, at the same time, demonstrates the first transstadial passage of H. canis in I. scapularis. Transstadial passage of Bbsl and B. odocoilei was also witnessed. A novel undescribed piroplasm (Babesia microti-like) was detected. An established population of I. scapularis ticks was detected at Ste-Anne-de-Bellevue, Quebec. Because songbirds widely disperse I. scapularis larvae and nymphs, exposure in an endemic area is not required to contract tick-borne zoonoses. Based on the diversity of zoonotic pathogens in I. scapularis ticks, clinicians need to be aware that people who are bitten by I. scapularis ticks may require select antimicrobial regimens.

Detection of Babesia odocoilei in Ixodes scapularis Ticks Collected in Southern Ontario, Canada

Tick-borne zoonotic diseases have an economic and societal impact on the well-being of people worldwide. In the present study, a high frequency of Babesia odocoilei, a red blood cell parasite, was observed in the Huronia area of Ontario, Canada. Notably, 71% (15/21) blacklegged ticks, Ixodes scapularis, collected from canine and feline hosts were infected with B. odocoilei. Consistent with U.S. studies, 12.5% (4/32) of questing I. scapularis adults collected by flagging in various parts of southwestern Ontario were positive for B. odocoilei. Our data show that all B. odocoilei strains in the present study have consistent genetic identity, and match type strains in the GenBank database. The high incidence of B. odocoilei in the Huronia area indicates that this babesial infection is established, and is cycling enzootically in the natural environment. Our data confirm that B. odocoilei has wide distribution in southern Ontario.

Detection of Babesia odocoilei in Ixodes scapularis Ticks Collected from Songbirds in Ontario and Quebec, Canada

Songbirds widely disperse ticks that carry a diversity of pathogens, some of which are pathogenic to humans. Among ticks commonly removed from songbirds, the blacklegged tick, Ixodes scapularis, can harbor any combination of nine zoonotic pathogens, including Babesia species. From May through September 2019, a total 157 ticks were collected from 93 songbirds of 29 species in the Canadian provinces of Ontario and Québec. PCR testing for the 18S gene of Babesia species detected Babesia odocoilei in 12.63% of I. scapularis nymphs parasitizing songbirds in Ontario and Québec; none of the relatively small numbers of Ixodes muris, Ixodes brunneus, or Haemaphysalis leporispalustris were PCR-positive. For ticks at each site, the prevalence of B. odocoilei was 16.67% in Ontario and 8.89% and 5.26% in Québec. Of 31 live, engorged I. scapularis larvae and nymphs held to molt, 25 ticks completed the molt; five of these molted ticks were positive for B. odocoilei. PCR-positive ticks were collected from six bird species—namely, Common Yellowthroat, Swainson’s Thrush, Veery, House Wren, Baltimore Oriole, and American Robin. Phylogenetic analysis documented the close relationship of B. odocoilei to Babesia canis canis and Babesia divergens, the latter a known pathogen to humans. For the first time in Canada, we confirm the transstadial passage of B. odocoilei in I. scapularis molting from larvae to nymphs. A novel host record reveals I. scapularis on a Palm Warbler. Our findings show that B. odocoilei is present in all mobile life stages of I. scapularis, and it is widely dispersed by songbirds in Ontario and Québec.

Presentation of Acrodermatitis Chronica Atrophicans Rashes on Lyme Disease Patients in Canada

Lyme disease (Lyme borreliosis) is a complex multisystem illness with varying clinical manifestations. This tick-borne zoonosis is caused by the spirochetal bacterium, Borrelia burgdorferi sensu lato (Bbsl) and, worldwide, presents with at least 20 different types of rashes. Certain cutaneous rashes are inherently interconnected to various stages of Lyme disease. In this study, five Canadian Lyme disease patients from a multi-age range presented various phases of the acrodermatitis chronica atrophicans (ACA) rash. In each case of ACA, the underlying etiological pathogen was the Lyme disease spirochete. Although ACA rashes are normally found on the lower extremities, this study illustrates that ACA rashes are not directly correlated with a tick bite, geographic area, age, Bbsl genospecies, exercise, or any given surface area of the body. Case 4 provides confirmation for an ACA rash and gestational Lyme disease. One patient (Case 5) puts forth a Bbsl and Bartonella sp. co-infection with a complex ACA rash. This study documents ACA rashes on Lyme disease patients for the first time in Canada.