Article

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: 2.88). 04/2013; 4(5). DOI: 10.1016/j.ttbdis.2013.03.001
Source: PubMed

ABSTRACT 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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Available from: Filipe Dantas-Torres, Aug 04, 2015
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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.
    Ticks and Tick-borne Diseases 06/2015; DOI:10.1016/j.ttbdis.2015.05.009 · 2.88 Impact Factor
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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: A B S T R A C T 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. Echi-nococcus 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 Toxo-plasma 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.
    International Journal for Parasitology: Parasites and Wildlife 12/2014; 4(1). DOI:10.1016/j.ijppaw.2014.12.001
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    • "That suggests strongly that the foxes are the source of infection because H. canis DNA has been rarely detected in questing I. ricinus ticks (Reye et al. 2010; Gabrielli et al. 2010). That supports the suggestion that I. ricinus does not act as a vector of H. canis (Giannelli et al. 2013). On the other hand, many I. ricinus-positive ticks were infested foxes proved to be negative for Hepatozoon spp., which raises the question about the role of this tick species in the natural cycle of H. canis. "
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    ABSTRACT: In this study, the prevalence of Hepatozoon spp. in red foxes (Vulpes vulpes) and their ticks from Germany, as well as molecular characterizations and phylogenetic relationship to other Hepatozoon spp. were investigated. DNA extracts of 261 spleen samples and 1,953 ticks were examined for the presence of Hepatozoon spp. by a conventional polymerase chain reaction (PCR) targeting the 18S rRNA gene. The ticks included four tick species: Ixodes ricinus, Ixodes canisuga, Ixodes hexagonus and Dermacentor reticulatus. A total of 118/261 foxes (45.2 %) and 148/1,953 ticks (7.5 %) were Hepatozoon PCR-positive. Amplicons from 36 positive foxes and 41 positive ticks were sequenced. All sequences obtained from foxes and 39/41 from ticks had a 99 % similarity to Hepatozoon canis, whereas two ticks’ sequences had a 99 % identity to Hepatozoon sp. The obtained Hepatozoon sequences in this study were phylogenetically related to other Hepatozoon sequences detected in other countries, which may represent strain variants. The high prevalence of H. canis DNA in red foxes in this study supports the suggested role of those animals in distribution of this parasite. Furthermore, detection of DNA of H. canis in foxes and all examined tick species collected from those foxes allows speculating about previously undescribed potential vectors for H. canis and suggests a potential role of the red fox in its natural endemic cycles.
    Parasitology Research 07/2014; 113(7). DOI:10.1007/s00436-014-3923-8 · 2.33 Impact Factor
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