Migration behaviour and pathogenesis of five ascarid nematode species in the Mongolian gerbil Meriones unguiculatus.

To understand the characteristic features of the Mongolian gerbil, Meriones unguiculatus, as an animal model of ascarid infections, the migration behaviour and pathogenesis of larvae were investigated in experimentally infected gerbils. Embryonated eggs from each of Toxocara canis, Baylisascaris procyonis, B. transfuga, Ascaris suum, and A. lumbricoides were orally inoculated into gerbils and larvae were recovered from various organs at designated periods. In T. canis-infected gerbils, larvae were present in the liver 3 days after infection and in the skeletal muscle and brain via the heart and lungs at a similar rate. In B. procyonis- and B. transfuga-infected gerbils, larvae were present in the lungs within 24 h after infection, with some having reached the brain by that time. After 24 h, larvae of B. procyonis tended to accumulate in the brain, while those of B. transfuga accumulated in skeletal muscles. In A. suum- and A. lumbricoides-infected gerbils, larvae remained in the liver on day 5 post-infection and elicited pulmonary haemorrhagic lesions, which disappeared 7 days after initial infection. Thereafter, no larvae of any type were recovered. Ocular manifestations were frequently observed in T. canis- and B. procyonis infected gerbils, but were rare in B. transfuga-infected gerbils. In the cases of A. suum and A. lumbricoides, migration to the central nervous system and eyes was extremely rare, and larvae had disappeared by 2 weeks post-infection. Fatal neurological disturbances were observed in B. procyonis-infected gerbils, whereas irreversible non-fatal neurological symptoms were observed in the case of B. transfuga.

Anthelmintic efficacy of milbemycin D against Toxocara cati and Ancylostoma tubaeforme in domestic cats.

Anthelmintic efficacy of milbemycin D was evaluated against Toxocara cati and Ancylostoma tubaeforme in domestic cats. Twelve cats naturally infected with each nematode species were allocated among 2 groups of 6 animals each, and milbemycin D was orally administered to the 2 groups of cats in doses of 0.05 mg/kg and 0.1 mg/kg body weight, respectively. In all the cats infected with T. cati, fecal egg counts decreased followed by their disappearance from the feces and 2-35 worms were excreted into the feces after the medication in both doses of 0.05 mg/kg and 0.1 mg/kg. At postmortem of these medicated groups, no worms were detected from 4 cats of each group, but 1 and 2 immature worms were recovered from the other 2 cats respectively. In the cats infected with A. tubaeforme, fecal egg counts decreased followed by the disappearance from the feces and 2-62 worms were excreted into the feces in all the cats of the 2 groups, no nematodes remaining at postmortem. These results indicate that milbemycin D is fully effective against T. cati and A. tubaeforme in cats in a dose of 0.05-0.1 mg/kg.

Diagnosis of Fasciola sp. infections in cattle by enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) was evaluated for diagnosis of experimental or naturally occurring Fasciola sp. infections in cattle. The positive rate for the ELISA in calves inoculated with Fasciola metacercariae were 21.1% by 2 weeks postinoculation (PI), 94.6% by 4 weeks PI and 100% by 6-21 weeks PI. The positive rate for the immunodiffusion test (Ouchterlony test) reached 91.7% by 2 weeks PI, however, it dropped to 77.8% by 10 weeks PI. The positive rate for the fecal egg examination was 0% by 10 weeks PI, 77.8% by 12 weeks PI and 100% by 14-21 weeks PI. The practical application of ELISA was tested by using 165 cows raised under field condition. All the 24 cows that were positive both in the fecal egg examination and the Ouchterlony test were ELISA positive. Of the 6 cows that were egg positive and Ouchterlony negative, 5 showed ELISA positive reactions. Of the 27 cows that were egg negative and Ouchterlony positive, 24 were ELISA positive. Of the 108 cows that were egg negative and Ouchterlony negative, 90 were ELISA negative. However, the other 18 cows had ELISA positive reactions. Our results suggested that the ELISA using crude adult antigen was superior to the Ouchterlony test and fecal egg examination for diagnosis of experimental or naturally occurring Fasciola sp. infections in cattle.