Case-control study of pathogens involved in piglet diarrhea.

Background: Diarrhea in piglets directly affects commercial swine production. The disease results from the interaction of pathogens with the host immune system and is also affected by management procedures. Several pathogenic agents such as Campylobacter spp., Clostridium perfringens, Escherichia coli, Salmonella spp., group A rotavirus (RV-A), coronaviruses (transmissible gastroenteritis virus; porcine epidemic diarrhea virus), as well as nematode and protozoan parasites, can be associated with disease cases.
Results: All bacterial, viral, protozoan, and parasitic agents here investigated, with the exception of Salmonella spp. as well as both coronaviruses, were detected in varying proportions in piglet fecal samples, and positive animals were equally distributed between case and control groups. A statistically significant difference between case and control groups was found only for Cystoisospora suis (p = 0.034) and Eimeria spp. (p = 0.047). When co-infections were evaluated, a statistically significant difference was found only for C. perfringens β2 and C. suis (p = 0.014).
Conclusions: The presence of pathogens in piglets alone does not determine the occurrence of diarrhea episodes. Thus, the indiscriminate use of antibiotic and anthelminthic medication should be re-evaluated. This study also reinforces the importance of laboratory diagnosis and correct interpretation of results as well as the relevance of control and prophylactic measures.