Natural infection by Cryptosporidium parvum and Giardia duodenalis in sheep and goats in Galicia (NW Spain)

During the period between January and June 2005, faecal samples were collected from 673 sheep and 184 goats selected at random from 87 herds in Galicia (NW Spain). The animals under study were classified into two age groups: <1 month (98 lambs and 36 goat kids) and adults (575 sheep and 148 goats). Only C. parvum oocysts were detected in faecal samples from lactating animals. C. parvum oocysts were detected in 30 sheep (31%) and in 11 goat kids (30%) from, respectively, 57 and 43% of herds. The presence of C. parvum was detected in 29 sheep (5%) and in 14 goats (9%), with no significant differences in the degree of parasitization in these two types of domestic ruminants. The intensity of infection in sheep ranged between 9 and 1067 OPG, whereas in goats, the number of oocyst shedding ranged between 14 and 1484 OPG, with no significant differences between the two groups. Giardia duodenalis cysts were detected in 188 sheep (33%) from 67 herds (98%) and the number of oocyst shedding ranged between 10 and 4319 CPG. In goats, G. duodenalis was detected in 49 adults (33%) from 25 herds (92%) and the intensity of infection ranged between 14 and 667 CPG, i.e. significantly less (P < 0.05) than in sheep. Concurrent infections by C. parvum and G. duodenalis were observed in only 9 sheep (2%) and 8 goats (5%). All adult animals sampled were asymptomatic, indicating the importance of sheep and goats in the epidemiology of both of these parasites.