Experimental evidence against transmission of Hepatozoon canis by Ixodes ricinus

Dipartimento di Medicina Veterinaria, Università degli Studi di Bari, 70010 Valenzano, Bari, Italy.
Ticks and Tick-borne Diseases (Impact Factor: 2.72). 04/2013; 4(5). DOI: 10.1016/j.ttbdis.2013.03.001
Source: PubMed


Hepatozoon canis is among the most widespread tick-borne protozoa infecting domestic and wild carnivores. Its distribution is related to the occurrence of its major vector, the brown dog tick Rhipicephalus sanguineus. However, the role of Ixodes ricinus as a vector of H. canis has been hypothesized. In the present study, the development of H. canis was investigated in I. ricinus and R. sanguineus nymphs collected from a naturally infested dog. All I. ricinus ticks examined (n=133) were negative by cytological examination at days 20, 30, and 90 post collection, although H. canis DNA was detected in one nymph at day 20 and in 2 nymphs at day 30 post collection. On the other hand, H. canis sporogony was documented by cytology, and H. canis DNA was detected by PCR in R. sanguineus at day 30 post collection. These results indicate that H. canis sporogony does not occur in I. ricinus, but in R. sanguineus, suggesting that I. ricinus does not act as a vector of H. canis.

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    • "Our data indicate that H. canis is more widely distributed in Hungary than previously thought (Farkas et al., 2014b), and the prevalence is relatively high in the mountain regions of the country with cool climate (Fig. 1). The spatial distribution of H. canis indicates that other tick vectors may be in the background of the countrywide distribution of H. canis (Giannelli et al., 2013; Najm et al., 2014). Moreover, as oral and transplacental transmission of the parasite were also demonstrated (Baneth et al., 2001), H. canis might spread within the fox population without the involvement of tick hosts. "
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    ABSTRACT: In recent years, Ehrlichia canis and Hepatozoon canis transmitted by Rhipicephalus sanguineus were reported from Hungary. The aim of the present study was to reveal the spatial distribution pattern of pathogens transmitted by R. sanguineus in a sentinel species, red fox (Vulpes vulpes) in Hungary and to analyse the relationship of these patterns with landscape and climate by geographical information systems. Fox carcasses, representing 0.5% of the total fox population were randomly selected out of all the foxes of Hungary. The spleen samples of the animals were tested by real-time PCR for Anaplasma platys, Babesia vogeli, E. canis and H. canis infection. Positive results were confirmed by conventional PCR followed by sequencing. The prevalence of H. canis infection was 22.2% (95% CI=18.4-26.4%), and this parasite was detected in all areas including the mountain regions of Hungary. These findings indicate that other tick species or other transmission routes (oral and transplacental) might be in the background of the countrywide distribution of H. canis. Anaplasma platys was not found; nevertheless, the prevalence of Anaplasma phagocytophilum infection transmitted by Ixodes ricinus was 12.5% (95% CI=9.7-16.1%) in foxes. B. vogeli and E. canis infection was not detected. There was no correlation between environmental parameter values in the home range of foxes and A. phagocytophilum or H. canis infection, which is in line with that observed in the case of tick species infesting foxes in Hungary. The results of this study indicate that R. sanguineus, if present, might be rare in Hungary. Our baseline study can be used for future evaluation of the effect of climate change on the spreading and emergence of R. sanguineus transmitted pathogens in Hungary. Copyright © 2015 Elsevier GmbH. All rights reserved.
    Full-text · Article · Jun 2015 · Ticks and Tick-borne Diseases
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    • "Other tick species that are endemic in these countries as well as in Austria, such as Dermacentor or Haemaphysalis species, might also act as vectors, as suggested for Haemaphysalis longicornis and Haemaphysalis flava in Japan and Amblyomma ovale and Rhipicephalus microplus in Brazil (de Miranda et al., 2011; Otranto et al., 2011; Hornok et al., 2013). Recent studies found I. ricinus to be unsuitable as vector (Giannelli et al., 2013). Similar to B. microti-like pathogens, transmission by competent ixodid vectors still has to be confirmed in further studies. "
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    ABSTRACT: Austria's mammalian wildlife comprises a large variety of species, acting and interacting in different ways as reservoir and intermediate and definitive hosts for different pathogens that can be transmitted to pets and/or humans. Foxes and other wild canids are responsible for maintaining zoonotic agents, e.g. Echinococcus multilocularis, as well as pet-relevant pathogens, e.g. Hepatozoon canis. Together with the canids, and less commonly felids, rodents play a major role as intermediate and paratenic hosts. They carry viruses such as tick-borne encephalitis virus (TBEV), bacteria including Borrelia spp., protozoa such as Toxoplasma gondii, and helminths such as Toxocara canis. The role of wild ungulates, especially ruminants, as reservoirs for zoonotic disease on the other hand seems to be negligible, although the deer filaroid Onchocerca jakutensis has been described to infect humans. Deer may also harbour certain Anaplasma phagocytophilum strains with so far unclear potential to infect humans. The major role of deer as reservoirs is for ticks, mainly adults, thus maintaining the life cycle of these vectors and their distribution. Wild boar seem to be an exception among the ungulates as, in their interaction with the fox, they can introduce food-borne zoonotic agents such as Trichinella britovi and Alaria alata into the human food chain.
    Full-text · Article · Dec 2014 · International Journal for Parasitology: Parasites and Wildlife
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    • "Furthermore, Italian and Austrian scientists suggested the potential role of I. ricinus as a vector of H. canis among domestic and wild canids [17,23]. However, the results of a later study indicated that I. ricinus ingested H. canis gamonts during the blood meal but further development and sporogony did not occur suggesting that I. ricinus does not act as a vector [47]. Hepatozoon canis oocysts have also been found in Rhipicephalus microplus (formerly Boophilus microplus) but the vector role of this tick species has not been confirmed [48]. "
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    ABSTRACT: Background Recently, Hepatozoon canis infection has been detected among shepherd, hunting and stray dogs in the southern part of Hungary, which is considered to be free of Rhipicephalus sanguineus sensu lato and close to the border with Croatia. The aim of this study was to acquire information on the possibility that red foxes and/or golden jackals could play a role in the appearance and spread of H. canis in Hungary. Methods A conventional PCR was used to amplify a 666 bp long fragment of the Hepatozoon 18S rRNA gene from blood samples collected from 334 foxes shot in 231 locations in 16 counties and 15 golden jackals shot in 9 locations in two southwestern counties close to Croatia. A second PCR assay was performed in some of the samples positive by the first PCR to amplify a larger segment (approximately 1500 bp) of the 18S rRNA gene of Hepatozoon spp. for further phylogenetic analysis. Results Hepatozoon infection was detected in canids shot in 30 locations and 9 counties. Altogether 26 foxes (8.0%, 95% CI: 5-11%) and 9 jackals (60%, 95% CI: 33-81%) were PCR positive. Hepatozoon canis sequences were obtained from 12 foxes and 7 jackals. DNA sequences from 16 animals were 99-100% similar to H. canis from Croatian foxes or dogs while two of the sequences were 99% similar to an Italian fox. Half (13/26) of the infected red foxes and all golden jackals were shot in the two southwestern counties. Conclusions This is the first report on molecular evidence of H. canis in red foxes (Vulpes vulpes) and golden jackals (Canis aureus) from Hungary, which is considered free from the tick vector of H. canis, R. sanguineus. Although no R. sanguineus sensu lato had been found on infected or non-infected wild canids, the detection of authochnous canine hepatozoonosis in Hungary might imply that the range of R. sanguineus sensu lato has reached this country.
    Full-text · Article · Jul 2014 · Parasites & Vectors
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