Discussion
Within seven months from its start, our tick monitoring citizen science
research succeeded to reveal the emergence of two adult Hyalommatick species in two different locations of Hungary. Our project
highlights the importance of public relations in the success of a
citizen science project. We could reach relatively high visibility (over
31000 individual website visitors) within seven months (data from Google
Analytics not shown). The highest number of daily visitors, 5453 could
be reached after an extensive media release of our project.
Participating civilians also benefit from initiatives that use citizen
science. First, in the optimal case, all such research is intended to
serve the interests of society directly or indirectly, so the interest
of civilian researchers is the success of the program. In addition, the
increased social awareness caused by various citizen science projects is
a positive side effect. Due to their involvement in the survey,
participants pay more attention to nature and to monitoring non-endemic
tick species in their environment and the relationship between
participating citizens, scientists and public health agencies may also
become closer. Our participants received reply from us regarding their
questions and samples within 24 hours. This was important because some
secondary media appearances, emphasizing the seriousness of
Crimean-Congo haemorrhagic fever, were frightening some of our
responders, and in most of the cases they were comforted by the fact
that the specimen they found was not a Hyalomma tick.
In addition to the advantages, we must not forget about the limitations
and disadvantages of the method. For example, at the beginning of any
program, it is important to pay close attention to accurately describing
the information requested from the public, failing which it can be very
time-consuming to select relevant data from the set of information
received. It may also be the case that, due to the incorrect or
unverifiable data received, the decision-making bodies may not take into
account the results of such a project. It is particularly difficult to
filter out or prevent the creation of such erroneous data, perhaps
because citizen science is still often characterized by a lack of
universal, reproducible methods. The introduction and strict adherence
to these methods can easily dampen the enthusiasm of the participating
civilians, which is why the high level of attention in project design is
important (MacPhail & Colla, 2020).
The form of the requested data may also be crucial for the preparation
of the research. In monitoring the distribution of tick species, where,
for example, citizen scientists may try to identify an animal found, the
participants have three ways to submit the requested information. They
can only send the name of the species identified, the photographic
documentation of the individual, or the specimen itself. All three
options have advantages and disadvantages, the first case favours large
amounts of incoming data, but there is no way to verify them. In the
second case, a lot depends on whether the person making the shot is
aware of what morphological characters make the identification possible,
e.g., from what angle and at what resolution it is worth taking
pictures. The exact identification is most secure when citizen
scientists send the specimen to be identified by professionals. We
advised the participants to do so, however, in addition to being the
most time consuming, this case raises other issues. Submission might
involve the destruction of the specimen, and on the other hand, it
increases the risk of human-tick contact (Eisen & Eisen, n.d.).
Therefore, we particularly made our participants aware of the risks and
suggested the safe removal, storage and postage of tick specimens.
The most commonly submitted tick species was I. ricinus . This is
in line with the widespread distribution of this species, however, it
also shows that participants do frequently not recognise the most common
tick species. Dermacentor ticks were also submitted in large
numbers. This is again partly due to the common occurrence of this tick
species throughout the country (G. Földvári et al., 2007), however the
on-line media also biased the study in this aspect. Unfortunately,
several news portals used images that featured a Dermacentorspecies instead of a Hyalomma tick. As a consequence, many
citizen scientists, especially dog owners, sent Dermacentorspecimens that are larger and quicker compared to I. ricinus and,
in addition, matched the mistakenly included photograph of some online
portals. We archived all tick specimens and data for further analyses,
thus this by-catch might provide important epidemiological data in the
future.
Mitochondrial gene-based genetic analysis is highly important to reveal
dispersal patterns and introduction routes of Hyalomma ticks
(Capek et al., 2014; Wallménius et al., 2014). Novel mitochondrial
sequence data for Hyalomma spp. is increasingly reported (Ciloglu
et al., 2021; Lang, Shan, Zhang, Liu, & Wang, 2022). The importance of
providing sequence data of these vector organisms is getting more
relevant in the light of disease emergence, especially the geographic
expansion of Crimean-Congo Haemorrhagic Fever virus during the last
decades (Akyildiz, Bente, Keles, Vatansever, & Kar, 2021; Arteaga et
al., 2021; Moraga-Fernández et al., 2021; Sánchez-Seco et al., n.d.). We
further highlight the importance of sequence data by integrating this
activity into the citizens science programme and also into the risk
assessment of CCHFV emergence and preparedness in our region. The two
sites were Hyalomma ticks were found in our study are
approximately 280 kilometres apart, with the first specimen discovered
on August 10 and the second on September 10, so exactly one month apart.
Due to the large geographical distance and the time difference, the two
specimens must have arrived in the country separately as a result of two
separate introductions. Although much more published sequence data would
be necessary, we suspect that the probable source of introduction was a
Eurasian population for the detected Hy. marginatum and a
population along the Africa-Europe bird migration route for Hy.
rufipes .
Another important issue is whether the specimens found entered the
country in the same year, e.g. as engorged nymphs dropping off from
migratory birds, or overwintered before finding them in the next year,
or even already hatched here as larvae in the previous year. The latter
possibility is of greatest concern because it would indicate the
establishment of a local population, making this species able to
successfully complete its entire life cycle in Hungary. This seems
unlikely currently, because a critical number of conspecificHyalomma adults would be needed to yield egg-laying fertilized
females. The moulting into adult in the year of drop-off, among many
other factors, is affected mainly by temperature. On the one hand, hot
springs are preferred by Hyalomma ticks, where the average daily
temperature above 8 ° C for Hy. marginatum ticks can be
determined as a criterion for moulting from nymph to adult (Gale et al.,
2012). Due to the colder-than-average April weather in Hungary in 2021,
this was only achieved in mid-May (National Meteorological Service).
Only adults found before this could have unambiguously overwintered in
the country, giving the opportunity to develop a local population.
However, during our program, both specimens of Hyalomma were
discovered well after May, so these adults were presumably introduced
the same year. Our tick monitoring program was not running during the
spring, and there is a possibility for overwintering adultHyalomma in Hungary, as it has recently been shown in the Czech
Republic (Rudolf et al., 2021). Unfed adult Hyalomma ticks
tolerate the cold months well, with the most critical period being late
summer and autumn due to the heat sensitivity of engorged nymphs
(Uiterwijk et al., 2021; Valcárcel et al., 2020). Thus, it is not the
cold winter but the cold autumn that is critical in shaping the
geographical spread of Hyalomma species. Climate change might
easily enhance establishment of new local Hyalomma populations
with elevating autumn temperatures in temperate Europe as exemplified by
the rising presence of the tick Hy. marginatum in Southern France
(Vial et al., 2016). Once imported, establishment of Hy.
marginatum on common local hosts, wild and domesticated mammals and
even urban ones like hedgehog has been shown in Hungary (G Földvári et
al., 2011) and also recently in Bulgaria (Arnaudov, Mikov, & Georgiev,
2022).
The ultimate reason for monitoring the emergence of adultHyalomma ticks is the possible introduction of tick-borne
pathogens, most importantly Crimean-Congo Haemorrhagic Fever Virus.
There are scattered historical data about the occurrence ofHyalomma ticks and CCHFV in Hungary as summarised in Figure 4.
Immature Hy. marginatum from a hedgehog in a city park (G
Földvári et al., 2011), immature Hy. rufipes and Hy.
marginatum from songbirds (S Hornok et al., 2013; S. Hornok et al.,
2016) and two adult Hy. rufipes from cattle were previously
detected in the country. Reported occurrence of CCHFV spans from
isolation from Ixodes ricinus ticks (Molnár, 1982), to
seropositive cattle, sheep (S. Horváth, 1974), brown hares (Németh et
al., 2013) and wild rodents (Földes et al., 2019). Most interestingly,
humans seropositive for CCHFV were reported well before the first
observation of adult Hyalomma ticks (L. B. Horváth, 1976). There
was also a reported human case of CCHF with unknown origin in 2004
(Országos Epidemiológiai Központ, 2008) and CCHFV seropositives were
detected in 12 healthy blood donors collected between 2008-2017 (Magyar
et al., 2021). All these data indicate that CCHFV might be transmitted
by tick species other than Hyalomma spp. and that the earlier
emergence of adult Hyalomma ticks might have been overlooked in
Hungary. In any case, we will continue with the citizen science based
systematic monitoring of Hyalomma ticks in the future. We also
plan to analyse these and future Hyalomma specimens for the
occurrence of CCHFV and other pathogens.