Studies on Parafilaria bovicola Tubangui, 1934 III. Pathological changes in infested calves

More lesions were found in the carcass of an animal that has been naturally infested with Parafilaria bovicola than in one artificially infested with a single subcutaneous injection of infective larvae of this species. This may be because natural infestations are either more frequent or more successful. Similarities in the distribution of lesions in naturally and experimentally infested animals suggest that certain predilection sites may be used by the intermediate fly hosts. Subcutaneous areas infiltrated with eosinophils are more conspicuous during the first 20 days after infestation and during the patent phase of the life cycle of P. bovicola. Yellowish discolorations caused by oedema are usually present in all lesions. When these are combined with eosinophil infiltrations, the lesions become yellowish-green. After the appearance of bleeding spots the green colour of lesions is dominated by the appearance of a brown pigment (haemosiderin) in numerous macrophages. The histopathological changes in the dermis, subcutis and superficial muscles bordering the affected areas are described.