Gastrointestinal parasites in pigs : prevalence, risk factors and control

Gastrointestinal parasites are common in pigs worldwide, and in all production types. Clinical disease is rare and mainly associated with heavy nematode infections, or piglets infected with the coccidia Cystoisospora suis. Subclinical infections are more common and may result in reduced growth and poor feed utilisation. This can in turn affect pig health as well as the sustainability and productivity of the farm. The aim of this thesis was to update the knowledge of gastrointestinal parasites in Swedish pig herds, as this was last done in the 1980s. Since then, major changes in the national pig production have occurred with e.g., higher demands on animal welfare and improved biosecurity. Management routines related to parasite control were investigated using a questionnaire. Strategic hygiene and biosecurity practices were commonly practiced for growing pigs but less so for adult animals. Moreover, antiparasitic drugs were frequently used by routine. The occurrence of gastrointestinal parasites was assessed in three different studies. Oesophagostomum spp. were the most common parasites and found mainly in sows. The prevalence of Ascaris suum in growing pigs was reduced compared to previous studies. C. suis was common in piglets on a herd basis and Cryptosporidium spp. were found on all sampled farms. Finally, the efficacy of the available anthelmintic drugs was investigated, and for the first time in Sweden a reduced efficacy of ivermectin on Oesophagostomum spp. was identified. In conclusion, several changes in both the prevalence and control of gastrointestinal parasites were identified in this thesis. This new knowledge can in turn contribute to healthier pigs and a more sustainable and profitable pig production