Abstract
A method for the detection of the first-stage larva of the bovine lung worm (BL) using a pointed-bottle centrifuge tube was reported in the preceding part of this series of studies. In the present investigation, it was compared with another method using the Baermann apparatus. As a result, there was no noticeable difference in the number of larvae released for 7.5 hours between the two methods. The former method, however, was capable of collecting two to three times as many larvae for 18 to 24 hours as the latter. A plateculture method used for eggs of intestinal nematodes almost failed to detect any larva of BL.
Cattle were infected experimentally with a moderate number of BL larvae and examined for the prepatent period and the time of disappearance of larvae. In those infected with 1, 800 to 2, 500 larvae, the prepatent period was 25 to 27 days and larvae were detected for 95 days or less.
The method using a pointed-bottle tube was performed in an outbreak of BL infection among 120 cattle on an island. As a result, varying numbers of larvae were detected from 87.6 per cent of the calves, of which the highest LPG was 1, 366. Larvae were found in 22.7 per cent of the adult cows, though a very few of them were harbored by each animal.
