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: 2.35). 04/2013; 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.

  • [Show abstract] [Hide abstract]
    ABSTRACT: This study was undertaken in two different climatic areas of Turkey to determine the presence of tick-borne pathogens of medicine and veterinary importance. The ticks were removed from humans, pooled according to species and developmental stages, and analyzed with PCR, reverse line blot (RLB) and sequencing. Of the 2333 removed ticks from 10 species, 1238 (53.06%) were obtained from the arid cold zone, and the remaining 1095 (46.93%) were obtained from the humid zone. The removed ticks were identified as Hyalomma marginatum, Hy. detritum, Hy. excavatum, Rhipicepalus bursa, Rh. turanicus, Rh. sanguineus, Dermacentor marginatus, Haemaphysalis punctata, Hae. sulcata, Ixodes ricinus, Haemaphysalis spp. nymphs and Ixodes spp. nymphs. The dominant species was I. ricinus (61.27%) in the humid zone, whereas the Haemaphysalis spp. nymph dominated (30.29%) in the arid zone. Infection rates were calculated as the maximum likelihood estimation (MLE) with 95% Confidence Intervals (CI). Of the 169 pools tested, 49 (28.99%) were found to be infected with the pathogens, and the overall MLE of the infection rate was calculated as 2.44% (CI 1.88-3.17). The MLE of the infection varied among tick species, ranging from 0.85% (CI 0.23-2.34) in Haemaphysalis spp. nymph to 17.93% (CI 6.94-37.91) in D. marginatus. Pathogens identified in ticks included Theileria annulata, Babesia ovis, B. crassa, Anaplasma/Ehrlichia spp., Anaplasma ovis, Ehrlichia canis, A. phagocytophilum, Hepatozoon canis and H. felis. Most tick pools were infected with a single pathogen. However, four pools infected with H. canis displayed mixed infections with B. crassa, A. phagocytophilum and E. canis. The sequencing indicated that Anaplasma/Ehrlichia spp. was 100% identical to the sequence of Ehrlichia sp. Firat 2 and 3 previously identified from Hy. anatolicum.
    Veterinary Parasitology 01/2013; · 2.38 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Hepatozoon canis is a common apicomplexan parasite of dogs. In Brazil, in addition to Rhipicephalus sanguineus, Amblyomma ovale, Amblyomma cajennense, and Rhipicephalus (Boophilus) microplus have been suggested to act as vectors. The present study aimed to evaluate, under controlled conditions, the acquisition of H. canis by A. ovale, R. sanguineus, and A. cajennense after feeding on naturally infected dogs. Cytological and histophatological examinations were performed to recover oocysts and other sporogonic stages of the protozoan from the experimentally infected nymphs and adults. None of the R. sanguineus (n=30) or A. cajennense nymphs (n=15) that were dissected after feeding on H. canis naturally infected dogs became infected by the hemoparasite. Likewise, none of the R. sanguineus (n=165) and A. cajennense (n=114) adult ticks that were fed as nymphs on dogs demonstrated infection. Additionally, A. cajennense adult ticks were incapable of acquiring the infection, since no parasite was found in 62 adults that fed on H. canis-infected dogs. With regard to A. ovale ticks, 2 different infestations were carried out. Firstly, a dog with naturally occurring hepatozoonosis was infested with A. ovale adults originating from Rondônia, Brazil. Ticks fed to full engorgement. A total of 31 adults was collected from the dog and dissected on the third day after natural detachment. Oocysts were detected in 13 (42%) of the ticks. The second experimental infestation was carried out using adult ticks originating from São Paulo, Brazil. Surprisingly, of the 103 dissected ticks, only one (1%) contained oocysts in the hemocoel. No other sporogonic stage was found. Results indicate that different strains of A. ovale ticks may exist in Brazil with different susceptibilities to pathogens. Furthermore, it is possible that R. sanguineus and A. cajennense have little or no importance in the transmission of H. canis in rural areas of Brazil.
    Ticks and Tick-borne Diseases 10/2013; · 2.35 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Hepatozoonosis caused by Hepatozoon canis (Eucoccidiorida, Hepatozoidae) is among the most widespread vector-borne infections of dogs, primarily transmitted by Rhipicephalus sanguineus sensu lato. Based on the absence of a consensus on the treatment regimes for canine hepatozoonosis, the present study aimed to evaluate the efficacy of imidocarb dipropionate (5-6 mg/kg subcutaneously once a week for 6 weeks), and of toltrazuril/emodepside (Procox®, 15 mg/kg once a day for 6 days) in association with clindamycin (15 mg/kg once a day for 21 days) in treating naturally infected dogs. At the enrolment time (T0), 32 dogs, cytologically or molecularly positive for H. canis, were assigned to test and control groups. Animals were treated according to the specific therapeutic protocol, and the presence of H. canis gamonts was assessed weekly by cytology and PCR throughout six months (T1-T19). In addition, any abnormality in leukocyte morphology was evaluated and recorded. Results indicate that, in spite of a reduction in the percentage of infected dogs, both treatments did not provide parasitological cure. Accordingly, new treatment protocols or active compounds against H. canis should be investigated.
    Veterinary Parasitology 01/2013; · 2.38 Impact Factor


Available from
May 28, 2014