Abstract:
BACKGROUND : Babesia gibsoni is the predominant tick-borne protozoan blood parasite affecting dogs throughout the
Oriental region. Babesia gibsoni is transmitted by Haemaphysalis longicornis, whereas a similar role has been suggested
for Rhipicephalus sanguineus. Haemaphysalis longicornis does not occur in Taiwan, but R. sanguineus is widely
distributed on dogs. However, clinical cases of babesiosis are mainly restricted to the northern part of the island. The
discrepancy between tick distribution and clinical cases stimulated us to investigate the tick species distribution on
dogs in northern Taiwan, with the aim to identify the local vector for canine babesiosis.
METHODS : Ticks were collected from stray dogs or free ranging pet dogs in northern Taiwan between 2015 and 2017
and, after identification, were tested for the presence of tick-borne Babesia parasites using PCR and reverse line blot
(RLB) hybridisation. Moreover, engorged ticks collected from the dogs were incubated at 28 °C to allow them to
oviposit. Their subsequent larval progeny was also examined by PCR/RLB.
RESULTS : A total of 1085 ticks collected from 144 stray dogs at different residential areas consisted of 5 different species:
H. hystricis (n = 435), R. sanguineus (n = 582), R. haemaphysaloides (n = 43), Amblyomma testudinarium (n = 14) and Ixodes
ovatus (n = 11) were identified. Babesia gibsoni DNA was detected in H. hystricis females (10.3%), males (7.0%) and in 2.
6% of the nymphs. One R. sanguineus female and one A. testudinarium female tick also carried B. gibsoni DNA. DNA of
B. gibsoni was demonstrated in 11 out of 68 (16.2%) batches of larval ticks derived from engorged H. hystricus ticks
only. Babesia vogeli DNA was detected only in R. sanguineus females (2.6%) and males (2.4%). DNA of B. vogeli was
detected in 13 out of 95 (13.7%) batches of larval ticks derived from engorged R.sanguineus females.
CONCLUSIONS : Babesia gibsoni DNA was detected in the larval progeny of H. hystricis ticks only, whereas B. vogeli was
restricted to the larvae of R. sanguineus. This provides evidence for transovarial passage of B. gibsoni in H. hystricis and
evidence that this tick does act as the local vector for this parasite on dogs in northern Taiwan where most cases of
babesiosis are reported. The vectorial capacity of R. sanguineus for babesiosis is probably restricted to the transmission
of B. vogeli only.
