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.