Factors associated with the occurrence and level of Isospora suis oocyst excretion in nursing piglets of Greek farrow-to-finish herds

BACKGROUND Piglet isosporosis is one of the most common parasitic diseases in modern pig production. To prevent clinical disease, prophylactic treatment of piglets with toltrazuril (BAYCOX® 5%, Bayer HealthCare, Animal Health, Monheim, Germany) is widely practiced in the past 20 years. There are only very few reports documenting the likely effect of managerial practices, such as hygiene measures, all-in-all-out management of farrowing facilities and piglet manipulations, and/or farm-specific environment - i.e. design and materials of the farrowing pen and room - in the risk of disease occurrence and transmission. Therefore, in this cross-sectional study, we identified litter- and herd-level factors associated with the odds and the level of Isospora suis oocyst excretion in nursing piglets of Greek farrow-to-finish pig herds. Faecal samples were collected from 314 liters of 55 randomly selected herds. Oocyst counts were determined by a modified McMaster technique and possible risk-factor data were collected through a questionnaire. In the analysis, we employed a two-part model that simultaneously assessed the odds and the level of oocyst excretion. RESULTS Factors associated with lower odds of oocyst excretion were: use of toltrazuril treatment, all-in all-out management of the farrowing rooms, no cross-fostering or fostering during the first 24 hours after farrowing, plastic flooring in the farrowing pens, farrowing rooms with more than fourteen farrowing pens and employment of more than two caretakers in the farrowing section. Factors associated with lower oocyst excretion level were: use of toltrazuril treatment and caretakers averting from entering into farrowing pens. CONCLUSION Apart from prophylactic treatment with toltrazuril, the risk and the level of I. suis oocyst excretion from piglets in their second week of life, was associated with managerial and environmental factors. Changes in these factors, which may enhance prevention of piglet isosporosis - either alternatively or supplementary to medical control - are of increasing importance because of the likely development of resistant parasites under the currently widespread use of anticoccidial compounds.