Detection of Cystoisospora suis in faeces of suckling piglets – when and how? A comparison of methods

Abstract

BackgroundCystoisospora suis is the causative agent of porcine neonatal coccidiosis, a diarrheal disease which affects suckling piglets in the first weeks of life. Detection of oocysts in the faeces of infected animals is frequently hampered by the short individual excretion period and the high fat content of faecal samples. We analysed oocyst excretion patterns of infected piglets, evaluated different detection methods for their detection limit and reproducibility, and propose a sampling scheme to improve the diagnosis of C. suis in faecal samples from the field using a protocol for reliable parasite detection.ResultsBased on a hypothesized model of the course of infection on a farm, three samplings (days of life 7–14-21 or 10–15-20) should be conducted including individual samples of piglets from each sampled litter. Samples can be examined by a modified McMaster method (lower detection limit: 333 oocysts per gram of faeces, OpG), by examining faecal smears under autofluorescence (lower detection limit: 10 OpG) or after carbol-fuchsin staining (lower detection limit: 100 OpG). Reproducibility and inter-test correlations were high with (R2 > 0.8). A correlation of oocyst excretion with diarrhoea could not be established so samples with different faecal consistencies should be taken. Pooled samples (by litter) should be comprised of several individual samples from different animals.ConclusionsSince oocyst excretion by C. suis-infected piglets is usually short the right timing and a sufficiently sensitive detection method are important for correct diagnosis. Oocyst detection in faecal smears of samples taken repeatedly is the method of choice to determine extent and intensity of infection on a farm, and autofluorescence microscopy provides by far the lowest detection limit. Other methods for oocyst detection in faeces are less sensitive and/or more labour- and cost intensive and their usefulness is restricted to specific applications.

Cystoisospora suis Control in Europe Is Not Always Effective

“…These rates are in line with a study from Sweden that showed a cumulative herd prevalence of 76% in piglets up to 4 weeks (3). However, a direct comparison of infection rates between studies must be interpreted with caution due to non-representative sampling and different diagnostic methods with different sensitivities (20,21). As Meyer et al (22) pointed out, individual samples from piglets from a litter pooled to a litter sample are preferable for examination.…”

“…We aimed to sample at least 10% of the litters that were born during the examination period, but a maximum of 30 litters/farms. To increase sensitivity each litter was sampled twice in one-week intervals due to the short periods of oocyst excretions (20). Number of litters examined/farm are shown in Supplementary Table 1.…”

“…Each sample was mixed well and aliquots of ca. 0.1-0.2 g of feces were examined by autofluorescence as described before (20). Samples were considered positive when at least one oocyst could be detected.…”

“…As C. suis induces intestinal damage during prepatency, i.e., before oocyst are excreted with the feces, efficient treatment has to be applied to piglets exposed to infection before the parasite can be diagnosed coproscopically (16,17). This highlights the importance of correct diagnosis of the presence of C. suis in a herd in order to obtain relevant information on the indication for and the correct time point of treatment (20).…”

Characterization of Cystoisospora suis sexual stages in vitro

“…The GAM proteins EmGam56 and EmGam82 were identified as antigens that conferred protection against different species of chicken Eimeria due to their conserved nature. A subunit vaccine for immunization was previously developed from E. maxima gamont proteins and commercialized for the prevention of coccidiosis [9,52].…”