a b s t r a c tHookworms of the genus Uncinaria have been widely reported from juvenile pinnipeds, however investigations of their systematics has been limited, with only two species described, Uncinaria lucasi from northern fur seals (Callorhinus ursinus) and Uncinaria hamiltoni from South American sea lions (Otaria flavescens). Hookworms were sampled from these hosts and seven additional species including Steller sea lions (Eumetopias jubatus), California sea lions (Zalophus californianus), South American fur seals (Arctocephalus australis), Australian fur seals (Arctocephalus pusillus), New Zealand sea lions (Phocarctos hookeri), southern elephant seals (Mirounga leonina), and the Mediterranean monk seal (Monachus monachus). One hundred and thirteen individual hookworms, including an outgroup species, were sequenced for four genes representing two loci (nuclear ribosomal DNA and mitochondrial DNA). Phylogenetic analyses of these sequences recovered seven independent evolutionary lineages or species, including the described species and five undescribed species. The molecular evidence shows that U. lucasi parasitises both C. ursinus and E. jubatus, whereas U. hamiltoni parasitises O. flavescens and A. australis. The five undescribed hookworm species were each associated with single host species (Z. californianus, A. pusillus, P. hookeri, M. leonina and M. monachus). For parasites of otarids, patterns of Uncinaria host-sharing and phylogenetic relationships had a strong biogeographic component with separate clades of parasites from northern versus southern hemisphere hosts. Comparison of phylogenies for these hookworms and their hosts suggests that the association of U. lucasi with northern fur seals results from a host-switch from Steller sea lions. Morphometric data for U. lucasi shows marked host-associated size differences for both sexes, with U. lucasi individuals from E. jubatus significantly larger. This result suggests that adult growth of U. lucasi is reduced within the host species representing the more recent hostparasite association. Intraspecific host-induced size differences are inconsistent with the exclusive use of morphometrics to delimit and diagnose species of Uncinaria from pinnipeds.
This paper presents the necropsy findings in South American fur seal (Arctocephalus australis) pups from Uruguayan colonies. Animals (n = 105) were aged between 0 and 18 months old. From 0 to 6 months, 69.4% of the pups showed a poor body condition, while 68.8% of animals from 7 to 18 months had fair-to-good body condition. From 6 to 7 months of age, the stomach content included fishes, crustaceans, and foreign bodies. Starvation in the first months of life and traumatic lesions in pups older than 9 months were the most frequent causes of death. Uncinaria spp. was the only parasite found in the small intestine between 0 and 6 month-old pups. Parasites with indirect cycle (Contracaecum spp., Corynosoma sp., Tetrabothriidae) were present from 6 months of age as well as the first report of the nematode Strongyloides spp. in pinnipeds. Orthohalarachne spp. was found in the respiratory tract. Mycobacterium pinnipedii was isolated from 9 animals without gross pathological lesions. Other pathological conditions were found in lesser extent. This information contributes to the main causes of death of A. australis pups at different ages and could be useful to perform further health studies on this wild pinniped species.
Six strains of Toxoplasma oocysts were used to infect groups of 4-24 Wistar rats, with each rat being fed 10 1 -10 4 oocysts from a single strain. After 2 months, the rats were killed, their brains screened for Toxoplasma cysts and then bioassayed in mice if negative. Toxoplasma was either observed in the form of brain cysts or was recovered using the bioassay, from 113 out of 138 (82%) rat brains. As few as ten oocysts were capable of initiating a brain infection that lasted for at least 2 months in eight of the nine rats inoculated. However, judging from bioassay 10 2 -10 4 oocysts did not give rise to progressively higher rates of infection. Brain cysts were seen in only 68 of 138 rats (49%). The number of Toxoplasma cysts formed in the brains of rats was generally in the order of tens to hundreds. The frequency of infection in the brains with Toxoplasma and the number of brain cysts formed appeared to be influenced by the individual resistance of the rats as well as by the doses of oocysts and the Toxoplasma strains used. The information gathered is considered to be a basis for a rat model of immunity against acquired toxoplasmosis.
Six groups totalling 53 Wistar rats were fed 10 4 oocysts from one of six different Toxoplasma strains at 15 days of pregnancy. The overall transplacental transmission rate was 51%. This varied between 10% and 80%, dependent on the strain used. The strains of Toxoplasma which are more pathogenic for mice were transmitted transplacentally more frequently than the strains of intermediate or low pathogenicity. There were no statistically significant differences in the rate of congenital transmission of Toxoplasma in rats fed oocysts (present work) or cysts (previous work).
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