Importance and Characterisation of Concurrent Pathogens in Diarrhoeic Calves from North-Western Spain

Area of Science:

• Veterinary Medicine
• Microbiology
• Animal Health

Background:

• Neonatal calf diarrhoea (NCD) is a primary cause of mortality in young calves.
• Previous research often focused narrowly on specific or traditionally recognized enteropathogens.
• Outbreaks typically involve multiple causative agents, complicating diagnosis and control.

Purpose of the Study:

• To determine the prevalence of thirteen enteropathogens in diarrhoeic calves under 30 days old in north-western Spain.
• To identify common co-occurrences of these pathogens in NCD cases.
• To assess the role of less commonly diagnosed agents in NCD.

Main Methods:

• Quantitative Polymerase Chain Reaction (qPCR) for detecting viruses and specific Escherichia coli pathotypes.
• Serum agglutination test for Salmonella spp. detection.
• Direct immunofluorescence assay for Cryptosporidium and Giardia duodenalis.
• Floatation technique for Eimeria oocyst identification.

Main Results:

• A high prevalence of co-infections was observed, with 172 distinct pathogen combinations identified.
• Cases involving viral agents and Cryptosporidium parvum were predominant.
• Multiple agents, up to seven, were detected concurrently in some cases.

Conclusions:

• Most NCD cases are caused by multiple interacting pathogens.
• Viral infections may predispose calves to Cryptosporidium parvum.
• Diagnostic panels for NCD should be expanded to include frequently overlooked agents for effective control.