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Bulletin No. 19 - Fall 2004
Parasitology- No Category
GJESTVANG M, LIUM B, GAMLEM H, GJERDE B
Acute respiratory distress and death caused by migrating larva of Ascaris suum in finishing pigs
Proceedings of International Pig Veterinary Society 18th Congress, June 27-July 1, 2004, Hamburg, Germany, Volume 2, Page 841, Abstract No. 1519
Ascaris suum in pigs is commonly associated with liver white spots at slaughter, and may cause major economic losses due to liver condemnations, reduced growth rate and lowered feed conversion in growing pigs. Heavy ingestion of infective eggs of A. suum may lead to massive larval migration through the liver and lungs causing respiratory distress. Acute death is very seldom. This paper describes the clinical picture and pathological findings in pigs from a finishing farm with an acute outbreak of fatal ascariasis. At day one 40 pigs weighing approximately 25kg, arrived from a farrowing herd. The pigs were placed in a room containing one large pen covered with deep sawdust bedding, which remained after the previous batch of finishing pigs. Starting late on Day 5, the pigs showed symptoms of respiratory distress. Five died on Day 7 and another 10 on Day 8. Body temperatures were within a normal range. On day 9, only 14 pigs were still alive, all with very pronounced respiratory symptoms. They were all euthanized due to welfare reasons. At necropsy, the lungs were enlarged, heavy and firm with scattered petecchial bleedings and consolidations, and the lumen of the trachea and the bronchi contained foamy, mucoid fluid. There were scattered hemorrhagic foci in the liver parenchyma. Histological examination of the lungs revealed a large number of parasitic structures and a marked exudation of leucocytes in the lung parenchyma, alveoli and bronchioles. In the liver tissue multifocal necrosis with infiltrating leucocytes were found. The number of eggs of A. suum in the bedding varied from 320 to 1240 EPG, and most of the eggs contained living larvae, and hence were infective. The clinical, pathological and parasitological findings indicate that the pigs had become heavily infected with infective eggs of A. suum at the time they arrived to the new herd. The time span from the pigs entered the new pen and until the start of the clinical symptoms corresponds very well with the described period of 4-7 days from a pig ingests infective eggs, and till the larvae have migrated to the lungs.
