Skip to main content
NCBI home page
International Journal for Parasitology: Parasites and Wildlife logoLink to International Journal for Parasitology: Parasites and Wildlife
. 2019 Apr 11;9:317–321. doi: 10.1016/j.ijppaw.2019.03.017

Cryptosporidium spp. in wild rats (Rattus spp.) from the Hainan Province, China: Molecular detection, species/genotype identification and implications for public health

Wei Zhao a,b,c, Huanhuan Zhou a,b,c, Yi Huang a,b,c, Liulian Xu a,b,c, Langyu Rao a,b,c, Shanshan Wang a,b,c, Wenqi Wang a,b,c, Yufang Yi a,b,c, Xiaojun Zhou a,b,c, Yue Wu a,b,c, Tianming Ma a,b,c, Gaoyu Wang a,b,c, Xiaoyuan Hu a,b,c, Ruoyan Peng a,b,c, Feifei Yin a,b,c,∗, Gang Lu a,b,c,∗∗
PMCID: PMC6626849  PMID: 31338292

Abstract

Wild rats (Rattus spp.) carry many zoonotic pathogens including Cryptosporidium. Due to the close proximity of rats to humans in urban environments, the potential for disease transmission is high. Cryptosporidium is a protozoan parasite which when ingested causes serious human illness. Despite its importance, genetic characterization of Cryptosporidium in wild rats in the Hainan province of China has not been performed. In this study, we analyzed the occurrence and genetics of Cryptosporidium in wild rats from Hainan, China. From December 2017 to October 2018, 150 wild rats were captured and fresh fecal material was collected from intestinal sections. Rat species were identified by PCR-based amplification and analysis of the vertebrate cytochrome b (cytb) gene. Cryptosporidium was examined by PCR amplification of the partial small subunit of ribosomal DNA (SSU rDNA). C. viatorum were subtyped by PCR analysis of the gp60 gene. A total of four rat species were identified including Asian house rats (Rattus tanezumi) (n = 46), brown rats (Rattus norvegicus) (n = 56), Edward's long-tailed rats (Leopoldamys edwardsi) (n = 38) and muridae (Niviventer fulvescens) (n = 10), with Cryptosporidium positive rates of 73.9%, 28.6%, 55.3% and 40.0%, respectively (average infection rate: 50.0%, 75/150. Sequence analysis confirmed the presence of four Cryptosporidium species and two genotypes including C. viatorum (n = 11); C. occultus (n = 2); C. muris (n = 1); and C. erinacei (n = 1); rat genotypes III (n = 13) and IV (n = 47). Three novel subtypes of C. viatorum were identified in 6 of the 11 infected Edward's long-tailed rats: XVcA2G1a (n = 4), XVcA2G1b (n = 1) and XVdA3 (n = 1). The identification of human pathogenic C. viatorum and zoonotic C. occultus, C. muris and C. erinacei, suggested that wild rats infected with Cryptosporidium pose a threat to human health. Taken together, these findings highlight the need to control the rat population in Hainan, China. The need to improve the public awareness of the risk of disease transmission from wild rats to humans is also highlighted.

Keywords: Cryptosporidium, Wild rat, Molecular detection, Zoonotic, Public health

Graphical abstract

Geographical locations of rat sources involved in the present study in Hainan Province, China.

Image 1

Open in a new tab

Highlights

  • •

    This is the first report of the identification of Cryptosporidium in wild rats in Hainan Province, China.

  • •

    A total of 75 out of 150 (50.0%) specimens were PCR-positive for Cryptosporidium.

  • •

    Six known species or genotypes and three novel subtypes of C. viatorum were identified.

  • •

    The possibility of transmission of Cryptosporidium between wild rats and humans was suggested.

1. Introduction

Cryptosporidium is a single-celled eukaryote initially recognized as an opportunistic pathogen in AIDS patients. Cryptosporidium was subsequently shown to cause disease in those with fully functional immune systems evidenced by the massive outbreak in 1993 in Milwaukee (Wisconsin) with >400,000 cases of diarrheal disease recorded (Mac Kenzie et al., 1994). To date, Cryptosporidium are recognized as one of the leading diarrhea-associated protozoa. Recent human studies have implicated Cryptosporidium as the second leading cause of death in children due to diarrheal disease which is responsible for ∼10% of global child mortality (Sow et al., 2016; GBD Diarrhoeal Diseases Collaborators, 2018). In addition to human infections, Cryptosporidium has been identified in numerous animal species including domesticated livestock, poultry, companion animals, and wildlife, demonstrating its zoonotic nature and threat to public health (Khan et al., 2018; Ryan et al., 2016; Pumipuntu and Piratae, 2018). Cryptosporidium has also been identified in some water and food products, indicating the possibility of water-borne and food-borne transmission (Rosado-García et al., 2017; Ryan et al., 2018). Due to both clinical and public health awareness, Cryptosporidium has been ranked as a category B bio-defense pathogen by the National Institutes of Health (NIH) and in the Environmental Protection Agency (EPA) microbial contaminant candidate list of concern for waterborne transmission (https://www.niaid.nih.gov/research/emerging-infectious-diseases-pathogens).

PCR-based techniques that employ suitable gene markers have been widely used for the accurate identification and characterization of microorganism species and strains (Ryan et al., 2017). In recent years, a dramatic increase in human-infective species and animal-specific genotypes have been reported (Ryan et al., 2016). Through amplification and sequencing of the small subunit (SSU) and rRNA gene analysis, at least 38 Cryptosporidium species and over 40 genotypes are now recognized (Feng et al., 2018). To date, more than 20 Cryptosporidium species/genotypes have been isolated in humans, eight of which are responsible for the majority of human cryptosporidiosis cases (Feng et al., 2018). Amongst them, C. parvum is generally accepted to be a zoonotic pathogen, based on genotypic subtyping that identified C. parvum subtypes in humans and epidemiologically-linked animals (Chalmers et al., 2011; Feng et al., 2018).

Rodents play a major role in the transmission of emerging pathogens including viruses, bacteria, rickettsia, and protozoa (Meerburg et al., 2009). Amongst them, wild rats are most common and typically reside in human populated areas, particularly rural areas with less than desirable hygiene conditions. The movement of rodents facilitates the transmission and spread of disease. This is largely due to their large numbers, mobile nature, and tolerance to pathogens (Koehler et al., 2018). Recent studies revealed the identity of Cryptosporidium spp. in rats in Asia, Australia and Europe, identifying the occurrence of 17 Cryptosporidium species or genotypes including C. parvum, C.ubiquitum, C. muris, C. andersoni, C. proliferans, C. scrofarum, C. meleagridis, C. occultus, C. viatorum and C. tyzzeri, C. canis and Cryptosporidium rat genotypes I to IV, Cryptosporidium pika genotype and Cryptosporidium Qinghai vole genotype. Amongst them, C. parvum, C. muris and rat genotype III were most frequently observed in rats, suggesting them to be major sources of human infection (Koehler et al., 2018; Zhao et al., 2018; Zhang et al., 2018).

In China, studies on zoonotic protozoa in rats are limited and no studies have been performed in Hainan (Zhao et al., 2015, 2018; Zhang et al., 2018). The aims of this study were to determine the prevalence of Cryptosporidium in wild rats captured from different areas of Hainan and to characterize the isolates to assess their zoonotic potential at the species and subtype level.

2. Materials and methods

2.1. Ethical committee approval

The research of protocol was reviewed and approved by the Research Ethics Committee and the Animal Ethical Committee of Hainan Medical University. In the present study, all the wild rats were handled and cared for according to the Chinese Laboratory Animal Administration Act of 1998.

2.2. Study site and rodent collections

From December 2017 to October 2018, a total of 150 fecal specimens were collected from wild rats from six areas of the Hainan Province, China (Fig. 1). All rats were captured in cage traps baited with sunflower seeds and peanut/sesame butter. In each location, 20 cage traps were installed at sunset and gathered before sunrise, with traps positioned 5 m apart in transects. All rats were transported to the laboratory within 48 h of capture and sacrificed through CO2 inhalation.

Fig. 1.

Fig. 1

Open in a new tab

Geographical locations of rat sources involved in the present study in Hainan Province, China.

2.3. Fecal sample collection and DNA extraction

Fresh fecal material (approximately 500 mg) was collected directly from the intestine of each rat. Each fecal specimen was washed with distilled water by centrifugation for 10 min at 1500 g at room temperature. Genomic DNA was directly extracted from ∼200 mg of each processed specimen using a QIAamp DNA Mini Stool Kit (Qiagen, Hilden, Germany) according to the manufacturer's protocol. To obtain high yields of DNA, the lysis temperature was increased to 95 °C. DNA was eluted in 200 mL of AE elution buffer (provided in the kit) and stored at −20 °C prior to PCR analysis.

2.4. Identification of rat species

The molecular identification of the rat species was performed from fecal DNA by PCR-based amplification of a 421 bp region of the universal vertebrate cytochrome b (cytb) gene. PCR conditions and primer design followed those described by Verma and Singh (2003). Each PCR consisted of 35 cycles of 94 °C for 30 s (denaturation), 51 °C for 30 s (annealing), and 72 °C for 30 s (extension); an initial denaturation step at 94 °C for 5 min and a final extension step at 72 °C for 5 min were also included.

2.5. Cryptosporidium genotyping and subtyping

All DNA preparations were tested for the presence of Cryptosporidium spp. by nested PCR amplification of an 830-bp nucleotide fragment of the SSU rRNA gene as previously described (Xiao et al., 1999). All PCR amplifications were performed with positive controls (C. homini DNA for Cryptosporidium) and negative controls (2μ deionized water) which contained no DNA. Subtyping of C. viatorum samples was performed through nested PCR amplification of ∼800–850-bp fragments of the gp60 gene as described by Stensvold et al. (2015). TaKaRa TaqDNA Polymerase (TaKaRa Bio Inc., Tokyo, Japan) was used for all PCR reactions. All secondary PCR products were subjected to electrophoresis on 1.5% agarose gels and visualized by DNAGREEN staining (Tiandz, Inc., Beijing, China).

2.6. DNA sequencing and analysis

All secondary PCR products were sequenced using the same secondary PCR primers on an ABI PRISM™ 3730 DNA Analyser (Applied Biosystems, Carlsbad, CA, USA) using a BigDye Terminator v3·1 Cycle Sequencing kit (Applied Biosystems). The accuracy of the sequencing data were confirmed by sequencing the PCR products in both directions. Further PCR products from specific DNA preparations were sequenced as required. Nucleotide sequences obtained in the present study were subjected to BLAST searches (http://www.ncbi.nlm.nih.gov/blast/) and then analyzed and aligned with each other and the published reference sequences of Cryptosporidium in GenBank, using ClustalX 1.81 (http://www.clustal.org/).

2.7. Nucleotide sequence accession numbers

Representative gp60 gene sequences of C. viatorum observed here were deposited in GenBank under accession numbers MK433560 to MK433562.

3. Results

3.1. Identification of rat species

PCR and sequencing analysis of cytb amplicons showed that 46 of the 150 samples tested were from Asian house rats (Rattus tanezumi), 56 were from brown rats (Rattus norveqicus), 38 were from Edward's long-tailed rats (Leopoldamys edwardsi) and 10 were from muridae (Niviventer fulvescens) (Table 1). All cytb gene sequences had 100% identity with the reference sequence: KT808632 for R. norveqicus, MG748345 for R. tanezumi, KP992477 for L. edwardsi and MG748255 for N. fulvescens. Rats were captured from six locations; 20 rats from Haikou City were identified as R. norvegicus, all 25 rats from Huangjinjiaoling were L. edwardsi and all 35 rats from Lingao City were R. tanezumi. Rats form Baisha City, Jianfengling, and Sanya City belonged to two, three and four species, respectively (Table S1).

Table 1.

Prevalence and distribution of Cryptosporidium species and subtypes in four species of wild rodent.

Rodent species No. of specimens Cryptosporidium species
No. of positive (%) Species/Genotype(s) (no. of specimens)
Asian house rat (Rattus tanezumi) 46 34 (73.9) Rat genotype IV (24); Rat genotype III (8); C. occultus (1); C. erinacei (1)
Brown Rat (Rattus norvegicus) 56 16 (28.6) Rat genotype IV (13); Rat genotype III (1); C. muris (1); C. occultus (1)
Edward's long-tailed rat (Leopoldamys edwardsi) 38 21 (55.3) C. viatorum (11); Rat genotype IV (8); Rat genotype III (2)
Muridae (Niviventer fulvescens) 10 4 (40.0) Rat genotype III (2); Rat genotype IV (2)
Total 150 75 (50.0) Rat genotype IV (47); Rat genotype III (13); C. viatorum (11); C. occultus (2); C. muris (1); C. erinacei (1)
Open in a new tab

3.2. Frequency of cryptosporidium in rat species

A total of 75/150 (50.0%) rat specimens were positive for Cryptosporidium by PCR analysis. Cryptosporidium was found in all the four rat species including 34 R. tanezumi, 16 R. norvegicus, 21 L. edwardsi and four N. fulvescens. R. tanezumi had the highest Cryptosporidium infection rates (73.9%), followed by L. edwardsi (55.3%), N. fulvescens (40.0%) and R. norvegicus (28.6%) (Table 1). Cryptosporidium was present in all six of the investigated areas with positive rates ranging from 25.0% to 88.6% (Table S1).

3.3. Genetic characterization and distribution of cryptosporidium species/subtypes

A total of 4 species and 2 genotypes of Cryptosporidium were identified in the wild rats examined, including C. viatorum, C. occultus, C. muris, C. erinacei, and Cryptosporidium rat genotypes III and IV. Analysis of the 18S rRNA sequences of Cryptosporidium rat genotype IV revealed 47 sequences belonging to four types. Amongst them, a single sequence representing 32 Cryptosporidium IV isolates was identical to Cryptosporidium IV isolated from R. norvegicus in Sweden (JN172970), whilst 12 sequences showed 100% homology to Cryptosporidium found in Spanish water (KY483983). Three Cryptosporidium IV isolates had 100% similarity to sequences of R. norvegicus in Heilongjiang of China (n = 2, MG917670) and storm water in New York of United States of America (n = 1, AY737584). All 13 sequences of rat genotype III had 100% homology to the Cryptosporidium isolate in R. rattus (wild black rats) from Australia (JX294371). Likewise, all 11 sequences of C. viatorum were identical to those reported in the Nigerian population (JX644908). The sequences of the other three Cryptosporidium species (C. occultus, C. muris, C. erinacei) have been previously described: for MG699179 C. occultus. for AB697054 C. muris and for KF612324 C. erinacei.

Cryptosporidium viatorum was subtyped by gp60 gene sequence analysis and six of the 11 specimens were successfully amplified. Three subtypes belonged to two subtype families, including XVc (XVcA2G1a and XVcA2G1b in four and one L. edwardsi, respectively) and XVd (XVdA3 in one L. edwardsi). All three subtypes were novel and have not previously been identified. A single nucleotide change was observed between XVcA2G1a and XVcA2G1b, both of which had 95.3% (875 of 918 bp) identity with the XVaA3e (KP115940) subtype isolated from a human in Sweden. The XVdA3 subtype had 87% homology to that of the XVbA2G1 subtype (MG021319) from R. lutreolus (Australian swamp rat).

Cryptosporidium rat genotypes III and IV were found in all four rat species, C. occultus in R. tanezumi and R. norvegicus, C. viatorum, C. muris, and C. erinacei only in L. edwardsi, R. norvegicus and R. tanezumi, respectively (Table 1). Geographical assessment demonstrated that Cryptosporidium rat genotype IV was present in all six locations, Cryptosporidium rat genotype III was in Jianfengling, Kaikou and Lingao Cities, whilst C. viatorum, C. occultus, C. muris, C. erinacei were in Huangjingjiaoling, Sanya, Haikou and Lingao Cities, respectively (Table S1).

4. Discussion

This study is the first report of Cryptosporidium in wild rats in Hainan, China. Cryptosporidium is commonly found in rodents and variable prevalence rates have been reported, including 8.0–31.4% in mice, 2.1–63.0% in rats and 0.8–73.0% in voles (Koehler et al., 2018; Zhao et al., 2018). Amongst the rodents, rats have been surveyed for Cryptosporidium in 25 studies, with brown rats, Asian house rats and black rats the most common species (Koehler et al., 2018). Prior to this study, at least 2828 rat fecal samples were examined from Egypt (20.9%), Nigeria (1.5%), Brazil (16.8%), Sweden (12.0%), Japan (2.1%–38.0%), China (4.0%–9.3%), the Philippines (18.6%), the UK (24.0% and 63.0%) and Iran (17.1%) (Koehler et al., 2018; Zhao et al., 2018). The prevalence of Cryptosporidium in wild rats from Hainan was higher than that in any other study worldwide except one conducted in the UK, where up to 63.0% (46/73) of brown rats were infected with Cryptosporidium. (Koehler et al., 2018; Webster and Macdonald, 1995). These findings highlight the importance of epidemiological investigations of Cryptosporidium in these animals. It is difficult to explain the discrepancies in the prevalences of Cryptosporidium spp. among different studies because prevalences are affected by many factors, including the host species composition, the geographical distributions in the sample populations, the sample sizes, the seasons, the examination methods and the ecological conditions.

According to previous epidemiological reports, nine species and four genotypes of Cryptosporidium have been detected in rats, in which C. parvum, C. muris and rat genotype III were the most frequent (Koehler et al., 2018). In Hainan, 11/75 (14.7%) isolates were C. viatorum which was first described in 2012 from travelers returning to the UK from the Indian subcontinent, and subsequently found in humans from Bangladesh, Barbados, Colombia, Ethiopia, Guatemala, India, Kenya, Nepal, Nigeria and Pakistan (Elwin et al., 2012; Stensvold et al., 2015; Khalil et al., 2018). There were no reports of C. viatorum in any animal species other than humans prior to recent studies reporting its occurrence in three Australian swamp rats (R. lutreolus) (Koehler et al., 2018). In this study, C. viatorum was found for the first time in Edward's long-tailed rats and brown rats, indicating that this genotype has a broader range of reservoir hosts than initially anticipated. C. viatorum has been frequently identified in urban wastewater in Shanghai City, China (Huang et al., 2017). The potential therefore exists for C. viatorum to spread to the environment and other hosts including humans from infected Edward's long-tailed rats.

C. viatorum-positive specimens were subtyped by gp60 sequence analysis. Of the 11 C. viatorum isolates obtained, six were successfully amplified and belonged to three subtypes including XVcA2G1a (n = 4), XVcA2G1b (n = 1) and XVdA3 (n = 1). To our knowledge, these have not been previously characterized and thus represent novel subtypes. To date, only eight subtypes of C. viatorum (XVaA3a to XVaA3f, XVaA6 and XVbA2G1) have been identified globally (Koehler et al., 2018). Subtypes XVaA3a to XVaA3f were identified only in humans (Stensvold et al., 2015), XVaA6 was isolated in wastewater (Huang et al., 2017), and XVbA2G1 was identified in three Australian swamp rats (Koehler et al., 2018). The new gp60 subtypes of C. viatorum identified in this study highlight its high intraspecific variation that may be host-associated. The true subtype constitution of C. viatorum now requires further confirmation through systematic epidemiological studies of Cryptosporidium from different hosts.

C. occultus (n = 2), C. muris (n = 1) and C. erinacei (n = 1) were found in the wild rats examined, all of which have the ability to infect humans and animals. C. occultus previously known as the Cryptosporidium suis-like genotype, has been identified in humans in Canada, cattle in Denmark, India and China, yaks in China, and in rats from the Philippines and China (Kváč et al., 2018; Zhao et al., 2018). C. muris was the most common Cryptosporidium species found in rats, and was identified in other animal hosts including mice, cats, marsupials (bilbies), deer, and non-human primates (Karim et al., 2014; Huang et al., 2018). In humans, C. muris is most commonly found in children and HIV + individuals from developing countries including Saudi Arabia, Iran, Thailand, Kenya, Slovakia, Chile, Peru and the Slovak Republic (Chappell et al., 2015). C. erinacei was previously known as the Cryptosporidium Hedgehog genotype, which was first reported in a hedgehog (Erinaceus europaeus L.) from Denmark in 2002 (Enemark et al., 2002; Kváč et al., 2014). In addition, C. erinacei has been identified in horses from Algeria and in an immunocompetent individual from the Czech Republic (Laatamna et al., 2013; Kváč et al., 2013). This is the first report of C. erinacei in Asian house rats, indicating that this species has an extensive host range. In fact, previous research has shown that this species was not infectious for SCID and BALB/c mice (Mus musculus), Mongolian gerbils (Meriones unguiculatus), and golden hamsters (Mesocricetus auratus), thus whether the finding of C. erinacei in Asian house rats represented a natural infection needs to be confirmed with more systematic characterization of cryptosporidiosis in those animals. Meanwhile, we are unable to determine the true source of infection and transmission dynamics of C. erinacei in Asian house rats due to the lack of C. erinacei data from humans and animals in the investigated areas. Taken together, these results suggest that C. occultus, C. muri and C. erinacei have the potential for zoonotic transmission, and must be considered a potential threat to human health, despite accounting for 5.3% (4/75) of all Cryptosporidium isolates in the investigated wild rats.

In this study, 60/75 (80.0%) of the infected wild rats had Cryptosporidium rat genotype III or IV, which appear to be rat-adapted genotypes. To date, Cryptosporidium rat genotype IV was only recorded in R. norvegicus (Zhao et al., 2018) whilst Cryptosporidium rat genotype III was found in cats, mice and rats (Ng-Hublin et al., 2013; Paparini et al., 2012; Lv et al., 2009; Yang et al., 2015). The potential of rat genotype III and IV to cause disease in humans or livestock is unknown, but both can contaminate water supplies evidenced by their detection in streams in the USA and raw water in the UK and China (Feng et al., 2009; Jiang et al., 2005; Chalmers et al., 2010). To improve our understanding of the extent of host adaptation of the Cryptosporidium genotypes isolated from rats, an examination of a larger range of animal and human isolates across larger geographical regions coupled to longitudinal studies are required. This will permit more accurate assessments of the role of wild rats in the transmission of Cryptosporidium to humans and other animals.

In conclusion, this study demonstrates the high prevalence and wide distribution of Cryptosporidium spp. in wild rats in Hainan, China. Considering the infestation of the sampled rats with human-pathogenic C. viatorum and zoonotic Cryptosporidium species/genotypes including C. occultus, C. muris and C. erinacei, they are likely to play a role in the transmission of Cryptosporidium to humans and may emerge as an important source of water contamination in Hainan. It is thus strongly recommended that measures should be taken to control the rodent populations in Hainan and that the local public are aware of the risk of disease transmission to humans through wild rats.

Declaration of interest

We have no conflict of interest to declare with this work.

Conflicts of interest

The authors declared that they have no conflicts of interest to this work.

Acknowledgements

This work was supported partially by the Innovation Research Team Project of Hainan Natural Science Foundation (2018CXTD340) and the National Natural Science Foundation of China (No. 81672072 and No. 81760378). The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Footnotes

Appendix A

Supplementary data to this article can be found online at https://doi.org/10.1016/j.ijppaw.2019.03.017.

Contributor Information

Feifei Yin, Email: yinfeifeiff@163.com.

Gang Lu, Email: luganghn@aliyun.com, ganglu2018@163.com.

Appendix A. Supplementary data

The following are the Supplementary data to this article:

Multimedia component 1
mmc1.xml (268B, xml)
Multimedia component 2
mmc2.doc (45KB, doc)

References

  1. Chalmers R.M., Robinson G., Elwin K., Hadfield S.J., Thomas E., Watkins J., Casemore D., Kay D. Detection of Cryptosporidium species and sources of contamination with Cryptosporidium hominis during a waterborne outbreak in north west Wales. J. Water Health. 2010;8:311–325. doi: 10.2166/wh.2009.185. [DOI] [PubMed] [Google Scholar]
  2. Chalmers R.M., Smith R.P., Hadfield S.J., Elwin K., Giles M. Zoonotic linkage and variation in Cryptosporidium parvum from patients in the United Kingdom. Parasitol. Res. 2011;108:1321–1325. doi: 10.1007/s00436-010-2199-x. [DOI] [PubMed] [Google Scholar]
  3. Chappell C.L., Okhuysen P.C., Langer-Curry R.C., Lupo P.J., Widmer G., Tzipori S. Cryptosporidium muris: infectivity and illness in healthy adult volunteers. Am. J. Trop. Med. Hyg. 2015;92:50–55. doi: 10.4269/ajtmh.14-0525. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Elwin K., Hadfield S.J., Robinson G., Crouch N.D., Chalmers R.M. Cryptosporidium viatorum n. sp. (Apicomplexa: cryptosporidiidae) among travellers returning to Great Britain from the Indian subcontinent, 2007-2011. Int. J. Parasitol. 2012;42:675–682. doi: 10.1016/j.ijpara.2012.04.016. [DOI] [PubMed] [Google Scholar]
  5. Enemark H.L., Ahrens P., Juel C.D., Petersen E., Petersen R.F., Andersen J.S., Lind P., Thamsborg S.M. Molecular characterization of Danish Cryptosporidium parvum isolates. Parasitology. 2002;125:331–341. doi: 10.1017/s0031182002002226. [DOI] [PubMed] [Google Scholar]
  6. Feng Y., Li N., Duan L., Xiao L. Cryptosporidium genotype and subtype distribution in raw wastewater in Shanghai, China: evidence for possible unique Cryptosporidium hominis transmission. J. Clin. Microbiol. 2009;47:153–157. doi: 10.1128/JCM.01777-08. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Feng Y., Ryan U.M., Xiao L. Genetic diversity and population structure of cryptosporidium. Trends Parasitol. 2018;34:997–1011. doi: 10.1016/j.pt.2018.07.009. [DOI] [PubMed] [Google Scholar]
  8. GBD 2017 Causes of Death Collaborators. Global, regional, and national age-sex-specific mortality for 282 causes of death in 195 countries and territories, 1980-2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet. 2018;392:1736–1788. doi: 10.1016/S0140-6736(18)32203-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Huang C., Hu Y., Wang L., Wang Y., Li N., Guo Y., Feng Y., Xiao L. Environmental transport of emerging human-pathogenic cryptosporidium species and subtypes through combined sewer overflow and wastewater. Appl. Environ. Microbiol. 2017;83 doi: 10.1128/AEM.00682-17. pii: e00682-17. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Huang J., Zhang Z., Zhang Y., Yang Y., Zhao J., Wang R., Jian F., Ning C., Zhang W., Zhang L. Prevalence and molecular characterization of cryptosporidium spp. and Giardia duodenalis in deer in henan and Jilin, China. Parasites Vectors. 2018;11:239. doi: 10.1186/s13071-018-2813-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Jiang J., Alderisio K.A., Xiao L. Distribution of cryptosporidium genotypes in storm event water samples from three watersheds in New York. Appl. Environ. Microbiol. 2005;71:4446–4454. doi: 10.1128/AEM.71.8.4446-4454.2005. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Karim M.R., Zhang S., Jian F., Li J., Zhou C., Zhang L., Sun M., Yang G., Zou F., Dong H., Li J., Rume F.I., Qi M., Wang R., Ning C., Xiao L. Multilocus typing of Cryptosporidium spp. and Giardia duodenalis from non-human primates in China. Int. J. Parasitol. 2014;44:1039–1047. doi: 10.1016/j.ijpara.2014.07.006. [DOI] [PubMed] [Google Scholar]
  13. Khalil S., Mirdha B.R., Paul J., Panda A., Singh Y. Molecular detection and identification of Cryptosporidium viatorum in a human immunodeficiency virus-seropositive patient. J. Glob. Infect. Dis. 2018;10:28–29. doi: 10.4103/jgid.jgid_26_17. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Khan A., Shaik J.S., Grigg M.E. Genomics and molecular epidemiology of Cryptosporidium species. Acta Trop. 2018;184:1–14. doi: 10.1016/j.actatropica.2017.10.023. [DOI] [PubMed] [Google Scholar]
  15. Koehler A.V., Wang T., Haydon S.R., Gasser R.B. Cryptosporidium viatorum from the native Australian swamp rat Rattus lutreolus - an emerging zoonotic pathogen? Int. J. Parasitol. Parasites. Wildl. 2018;7:18–26. doi: 10.1016/j.ijppaw.2018.01.004. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Kváč M., Hofmannová L., Hlásková L., Květoňová D., Vítovec J., McEvoy J., Sak B. Cryptosporidium erinacei n. sp. (Apicomplexa: cryptosporidiidae) in hedgehogs. Vet. Parasitol. 2014;201:9–17. doi: 10.1016/j.vetpar.2014.01.014. [DOI] [PubMed] [Google Scholar]
  17. Kváč M., Saková K., Kvĕtoňová D., Kicia M., Wesołowska M., McEvoy J., Sak B. Gastroenteritis caused by the Cryptosporidium hedgehog genotype in an immunocompetent man. J. Clin. Microbiol. 2013;52:347–349. doi: 10.1128/JCM.02456-13. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Kváč M., Vlnatá G., Ježková J., Horčičková M., Konečný R., Hlásková L., McEvoy J., Sak B. Cryptosporidium occultus sp. n. (Apicomplexa: cryptosporidiidae) in rats. Eur. J. Protistol. 2018;63:96–104. doi: 10.1016/j.ejop.2018.02.001. [DOI] [PubMed] [Google Scholar]
  19. Laatamna A.E., Wagnerová P., Sak B., Květoňová D., Aissi M., Rost M., Kváč M. Equine cryptosporidial infection associated with Cryptosporidium hedgehog genotype in Algeria. Vet. Parasitol. 2013;197:350–353. doi: 10.1016/j.vetpar.2013.04.041. [DOI] [PubMed] [Google Scholar]
  20. Lv C., Zhang L., Wang R., Jian F., Zhang S., Ning C., Wang H., Feng C., Wang X., Ren X., Qi M., Xiao L. Cryptosporidium spp. in wild, laboratory, and pet rodents in China: prevalence and molecular characterization. Appl. Environ. Microbiol. 2009;75:7692–7699. doi: 10.1128/AEM.01386-09. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Mac Kenzie W.R., Hoxie N.J., Proctor M.E., Gradus M.S., Blair K.A., Peterson D.E., Kazmierczak J.J., Addiss D.G., Fox K.R., Rose J.B. A massive outbreak in Milwaukee of Cryptosporidium infection transmitted through the public water supply. N. Engl. J. Med. 1994;331:161–167. doi: 10.1056/NEJM199407213310304. [DOI] [PubMed] [Google Scholar]
  22. Meerburg B.G., Singleton G.R., Kijlstra A. Rodent-borne diseases and their risks for public health. Crit. Rev. Microbiol. 2009;35:221–270. doi: 10.1080/10408410902989837. [DOI] [PubMed] [Google Scholar]
  23. Ng-Hublin J.S., Singleton G.R., Ryan U. Molecular characterization of Cryptosporidium spp. from wild rats and mice from rural communities in the Philippines. Infect. Genet. Evol. 2013;16:5–12. doi: 10.1016/j.meegid.2013.01.011. [DOI] [PubMed] [Google Scholar]
  24. Paparini A., Jackson B., Ward S., Young S., Ryan U.M. Multiple Cryptosporidium genotypes detected in wild black rats (Rattus rattus) from northern Australia. Exp. Parasitol. 2012;131:404–412. doi: 10.1016/j.exppara.2012.05.009. [DOI] [PubMed] [Google Scholar]
  25. Pumipuntu N., Piratae S. Cryptosporidiosis: a zoonotic disease concern. Vet. World. 2018;11:681–686. doi: 10.14202/vetworld.2018.681-686. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Rosado-García F.M., Guerrero-Flórez M., Karanis G., Hinojosa M.D.C., Karanis P. Water-borne protozoa parasites: the Latin American perspective. Int. J. Hyg Environ. Health. 2017;220:783–798. doi: 10.1016/j.ijheh.2017.03.008. [DOI] [PubMed] [Google Scholar]
  27. Ryan U., Hijjawi N., Xiao L. Foodborne cryptosporidiosis. Int. J. Parasitol. 2018;48:1–12. doi: 10.1016/j.ijpara.2017.09.004. [DOI] [PubMed] [Google Scholar]
  28. Ryan U., Paparini A., Oskam C. New technologies for detection of enteric parasites. Trends Parasitol. 2017;33:532–546. doi: 10.1016/j.pt.2017.03.005. [DOI] [PubMed] [Google Scholar]
  29. Ryan U., Zahedi A., Paparini A. Cryptosporidium in humans and animals-a one health approach to prophylaxis. Parasite Immunol. 2016;38:535–547. doi: 10.1111/pim.12350. [DOI] [PubMed] [Google Scholar]
  30. Sow S.O., Muhsen K., Nasrin D., Blackwelder W.C., Wu Y., Farag T.H., Panchalingam S., Sur D., Zaidi A.K., Faruque A.S., Saha D., Adegbola R., Alonso P.L., Breiman R.F., Bassat Q., Tamboura B., Sanogo D., Onwuchekwa U., Manna B., Ramamurthy T., Kanungo S., Ahmed S., Qureshi S., Quadri F., Hossain A., Das S.K., Antonio M., Hossain M.J., Mandomando I., Nhampossa T., Acácio S., Omore R., Oundo J.O., Ochieng J.B., Mintz E.D., O'Reilly C.E., Berkeley L.Y., Livio S., Tennant S.M., Sommerfelt H., Nataro J.P., Ziv-Baran T., Robins-Browne R.M., Mishcherkin V., Zhang J., Liu J., Houpt E.R., Kotloff K.L., Levine M.M. The burden of cryptosporidium diarrheal disease among children < 24 Months of age in moderate/high mortality regions of sub-saharan africa and south Asia, utilizing data from the global enteric multicenter study (GEMS) PLoS Neglected Trop. Dis. 2016;10:e0004729. doi: 10.1371/journal.pntd.0004729. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Stensvold C.R., Elwin K., Winiecka-Krusnell J., Chalmers R.M., Xiao L., Lebbad M. Development and application of a gp60-based typing assay for Cryptosporidium viatorum. J. Clin. Microbiol. 2015;53:1891–1897. doi: 10.1128/JCM.00313-15. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Verma S.K., Singh L. Novel universal primers establish identity of an enormous number of animal species for forensic application. Molecualr. Ecology. 2003;3:28–31. [Google Scholar]
  33. Webster J.P., Macdonald D.W. Cryptosporidiosis reservoir in wild brown rats (Rattus norvegicus) in the UK. Epidemiol. Infect. 1995;115:207–209. doi: 10.1017/s0950268800058271. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. Xiao L., Escalante L., Yang C., Sulaiman I., Escalante A.A., Montali R.J., Fayer R., Lal A.A. Phylogenetic analysis of Cryptosporidium parasites based on the small-subunit rRNA gene locus. Appl. Environ. Microbiol. 1999;65:1578–1583. doi: 10.1128/aem.65.4.1578-1583.1999. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Yang R., Ying J.L., Monis P., Ryan U. Molecular characterisation of cryptosporidium and giardia in cats (Felis catus) in western Australia. Exp. Parasitol. 2015;155:13–18. doi: 10.1016/j.exppara.2015.05.001. [DOI] [PubMed] [Google Scholar]
  36. Zhang X., Jian Y., Li X., Ma L., Karanis G., Karanis P. The first report of Cryptosporidium spp. in Microtus fuscus (Qinghai vole) and Ochotona curzoniae (wild plateau pika) in the Qinghai-Tibetan Plateau area, China. Parasitol. Res. 2018;117:1401–1407. doi: 10.1007/s00436-018-5827-5. [DOI] [PubMed] [Google Scholar]
  37. Zhao W., Wang J., Ren G., Yang Z., Yang F., Zhang W., Xu Y., Liu A., Ling H. Molecular characterizations of cryptosporidium spp. and Enterocytozoon bieneusi in brown rats (Rattus norvegicus) from Heilongjiang province, China. Parasites Vectors. 2018;11:313. doi: 10.1186/s13071-018-2892-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. Zhao Z., Wang R., Zhao W., Qi M., Zhao J., Zhang L., Li J., Liu A. Genotyping and subtyping of Giardia and Cryptosporidium isolates from commensal rodents in China. Parasitology. 2015;142:800–806. doi: 10.1017/S0031182014001929. [DOI] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Multimedia component 1
mmc1.xml (268B, xml)
Multimedia component 2
mmc2.doc (45KB, doc)

Articles from International Journal for Parasitology: Parasites and Wildlife are provided here courtesy of Elsevier

RESOURCES