Hepatozoon canis: The prevalence of antibodies and gametocytes in dogs in Israel

A survey for the prevalence of antibodies to Hepatozoon canis and for intraneutrophilic H. canis gametocytes in the peripheral blood neutrophils of dogs in Israel showed that 33.1% were seropositive, while only 1% of the dogs sampled had detectable parasites in their blood smears. Exposure to H. canis is widespread but it appears that most infected dogs undergo a subclinical infection and only a small proportion develop clinical disease.Abbreviations IFAT indirect fluorescent antibody test     

Canine vector-borne disease pathogens in dogs from south-east Queensland and north-east Northern Territory

Objectives To determine the prevalence of canine vector‐borne diseases (CVBD: Babesia spp., Anaplasma spp., Ehrlichia spp., haemotropic mycoplasmas and Hepatozoon) in Australian dogs; namely, dogs from pounds in south‐east Queensland and an indigenous Aboriginal community in the north‐east of the Northern Territory. Design and procedure Blood samples were collected from 100 pound dogs and 130 Aboriginal community dogs and screened for the CVBD pathogens using polymerase chain reaction (PCR). All positive PCR products were sequenced for species confirmation. Results In total, 3 pound dogs and 64 Aboriginal community dogs were infected with at least one CVBD pathogen. Overall, B. vogeli was detected in 13 dogs, A. platys in 49, M. haemocanis in 23, Candidatus Mycoplasma haematoparvum in 3 and C. M. haemobos in 1 dog. Co‐infections were detected in 22 Aboriginal community dogs. Conclusions This study found B. vogeli, A. platys and haemotropic mycoplasma infections to be common in dogs in subtropical and tropical areas of Australia. This study also reports for the first time the prevalence and genetic characterisation of haemotropic mycoplasmas in dogs in Australia.     

DETERMINATION OF TIME OF ONSET AND LOCATION OF EARLY SKELETAL LESIONS IN YOUNG DOGS EXPERIMENTALLY INFECTED WITH HEPATOZOON AMERICANUM USING BONE SCINTIGRAPHY

Canine hepatozoonosis caused by Hepatozoon americanum has periosteal proliferation on long bones, pelvis, vertebrae, and skull. The pathogenesis of the periosteal proliferation is unknown but may be similar to hypertrophic osteopathy. Objectives were to determine the time frame for onset of bone lesions, to characterize spatial distribution of early bone lesions, and to describe the scintigraphic appearance of bone lesions in six immature dogs infected with 400 H. americanum oocysts on day 0. 99mTc-MDP bone scintigraphy was performed before and after infection. The onset bone lesions noted using scintigraphy was before day 35/36 in three dogs, day 46 in one dog, day 53 in one dog, and between days 46 and 67 in one dog. Early bone lesions primarily occur proximal to the carpus/tarsus and on the axial skeleton. Bone lesions were diffuse, bilaterally symmetric, homogenous, high intensity regions of radiopharmaceutical uptake.     

Looks can deceive: Molecular identity of an intraerythrocytic apicomplexan parasite in Australian gliders

Two yellow-bellied gliders (Petaurus australis) had an intraerythrocytic parasite closely related to the cyst-forming coccidia (Apicomplexa: Sarcocystidae). The parasitaemia persisted for 3 months or more but was observed to clear within 3 years in captivity. The parasite appears not to significantly debilitate its infected host. Traditionally, using morphological identification, the intraerythrocytic parasite would have been classified within the Hepatozoon species typically found in red blood cells. However, molecular diagnostic techniques targeting the parasite's SSU rDNA and LSU rDNA demonstrated the unusual identity of this blood parasite and disputed its identity as a haemogregarine parasite of the genus Hepatozoon. The sequence was compared with available sequences from diverse mammalian and non-mammalian blood parasites (malaria, piroplasms, hemosporidia and sarcosporidia). The intraerythrocytic blood parasite was found to be most closely related to the cyst-forming coccidia including Besnoitia spp., Cystoisospora spp., Hammondia spp., Hyaloklossia lieberkuehni, Neospora caninum, Sarcocystis spp. and Toxoplasma gondii. The life cycle of this intraerythrocytic parasite remains unknown. The presented DNA identification demonstrates its suitability for an improved identification of blood parasites.     

Hematologic, cytochemical, ultrastructural, and molecular findings of Hepatozoon-infected flat-headed cats (Prionailurus planiceps)

BACKGROUND: The flat-headed cat (Prionailurus planiceps) is a small wild cat of Southeast Asia and is considered extremely endangered. Little is known about the hematologic values, blood cell morphology, or hemoparasites of this species in relation to other Felidae. OBJECTIVES: The objective of this study was to report basic hematologic values and describe the light microscopic, cytochemical, and ultrastructural characteristics of blood cells in 2 wild-caught flat-headed cats. In addition, molecular analysis was done of a Hepatozoon organism found in the neutrophils of both cats. METHODS: Blood samples were collected into EDTA from the cephalic vein. A CBC, manual differential count, manual reticulocyte count, cytochemical stains (Sudan black B [SBB], alpha-naphthyl acetate esterase [ANAE], and beta-glucuronidase), and scanning and transmission electron microscopy were done using standard methods. RESULTS: HCT was slightly lower and reticulocyte counts and red cell distribution width were higher than the expected values for other species of cats. Hepatozoon organisms were found in the cytoplasm of neutrophils in both cats, but the number of infected neutrophils was very low (1%-2%). Neutrophils stained strongly positive for SBB, but were negative for ANAE and beta-glucuronidase. Hepatozoon-infected neutrophils were negative for SBB, but focally positive for ANAE and beta-glucuronidase. By transmission electron microscopy, gamonts of Hepatozoon sp were observed in neutrophils, and rarely free in plasma. Infected neutrophils had fewer specific granules and more mitochondria compared with noninfected neutrophils. PCR products of partial 18S rRNA revealed that the isolate of Hepatozoon in the flat-headed cats was closely related to that of the frog Hepatozoon sp. CONCLUSIONS: These results add to our understanding of hematologic values and blood cell morphology in Hepatozoon-infected flat-headed cats as well as the molecular analysis of the Hepatozoon organism, and may be useful for the health management and evaluation of hemoparasitic disease in this species.     

Infectivity of Hepatozoon americanum cystozoites for a dog

Hepatozoon americanum cystozoites from experimentally infected, laboratory-raised rodents were fed to a Hepatozoon-free dog. Gamonts were detected by examination of blood smear 42 and 56 days post-exposure. PCR analysis of blood was positive for the 18S rRNA Hepatozoon gene on days gamonts were demonstrated. Meronts were detected histologically in a skeletal muscle biopsy 90 days after ingestion of cystozoites. Sequencing confirmed that the parasite in the dog was H. americanum. Xenodiagnosis was conducted by replete feeding of Ambylomma maculatum larvae on the dog; 40 days after detachment, sporulated oocysts were recovered from recently molted nymphs.     

Hepatozoon canis infecting dogs in the State of Espírito Santo, southeastern Brazil

From May 2007 to March 2008, blood samples were collected from 92 healthy dogs living in 21 households (17 farms in rural area, and 4 homes in urban area) in 6 counties of the State of Espírito Santo, southeastern Brazil. In addition, ticks were collected from these dogs. A mean of 4.4 ± 3.0 dogs (range: 1–12) were sampled per household; 78 and 14 dogs were from rural and urban areas, respectively. Polymerase chain reaction (PCR) designed to amplify fragments of the 18S rDNA gene of Babesia spp or Hepatozoon spp revealed amplicons of the expected size in 20 (21.7%) dogs for Babesia, and 54 (58.7%) dogs for Hepatozoon. All Babesia-positive dogs were also Hepatozoon-positive. Among the 21 households, 15 (71.4%) from 3 counties had at least one PCR-positive dog, including 13 farms (rural area) and 2 homes (urban area). A total of 40 PCR products from the Hepatozoon-PCR, and 19 products from the Babesia-PCR were submitted to DNA sequencing. All generated sequences from Hepatozoon-PCR were identical to each other, and to corresponding 18S rDNA sequences of H. canis in GenBank. Surprisingly, all generated sequences from the Babesia PCR were also identical to corresponding 18S rDNA sequences of H. canis in GenBank. Dogs from 10 rural and 2 urban households were found infested by Rhipicephalus sanguineus ticks. Immature of Amblyomma cajennense ticks were found in dogs from only 4 rural households (also infested by R. sanguineus). All but one household with R. sanguineus-infested dogs had at least one Hepatozoon-infected dog. Statistical analysis showed that the presence of ticks (i.e. R. sanguineus) infesting dogs in the households was significantly (P < 0.05) associated with at least one PCR-positive dog. There was no significant association (P > 0.05) between PCR-positive dogs and urban or rural households. Canine hepatozoonosis caused by H. canis is a high frequent infection in Espírito Santo, Brazil, where it is possibly vectored by R. sanguineus. Since all infected dogs were found apparently healthy, the pathogenicity of H. canis for dogs in Espírito Santo is yet to be elucidated.     

Hematology,morphology, cytochemical staining,and ultrastuctural characteristics of blood cells in king cobras (Ophiophagus hannah)

Background — King cobras (Ophiophagus hannah) have been captive‐bred at Queen Saovabha Memorial Institute since 1996 to supply venom for antivenom production. Hematologic tests would be useful for evaluating the health of the snakes, however, basic hematologic data and morphology have not been described for this species. Objective — The purpose of this study was to determine basic hematologic values and evaluate light microscopic, cytochemical, and electron microscopic characteristics of king cobra blood cells. Methods — Blood samples from 13 wild‐caught and 15 captive‐bred king cobras were collected into EDTA from the ventral caudal vein. A CBC was done using standard methods. Significant differences between groups were determined using t‐tests. Cytochemical stains (periodic acid‐Schiff [PAS], Sudan black B [SBB], a‐naphthyl acetate esterase [ANAE], acid phosphatase [AcP], and p‐glucuronidase [p‐glu]), and scanning and transmission electron microscopy were done using standard techniques. Results — Eighteen snakes (64.3%) were positive for Hepatozoon infection. Hepatozoon organisms were detected nearly twice as frequently in wild‐caught (11/13) as in captive‐bred (7/15) snakes.Total WBC, azurophil, and lymphocyte counts were higher and fib‐rinogen concentration was lower in Hepatozoon‐positive snakes. Captive‐bred snakes had higher RBC values, lower azurophil, het‐erophil and punctate reticulocyte percentages, and higher lymphocyte numbers compared with wild‐caught snakes. Lymphocytes were the most commonly observed WBCs, and stained positive with PAS, ANAE, AcP, and (3–glu. Azurophil granules stained positive with SBB, PAS, and ANAE. Heterophils were the largest WBCs; their granules stained with SBB, ANAE, and (3–glu. Basophil granules stained with PAS, SBB, ANAE, and (3–glu. Thrombocytes were strongly positive with PAS. Transmission electron microscopic examination revealed organelles within all WBCs except eosinophils and revealed the gamonts of Hepatozoon sp in RBCs and azurophils. Conclusions — These results provide comparative hematologic data and a guide for identification of blood cells in wild‐caught and captive‐bred king cobra snakes. Hepatozoon infection was relatively common, but was not associated with severe hematologic abnormalities.