Hammondia heydorni infection in camels (Camelus dromedarius) and water buffaloes (Bubalus bubalis) in Egypt

Molecular phylogenetic analyses of tissue coccidia (sarcocystidae; apicomplexa) based on nuclear 18s RDNA and mitochondrial COI sequences confirms the paraphyly of the genus Hammondia

Partial mitochondrial cytochromecoxidase subunit I (mt COI) sequences were generated from:Toxoplasma gondii(strains CTG, GTI, MAS, ME49, PTG, TgCatBr5, TgCat, Br64, TgCgCal, TgToucan);Neospora caninum(Strain NC1);Hammondia hammondi(Strain H.H–20);H. heydorni; H. cf.triffittae; Cystoisospora felis; C. suis; C. canis; C. rivolta; C. cf.ohioensis; Caryospora bigenetica; Sarcocystis rileyi; andS. neurona. Nuclear 18S rDNA sequences were generated forH. heydorni, H. hammondi, C. suis, C. canis, C. felis, C. rivolta, C. cf.ohioensis, S. neurona, andS. rileyi. Aligned, concatenated 18S rDNA and COI sequences were Bayesian analysed using partitioned nucleotide substitution models [HKY + I + G for 18S; GTR + I + G codon (code = metmt) for COI]. Phylogenetic hypotheses supported a monophyletic Sarcocystidae and its subfamilie with two major clades within the Toxoplasmatinae: (1) a monophyletic clade ofCystoisosporaspp. withNephroisospora eptesici; and (2) a clade ofToxoplasma, NeosporaandHammondia. Within the latter,Hammondiawas shown to be paraphyletic;H. heydorniandH. triffittaewere monophyletic withN. caninum[canine definitive hosts (DHs)], whereasH. hammondiwas monophyletic withT. gondii(feline DHs). A new genus is erected to resolve the paraphyly of the genusHammondiaconfirmed using mt COI and combined 18S/COI sequence datasets.

Hammondia triffittae n. comb. of foxes (Vulpes spp.): biological and molecular characteristics and differentiation from Hammondia heydorni of dogs

Genomic DNAs from 3 oocyst isolates of Hammondia sp. from foxes (Vulpes vulpes and V. lagopus) and 1 oocyst isolate of Hammondia heydorni from a dog, were examined by PCR and sequence analysis of 6 loci in order to determine whether the isolates were conspecific. Consistent genetic differences were found between the fox and dog isolates, respectively, at the ITS-2 region, the lsu rRNA gene, the alpha tubulin gene and the HSP70 gene, but not at the ssu rRNA gene or ITS-1 locus. Infection experiments established that dogs were unsuitable as definitive hosts for Hammondia sp. of foxes; hence this species is regarded as separate from H. heydorni of wolf-like canids, but probably identical with Isospora triffittae (syn. Isospora triffitti) previously reported from foxes. This species has therefore been named Hammondia triffittae n. comb. Reindeer, moose, sheep, goats, foxes and rabbits may act as intermediate hosts for H. triffittae. Muscle tissues of inoculated intermediate hosts were infectious for foxes from 16 days post-infection. Oocysts of H. triffittae were subspherical, averaging 12·5×10·9 μm in size. The lsu rRNA gene and the alpha tubulin gene seem to be suitable genetic markers for differentiating between H. triffittae and H. heydorni.

Hammondia heydorni from the Arabian mountain gazelle and red fox in Saudi Arabia

Unsporulated oocysts were detected in the feces of an Arabian red fox (Vulpes vulpes arabica) between 6 and 8 days after it had been fed meat from Arabian mountain gazelles (Gazella gazella) known to contain sarcocysts. No oocysts were discovered in the feces of other experimental cubs, although sporocysts of Sarcocystis spp. were passed subsequently by all cubs that were fed gazelle meat, including those fed with reem (G. subgutturosa marica). The oocysts sporulated in 3 days at room temperature (25 +/- 2 C); they were 10.9 +/- 1.4 x 10.1 +/- 1.3 microm, with 2 sporocysts measuring 6.0 +/- 0.6 x 4.7 +/- 0.8 microm, each with 4 sporozoites. Sporulated oocysts were identified as those of Hammondia heydorni using molecular and standard morphometric techniques. Sequence differences between 2 fox and 3 dog isolates of H. heydorni were detected and allowed differentiation between the 2 populations of the organism. The involvement of Neospora caninum was excluded using molecular methods. The Arabian red fox and the Arabian mountain gazelle in Saudi Arabia are new, definitive and intermediate hosts for H. heydorni.

Improved production of Neospora caninum oocysts, cyclical oral transmission between dogs and cattle, and in vitro isolation from oocysts

Scarce information is available about Neospora caninum oocysts and sporozoites, in part because only small numbers of oocysts have typically been produced by experimentally infected dogs. We hypothesized that I reason for low experimental production of oocysts is that dogs have been fed tissues from experimentally infected mice instead of tissues from cattle (which are natural intermediate hosts of N. caninum). In this study, 9 dogs were fed tissues from N. caninum-infected calves, and oocyst production was compared with 6 dogs that were fed infected mouse carcasses. The number of oocysts produced by dogs that ingested infected calf tissues (mean = 160,700) was significantly greater (P = 0.03) than the number of oocysts shed by dogs that ingested infected mice (mean = 5,400). The second goal of our experiment was to demonstrate cyclical oral transmission of N. caninum between dogs and cattle. As few as 300 oocysts were used to successfully infect calves, and tissues from these calves induced patent infections in 2 of 3 dogs; oocysts from I of these dogs were administered to another calf, and tissues from this calf subsequently induced a third dog to shed oocysts. Oocysts were confirmed to be N. caninum using a species-specific polymerase chain reaction technique. In addition, sporulated oocysts were used to recover N. caninum in vitro after digestion in an acid-pepsin solution and inoculation of cell monolayers.

Redescription of Neospora caninum and its differentiation from related coccidia

Neospora caninum is a protozoan parasite of animals, which before 1984 was misidentified as Toxoplasma gondii. Infection by this parasite is a major cause of abortion in cattle and causes paralysis in dogs. Since the original description of N. caninum in 1988, considerable progress has been made in the understanding of its life cycle, biology, genetics and diagnosis. In this article, the authors redescribe the parasite, distinguish it from related coccidia, and provide accession numbers to its type specimens deposited in museums.

Pig, donkey and buffalo meat as a source of some coccidian parasites infecting dogs

Experimental infection of dogs with meat samples (oesophagus, heart and diaphragm) from each of 105 pigs, 11 donkeys and 17 Egyptian water buffaloes indicated that they contained the infective stages of some coccidian parasites of dogs. The dogs which were fed pig meat shed in their faeces Isospora ohioensis, I. canis oocysts and Sarcocystis miescheriana sporocysts after prepatent periods of 3-5, 4-7 and 9-10 days, respectively. The dogs which were fed donkey meat excreted only I. ohioensis oocysts and Sarcocystis bertrami sporocysts after prepatent periods of 3 and 11 days, respectively. However, the dogs which were fed buffalo meat shed in their faeces I. ohioensis, I. canis and Hammondia heydorni oocysts with prepatent periods of 1, 1 and 7 days, respectively.

Isolation of tissue cysts of Toxoplasma, Isospora, Hammondia and Sarcocystis from camel (Camelus dromedarius) meat in Saudi Arabia

Meat samples were collected from the oesophagus and tongue of 38 camels slaughtered at the main abattoir of Al-Ahsa city, Saudi Arabia. Five cats and three dogs, conventionally reared and coccidia-free, were caged individually in steel cages. Camel meat was pooled, minced and fed to four cats and two dogs. One cat and one dog were not fed meat and were kept as noninfected controls. Faecal samples from infected and control animals were examined daily for a period of 2 months after feeding the meat. Three cats fed camel meat passed in their faeces oocysts of Toxoplasma gondii, Isospora felis and Isospora rivolta. The fourth cat passed only T. gondii and I. felis oocysts. One of the dogs fed camel meat passed oocysts of Isospora canis, Hammondia heydorni and Sarcocystis cameli sporocysts. The second dog excreted only S. cameli sporocysts.

Camel (Camelus dromedarius) and sheep (Ovis aries) meat as a source of dog infection with some coccidian parasites

Experimental infection of dogs with camel (Camelus dromedarius) meat resulted in infection of the dogs with Isospora canis, Hammondia heydorni and Sarcocystis cameli. The dogs fed sheep (Ovis aries) meat passed oocysts of Isospora canis, Isospora ohioensis and sporocyts of Sarcocystis spp. Extraintestinal stages were detected in the intestinal lymph node of a rabbit killed 4 days following inoculation with Isospora ohioensis oocysts. Dogs fed the rabbit (killed 4 days after inoculation with I. ohioensis) passed I. ohioensis oocysts in their faeces 8 days post-infection.

Development of Hammondia heydorni in cultured bovine and ovine cells

Sporozoites were excysted from oocysts of Hammondia heydorni obtained from a naturally-infected dog and inoculated into monolayer cultures of bovine pulmonary artery endothelial cells (CPA), Madin-Darby bovine kidney (MDBK) cells, bovine monocytes (M617), or ovine monocytes (WOMO). Sporozoites penetrated all four cell lines and underwent asexual reproduction by endodyogeny (as determined by electron microscopy) to form cyst-like structures at four to nine days after sporozoite inoculation (DAI). At 4-10 DAI, considerably more zoites were harvested from M617 cultures (80.1 x 10(6) zoites) than from CPA (17.4 x 10(6], MDBK (47.3 x 10(6], and WOMO (53.5 x 10(6]. Little or no parasite multiplication occurred at 10-16 DAI. Zoites harvested at 7 DAI and transferred to freshly prepared cultures did not penetrate cells nor develop further.

Further characterization of the biology of Hammondia heydorni

Hammondia heydorni oocysts, recovered from the diarrheic feces of a dog suffering from corticosteroid toxicosis, were sporulated and characterized morphometrically. Sporulated H. heydorni oocysts were administered to three dogs, five goats, a calf and three guinea pigs, and tissues from these inoculated animals fed to coccidia-free dogs to determine species susceptibility to H. heydorni. Morphometric characteristics of H. heydorni oocysts were similar to previous descriptions. Oocysts were not excreted in the feces of dogs inoculated with oocysts. Dogs fed tissues from goats killed 14, 28 or 42 days after inoculation (d.a.i.) with oocysts excreted H. heydorni oocysts in their feces after consuming goat tissues. Dogs fed tissues from a calf killed at 28 d.a.i., and from goats killed 21 and 56 d.a.i., did not excrete oocysts in their feces. Developmental stages of H. heydorni were not observed in histologic sections of tissues from any of the animals.