Genotyping and zoonotic potential of Cryptosporidium and Enterocytozoon bieneusi in pigs transported across regions in China

https://doi.org/10.1016/j.micpath.2021.104823Get rights and content

Highlights

  • A high E. bieneusi infection rate with 7 possible novel ITS genotypes and 10 known genotypes belonged to zoonotic group 1.

  • Cryptosporidium parvum was identified in pigs.

  • Parasitic transmission during animals transportation across regions.

Abstract

Cryptosporidium spp. and Enterocytozoon bieneusi are common and important enteric parasites that can infect humans and animals, causing diarrhoea and systemic diseases. The objectives of the present study were to examine the prevalence and genetic variations of Cryptosporidium and E. bieneusi in pigs transferred from northeastern China to Ningbo city in Zhejiang Province. Cryptosporidium spp. was detected in 0.9% (2/216) of these samples and belonged to the zoonotic species Cryptosporidium parvum. A high E. bieneusi infection rate (25.0%, 54/216) was observed in this study, with 7 possible novel ITS genotypes (JLNB-1 to JLNB-7) and 10 known genotypes (EbpA, CM11, H, CM6, pigEBITS1, EbpC, CS-4, pigEBITS5, CHS5, and Henan-Ⅳ) identified, and zoonotic EbpA was the dominant genotype. Genotypes H and pigEBITS1 were reported for the first time in pigs in China. Phylogenetic analysis indicated that all the genotypes found in these samples belonged to zoonotic group 1. These findings indicated the potential threat of Cryptosporidium and E. bieneusi to humans or the environment during cross-regional transportation. An effective management control system should be built to avoid parasitic transmission as well as other animal diseases while travelling across different regions. In further studies, attention should be given to the transmission routes and the role of pigs as a potential source of human Cryptosporidium and E. bieneusi infections in China.

Introduction

Cryptosporidium spp. and Enterocytozoon bieneusi are important opportunistic intestinal protozoa causing acute or self-limited diarrhoea and enteric diseases in humans and various animals [1,2] and are associated with increased mortality in immunocompromised individuals, such as AIDS patients [3,4]. The two pathogens have zoonotic potential and can be transmitted by contact with faeces containing oocysts/spores from water or faecal specimens, contributing to the burden of moderate-to-severe diarrhoea, especially in developing countries [3,5,6].

Cryptosporidium is a common intestinal parasite in humans, which can cause an alimentary infectious disease with diarrhoea in a wide range of domestic and wild animals worldwide. To date, at least 42 Cryptosporidium species and 70 genotypes have been found in various hosts [[7], [8], [9], [10], [11]]. Among these species, Cryptosporidium suis and Cryptosporidium scrofarum (formerly Cryptosporidium pig genotype II) are the main species in pigs, with Cryptosporidium muris, Cryptosporidium parvum, Cryptosporidium andersoni, and Cryptosporidium tyzzeri (formerly Cryptosporidium mouse genotype I) also being found occasionally [[12], [13], [14]].

Microsporidia are unicellular enteric pathogens, and approximately 17 species can infect humans, with E. bieneusi being the most common one [3]. In addition, E. bieneusi has been detected in a wide range of animals, such as wild and domestic animals, including companion mammals and birds, causing gastrointestinal infection [15]. Increasing studies have reported that E. bieneusi is closely related to increased morbidity and mortality in immunodeficient patients, such as HIV/AIDS patients with chronic diarrhoea [3,16]. Genotyping tools and phylogenetic analysis for E. bieneusi have been frequently used to understand its host specificity and transmission routes. Currently, amplification and sequencing of the ribosomal internal transcribed spacer (ITS) is widely applied for detecting and genotyping E. bieneusi based on its great genetic diversity [17]. To date, over 500 E. bieneusi genotypes have been identified using the ITS gene in humans, mammals, birds and water [18].

In addition, these E. bieneusi ITS genotypes can be clustered into at least 11 large groups (groups 1–11) based on phylogenetic analysis of ITS sequences [17,19,20]. Group 1 is a large group that is closely related to zoonotic potential for microsporidiosis and is found mainly in both humans and animals. In recent years, group 2 has been considered as zoonotic potential with the four getypes BEB4, BEB6, I, and J were found in cattle, deer, sheep, and goats. Whereas groups 3–11 seem to be have a narrow host range [17,19].

In some parts of China, it has been reported that locally raised pigs are infected with Cryptosporidium and E. bieneusi with zoonotic potential, while pigs are important economic animal husbandry. Widespread cross-regional transport of live pigs exists in the country, and to our knowledge, this study is the first report on the molecular characteristics of Cryptosporidium and E. bieneusi isolated from weaned piglets transported between cities in China.

Section snippets

Ethical statement

The study was revised and approved by the ethics committee of the National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention (reference No. 2019003).

Sample collection

A total of 216 faecal specimens were obtained from weaned piglets in November 2019 in Ningbo city in Zhejiang Province in eastern China. In detail, these piglets were raised in three large-scale piggeries from Siping city (72) in Jilin Province or Jinzhou city (72) or Huludao city (72) in Liaoning Province in

Prevalence of Cryptosporidium and E. bieneusi in pigs

Of the 216 faecal specimens collected from weaned piglets, two (0.9%, 2/216) Cryptosporidium-positive samples were identified, and sequencing results showed that both isolates were C. parvum. BLAST analysis indicated that the sequences had 100% homology with the C. parvum sequence (GenBank accession number MK990043).

A higher rate of 25.0% (54/216) was found for E. bieneusi infection. Among the three cities, 39 pigs from Siping were identified to be infected with E. bieneusi and had the highest

Discussion

In China, pigs are the main economic animals and play an important role in animal husbandry. In the present study, 216 faecal samples were examined by nested PCR amplification of the small ribosomal subunit RNA (SSU rRNA) gene and the ITS region for the prevalence of Cryptosporidium and E. bieneusi from weaned piglets raised in three different piggeries (northeastern China) but slaughtered in Ningbo (southeastern China). The overall infection rates of Cryptosporidium and E. bieneusi were 0.9%

Conclusions

The results of this investigation demonstrated the prevalence of C. parvum and E. bieneusi infections in pigs. C. parvum infection in pigs is rare, and the high prevalence of E. bieneusi in these pigs suggests that more attention should be paid to assessing the epidemiological role of pigs as reservoir hosts. The seven new genotypes and ten known genotypes identified in this study were all classified into zoonotic group 1, indicating potential transmission between pigs and humans. Therefore,

Author statement

The authors declare that they have no known competing financial interest or personal relationship that influenced the work reported in this study.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work was supported by the National Science and Technology Major Project, China (Nos. 2018ZX10201002-009 and 2018ZX10713001-004), and the National Key R&D Program of China, China (No. 2017YFD0500400). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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