Parafilaria bovicola (Tubangui 1934) in cattle: epizootiology-disease occurrence.

Parafilaria bovicola, a filariid nematode affecting cattle, was first identified in Sweden in 1978. The parasite (female, 5 to 6 cm long, 500 micrometer wide; male, half that size) is associated with lesions caused when the worm is moving subcutaneously and IM, giving rise to condemnation losses of approximately 6 kg of meat in an affected animal at slaughter. Several hypotheses were tested in a questionnaire survey among cattle owners in he enzootic area of the disease, attempting to investigate factors associated with its occurrence in Sweden (i) Condemnation losses due to P bovicola were overrepresented among animals that came from herds held on pasture the previous year, as opposed to animals from farms with indoor cattle management only, indicating that infection of cattle occurs while they are on pasture. (ii) A statistically significant difference was found between affected and nonaffected herds with respect to age groups, with most cattle affected belonging to the 1- to 2-year age group. And (iii), frequency of Parafilaria-induced lesions showed a seasonal trend, increasing sharply in late December, remaining at about 30% of the slaughter population until July, at which time it dropped to insignificant levels. Seemingly delaying the time of slaughter of animals until the 2nd half of the year may ensure time for lesions to heal and lessen economic losses due to condemnations.