Evaluation of immunochromatographic point-of-care tests for the detection of calf diarrhoea pathogens in faecal samples

ABSTRACT

We have evaluated the diagnostic performance of immunochromatographic point-of-care tests (POCT) for the detection of rotavirus, coronavirus, Escherichia (E.) coli F5, Cryptosporidium (C.) parvum, Clostridium (Cl.) perfringens and Giardia (G.) intestinalis in fresh and thawed faecal samples from calves aged up to six months with diarrhoea. We performed POCTs to detect rotavirus, coronavirus, E. coli F5, C. parvum, Cl. perfringens and G. intestinalis on fresh samples in a field study and re-evaluated the performance for C. parvum, Cl. perfringens and G. intestinalis using thawed samples. We calculated the performance based on the results of the reference methods, which were RT-qPCR for the detection of rota- and coronavirus and bacteriological culturing and PCR to detect E. coli F5 and Cl. perfringens a and ss2 toxins. C. parvum was detected by phase-contrast microscopy and G. intestinalis by immunofluorescence microscopy. We collected 177 faecal samples from diarrhoeic calves. We found good performance for the POCT targeting rotavirus (sensitivity (SE)=92.9%;specificity (SP)=95.6%) and C. parvum (SE=63.3%;SP=96.2%). For E. coli F5, the number of true positive samples (n=1) was too low to evaluate the performance. The POCT to detect coronavirus gave a poor performance (SE=3.3%;SP=96.6%) and the POCT to detect Cl. perfringens a moderate performance (SE=52.8%;SP=78.2%). G. intestinalis POCT showed a higher sensitivity to immunofluorescence microscopy in thawed than in fresh faecal samples (SE=43.9% versus SE=29.2%). There are substantial differences in diagnostic performance between the commercially available immunochromatographic POCTs. Still, POCT can make a valuable contribution to the diagnosis and prevention of calf diarrhoea.