Major Pathogens Found in Sick Piglets

Major Pathogens Found in Sick Piglets

We have been concerned with health consultation and diagnostic examination of pig farms in central and northern Japan. The purpose of this study is to elucidate relationship between the infectious diseases and piglet age by epidemiological survey of the causative pathogens from 2004 to 2008.

Materials and Methods
1094 samples in total, carcass and feces of diarrhea, were collected from 62 farms in Kanto, 71 in Tohoku and Hokkaido district of Japan. For detection of pathogens, cultural isolation and identification were employed for Actinobacillus pleuropneumoniae, Haemophilus parasuis, Pasteurella multocida, Clostridium perfringens, Escherichia coli, Salmonella sp. and Streptococcus sp.; PCR methods for PRRSV, PCV2, and Lawsonia intracellularis; latex agglutination method for Rotavirus; and microscopic examination for fecal parasites such as Coccidium and Trichuris suis.

The incidence of detected pathogens at each growth stage of piglets. Additional pathogens detected in PRRSV positive samples (194 cases) and those in PCV2 positive samples (34 cases) . In 0 to 30-days old piglets, C. perfringens and Shiga toxin- producing E. coli (STEC) were found at high rates, 40.5 and 23.5%, respectively. STEC, H. parasuis, P. multocida, and C. perfringens were dominated in 30 to 60-days old animals (20.4, 14.8, 14.6, and 14.1%, respectively). Whereas, the major pathogens changed in the course of piglet growth. PRRSV, P.multocida, and A. pleuropneumoniae were found at high rates (24.9, 20.2, and 18.1%, respectively) in 60 to 90-days old ones; A. pleuropneumoniae, C. perfringens, and P. multocida were abundant in 90 to 120-days old ones (19.2, 17.4 and 15.6%, respectively). Accompanied pathogen to PRRSV was found as P. multocida at the highest rate (40.6%), followed by H. parasuis (24.5%) and A. pleuropneumoniae (19.6%). The mixed infection with PCV2 positive cases was attributed to H. parasuis (48.0%), P. multocida (44.0%), and A. pleuropneumoniae (16.0%).

The results indicate pathological relevance between the pathogens and the age of piglets. Namely, the pathogens causing digestive system diseases were dominant in the early stage of growth, while the agents causing digestive and respiratory system diseases were detected at a nearly same rate in 30 to 60-days old piglets. After 60 days, prevailing pathogens were almost limited to respiratory diseases. In any stage of animal growth, most of the detected pathogens were causative of chronic or opportunistic diseases, and it was suggested that they could develop into complex syndromes by mixed infection with PRRSV or PCV2.

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