Open Access

Prevalence and multilocus genotyping of Giardia duodenalis in dairy calves in Xinjiang, Northwestern China

Parasites & Vectors20169:546

https://doi.org/10.1186/s13071-016-1828-3

Received: 15 July 2016

Accepted: 2 October 2016

Published: 13 October 2016

Abstract

Background

Giardia duodenalis is an important protozoan parasite. It is an established zoonotic pathogen and dairy calves have been implicated as one of the most important sources of human infection. This study was conducted to assess the prevalence and multilocus genotyping of G. duodenalis in dairy calves in the Xinjiang Uyghur Autonomous Region, northwestern China.

Findings

A total of 514 fresh fecal samples were randomly collected from dairy calves in 15 farms in Xinjiang, 13.4 % (69/514) tested positive for G. duodenalis by polymerase chain reaction (PCR) detection of the small subunit ribosomal RNA (SSU rRNA) gene, with the prevalence being 9.7 % (23/237) and 16.6 % (46/277) in pre- and post-weaned calves, respectively. Sequence analysis of the SSU rRNA gene predominantly detected G. duodenalis assemblage E (92.8 %, 64/69), whereas assemblage A was identified in five samples (7.2 %, 5/69). All G. duodenalis-positive samples were assayed with PCR followed by sequencing at β-giardin (bg), glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi) genes, and 29, 37 and 33 sequences were obtained, respectively. The presence of mixed G. duodenalis assemblage A and E was detected in only one sample. Multilocus genotyping yielded 15 multilocus genotypes (MLGs), one new assemblage A MLG, and 14 assemblage E MLGs. All assemblage E MLGs identified here differed genetically from those of cattle from Henan Province, Central China.

Conclusions

Our data indicate that G. duodenalis is a common parasite in dairy calves in Xinjiang, China, and calves appear to be a reservoir of G. duodenalis that is infectious to humans. The differences in the distribution of G. duodenalis assemblage E MLGs from cattle were likely to be because of geographical segregation.

Keywords

Giardia duodenalis Prevalence Genotyping Dairy calves

Background

Giardia duodenalis (syns G. lamblia, G. intestinalis) is one of the most frequent enteroparasites worldwide with a broad host range that includes humans, livestock, companion animals and wildlife [1]. Giardia cysts commonly occur in the aquatic environment and transmission of Giardia cysts to humans occurs mainly through indirect routes such as contaminated surface water or foods or through direct contact with infected individuals [2]. Cattle are considered as a source of waterborne outbreaks of giardiosis in humans because of the reported high prevalence of G. duodenalis infection combined with the large output of feces, potentially leading to contamination of surface and ground water [3, 4].

Giardia duodenalis consists of at least eight genetically different assemblages, A–H, of which assemblages A and B infect both humans and other mammals, while the remaining assemblages (C–H) appear to be host-specific [5]. Surveys of dairy cattle worldwide have reported predominant prevalence of assemblage E, followed by the zoonotic assemblages A and B [1, 6]. Recently, feline-specific assemblage F was found in asymptomatic adult cattle in northern Spain [7]. Giardia duodenalis infections in adult dairy cattle are generally lower than in calves, but calves were more frequently infected with zoonotic assemblages A and B compared with assemblage E [811]. A study in New Zealand identified assemblages A and B in 40 G. duodenalis isolates from calves and from 30 humans living in the same region; the isolates were collected over a similar period, suggesting that calves posed a great risk of G. duodenalis infection to humans [12].

Little is known about the prevalence of G. duodenalis in calves in China, and current data on the assemblage distribution and multilocus genotyping of G. duodenalis in dairy calves remain unclear. In the present study, fecal samples from dairy calves were collected in the Xinjiang Uyghur Autonomous Region were analyzed for the presence of G. duodenalis using polymerase chain reaction (PCR) of the small subunit ribosomal RNA (SSU rRNA) gene. All G. duodenalis-positive samples were characterized for β-giardin (bg), glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi) genes to elucidate G. duodenalis genotypes.

Methods

Study area and sample collection

From August to September 2013, a total of 514 fecal samples consisting of 237 from pre-weaned calves (0–60 days) and 277 from post-weaned calves (61–150 days) were randomly collected from 15 intensively reared dairy cattle farms near the cities of Wujiaqu, Changji, Urumqi, Korla, Tacheng, Zhaosu and Aksu in Xinjiang Uyghur Autonomous Region (73°40'E–96°18'E, 34°25'N–48°10'N), northwestern China (Table 1). The farms are among the largest dairy farms aslo ranked among the top producing dairy farms in the region, consisting of 200–5,000 animals per farm. Before the sampling, we did not have data about the epidemiological situation of the farms. The farms were visited on a single occasion and the fecal samples were randomly collected from 20–30 % of the animals. The pre-weaned calves were bred in different calf hutch, respectively. The post-weaned calves were intensively reared in different stalls, with 10–30 calves per stall. At the time of fecal collection, no apparent diarrhea was seen in the herds. Fecal samples were collected directly from the rectum using disposable gloves and plastic containers. Fecal samples were maintained at 4 °C before DNA extraction.
Table 1

Prevalence of G. duodenalis and assemblages determined by sequence analysis of the SSU rRNA, bg, gdh and tpi genes

Farm

No. of samples

No. of positive for G. duodenalis (%) [95 % CI]

SSU rRNA gene (n)

bg (n)

gdh (n)

tpi (n)

WujiaquA

18

0

    

WujiaquB

31

1 (3.2) [0–7.6]

E (1)

 

E (1)

E (1)

WujiaquC

20

3 (15.0) [6.2–23.8]

E (2), A (1)

E (1), A (1)

A (1)

A (1)

Changji

33

1 (3.0) [0–7.2]

A (1)

  

A (1)

Urumqi

32

3 (9.4) [3.8–15.0]

E (3)

E (1)

E (1)

 

KorlaA

11

1 (9.1) [0–21.5]

E (1)

   

KorlaB

13

1 (7.7) [0–18.3]

E (1)

   

KorlaC

32

2 (6.3) [1.2–11.4]

E (1), A(1)

A (1)

E (1), A (1)

E (1), A (1)

KorlaD

33

2 (6.1) [1.1–11.1]

E (1), A(1)

   

Tacheng

8

0

    

Zhaosu

8

1 (12.5) [0–29.5]

A (1)

 

A (1)

A (1)

AksuA

48

9 (18.8) [14.0–23.6]

E (9)

E (8)

E (7)

E (6)

AksuB

58

7 (12.1) [8.3–15.9]

E (7)

E (2)

E (3)

E (2)

AksuC

70

17 (24.3) [20.5–28.1]

E (17)

E (8)

E (12)

E (11)

AksuD

99

21 (21.2) [18.3–24.1]

E (21)

E (7)

E (9)

E (7), A (1)

Total

514

69 (13.4) [12.6–14.2]

E (64), A (5)

E (27), A (2)

E (34), A (3)

E (28), A (5)

Abbreviations: CI 95 % confidence interval, A assemblage A, E assemblage E

DNA extraction and PCR amplification

Genomic DNA was extracted from all fecal samples using the E.Z.N.A.R® Stool DNA Kit (Omega Biotek, Norcross, GA, USA) according to the manufacturer’s instructions. For screening G. duodenalis, previously described nested PCR assays were used to amplify the SSU rRNA gene [13]. Because there is no variability in the SSU rRNA gene among G. duodenalis assemblages, we analyzed multilocus sequence polymorphisms based on β-giardin (bg) [14], glutamate dehydrogenase (gdh) [15] and triose phosphate isomerase (tpi) [16] genes to determine G. duodenalis subtypes. DNA from all G. duodenalis-positive samples were subjected to further PCR analysis of the bg, gdh and tpi genes according to previously described nested PCR protocols [1417].

Sequence analysis

PCR amplicons were sent to Beijing Nuosai Biological Engineering Biotechnology Company for bi-directional sequencing on an ABI PRISM™ 3730 XL DNA Analyzer using the BigDye Terminator v3.1 Cycle Sequencing Kit (Applied Biosystems, Foster City, CA, USA). Sequences were identified by alignment with reference sequences downloaded from GenBank using MEGA 5 software (http://www.megasoftware.net/). To study the relationship between different isolates in more detail, phylogenetic analyses were performed using a concatenated dataset of bg, gdh and tpi gene sequences with the multilocus genotypes (MLGs) of G. duodenalis. The reference MLGs of G. duodenalis in cattle from Henan Province, Central China originate from a previous study [17]. The nucleotide neighbor-joining phylogenetic trees were based on the Tamura-Nei model. The reliability of these trees was assessed by bootstrap analysis with 1,000 replicates. Nucleotide sequences obtained in this study have been deposited in the GenBank database under accession numbers KT369759–KT369788.

Statistical analysis

The Chi-square test was used to compare G. duodenalis infection rates between age groups. Differences were considered statistically significant when P < 0.05.

Results and discussion

Giardia duodenalis infections have been frequently reported in calves and the prevalence of G. duodenalis in fecal samples from calves has shown wide variation (0–100 %) [5, 8, 10, 13, 1727]. In the present study, 69 samples were positive for amplification of the SSU rRNA gene and the overall prevalence for G. duodenalis was 13.4 % (69/514) (Table 1). The overall prevalence was lower than that previously reported in Belgium (22 %, 110/499) [8], Australia (26.9 %, 98/364) [10], Norway (49 %, 679/1386) [21], and Europe (Germany, UK, France, and Italy; 45.4 %, 942/2072) [23], and higher than that in Germany (7.2 %, 112/1564) [25]. However, it is difficult to compare prevalence data, which are influenced by a range of factors, including the diagnostic method and study design, geographical conditions, age of animals, number of samples from each farm, total number of samples and sampling season.

There was a significant association of G. duodenalis infection with the age of animals. In the present study, the prevalence in post-weaned calves (16.6 %) was higher than the prevalence in pre-weaned calves (9.7 %) (Table 2). Chi-square testing showed that G. duodenalis prevalence was significantly different between the two age groups (χ 2 = 5.23, df = 1, P = 0.022). This is similar to reports from Canada [18], Norway [21], United States [19, 20] and Germany [25]. In contrast, other authors reported pre-weaned calves in Henan Province, Heilongjiang Province, Jilin Province, Liaoning Province, Shaanxi Province and Ningxia Hui Autonomous Region, China to have the highest prevalence [11, 17, 2628]. These differences may be the result of different diagnostic modalities or varying environmental, geographical, or management factors.
Table 2

Prevalence of Giardia duodenalis and distribution of assemblages by age

Age

No. of samples

No. of positive for G. duodenalis (%) [95 % CI]

SSU rRNA gene (n)

bg (n)

gdh (n)

tpi (n)

Pre-weaned

237

23 (9.7) [8.4–11.0]

E (20), A (3)

E (9), A (1)

E (10), A (2)

E (9), A (3)

Post-weaned

277

46 (16.6) [15.3–17.9]

E (44), A (2)

E (18), A (1)

E (24), A (1)

E (18), A (2)

Abbreviations: CI 95 % confidence interval, A assemblage A, E assemblage E

Sequence analyses of the amplified SSU rRNA gene fragments were successful for all 69 PCR-positive samples, five of which were G. duodenalis assemblage A (7.2 %, 5/69) and the rest were assemblage E (92.8 %, 64/69) (Table 1). The genetic diversity of these positive G. duodenalis isolates was determined by amplification and sequencing of the bg, gdh and tpi genes, with 29 bg, 37 gdh and 33 tpi gene sequences being obtained (Table 1). Only one isolate (XJ1680) was identified as assemblage E by its SSU rRNA gene sequence but as assemblage A by its tpi gene sequence. These findings are similar to those in previous reports of calves from Canada [9], Australia [10], China [17, 26, 27], United States [19, 20, 22], Belgium [23] and Germany [29]. In China, G. duodenalis assemblage B was also found in calves from Ningxia Hui Autonomous Region [11] and Heilongjiang Province [28].

A comparison of the G. duodenalis assemblages between the age groups is presented in Table 2. Both assemblages, A and E, of G. duodenalis were detected in pre- and post-weaned calves in the present study, which is consistent with other studies in Henan and Shaanxi Province, China [17, 27], United States [19, 20] and Europe [23]. However, there was a higher prevalence of assemblage A in pre-weaned calves than was observed in this study. While assemblages B and E of G. duodenalis were detected in pre-weaned calves, only assemblage E was detected in post-weaned calves in Ningxia Hui Autonomous Region, China [11].

Based on multilocus genotyping, the MLG model was used to better understand the characteristics of G. duodenalis in humans and animals from different geographic regions, which is helpful for unveiling zoonotic potential and dynamic transmission [2, 30]. In the present study, of the 29 isolates successfully sequenced for bg gene, two were identified as one assemblage A sequence, while 27 were identified as seven assemblage E sequences (Table 3). For the gdh gene, of the 37 G. duodenalis isolates successfully sequenced, three were identified as one assemblage A sequence, while 34 were identified as 11 assemblage E sequences (Table 3). For the tpi gene, of the 33 G. duodenalis isolates successfully sequenced, five were identified as two assemblage A sequences, while 28 were identified as eight assemblage E sequences (Table 3). All three genes were successfully amplified and sequenced from 17 isolates, one or two genes were amplified from 31 isolates, while the remaining 21 samples were repeatedly negative (Table 3). The 17 isolates that were successfully genotyped at all three genes formed one assemblage A MLG and 14 different assemblage E MLGs (Table 3). In the present study, one assemblage A MLG from two calf isolates was identified as a novel MLG A (Fig. 1). Whether this MLG A has zoonotic potential requires systematic molecular epidemiological investigations in humans and animals. For assemblage E, phylogenetic analysis showed all assemblage E MLGs clustered broadly with previously reported cattle isolates from Henan Province, Central China (Fig. 2). Meanwhile, of the 22 assemblage E MLGs were detected in dairy calves and Qinchuan calves in Shaanxi Province, China, none of MLGs was identical to the results in Henan Province [17, 27]. These findings suggest that there might be geographical distribution differentiation among isolates.
Table 3

Multilocus characterization of Giardia duodenalis isolates based on bg, gdh and tpi genes

Calf ID

Genotype (GenBank accession no.)

MLG type (n)

bg

gdh

tpi

XJ214, XJ646

A (KT369769)

A (KT369777)

A1 (KT369759)

MLG A (1)

XJ224

  

A1

 

XJ1109

 

A

A1

 

XJ1680

  

A2 (KT369760)

 

XJ133, XJ1348

 

E1 (KT369778)

E1 (KT369761)

 

XJ211, XJ1704

E1 (KT369770)

   

XJ442

E2 (KT369771)

E2 (KT369779)

  

XJ631

 

E3 (KT369780)

E2 (KT369762)

 

XJ1226, XJ1234

E3 (KT369772)

E4 (KT369781)

E2

MLG E1 (2)

XJ1233

E3

E5 (KT369782)

  

XJ1237

E3

E1

E3 (KT369763)

MLG E2 (1)

XJ1239

E4 (KT369773)

 

E4 (KT369764)

 

XJ1250

 

E6 (KT369783)

  

XJ1260

E3

E1

E2

MLG E3 (1)

XJ1261, XJ1457

E3

 

E2

 

XJ1263

E5 (KT369774)

E1

  

XJ1349

E3

E1

  

XJ1353

E6 (KT369775)

E5

E2

MLG E4 (1)

XJ1469

 

E7 (KT369784)

E3

 

XJ1483

E3

E8 (KT369785)

E2

MLG E5 (1)

XJ1488

E3

E5

E5 (KT369765)

MLG E6 (1)

XJ1490

E3

E5

E6 (KT369766)

MLG E7 (1)

XJ1492

 

E8

E3

 

XJ1493, XJ1656, XJ1676, XJ1709

 

E1

  

XJ1500

 

E9 (KT369786)

  

XJ1501

E3

E4

E7 (KT369767)

MLG E8 (1)

XJ1504

 

E5

  

XJ1506

E3

E1

E8 (KT369768)

MLG E9 (1)

XJ1509

E3

E10 (KT369787)

E7

MLG E10 (1)

XJ1510

E3

E1

E7

MLG E11 (1)

XJ1516, XJ1670

  

E2

 

XJ1647

E3

E11 (KT369788)

  

XJ1675

 

E1

E7

 

XJ1681

E2

 

E2

 

XJ1682

E7 (KT369776)

E1

E1

MLG E12 (1)

XJ1689

E3

E1

E2

MLG E13 (1)

XJ1693

E2

   

XJ1699

 

E5

E1

 

XJ1706

E1

E1

E2

MLG E14 (1)

Fig. 1

Phylogenetic relationships between Giardia duodenalis assemblage A multilocus genotypes (MLGs). The phylogenetic tree was constructed using a concatenated dataset of bg, tpi and gdh gene sequences, and the neighbor-joining method analysis resulted in identical topologies. Isolates from the present study are indicated by black triangles

Fig. 2

Phylogenetic relationships between Giardia duodenalis assemblage E multilocus genotypes MLGs. The phylogenetic tree was constructed using a concatenated dataset of bg, tpi and gdh gene sequences, and the neighbor-joining method analysis resulted in identical topologies. Isolates from the present study are indicated by black triangles

Conclusion

The results of the present study confirm previous findings in other areas of China that G. duodenalis infections are common in dairy calves. The livestock-specific G. duodenalis assemblage E was the predominant assemblage, but the zoonotic assemblage A was also present in Xinjiang, China. The differences in the distribution of G. duodenalis assemblage E MLGs from cattle likely indicate a geographical segregation. Moreover, more multilocus genotyping studies are needed, which may help to identify polymorphisms and to elucidate the zoonotic potential of G. duodenalis.

Abbreviations

bg

β-giardin

gdh

Glutamate dehydrogenase

MLGs: 

Multilocus genotyping

PCR: 

Polymerase chain reaction

SSU rRNA: 

Small subunit ribosomal RNA

tpi

Triosephosphate isomerase

Declarations

Acknowledgments

We would like to thank Xu Wang and Jun Ji for collecting samples.

Funding

This study was financially supported in part by the Key Program of the National Natural Science Foundation of China (31330079), the Innovation Scientists and Technicians Troop Construction Projects of Henan Province (134200510012), the Key National Science and Technology Specific Projects (2012ZX10004220-001), and President Foundation of Tarim University (TDZKJC201601).

Availability of data and material

The datasets supporting the conclusions of this article are included within the article. Representative sequences are submitted to the GenBank database under accession numbers: KT369759–KT369788.

Authors’ contribution

LXZ conceived and designed the experiments. MQ, HYW, and BJ did the sample collection and the molecular genetic studies. MQ, RJW and FZJ performed the sequence analyzes. LXZ, CSN, and MQ wrote and corrected the manuscript. All authors read and approved the final manuscript.

Competing interests

The authors declare that they have no competing interests.

Consent for publication

Not applicable.

Ethics approval and consent to participate

This study was performed according to the recommendations of the Guide for the Care and Use of Laboratory Animals of the Ministry of Health, China. The research protocol was reviewed and approved by the Research Ethics Committee of Henan Agricultural University. Permission was obtained from the farm owners before collecting the fecal samples.

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors’ Affiliations

(1)
College of Animal Science and Veterinary Medicine, Henan Agricultural University
(2)
College of Animal Science, Tarim University
(3)
Department of Animal Science, Henan Vocational College of Agriculture

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Copyright

© The Author(s). 2016

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