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Age, not Infection Dose, Determines the Outcome of Isospora suis Infections in Suckling Piglets

Worliczek, Hanna L., Mundt, Hans-Christian, Ruttkowski, Bärbel, Joachim, Anja
Parasitology research 2009 v.105 no.1 pp. 157-162
Isospora suis, birth weight, diarrhea, disease control, excretion, models, oocysts, parturition, piglets, suckling, weight gain
Data from 13 trials involving 124 suckling piglets experimentally infected with Isospora suis were evaluated for the effects of infection dose and age on the clinical and parasitological outcome of infection in four different models, infections with 1,000 oocysts on the 1st day of life (d.o.l.) (model 1; 9 piglets/3 litters), 1,000 oocysts on the 4th d.o.l. (model 2; 25 piglets/11 litters), 1,500 oocysts on the 4th d.o.l. (model 3; 40 piglets/20 litters) and 10,000 oocysts on the 4th d.o.l. (model 4; 50 animals/10 litters). Weights were determined on the day of birth and in weekly intervals. Faecal consistency and quantitative oocysts excretion were evaluated for 2 weeks starting 4 days after infection (d.p.i.). The weight gain depression was most noticeable in model 2 (infection on the 1st d.o.l.), where animals only gained 2.08 x their birth weight until the 22nd d.o.l., compared to 2.31-2.52 x in the other groups. This correlated with the occurrence of watery diarrhoea which was found in 37 % of the samples in the acute phase (4-11 d.p.i.) in model 2 but only in 12-20 % of the samples in the other models. Median oocyst excretion peaked earlier in the models with higher infection doses but reached the highest values in model 2 (early infection). As in previous studies, this cross-sectional analysis of a larger number of animals confirms the influence of age on the outcome of isosporosis in suckling piglets, stressing the need to control the infection at an early life phase.