Detection and molecular characterisation of Cryptosporidium spp. in Swedish pigs

Abstract

Background Cryptosporidium is a genus of apicomplexan parasites that cause enteric disease in vertebrates. In pigs, infections are most often asymptomatic, but may result in diarrhoea and poor growth. The most common species detected in pigs are C. suis and C. scrofarum with low zoonotic potential. C. parvum , with higher zoonotic potential, may also be found. As previous knowledge on the occurrence of Cryptosporidium in Swedish pigs is scarce, this was investigated in our study. Faecal samples from 13 pig herds were collected and a total of 222 pooled pen samples, from suckling piglets (n = 48), growers, aged 6–12 weeks (n = 57), fatteners, aged 13–24 weeks (n = 67) and adult animals (n = 50) were included. Samples were analysed using microscopy and positive samples were further analysed using polymerase chain reaction and sequencing of the 18S rRNA gene and the 28S rRNA gene to determine species. Results Cryptosporidium spp. were detected in all sampled herds and in 25% (56/222) of the individual pen samples. Infections were most common in growers and fatteners with 51% (29/57) and 35% (20/67) positive samples in each group, respectively. The piglets had 8% (4/48) positive samples and adults had 6% (3/50). Species determination showed C. suis and C. scrofarum in piglets and growers, C. scrofarum in the fatteners, and C. suis and C. parvum in the adults. Although no mixed infections could be confirmed we saw signs of double peaks in the 28S rRNA gene chromatograms, possibly indicating more than one species present per sample. Conclusion Cryptosporidium spp. were detected on every sampled farm and in 25% of the individual pen samples in our study. We therefore conclude that Cryptosporidium spp. are present and likely common in Swedish pig herds, where pigs are loose and reared on solid floors. However, none of the farms reported any problems with poor weight gain, diarrhoea, or reduced appetite in their pig herds. The pig adapted C. suis and C. scrofarum were the predominant species identified. Two samples were positive for the more zoonotic C. parvum , and pigs should hence not be disregarded as a possible source of zoonotic cryptosporidiosis.

Parasitic Intestinal Protists of Zoonotic Relevance Detected in Pigs by Metabarcoding and Real-Time PCR

“…Cryptosporidium parvum, which has previously been reported in pigs in Sweden [40] but not in Denmark [41], was not detected in the present study.…”

CryptoGenotyper: A new bioinformatics tool for rapid Cryptosporidium identification

“…Additionally, chromatograms from 187 samples genotyped at the National Veterinary Institute (SVA, Uppsala, Sweden) between 2013 and 2020 were inputted into the tool using both forward and reverse sequences for each sample. These samples were collected from several studies ( Pettersson et al, 2020 ; Åberg et al, 2020 ; Åberg et al, 2019 ; Björkman et al, 2018 ; Björkman et al, 2015 ; Alsmark et al, 2018 ; unpublished), outbreak investigations and sporadic cases sent for routine diagnosis. The samples were comprised of 123 cattle, 34 pigs, 20 squirrels, 4 sheep, 2 horses, 2 chital deer and 1 roe deer.…”

“…Samples tested from SVA were purified using a saturated salt/glucose flotation method and DNA was extracted as described in their respective studies ( Pettersson et al, 2020 ; Åberg et al, 2020 ; Åberg et al, 2019 ; Björkman et al, 2018 ; Björkman et al, 2015 ; Alsmark et al, 2018 ), with samples from unpublished data processed by the same method as described in Pettersson et al (2020) .…”

“…Samples for SSU rRNA and gp60 gene targets at the NML were amplified and purified as previously described by Guy et al (2021) whereas the SSU rRNA samples from the SVA were processed as described by Pettersson et al (2020) . For both laboratories, the SSU rRNA gene was amplified following the assay conditions as previously described ( Xiao et al, 1999 , Xiao et al, 2000 ).…”

Diarrhoea‐causing enteric protist species in intensively and extensively raised pigs ( Sus scrofa domesticus ) in Southern Spain. Part I: Prevalence and genetic diversity

“…At least 46 Cryptosporidium species are currently recognized as taxonomically valid (Ježková et al., 2021; Zahedi et al., 2021), of which host‐adapted C. suis and C. scrofarum , zoonotic C. parvum , and to a much lesser extent, C. felis , C. muris , C. tyzzeri and C. andersoni have been identified in pigs (De Felice et al., 2020; Němejc et al., 2013; Petersen et al., 2015; Pettersson et al., 2020; Wang et al., 2020). Cryptosporidium species distribution in infected pigs seems to follow an age‐related pattern, although no associations between species and clinical signs or intensity of oocyst shedding have been demonstrated (Němejc et al., 2013).…”