Abstract
Giardia duodenalis is an important zoonotic parasite that causes economic losses to animal husbandry and threatens public health. In the present study, a total of 1466 fresh fecal samples were collected from sheep (n = 797), goats (n = 561) and beef cattle (n = 108) in Southwest Inner Mongolia, China. Giardia duodenalis was initially screened via nested polymerase chain reaction (PCR) targeting the β-giardin (bg) gene, and bg-positive samples were subjected to PCR amplification targeting the glutamate dehydrogenase (gdh) and triose phosphate isomerase (tpi) genes. A total of 4.0% of samples (58/1466) were positive for G. duodenalis, with a prevalence of 3.4% in sheep, 3.7% in goats and 5.2% in beef cattle. Three G. duodenalis assemblages (A, B, and E) were identified, with E as the prevalent assemblage. Four and one novel assemblage E sequences were obtained for the gdh and tpi loci, respectively and four assemblage E multilocus genotypes (MLG) were obtained. This study demonstrates high genetic variations in G. duodenalis assemblage E, and provides baseline data for preventing and controlling G. duodenalis infection in livestock in Inner Mongolia.
Keywords: Giardia duodenalis, Molecular characterization, Ruminants, Inner Mongolia
Abstract
Giardia duodenalis est un parasite zoonotique important, qui cause des pertes économiques à l’élevage et menace la santé publique. Dans la présente étude, un total de 1466 échantillons fécaux frais ont été prélevés sur des moutons (n = 797), des chèvres (n = 561) et des bovins de boucherie (n = 108) dans le sud-ouest de la Mongolie intérieure, en Chine. Giardia duodenalis a été initialement criblé via une réaction en chaîne par polymérase imbriquée ciblant le gène de la β-giardine (bg), et les échantillons bg-positifs ont été soumis à une amplification par PCR ciblant les gènes de la glutamate déshydrogénase (gdh) et de la triose phosphate isomérase (tpi). Au total, 4,0 % (58/1466) des échantillons étaient positifs pour G. duodenalis, avec une prévalence de 3,4 % chez les ovins, 3,7 % chez les caprins et 5,2 % chez les bovins. Trois assemblages de G. duodenalis (A, B et E) ont été identifiés, E étant l’assemblage prédominant. Respectivement quatre et une nouvelle séquences de l’assemblage E ont été obtenues dans les loci gdh et tpi, et quatre génotypes multilocus (MLG) de l’assemblage E ont été mis en évidence. Cette étude montre des variations génétiques élevées dans l’assemblage E de G. duodenalis et fournit des données de base pour prévenir et contrôler l’infection à G. duodenalis chez le bétail en Mongolie intérieure.
Introduction
Giardia duodenalis (synonym G. intestinalis and G. lamblia) is one of the most common intestinal pathogens in both humans and animals [25]. The symptoms of Giardiasis are diarrhea, abdominal pain and weight loss [1, 10, 30]. Livestock has been reported as a common reservoir of G. duodenalis, with an individual prevalence ranging from 0 to 73% [9, 17]. Although G. duodenalis infection is commonly asymptomatic, many reports of Giardiasis in calves, goats and lambs show decreased weight gain and impairment in feed efficiency, causing significant economic losses to the farm [1, 12, 29].
Giardia duodenalis has a complex assemblage with a classification that is based on sequence analyses. The genetic locus of small subunit rRNA (SSU rRNA) [2], beta-giardin (bg) [16], glutamate dehydrogenase (gdh) [4], and triose phosphate isomerase (tpi) is commonly used for PCR to characterize G. duodenalis [28]. Multilocus genotype (MLG) analysis based on bg, gdh, and tpi is widely used for identifying genetic variations in G. duodenalis [6, 8].
Thus far, eight assemblages (A–H) of G. duodenalis have been identified based on genetic analysis and specific hosts [19]. Assemblages A and B have low host specificity and can infect humans as well as several other vertebrates; there are three assemblage A subgroups (AI, AII and AIII) and subgroup AIII has only been found in wildlife. However, assemblages C–H seem to be host-adapted; of these, assemblages C and D are mainly found in canines, assemblage E in artiodactyls, assemblage F in felines, assemblage G in rodents, and assemblage H in seals and some aquatic mammals [5, 24]. Previous studies have shown that artiodactyls are predominately infected by assemblages A and E, and a few reports have described assemblage B in artiodactyls [32, 33].
Giardia duodenalis is widely distributed in sheep, goats, and cattle (including dairy cattle, beef cattle, and yaks) in China [17]. Inner Mongolia is the third largest province in China, and animal husbandry makes an important economic contribution to the area. In Inner Mongolia, there are only three reports of G. duodenalis, in sheep and Bactrian camels [6, 34, 37]. More investigations are needed to facilitate improved interventions and minimize the burden of G. duodenalis in livestock. The objectives of this study were to further investigate and expand the prevalence information on G. duodenalis in ruminants in Southwest Inner Mongolia, China.
Materials and methods
Ethical standards
Following the Chinese Laboratory Animal Administration Act of 1988, the research protocol was reviewed and approved by the Research Ethics Committee of Henan Agricultural University (Approval No. IRB-HENAU-20180914-01). Appropriate permission from farmers was obtained before collecting fecal samples, and no animals were harmed.
Sample collection
From October 2019 to July 2021, a total of 23 farms were chosen randomly in northwest Inner Mongolia, China (Fig. 1). A total of 1466 fresh fecal specimens were collected from sheep (n = 797), goats (n = 561), and beef cattle (n = 108), respectively (Table 1). Of these, 1083 were from more than 12-month-old livestock, and 383 were from 7–12 month-old livestock; 419 samples were collected in the summer, 289 in autumn and 758 in winter (Table 2). Fresh fecal samples were collected by rectal sampling from ruminants in pens, and samples were gathered from the top layer of feces when grazing livestock defecated on the ground to ensure that there was no contamination [27]. Samples were stored in clean bags and transported in foam containers under ice conditions. No abnormal fecal specimens were observed during sample collection.
Figure 1.
Location of the study area in Alxa League, Southwest Inner Mongolia, China. Sampling sites are marked by filled spots.
Table 1.
Sampling information and the occurrence of G. duodenalis in ruminants in Southwest Inner Mongolia, China.
| Administrative region | Sampling site | Sample number | Positive % (no. positive/no. sampled) | Animal Species | Feeding models |
|---|---|---|---|---|---|
| Alxa Left Banner (Inner Mongolia) | 1 | 20 | 10.0 (2/20) | Goat | Pastoral |
| 2 | 137 | 1.5 (2/137) | Sheep | Captive | |
| 3 | 30 | 0 | Goat | Pastoral | |
| 4 | 45 | 0 | Goat | Pastoral | |
| 5 | 57 | 0 | Goat | Pastoral | |
| 6 | 21 | 0 | Sheep | Pastoral | |
| 7 | 51 | 5.9 (3/51) | Goat | Pastoral | |
| 8 | 104 | 6.7 (7/104) | Sheep | Pastoral | |
| 9 | 22 | 27.3 (6/22) | Sheep | Captive | |
| 108 | 9.3 (10/108) | Beef cattle | Captive | ||
| 10 | 120 | 10.0 (12/120) | Goat | Pastoral | |
| 9 | 0 | Sheep | Pastoral | ||
| 11 | 158 | 0 | Sheep | Pastoral | |
| 12 | 35 | 11.4 (4/35) | Goat | Pastoral | |
| 10 | 0 | Sheep | Pastoral | ||
| 13 | 42 | 2.4 (1/42) | Goat | Pastoral | |
| 14 | 29 | 6.9 (2/29) | Sheep | Pastoral | |
| 15 | 0 | Goat | Pastoral | ||
| 15 | 22 | 0 | Goat | Pastoral | |
| 16 | 69 | 2.9 (2/69) | Sheep | Pastoral | |
| 17 | 15 | 0 | Goat | Pastoral | |
| 18 | 20 | 0 | Goat | Pastoral | |
| 19 | 118 | 0 | Sheep | Captive | |
| 20 | 20 | 0 | Sheep | Captive | |
| Alxa Right Banner (Inner Mongolia) | 21 | 21 | 0 | Sheep | Pastoral |
| 22 | 122 | 3.3 (4/122) | Sheep | Captive | |
| 23 | 46 | 6.5 (3/46) | Sheep | Captive | |
| Total | 1466 | 4.0 (58/1466) |
Table 2.
Prevalence of G. duodenalis under different conditions.
| Factors | Category | Positive % (no. positive/no. sampled) |
||
|---|---|---|---|---|
| Sheep | Goats | Beef cattle | ||
| Feeding model | Pastoral | 3.3 (11/332) | 3.7 (21/561) | 0 |
| Captive | 3.4 (16/465) | 0 | 9.3 (10/108) | |
| Age group | 6–12 months | 2.3 (7/306) | 1.6 (1/63) | 35.7 (5/14) |
| >12 months | 4.1 (20/491) | 4.0 (20/498) | 5.3 (5/94) | |
| Season | Summer | 2.0 (7/348) | 4.2 (3/71) | 0 |
| Autumn | 1.5 (2/137) | 2.0 (3/152) | 0 | |
| Winter | 5.8 (18/312) | 4.4 (15/338) | 9.3 (10/108) | |
Table 3.
Intra-assemblage substitutions in bg, gdh, and tpi sequences within G. duodenalis assemblage E.
| Sequence (no.) | Nucleotide positions |
GenBank ID | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| gdh | 51 | 72 | 105 | 166 | 210 | 215 | 282 | 327 | 455 | |
| E9 (1) | C | C | C | A | G | T | T | T | G | KT698969 |
| E45 (4) | – | – | – | – | – | – | – | – | A | KC960648 |
| E46 (2) | – | – | – | – | – | – | G | – | – | MK442907 |
| E47 (1) | – | – | T | – | – | – | – | – | G | KY655475 |
| E48 (4) | – | – | – | – | – | – | G | – | G | MK442905 |
| E49a (1) | – | – | – | G | – | G | – | – | – | OL456202 |
| E50a (1) | – | – | – | – | – | – | – | G | – | OL456203 |
| E51a (2) | – | – | – | – | A | – | – | – | – | OL456204 |
| E52a (1) | T | T | – | – | – | – | – | – | G | OL456206 |
| bg | 68 | 110 | 173 | 275 | 401 | 416 | ||||
| E1 (6) | C | C | A | C | G | C | MK610388 | |||
| E27 (1) | T | T | G | – | – | T | MK610379 | |||
| E35 (29) | – | – | – | – | – | T | MK610387 | |||
| E36 (16) | T | – | – | – | A | T | MT108433 | |||
| E37 (2) | T | – | – | – | – | T | MF671888 | |||
| E38 (1) | T | – | G | – | – | T | MT713328 | |||
| E39 (1) | T | – | – | – | – | – | MK610389 | |||
| E40 (1) | T | – | – | T | – | T | LC484286 | |||
| tpi | 37 | 58 | 91 | 95 | 145 | 316 | ||||
| E1 (1) | G | T | T | A | A | T | KY769102 | |||
| E3 (2) | – | – | – | G | – | – | KY769100 | |||
| E5 (1) | A | – | – | – | G | – | EF654686 | |||
| E32a(1) | – | C | G | A | – | C | OL456207 | |||
N-dash (–) indicates that the sequence is the same as the reference sequence.
Novel sequence.
Table 4.
Multilocus characterization of G. duodenalis isolates based on the beta-giardin (bg), glutamate dehydrogenase (gdh), and triose phosphate isomerase (tpi) genes in hosts.
| Serial number of samples | Host | Genotype or subtype |
MLGs (bg-gdh-tpi) | ||
|---|---|---|---|---|---|
| bg | gdh | tpi | |||
| 7 | Goat | E35 | E51 | – | – |
| 11 | Goat | E35 | E51 | – | – |
| 52 | Sheep | E1 | E45 | – | – |
| 60 | Sheep | E39 | E46 | – | – |
| 189 | Goat | E1 | E45 | – | – |
| 437 | Goat | E35 | – | – | – |
| 446 | Goat | E35 | E48 | – | – |
| 447 | Goat | E27 | E48 | E3 | MLG-E1 |
| 466 | Sheep | E35 | – | – | – |
| 484 | Sheep | E35 | – | – | – |
| 485 | Sheep | E35 | – | – | – |
| 488 | Sheep | E35 | – | – | – |
| 489 | Sheep | E35 | – | – | – |
| 491 | Sheep | E35 | – | – | – |
| 506 | Sheep | E35 | – | – | – |
| 561 | Sheep | E35 | – | – | – |
| 562 | Sheep | E35 | – | – | – |
| 563 | Sheep | E35 | – | – | – |
| 564 | Sheep | E35 | – | – | – |
| 573 | Sheep | E35 | E45 | – | – |
| 579 | Sheep | E35 | E49 | E1 | MLG-E2 |
| 580 | Sheep | E35 | – | – | – |
| 597 | Goat | E36 | – | – | – |
| 599 | Goat | E36 | – | – | – |
| 603 | Goat | E36 | – | – | – |
| 604 | Goat | E36 | – | – | – |
| 605 | Goat | E36 | – | – | – |
| 607 | Goat | E36 | – | – | – |
| 612 | Goat | E36 | – | – | – |
| 616 | Goat | E36 | – | – | – |
| 620 | Goat | E36 | – | – | – |
| 642 | Goat | E35 | – | E5 | – |
| 782 | Goat | E36 | – | – | – |
| 791 | Goat | E36 | – | B | Mixed |
| 793 | Goat | E36 | – | – | |
| 800 | Goat | E36 | – | – | |
| 836 | Goat | E36 | – | – | |
| 880 | Sheep | E35 | E48 | – | |
| 894 | Sheep | AI | – | – | |
| 1061 | Sheep | E36 | – | – | |
| 1062 | Sheep | E36 | – | – | |
| 1109 | Beef cattle | E38 | – | – | |
| 1137 | Beef cattle | E37 | E47 | E3 | MLG-E3 |
| 1139 | Beef cattle | E35 | E50 | – | |
| 1152 | Beef cattle | E35 | – | – | |
| 1154 | Beef cattle | E40 | – | – | |
| 1201 | Beef cattle | E1 | – | – | |
| 1202 | Beef cattle | E35 | – | – | |
| 1210 | Beef cattle | E1 | E9 | – | |
| 1212 | Beef cattle | E35 | E45 | – | |
| 1213 | Beef cattle | E37 | E46 | – | |
| 1375 | Sheep | E35 | E52 | E32 | MLG-E4 |
| 1430 | Sheep | E1 | – | – | |
| 1439 | Sheep | E35 | – | – | |
| 1441 | Sheep | E1 | – | – | |
| 1503 | Sheep | E35 | – | – | |
| 1532 | Sheep | E35 | E48 | – | |
| 1537 | Sheep | E35 | – | – | |
N-dash (–) indicates that no data were obtained.
DNA extraction and PCR amplification
The genomic DNA of each fecal sample was extracted using a commercial E.Z.N.A Stool DNA kit (Omega Bio-Tek Inc., Norcross, GA, USA), strictly following the specifications of the manufacturer. All the extracted DNA samples were stored at −20 °C.
Giardia duodenalis was initially screened via nested PCR amplification targeting the bg [7] gene, and then studied by a MLG analysis based on the gdh [4] and tpi [28] genes. After amplification, the DNA fragments were separated by agarose gel electrophoresis (1% agarose) stained with DNA Green (TIANDZ, Beijing, China) and observed using a Tanon 3500 Gel Image Analysis System (TANON, Shanghai, China). Amplified samples with the target band were selected as positive PCR production (bg is 511 bp, gdh is 520 bp, tpi is 530 bp).
Sequence analysis
Positive PCR amplicons with the target band were sequenced by SinoGenoMax (Beijing, China). Bidirectional sequencing was chosen to ensure the veracity of sequences. The sequences in this study aligned with reference sequences from GenBank using ClustalX 2.1 (http://www.clustal.org/). Samples were amplified at the bg, gdh and tpi loci to form MLGs to further reveal genetic diversity. The same nomenclature system as in previous reports was used in naming G. duodenalis assemblage E subtypes at each genetic locus. Undesignated subtype sequences previously published and novel subtype sequences identified in this study were named accordingly as E36–E40 at the bg locus, E45–E52 at the gdh locus, and E32 at the tpi locus [6, 7, 22] (Table 3).
Phylogenetic analysis was conducted using the maximum composite likelihood model, and bootstrap values were calculated by analyzing 1000 replicates and the other chosen default parameters in MEGA 7.0 software (http://www.megasoftware.net/).
Statistical analysis
A Chi-square test was performed, and 95% confidence intervals (CIs) were calculated using Crosstab in SPSS, version 24.0 (SPSS Inc., Chicago, IL, USA). A Pearson’s chi-squared test was used for comparisons between two groups, and p < 0.05 was considered statistically significant.
Nucleotide sequence accession numbers
The representative nucleotide sequences were submitted to the GenBank at the National Center for Biotechnology Information under accession numbers: OL456202, OL456203, OL456204 and OL456206 for the gdh gene, and OL456207 for the tpi gene.
Results
Occurrence of G. duodenalis in ruminants
A total of 58 (4.0%) G. duodenalis-positive fecal samples were identified by the nested PCR analysis based on the bg gene, with 3.4% (27/797) in sheep, 3.7% (21/561) in goats and 9.2% (10/108) in beef cattle. The infection rates in winter were significantly higher than in summer (p = 0.009, 95% CI: 0.202–0.818) and autumn (p = 0.006, 95% CI: 0.115–0.747).
Among the positive samples in sheep, 11 were from pastoral sheep and 16 were from captive sheep, and there was no significant difference in G. duodenalis infection between pastoral and captive sheep (p = 0.922, 95% CI: 0.440–2.100). The G. duodenalis infection rate was significantly different between different age groups of beef cattle (p < 0.001, 95% CI: 2.399–40.770). There were no significant differences in prevalence of G. duodenalis among different age groups of sheep (p = 0.108, 95% CI: 0.211–1.183) and goats (p = 0.222, 95% CI: 0.041–2.292) (Table 2).
Sequence and subtype analysis
A total of 58 bg sequences, 17 gdh sequences and 6 tpi sequences were obtained. Three kinds of assemblages were identified, including G. duodenalis assemblage A (n = 1), assemblage E (n = 56), and a mix of assemblages B and E (n = 1). Additionally, 4 samples were simultaneously amplified at all three intra-assemblage variation genetic loci (bg, gdh, tpi), forming 4 novel assemblage E MLGs (MLG-E1 to MLG-E4). The MLG-E2 and MLG-E4 sequences were obtained from sheep; the MLG-E1 sequences were obtained from goats, and the MLG-E3 sequences were obtained from beef cattle (Table 4).
Phylogenetic analysis
Based on the G. duodenalis bg-sequences, gdh-sequences and tpi-sequences, three phylogenetic trees were constructed to evaluate the genetic relationships of the G. duodenalis isolates. The results showed that G. duodenalis isolates from this study were clustered within the G. duodenalis assemblage E, and high genetic diversity was observed in the assemblage E subtypes (Figs. 2–4).
Figure 2.
Phylogenetic relationships of beta-giardin (bg) nucleotide sequences of G. duodenalis assemblages (A–G) and assemblage E subtypes, using the maximum composite likelihood model. Percent bootstrap values greater than 50% from 1000 replicates are shown next to the branches. The hollow triangles represent published isolates in this study.
Figure 4.
Phylogenetic relationships of triose phosphate isomerase (tpi) nucleotide sequences of G. duodenalis assemblages (A–G) and assemblage E subtypes, using the maximum composite likelihood model. Percent bootstrap values greater than 50% from 1000 replicates are shown next to the branches. The black triangles and hollow triangles represent published and novel isolates in this study.
Figure 3.
Phylogenetic relationships of glutamate dehydrogenase (gdh) nucleotide sequences of G. duodenalis assemblages (A–H) and assemblage E subtypes, using the maximum composite likelihood model. Percent bootstrap values greater than 50% from 1000 replicates are shown next to the branches. The black triangles and hollow triangles represent published and novel isolates in this study.
Discussion
This study presented G. duodenalis distribution in sheep, goats and beef cattle in Southwest Inner Mongolia. Giardia duodenalis in this study were detected by bg locus, and the total infection rate was 4.0%. In previous reports using the same method, there was a higher G. duodenalis infection rate in Tan sheep in northwestern China (10.95%) [22], cattle in Turkey (30.2%) [21], beef cattle in Scotland (10.1%) [3], Tibetan sheep (13.1%) and yaks (10.4%) in Qinghai province, China [14]. However, there was a similar infection rate in healthy adult domestic ruminants in central Iran (5.2%) [15], and sheep in Inner Mongolia, China (4.3%) [34], which were detected by the tpi locus. Based on the SSU rRNA gene, G. duodenalis was detected in livestock in the United Kingdom (34.3%) and sheep in Inner Mongolia, China (64.1%) [6, 18].
The SSU rRNA, bg and tpi loci have frequently been used to detect G. duodenalis. In this study, G. duodenalis in fecal samples was detected by nested-PCR of the bg locus, and only 29.3% and 10.3% bg-positive samples were amplified based on the gdh and tpi loci, which were similar to previous studies [3, 14, 21, 22]. The difference between the G. duodenalis infection rate in this study and that in other studies which used the bg locus may be partially attributed to the state of feces, age group, sample size, detection methods and climate.
All samples in this study were collected from non-diarrhea livestock in the age groups of seven months and older. The G. duodenalis infection rate was significantly different between different age groups of beef cattle (p < 0.001). Previous studies showed a higher prevalence in sheep, goats and cattle before weaning, and G. duodenalis infection is inversely associated with animal age [8, 17, 35]. The G. duodenalis infection rates in winter were significantly higher than in summer and autumn (p < 0.01), and the same phenomenon was reported in dairy calves in Norway and pigs in Denmark [13, 23]; however, the season was not significantly associated with giardiasis infection of yaks in Qinghai, China [26].
Giardia duodenalis assemblages A, B and E were identified, and G. duodenalis assemblage E was the dominant assemblage found in this study, which is consistent with previous reports [6, 7, 25]. Giardia duodenalis assemblages A and E were identified as the two most common assemblages in sheep, goats and cattle, with assemblage B reported occasionally [11, 25, 35, 36]. A few studies have reported assemblage C and assemblage D in livestock, but it is unknown whether this was an actual infection or mechanical transmission [15, 18, 20, 31]. The G. duodenalis assemblages in this study were also reported in humans, companion animals and wildlife [24], and more research is needed to verify the potential impact on public health safety.
High genetic diversity was observed in the assemblage E subtypes. At the bg locus, eight published assemblage E subtypes were found in sheep, goats and beef cattle, and the bg-positive samples were analyzed by the multilocus genotyping tool with high resolution (gdh and tpi) to further reveal the genetic variations in G. duodenalis. A total of four and one novel assemblage E subtypes were found at the gdh and tpi loci, respectively and the analysis yielded four novel MLGs of assemblage E. A high degree of genetic diversity in G. duodenalis assemblage E has been reported in livestock, which was probably a cause of the high occurrence rate of G. duodenalis in Tibetan sheep and yaks [14, 32]. In this study, the same G. duodenalis assemblage E subtypes (E1, E35 at the bg locus and E45 at the gdh locus) were found in sheep, goats and beef cattle simultaneously, which may indicate a potential occurrence of cross-species transmission. Cross-species transmission of G. duodenalis assemblage E subtypes was also found in Tibetan sheep and yaks [14], black-boned sheep and black-boned goats [7].
Conclusion
The results of this study show that G. duodenalis is a common parasite in sheep, goats and beef cattle in Inner Mongolia, and the infection rate is related to the season, and age of beef cattle. Based on molecular analysis, three G. duodenalis assemblages (A, B and E) were found and assemblage E was predominant. Novel subtypes found in this study show further genetic diversity of G. duodenalis assemblage E. This study provides baseline data for preventing and controlling G. duodenalis infection in livestock.
Acknowledgments
This work was partially supported by the National Key Research and Development Program of China (2019YFC1605700), the Leading Talents of Thousand Talents Program of Central China (19CZ0122), the National Natural Science Foundation of China (32102689), and the Outstanding Talents of Henan Agricultural University (30501055).
Cite this article as: Fu Y, Dong H, Bian X, Qin Z, Han H, Lang J, Zhang J, Zhao G, Li J & Zhang L. 2022. Molecular characterizations of Giardia duodenalis based on multilocus genotyping in sheep, goats, and beef cattle in Southwest Inner Mongolia, China. Parasite 29, 33.
Footnotes
Edited by: Emmanuel Liénard
Conflict of interest
The authors declare that there are no conflicts of interest.
References
- 1.Aloisio F, Filippini G, Antenucci P, Lepri E, Pezzotti G, Caccio SM, Pozio E. 2006. Severe weight loss in lambs infected with Giardia duodenalis assemblage B. Veterinary Parasitology, 142(1–2), 154–158. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Appelbee AJ, Frederick LM, Heitman TL, Olson ME. 2003. Prevalence and genotyping of Giardia duodenalis from beef calves in Alberta. Canada. Veterinary Parasitology, 112(4), 289–294. [DOI] [PubMed] [Google Scholar]
- 3.Bartley PM, Roehe BK, Thomson S, Shaw HJ, Peto F, Innes EA, Katzer F. 2019. Detection of potentially human infectious assemblages of Giardia duodenalis in fecal samples from beef and dairy cattle in Scotland. Parasitology, 146(9), 1123–1130. [DOI] [PubMed] [Google Scholar]
- 4.Cacciò SM, Beck R, Lalle M, Marinculic A, Pozio E. 2008. Multilocus genotyping of Giardia duodenalis reveals striking differences between assemblages A and B. International Journal for Parasitology, 38(13), 1523–1531. [DOI] [PubMed] [Google Scholar]
- 5.Caccio SM, Lalle M, Svard SG. 2018. Host specificity in the Giardia duodenalis species complex. Infection, Genetics and Evolution, 66, 335–345. [DOI] [PubMed] [Google Scholar]
- 6.Cao L, Han K, Wang L, Hasi S, Yu F, Cui Z, Hai Y, Zhai X, Zhang L. 2020. Genetic characteristics of Giardia duodenalis from sheep in Inner Mongolia, China. Parasite, 27, 60. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Chen D, Zou Y, Li Z, Wang SS, Xie SC, Shi LQ, Zou FC, Yang JF, Zhao GH, Zhu XQ. 2019. Occurrence and multilocus genotyping of Giardia duodenalis in black-boned sheep and goats in southwestern China. Parasites & Vectors, 12(1), 102. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Cui Z, Wang L, Cao L, Sun M, Liang N, Wang H, Chang Y, Lin X, Yu L, Wang R, Zhang S, Ning C, Zhang L. 2018. Genetic characteristics and geographic segregation of Giardia duodenalis in dairy cattle from Guangdong Province, southern China. Infection, Genetics and Evolution, 66, 95–100. [DOI] [PubMed] [Google Scholar]
- 9.Delling C, Daugschies A. 2022. Literature Review: Coinfection in young ruminant livestock – Cryptosporidium spp. and its companions. Pathogens, 11(1), 103. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Einarsson E, Ma’ayeh S, Svard SG. 2016. An up-date on Giardia and giardiasis. Current Opinion in Microbiology, 34, 47–52. [DOI] [PubMed] [Google Scholar]
- 11.Feng Y, Xiao L. 2011. Zoonotic potential and molecular epidemiology of Giardia species and giardiasis. Clinical Microbiology Reviews, 24(1), 110–140. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Geurden T, Vanderstichel R, Pohle H, Ehsan A, von Samson-Himmelstjerna G, Morgan ER, Camuset P, Capelli G, Vercruysse J, Claerebout E. 2012. A multicentre prevalence study in Europe on Giardia duodenalis in calves, with molecular identification and risk factor analysis. Veterinary Parasitology, 190(3–4), 383–390. [DOI] [PubMed] [Google Scholar]
- 13.Hamnes IS, Gjerde B, Robertson L. 2006. Prevalence of Giardia and Cryptosporidium in dairy calves in three areas of Norway. Veterinary Parasitology, 140(3–4), 204–216. [DOI] [PubMed] [Google Scholar]
- 14.Jin Y, Fei J, Cai J, Wang X, Li N, Guo Y, Feng Y, Xiao L. 2017. Multilocus genotyping of Giardia duodenalis in Tibetan sheep and yaks in Qinghai, China. Veterinary Parasitology, 247, 70–76. [DOI] [PubMed] [Google Scholar]
- 15.Kiani-Salmi N, Fattahi-Bafghi A, Astani A, Sazmand A, Zahedi A, Firoozi Z, Ebrahimi B, Dehghani-Tafti A, Ryan U, Akrami-Mohajeri F. 2019. Molecular typing of Giardia duodenalis in cattle, sheep and goats in an arid area of central Iran. Infection, Genetics and Evolution, 75, 104021. [DOI] [PubMed] [Google Scholar]
- 16.Lalle M, Pozio E, Capelli G, Bruschi F, Crotti D, Cacciò SM. 2005. Genetic heterogeneity at the beta-giardin locus among human and animal isolates of Giardia duodenalis and identification of potentially zoonotic subgenotypes. International Journal for Parasitology, 35(2), 207–213. [DOI] [PubMed] [Google Scholar]
- 17.Li J, Wang H, Wang R, Zhang L. 2017. Giardia duodenalis infections in humans and other animals in China. Frontiers in Microbiology, 8, 2004. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Minetti C, Taweenan W, Hogg R, Featherstone C, Randle N, Latham SM, Wastling JM. 2014. Occurrence and diversity of Giardia duodenalis assemblages in livestock in the UK. Transboundary and Emerging Diseases, 61(6), e60–67. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Monis PT, Caccio SM, Thompson RC. 2009. Variation in Giardia: towards a taxonomic revision of the genus. Trends in Parasitology, 25(2), 93–100. [DOI] [PubMed] [Google Scholar]
- 20.Ng J, Yang R, Whiffin V, Cox P, Ryan U. 2011. Identification of zoonotic Cryptosporidium and Giardia genotypes infecting animals in Sydney’s water catchments. Experimental Parasitology, 128(2), 138–144. [DOI] [PubMed] [Google Scholar]
- 21.Onder Z, Simsek E, Duzlu O, Yetismis G, Ciloglu A, Okur M, Kokcu ND, Inci A, Yildirim A. 2020. Molecular prevalence and genotyping of Giardia duodenalis in cattle in Central Anatolia Region of Turkey. Parasitology Research, 119(9), 2927–2934. [DOI] [PubMed] [Google Scholar]
- 22.Peng JJ, Zou Y, Li ZX, Liang QL, Song HY, Li TS, Ma YY, Zhu XQ, Zhou DH. 2020. Prevalence and multilocus genotyping of Giardia duodenalis in Tan sheep (Ovis aries) in northwestern China. Parasitology International, 77, 102126. [DOI] [PubMed] [Google Scholar]
- 23.Petersen HH, Jianmin W, Katakam KK, Mejer H, Thamsborg SM, Dalsgaard A, Olsen A, Enemark HL. 2015. Cryptosporidium and Giardia in Danish organic pig farms: Seasonal and age-related variation in prevalence, infection intensity and species/genotypes. Veterinary Parasitology, 214(1–2), 29–39. [DOI] [PubMed] [Google Scholar]
- 24.Ryan UM, Feng Y, Fayer R, Xiao L. 2021. Taxonomy and molecular epidemiology of Cryptosporidium and Giardia - a 50 year perspective (1971–2021). International Journal for Parasitology, 51(13–14), 1099–1119. [DOI] [PubMed] [Google Scholar]
- 25.Santin M. 2020. Cryptosporidium and Giardia in ruminants. Veterinary clinics of North America. Food Animal Practice, 36(1), 223–238. [DOI] [PubMed] [Google Scholar]
- 26.Song JK, Wang D, Ren M, Yang F, Wang PX, Zou M, Zhao GH, Lin Q. 2021. Seasonal prevalence and novel multilocus genotypes of Giardia duodenalis in Yaks (Bos grunniens) in Qinghai Province, Western China. Iranian Journal of Parasitology, 16(4), 548–554. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Song Y, Li W, Liu H, Zhong Z, Luo Y, Wei Y, Fu W, Ren Z, Zhou Z, Deng L, Cheng J, Peng G. 2018. First report of Giardia duodenalis and Enterocytozoon bieneusi in forest musk deer (Moschus berezovskii) in China. Parasites & Vectors, 11(1), 204. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Sulaiman IM, Fayer R, Bern C, Gilman RH, Trout JM, Schantz PM, Das P, Lal AA, Xiao L. 2003. Triosephosphate isomerase gene characterization and potential zoonotic transmission of Giardia duodenalis. Emerging Infectious Diseases, 9(11), 1444–1452. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 29.Sweeny JP, Ryan UM, Robertson ID, Jacobson C. 2011. Cryptosporidium and Giardia associated with reduced lamb carcase productivity. Veterinary Parasitology, 182(2–4), 127–139. [DOI] [PubMed] [Google Scholar]
- 30.Thompson RC, Palmer CS, O’Handley R. 2008. The public health and clinical significance of Giardia and Cryptosporidium in domestic animals. Veterinary Journal, 177(1), 18–25. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31.Utaaker KS, Myhr N, Bajwa RS, Joshi H, Kumar A, Robertson LJ. 2017. Goats in the city: prevalence of Giardia duodenalis and Cryptosporidium spp. in extensively reared goats in northern India. Acta Veterinaria Scandinavica, 59(1), 86. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 32.Wang H, Qi M, Zhang K, Li J, Huang J, Ning C, Zhang L. 2016. Prevalence and genotyping of Giardia duodenalis isolated from sheep in Henan Province, central China. Infection, Genetics and Evolution, 39, 330–335. [DOI] [PubMed] [Google Scholar]
- 33.Wang H, Zhao G, Chen G, Jian F, Zhang S, Feng C, Wang R, Zhu J, Dong H, Hua J, Wang M, Zhang L. 2014. Multilocus genotyping of Giardia duodenalis in dairy cattle in Henan, China. PLoS One, 9(6), e100453. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 34.Ye J, Xiao L, Wang Y, Guo Y, Roellig DM, Feng Y. 2015. Dominance of Giardia duodenalis assemblage A and Enterocytozoon bieneusi genotype BEB6 in sheep in Inner Mongolia, China. Veterinary Parasitology, 210(3–4), 235–239. [DOI] [PubMed] [Google Scholar]
- 35.Yin YL, Zhang HJ, Yuan YJ, Tang H, Chen D, Jing S, Wu HX, Wang SS, Zhao GH. 2018. Prevalence and multi-locus genotyping of Giardia duodenalis from goats in Shaanxi province, northwestern China. Acta Tropica, 182, 202–206. [DOI] [PubMed] [Google Scholar]
- 36.Zhang W, Zhang X, Wang R, Liu A, Shen Y, Ling H, Cao J, Yang F, Zhang X, Zhang L. 2012. Genetic characterizations of Giardia duodenalis in sheep and goats in Heilongjiang Province, China and possibility of zoonotic transmission. PLoS Neglected Tropical Diseases, 6(9), e1826. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 37.Zhao SS, Li YH, Zhang Y, Zhou Q, Jing B, Xu CY, Zhang LX, Song JK, Qi M, Zhao GH. 2020. Multilocus genotyping of Giardia duodenalis in Bactrian camels (Camelus bactrianus) in China. Parasitology Research, 119(11), 3873–3880. [DOI] [PubMed] [Google Scholar]