3.2 Implications for human health
In the light of reported evidence by Traavik and Brunvold, (1978), where
the isolated Runde coronavirus agent from virus families that have RNA
genomes, it is conceivable that this RNA virus may have “proofreading”
systems deficiency than DNA viruses, and therefore it may be more
inclined to develop and maintain genome mutations (Graepel et al.,
2017). Thus, it would be reasonable to assume that this RNA virus is
more likely to emerge, and for it to be capable to replicate in the
cytoplasm is the best speculator of cross-species transmission from
animals (for example, the above mentioned seabirds, bats and pangolins)
to humans (Pulliam & Dushoff, 2009). Therefore, it is critical to
consider this assumption since, bat ticks can also bite humans and they
are capable to transmit viruses between bats and human (Socolovschi,
Kernif, Raoult & Parola, 2012; Jaenson et al., 1994). The
epidemiological importance for the transmission of diseases to humans
from bats and bat associated ticks has become a major concern, although
limited by lack of detailed information about bat ticks pathogen
association and distribution (Loftis et al. 2005). However,
growing urbanisation and bats adaptation to urban habitats has raised
the chances for contact between domestic animals and humans with bat
associated ticks and bats (Hornok et al., 2016; Krauel & LeBuhn, 2016).
Moreover, Guglielmone et al. (2014) reported ten different types of tick
species feeding on pangolins also feeding on unlikely animal hosts. Some
of the pangolin’s ticks have been reported to bite humans (Estrada-Pena
& Jongejan, 1999; Parola et al., 2013; Durden, Merker, & Beati, 2008;
Burridge, 2001; Audy, Nadchatram, & Lim, 1960). Limited reports of
seabird tick bites to humans have been recognized (Gylfe et al., 1999;
Duneau et al., 2008; Dietrich et al., 2010).
However, the fact that there are few reported cases of tick bites (ticks
associated with seabird, bat and pangolin); it does not suggest that
tick bites to humans do not occur. This can be due to unreported cases
and undeveloped illness by the bitten person. Besides, areas where
seabird, bat and pangolin ticks co-occur with other tick species that
are significant vectors of animal and human pathogens signify likely
contact areas for pathogen transmission. Anthroponotic factors related
to the modern lifestyle can facilitate the emerging of tick-borne
viruses. Today, we persistently recognize and obliged to deal with new
cases of emerging viruses including tick-borne viral diseases (e.g. Wang
et al. (2019), reported a new segmented virus associated with human
febrile illness and ticks in China). Moreover, due to anthroponotic
factors, it is not surprising that the outbreak of SARS-CoV-2 has been
tentatively related with a seafood market in Wuhan, China, where the
trading of wild animals may be the cause of zoonotic infection (Lu
et al., 2020; Cohen, 2020). This assumption can be true since different
kinds of mammalian species were purchase before SARS-CoV-2 outbreak at
the Huanan seafood market as mentioned by Cohen (2020). Malayan
pangolins (Manis javanica ) smuggled into Southern China, are the
only mammals except for Rhinolophus affinis bat (sampled from
Yunnan in the year 2013) recognized to be affected by a SARS-CoV-2
related coronavirus (Lam et al., 2020; Zhou et al., 2020). This current
finding by Lam et al. (2020), cannot be ignored, since the sampled
pangolins independently acquired SARS-CoV-2 related viruses from bats or
different animal host. However, their position as intermediate host in
the development of human SARS-CoV-2 is still unclear. There is a clear
dearth of consensus among researchers about the occurrence of
coronaviruses, together with those associated to SARS-CoV-2, in
different kinds of wild mammals found in Asia (Wang et al., 2005; Liu,
Chen, & Chen, 2019; Wang et al., 2017). These are the most relevant
findings and perhaps also the most significant, since, different tick
species can be associated with both mammals (bats and pangolins), and
they may also harbour coronavirus as proven by Traavik, Meel and
Kjeldsberg (1977), Traavik and Mehl (1975) and Saikku et al., 1980.
All these above-mentioned findings are thought-provoking, and it could
be hypothesized that ticks may possibly transmit SARS-CoV-2 to humans
via different ways.