Longitudinal investigation of protozoan parasites in meat lamb farms in southern Western Australia

Abstract

14In this study, 96 faecal samples were collected from pregnant Merino ewes, at two broad-15 acre, commercial sheep farms in southern Western Australia, on two separate occasions 16 (16 and 2 weeks prior to lambing). Following lambing, 111 (Farm A) and 124 (Farm B) 17 female crossbred lambs (2 -6 weeks old), were individually identified using ear tags (a 18 numbered tag and a radio-frequency tag). A total of 1,155 faecal samples were collected 19 only from these individually identified lambs on five separate sampling occasions. All 20 samples were screened using PCR to detect Cryptosporidium (18S rRNA and actin loci) 21and Giardia duodenalis (glutamate dehydrogenase and triosephosphate isomerise loci). 22The overall prevalences (lambs positive for a parasite on at least one of the five 23 samplings) at Farm A and B were 81.3% and 71.4%, respectively for Cryptosporidium and 24 similarly 67.3% and 60.5% for Giardia, respectively. Cryptosporidium and Giardia 25 prevalences at individual samplings ranged between 18.5 -42.6% in lambs and were 26 <10% in the ewes. Cryptosporidium xiaoi was the most prevalent species detected at all 27 five samplings and was also isolated from lamb dam water on Farm B. Cryptosporidium 28 ubiquitum was most commonly detected in younger lambs and C. parvum was detected in 29 lambs at all five samplings, typically in older lambs and as part of a mixed species infection 30 with C. xiaoi. A novel, possibly new genotype (sheep genotype I), was identified in six 31Cryptosporidium isolates from Farm B. Giardia duodenalis assemblage E was the most 32 common genotype detected at all five samplings, with greater proportions of assemblage A 33 and mixed assemblage A and E infections identified in older lambs. This longitudinal study 34 identified high overall prevalences of Cryptosporidium and Giardia in lambs grazed 35 extensively on pastures, whilst reinforcing that sampling a random selection of animals 36 from a flock/herd on one occasion (point prevalence), underestimates the overall 37 prevalence of these parasites in the flock/herd across an extended time period. Based on 38 these findings, grazing lambs were identified as a low risk source of zoonotic 39Page 3 of 36 Cryptosporidium and Giardia species/genotypes, with these protozoa detected at all five 40 samplings in some lambs, indicating that these individuals were either unable to clear the 41 naturally acquired protozoan infections or were repeatedly re-infected from their 42 environment or other flock members. 43

Cryptosporidiumspecies in Australian wildlife and domestic animals

“…Ryan et al 2005;Yang et al 2009, Wang et al 2010bSweeny et al 2011b). In Australia, reported prevalences for ewes in Western Australia ranged from 6·3-8·3% (Sweeny et al 2011b) and for lambs from 9·3-56·3% on different properties (Ryan et al 2005;Yang et al 2009;Sweeny et al 2011a, b). A total of 9 species/genotypes of Cryptosporidium have been reported in sheep and lambs in Australia; C. parvum, C. hominis, C. xiaoi, C. bovis, C. ubiquitum, sheep genotype I, C. andersoni, pig genotype II, C. fayeri and C. suis and sheep genotype I (Ryan et al 2005;Giles et al 2009;Yang et al 2009;Robertson, 2009;Sweeny et al 2011a, b), with C. xiaoi and C. ubiquitum most common although Yang et al (2009) found high proportions of C. parvum isolates in pre-weaned sheep in Western Australia when a C. parvum-specific PCR was used.…”

Greater intensity and frequency of Cryptosporidium and Giardia oocyst shedding beyond the neonatal period is associated with reductions in growth, carcase weight and dressing efficiency in sheep

“…Cryptosporidium (including C. parvum) and Giardia were identified in all eight flocks included in the present study, and have been widely reported in sheep in Australia (Ryan et al, 2005;Yang et al, 2009;Sweeny et al, 2011;Sweeny et al, 2012a;Yang et al, 2014a;Yang et al, 2014b) and worldwide (Xiao 2010). Therefore the observations of reduced HSCW and dressing % associated with these organisms have important implications for sheep meat industries worldwide.…”

“…DNA from samples from Western Australia was previously analysed using different primers as described in Sweeny et al (2011).…”

“…The prevalence of Cryptosporidium and Giardia in sheep varies between studies conducted worldwide but for Cryptosporidium generally ranges from 15%-27% in lambs (Santín et al, 2007;Robertson et al, 2010;Ye et al, 2013;Yang et al, 2014a) and for Giardia generally ranges from 1.5-55.6% (Feng and Xiao, 2011). The genus Cryptosporidium consists of 26 valid species and more than 50 genotypes with C. xiaoi, C. ubiquitum and C. parvum most frequently identified in sheep (Ryan et al, 2005;Santín et al, 2007;Soltane et al, 2007, Geurden et al, 2008, Mueller-Doblies et al, 2008, Quílez et al, 2008, Fayer and Santín, 2009Giles et al, 2009;Paoletti et al, 2009, Yang et al, 2009Díaz et al, 2010;Robertson et al, 2010;Wang et al, 2010;Fiuza et al, 2011;Shen et al, 2011;Sweeny et al, 2011;Sweeny et al, 2012a;Cacciò et al, 2013;Connelly et al, 2013;Imre et al, 2013;Yang et al, 2014a). Giardia duodenalis is the species infecting mammals and consists of eight major genetic groups (assemblages), two of which (A and B) are found in both humans and animals (including sheep) and are considered zoonotic, whereas the remaining six (C-H) are hostspecific and do not infect humans (Feng and Xiao, 2011;Ryan and Caccio, 2013).…”

Criptosporidiose em animais domésticos: aspectos epidemiológicos

“…Distribuída no mundo todo, está última espécie foi isolada em seres humanos (ONG et al, 2002;XIAO, 2010), mas tem sido observada em cordeiros com menos de doze meses de idade (SANTÍN; FAYER, 2007;YANG et al, 2009;FURUSETH HANSEN, 2010;WANG et al, 2010;SWEENY et al, 2011). Subtipagem de sete isolados de C. parvum, baseados na análise da sequência do gene GP60, revelou a presença de cinco diferentes subtipos (IIaA17G1R1, IIaA16G1R1, IIdA20G1, IIdA24G1 and IIdA22G2R1) pertencentes a duas famílias de subtipos zoonóticos (IIa and IId).…”