Aetiological Diagnosis of Diarrhoea in Neonatal Piglets in Ontario Between 2001 and 201023 May 2014
Clostridium difficile appears to be an emerging pathogen, while E.coli (ETEC) and rotavirus remain causes of concern in cases of diarrhoea in young piglets in Ontario, according to University of Guelph researchers speaking at the 33rd Centralia Swine Research Update in January 2014.
Neonatal piglet diarrhoea is a major cause of pre-weaning mortality, resulting in significant economic loss for swine producers, according to G. Chan and colleagues at the University of Guelph.
The relative importance of different diseases contributing to neonatal piglet diarrhoea appears to be changing, possibly because of changes in husbandry and management practices, advances in diagnostic techniques, and/or the emergence of new diseases.
In particular, the emergence of a new disease, porcine epidemic diarrhoea (PED) in the United States illustrates the importance of monitoring cases of piglet diarrhoea.
The purpose of the study was to use laboratory diagnostic data to identify the frequency and trends of different pathogens contributing to neonatal piglet diarrhoea on Ontario swine farms from 2001 to 2010.
Materials and Methods
The data were provided by the Animal Health Laboratory (AHL) at the University of Guelph, and included laboratory submissions from Ontario swine farms from 2001-2010. The data included gastrointestinal tract (GIT) cases where live or dead piglets between one and seven days of age were submitted.
Multivariable logistic regression models were used to analyze the association between the diagnosis of enterotoxigenic E. coli (ETEC), Clostridium perfringens, Clostridium difficile, rotavirus and Cystisospora suis, respectively, and independent variables.
The independent variables included in the analysis were the age of piglet in days, year of submission, season of submission and diagnosis of other enteric pathogens.
A total of 237 GIT cases involving the submission of live or dead piglets, one to seven days of age were submitted to the AHL, from 2001 to 2010.
The number of these GIT cases submitted per year ranged from 10 to 39, with an average of 24 cases per year. There were 79 (33 per cent) GIT cases submitted to the AHL where an aetiological agent was not identified.
There were a total of 51 (22 per cent) GIT cases in the fall, 50 cases in the spring (21 per cent), 46 (19 per cent) cases in the summer and 90 (38 per cent) cases in the winter.
ETEC was diagnosed as the cause of GIT disease for 63 cases that involved a single aetiological agent, and 10 cases that involved multiple aetiological agents (31 per cent of total cases). ETEC was less likely recovered from a GIT case if C. difficile, C. perfringens or rotavirus were detected (P< 0.05). ETEC was more likely diagnosed for GIT cases that occurred in the winter compared to the spring and the summer.
C. perfringens was diagnosed as the cause of GIT disease for 19 cases that involved a single etiological agent, and nine cases that involved multiple aetiological agents (12 per cent of total cases). A total of 155 GIT cases were cultured for C. perfringens and the organism was isolated in 133 (86 per cent) cases. GIT cases were less likely to be diagnosed with C. perfringens with increasing age of the piglets and if ETEC was detected.
Rotavirus was diagnosed as the cause of GIT disease for 18 cases that involved a single aetiological agent, and 10 cases that involved multiple aetiological agents (12 per cent of total cases). Rotavirus was more likely diagnosed for GIT cases that occurred in the fall compared the spring and the summer.
C. difficile was diagnosed as the cause of GIT disease for 10 cases that involved a single aetiological agent, and 11 cases that involved multiple aetiological agents (nine per cent of total cases). C. difficile was less likely diagnosed with increasing age of the piglets. C. difficile was less likely diagnosed if ETEC was detected, but more likely diagnosed if Salmonella sp. was detected.
Cystisospora suis was diagnosed as the cause of GIT disease for 13 cases that involved a single etiological agent, and two cases that involved multiple aetiological agents (six per cent of total cases). Cystisospora suis infection was more likely diagnosed for GIT cases that occurred in the summer compared to the spring, and the winter.
Transmissible gastroenteritis virus was diagnosed as the cause of GIT disease for six cases that involved a single aetiological agent and one case that involved multiple aetiological agents (three per cent of total cases).
Neonatal diarrhoea cases were most frequent during winter, a well-established finding in countries with harsh winters.
The major known pathogens that contributed to neonatal piglet diarrhoea from 2001 to 2010 were ETEC, rotavirus, C. perfringens and C. difficile. The combined GIT cases involving these pathogens contribute to more than half of the GIT cases submitted to the AHL.
In one-third of the GIT cases involving piglets less than a week of age, no causative agent was identified. The lack of diagnosis for some GIT cases is possibly due to inappropriate samples submitted to the diagnostic laboratory; piglets in the acute stage of disease have the highest pathogen load and therefore are more likely to yield diagnostically useful information.
There may be other unknown pathogens involved in the undiagnosed GIT cases submitted to the AHL and further investigation is required to determine the current causes of piglet diarrhoea in Ontario swine farms.
This study identified several current pathogens involved in neonatal diarrhoea for Ontario swine farms.
Clostridium difficile appears to be an emerging pathogen, and ETEC and rotavirus remain as pathogens of concern for neonatal piglet diarrhoea.
Further research in the diagnostic method of these pathogens may be useful in improving the diagnostic rate for GIT cases.
The data suggested that C. perfringens type A may be an important pathogen for neonatal piglet diarrhoea but the lack of specific diagnostic criteria made it difficult to determine the significance of isolating this bacteria from a pig with diarrhoea.
Acknowledgements: The research was funded by the Ontario Ministry of Agriculture Food and Rural Affairs, in part by a grant through the Animal Health Strategic Initiative.
Chan G., A. Farzan, J. DeLay, B. McEwen, J. Prescott, R. Friendship. 2014. Aetiological diagnosis of diarrhoea in neonatal piglets in Ontario between 2001 and 2010. Proceedings of 33rd Centralia Swine Research Update.