The prevalence of macroscopic sarcocysts in New Zealand cattle at slaughter.

A survey carried out to determine the prevalence of visible Surcocystis spp. infection in 100 slaughtered cattle in a South Island abattoir revealed 64% infected. Although all ages, genders, breeds and export grades were infected, only host age had a statistically significant effect on the infection rate. Infections were most common in the rectus abdominis and the psoas muscles (47% and 41% respectively). Most infections were light, with less than ten macrocysts seen, though infections of more than 50 macrocysts occurred. The average macrocyst length was 4.WO.10 mm (SE) (n = 233), the average cyst wall thickness 5.3 +/- 0.2 microm (SE) (n = 45). It is thought that the actual prevalence of infection is higher than that recorded and reasons for this are discussed.