Olsen John Elmerdahl, Svensmark Birgitta, Agerskov Lene, Krogh Kenneth, Olsen Rikke H
Section of Veterinary Clinical Microbiology, Department of Veterinary and Animal Sciences, University of Copenhagen, Copenhagen, Denmark.
LVK, Hobro, Denmark.
Vet Rec. 2025 Jun 20:e5431. doi: 10.1002/vetr.5431.
Calf diarrhoea is a common disease manifestation caused by a variety of pathogens, which are often concurrently detectable in faecal samples from affected calves. It is unknown if co-infections lead to more severe diarrhoea than single-pathogen infections.
A total of 170 faecal samples were obtained from diarrhoeic calves, and the faecal material was graded in diarrhoeic severity from I to III. The pathogens present in the samples were then identified using a multiplex qPCR assay.
Clostridium perfringens type A and Cryptosporidium parvum were the most frequently detected pathogens and were present in 47% and 42% of the faecal samples, respectively. C. parvum was the most frequently detected pathogen in samples with diarrhoeic grade III, while Escherichia coli F5-positive samples had the highest relative frequency of samples with diarrhoeic grade III. Approximately one-third of the samples contained at least two different pathogens. For all diarrhoeic grades, the number of samples with one or more pathogens detected was greater than the number of samples with no pathogens detected, but this difference was only significant for diarrhoeic grade III.
Only pathogens detected by one specific multiplex qPCR assay were identified, meaning that other pathogens causing diarrhoea in these calves could have been overlooked.
Co-infections were not associated with a higher diarrhoeic grade compared to single-pathogen infections in calves. In single-pathogen infections, C. parvum was significantly more prevalent in samples with diarrhoeic grade III, when compared to diarrhoeic grades I and II combined.
犊牛腹泻是由多种病原体引起的常见疾病表现，在患病犊牛的粪便样本中常常能同时检测到这些病原体。目前尚不清楚混合感染是否会导致比单一病原体感染更严重的腹泻。
从腹泻犊牛身上共采集了170份粪便样本，并将粪便物质按腹泻严重程度分为I至III级。然后使用多重定量聚合酶链反应（qPCR）检测法鉴定样本中存在的病原体。
A型产气荚膜梭菌和微小隐孢子虫是最常检测到的病原体，分别存在于47%和42%的粪便样本中。微小隐孢子虫是腹泻III级样本中最常检测到的病原体，而产肠毒素大肠杆菌F5阳性样本在腹泻III级样本中的相对频率最高。大约三分之一的样本含有至少两种不同的病原体。对于所有腹泻等级，检测到一种或多种病原体的样本数量大于未检测到病原体的样本数量，但这种差异仅在腹泻III级时显著。
仅鉴定了通过一种特定的多重qPCR检测法检测到的病原体，这意味着这些犊牛中其他引起腹泻的病原体可能被忽视了。
与犊牛单一病原体感染相比，混合感染与更高的腹泻等级无关。在单一病原体感染中，与I级和II级腹泻合并样本相比，微小隐孢子虫在腹泻III级样本中明显更普遍。
