Pathogenesis of the Lesions Caused by Cyathostoma bronchialis in the Respiratory Tract of Geese

Abstract

Cyathostoma bronchialis causes bronchitis of the tertiary, secondary, and primary bronchi during its development in geese. Extreme hyperplasia of the epithelium of the primary bronchi is the foremost lesion seen during prepatency. During patency, generalized pneumonitis in response to aspirated nematode eggs is the most prominent lession, and is accompanied by bronchitis of the primary bronchi and air sacculitis. Fernando, Hoover, and Ogungbade (1973) described the development and migration of Cyathostoma bronchialis (Muehlig, 1884) Chapin, 1925, in geese. In the present paper the pathogenesis of the pulmonary lesions during the migration and patency of C. bronchialis is described, and compared to that of Syngamus trachea in gallinaceous birds. MATERIALS AND METHODS Twoto 4-week-old domestic geese (Anser cygnoides) were fed naturally infected earth worms, as described previously (Fernando et al., 1973), and killed daily from 2 to 6 days and at 8, 10, 12, 14, 15, 17, 21, and 28 days after infection. At least 2 infected geese were killed each day except on day 28, when only 1 bird was killed. One uninfected control was killed each day up to 10 days postinfection. Worms were recovered from 1 lung by the Baermann technique up to 5 days postinfection and from the trachea thereafter. From all birds, 1 lung, with trachea attached, was fixed in 10% formalin. Hematoxylin and eosin-stained 5-/um paraffin sections of these tissues were examined to evaluate the lesions caused by C. bronchialis at the different periods after infection. Received for publication 16 April 1973. * Data for the goose killed at 28 days postinfection was from a thesis presented by S. G. Ogungbade to the University of Guelph in partial fulfillment of the M.Sc. degree. t Department of Pathology. $ Department of Clinical Studies. RESULTS As the number of infective larvae given each goose was unknown, the number of worms recovered postmortem was assumed to be the approximate number causing the lesions reported below. The numbers of worms recovered per goose are given in Table I. We did not find any lesions prior to day 3 postinfection. 3 to 4 days postinfection Worms were seen in parabronchi (Fig. 1) and secondary bronchi close to the lung surface, but by day 4 there were more in the secondary bronchi. The worms almost occluded the parabronchi they occupied. A number of pulmonary lobules had obvious lesions. The interlobular arteries adjacent to these lobules were cuffed by lymphoid cells. The air capillaries of these lobules were obscured by lymphoid hyperplasia (Fig. 2). These lesions were more extensive at 4 days postinfection, and the affected areas were usually close to the lung surface. 5 to 6 days postinfection Worms were found in the primary bronchi. The lymphoid hyperplasia of the air capillaries was less obvious than at 3 and 4 days. Many parabronchi and secondary bronchi were cuffed by lymphoid tissue. The lamina proprial vessels of the secondary bronchi were FIGURES 1-4. Cyathostoma bronchialis in goose lung. H and E. Days postinfection in parentheses. 1. Larva distending parabronchus (3d). X 400. 2. Lymphoid hyperplasia obscuring air capillaries between interlobular artery and neighboring parabronchus. Note ganglion (arrow), between artery and parabronchus, a prominent feature of goose lungs (4d). X 400. 3. Leukocyte infiltration of lamina propria and epithelium of a secondary bronchus (6d). X 400. 4. Hyperplasia of epithelium of a primary bronchus showing many mitotic figures (arrow) (6d). X 400.