Lyme borreliosis, also known as Lyme disease, is the most common tick-borne disease in North America and Europe [1
]. The disease is initiated by an infection with a member of at least 19 species of bacteria in the Borrelia
genus known as the Lyme borreliosis group or Borrelia burgdorferi sensu lato
]. If undetected and untreated, Lyme borreliosis can cause debilitating and, in some cases, fatal, multisystem symptoms [5
In North America, Ixodes scapularis
is the primary vector in the eastern and central parts of the continent, and Ixodes pacificus
is prevalent in in the western regions, although Ixodes cookei
, Ixodes angustus
, and Ixodes muris
have also been found to be vectors, and other species are potential vectors [8
]. In Europe, the Ixodes ricinus
species group is the primary vector [1
]. Tick populations are expanding their range in response to climate change in North America, and this has brought them to Canada [12
]. However, the prediction of new areas of population expansion is challenging because of the constant seeding of adventitious ticks introduced by migratory birds and mammals [13
]. The survival of these ticks in either transient or small local populations, only some of which may proliferate into large, established “endemic” tick populations, is difficult to detect, yet important, as even small and transient populations pose a health risk to those living in those areas.
As ticks are expanding their range, the risk to public health has mobilized considerable resources to generate Lyme borreliosis risk maps and models [17
]. These maps and models draw, in various measures, upon passive tick surveillance—ticks collected on companion animals and humans—or field collection of ticks, also known as active surveillance or tick dragging. In addition, case reports from humans, environmental factors such as climate, biogeography, distribution of the wildlife species needed to sustain tick and Borrelia
populations, and canine Lyme seropositivity studies have been used to predict the risk of Lyme borreliosis [18
]. While these risk models aim to predict areas where tick populations may establish, with the attendant evaluated risk of tick-vectored diseases, these models all require field validation, most frequently by active surveillance. Active surveillance, collecting ticks on a cloth dragged through potential tick habitat, is widely recognized to suffer from being a low-sensitivity method of tick detection. For example, Koffi et al. (2012) [19
] reported that only 60% of the predicted tick high-risk areas yielded ticks upon field sampling. Similarly, a retrospective study of active surveillance of areas that subsequently became endemic showed only 50% sensitivity [20
]. Thus, the low sensitivity of this form of surveillance is useful when defining tick endemic areas, large areas with high tick density, but is not well suited for identifying areas where tick populations are emerging. Additionally, field sampling is a logistically complex and expensive process, and, as a result, field teams generally only visit a site once. If the weather, day, time, or any of a host of other factors is not suitable, ticks may not be recovered. It is here that citizen science can play an important role by mobilizing citizens to monitor their own neighbourhoods and regions.
Citizen science involves engaging members of the general community in order to “crowdsource” data acquisition. The value of citizen science for researchers lies in the capacity for a tremendous expansion in data acquisition capacity. Universities are well positioned to engage in such community-centered research initiatives as many already have active community-engagement policies and practices; the same rational applies to public health researchers. From the community perspective, citizen science allows members of the public to not only explore an intrinsic interest in the natural world, but also engage in research relevant to their own health and that of their families and community members. When individuals are engaged in scientific research, as they are in citizen science projects, there is a heightened trust in science leading to personal empowerment, which underlies changes in behaviour that are needed to adapt to the changing environmental risk. The value of the citizen science approach has been appreciated, and citizen science has been extensively incorporated into ecological studies, but much less so in public health initiatives [21
Passive tick surveillance involves members of the public, veterinary or humanmedical professionals submitting ticks for study. This type of “crowdsourcing” of ticks is highly effective for surveillance [17
] as well as in providing ticks for a tick bank, bioclimatic modeling, or other purposes, as exemplified by the study of Laaksonen et al. (2017) [23
], in which nearly 20,000 crowdsourced ticks were used to map changed tick distributions and new tick-vectored pathogens in Finland. If such initiatives return the results of tick pathogen testing to the donor, both partners benefit. However, with increased community involvement, even greater engagement and mutual benefit is achieved [21
One way to increase community participation is by partnering with community volunteers in active tick surveillance. Members of the public are in a position to intensively monitor the same site, for example a backyard, favorite park, or school playground, over one or many seasons. For example, Seifert et al. (2016) [24
] described the success of a program of tick education implemented in rural high schools, a tribal school, and a correctional facility that involved training volunteers in active tick surveillance. This project demonstrated that this active participation increased student knowledge of tick biology, awareness of tick bite prevention strategies, recognition of common signs and symptoms of Lyme disease, and student interest in science. All of these outcomes are highly desirable from the public health, medical, and societal perspectives. On a national scale, Garcia-Marti et al. (2017) [25
] reported on the impressive results of a large study in Holland. In this project, trained volunteers conducted active surveillance, producing extensive and detailed collection records composed of over 3000 observations at 15 sites over nine years. This large and comprehensive dataset allowed geographic and spaciotemporal mapping of tick populations and pathogens at the national level. While traditional public health active surveillance initiatives are constructed around a standardized research methodology, as demonstrated by Garcia-Marti et al. (2017) [25
], the variability in collection methodology implicit in citizen science initiatives is still compatible with highly effective public health surveillance.
The research question addressed here focuses on the relative strengths and advantages of academic, public health, and community-driven tick surveillance efforts. We approached this question by comparing the outcomes of each of these surveillance approaches, conducted during the same time period and in the same region. The volunteer community surveillance initiatives generated the greatest number of ticks, over a period of several years, at virtually no cost. While non-conventional and diverse methodology was used, these community tick collections provide detailed information on tick seasonal activity, abundance, density, infection rate, ability to overwinter, and similar biological factors, data not otherwise readily attainable. Most importantly, this initiative resulted in extensive community-based peer education efforts. Thus, partnerships between community volunteers and researchers promotes both research and education on the health risk posed by ticks.
During the spring and summer of 2014 (May–September), public health, academic, and citizen science tick surveillance projects were conducted in New Brunswick, Canada (Table 1
). Initially, academic researchers already engaged in active tick surveillance were approached by community members interested in monitoring their local areas for ticks, and community members joined the academic researchers for 16 of the 66 academic tick drags conducted across the province. Additionally, some community members chose to monitor ticks independently and simply used academic researchers as resources for tick identification and testing. During the same period, a public health surveillance project was conducted in the province.
Some of the community-initiated surveillance efforts were discontinued after one or a few field collections (Table 1
—health center, recreational, forestry lot collections). However, four of the community-initiated surveillance efforts continued over multiple years and encompassed many individual collections (Table 1
—St. John, Nova Scotia, Hampton, Rothesay). Of these surveillance initiatives, three of the community collections (St. John, Hampton, Rothesay) overlapped spatially and temporally with a subset of the academic and public health site visits, offering the opportunity to compare surveillance strategies and tick recoveries (Table 2
The community-initiated efforts differed from the academic and public health surveillance efforts in a number of ways, including the criteria for surveillance location, the area surveyed, the number of site visits, the sampling effort, and the sampling methodology. While research teams sampled each location only once for 3 person-hours per site, in some cases (St. John and Hampton collections) the same site was sampled by the same collector daily or every few days from early spring to late fall over the course of three years. The Nova Scotia and Rothesay collections involved a broader opportunistic approach where different “likely” regions within convenient distance of the collector’s home were sampled on a daily, weekly, or biweekly schedule (Nova Scotia), or on a less frequent schedule (Rothesay). The areas selected for surveillance by the citizen scientist tick collectors were areas of concern for the collectors, their families, or communities, whereas academic or public health researchers tend to select sites to answer specific research questions. Research surveillance seeks to standardize search effort, area surveyed, and tick collector expertise. In contrast, these parameters varied for the citizen science collectors depending on the weather, terrain, prior recoveries, collector interest, collector visual acuity, collector health, and many other variables. Nevertheless, these collections all have value. These collections generate ticks that are themselves of value (Table 1
), they generate data on the presence of ticks (Table 2
, Figure 1
), and they promote greater community awareness of ticks (Figure 2
The St. John collection is remarkable for the very careful and frequent monitoring of a small site (family backyard) which allowed recovery of ticks at multiple life stages, including larval and nymphal ticks, as well as adults. This intensive sampling of one location also allowed the mapping of seasonal emergence of the different life stages (Figure 1
), information that is generally not available from surveillance efforts using standard methodology. This type of intensive one-site sampling also lends itself to analysis of climactic factors, as described by Garcia-Marti et al. [25
]. The region sampled in this collection, and the other sustained collections, were considered endemic or suspected endemic and so would not otherwise be eligible for surveillance by regional public health officials. Interestingly, tick abundance increased over the three years of intensive monitoring (Figure 1
). Although this might represent improved tick surveillance methodology, the number of ticks in this collection and the recovery of larvae each year suggest that the surveillance was meticulous. This may suggest that the risk of tick-vectored disease is dynamic, even in endemic areas. The Nova Scotia collection is remarkable for the sheer number of ticks collected, although primarily adults were selected for collection. This collection also features careful notes on microclimate and vegetation conducive to tick recovery (data not shown), which is of considerable practical interest to residents of the area.
A subset of the ticks recovered from the university surveillance efforts, the St. John, Nova Scotia, Hampton, and Rothesay collections were tested for B. burgdorferi infection by nested PCR. From the university collection, 0/6 (0%) tested positive for both genes (OspA and FlagB). From the St. John, Nova Scotia, Hampton, and Rothesay collections, 2/13 (15%), 6/20 (30%), 5/70 (7%), and 0/27 (0%) were positive, respectively, for both genes (OspA and FlagB).
In addition to providing collected ticks and associated collection data to researchers, two of the community members have been very active in displaying their collections in their community and all have been strong local advocates for tick bite preventative behaviours, helping the public appreciate the presence, abundance and small size of ticks, hence the need for careful tick checks of children, adults, and pets. These activities have included showing the collected ticks at schools, farmer’s markets, and other community and social gatherings (Figure 2
). By having these activities initiated within the community by trusted community members, these initiatives are a powerful means to raise public awareness of the risk of tick-borne diseases in the local area.