Molecular detection and genetic characterizations of Cryptosporidium spp. in farmed foxes, minks, and raccoon dogs in northeastern China

Cryptosporidium Spp. in Mink, Foxes, and Raccoon Dogs in Five Provinces of Northern China

Cryptosporidium spp. is a common intestinal pathogen that causes diarrhea in both humans and animals. Northern China has a large-scale fur animal farming industry. Although there have been related studies, systematic data remain lacking. In this study, a total of 871 fecal samples were collected from fur animals in Shandong, Hebei, Liaoning, Jilin, and Heilongjiang provinces. Using nested polymerase chain reaction, 75 Cryptosporidium-positive samples were detected, and the overall infection rate was 8.61%. The infection rates ranged from 4.23% to 16.81% across different provinces, with the highest rate was observed in Shandong (16.81%, 19/113), followed by Jilin (15.07%, 11/73). Additionally, foxes (15.06%, 53/352) showed a higher infection rate compared with mink (4.55%, 13/286) and raccoon dogs (3.86%, 9/233), suggesting that foxes may be more susceptible. Four species/genotypes were identified: Cryptosporidium canis (n = 66), Cryptosporidium meleagridis (n = 1), Cryptosporidium parvum (n = 1), and mink genotype (n = 7). Among these, C. parvum and C. meleagridis were found in raccoon dogs and foxes, respectively, while the mink genotype was detected only in mink. C. canis was present in all three animal species and was the dominant species in foxes. These findings indicate that farmed fur animals may serve as potential reservoirs for Cryptosporidium transmission to humans. This study provides essential epidemiological data on Cryptosporidium infections in fur animals, contributing to a better understanding of its distribution and potential zoonotic risk.

Occurrence rate and species and subtypes of Cryptosporidium spp. in pet dogs in Yunnan Province, China

BACKGROUND

Cryptosporidium spp. is a ubiquitous, globally distributed intestinal protozoan infecting humans and at least 260 animal hosts. Due to close human contact with pet dogs and identification of zoonotic Cryptosporidium species and subtypes in these animals, dog health is not only a veterinarian issue but also a public health issue. This study aimed to understand occurrence and genetic characterization at both genotype and subtype levels in pet dogs in Yunnan Province, China.

RESULTS

A total of 589 fresh fecal specimens were collected from adult pet dogs in the rural areas of eight cities/autonomous prefectures of Yunnan Province, China. 16 fecal specimens were positive for Cryptosporidium spp. by polymerase chain reaction (PCR) amplification and sequence analysis of the small subunit ribosomal RNA (SSU rRNA) gene, with an average occurrence rate of 2.7% (16/589) being observed. Three zoonotic Cryptosporidium species were identified: C. parvum (n = 7), C. suis (n = 5) and C. canis (n = 4). At the 60-kDa glycoprotein (gp60) locus, only three C. parvum and two C. canis specimens were successfully amplified and sequenced, with subtype IIaA17G2R1 (n = 3) and subtypes XXa4 (n = 1) and XXa5 (n = 1) being identified, respectively.

CONCLUSIONS

The present finding of three zoonotic Cryptosporidium species in dogs implied that dogs infected with Cryptosporidium spp. may pose a threat to human health. C. suis was identified in dogs in this study for the first time, expanding the host range of this species. Identification of C. parvum subtype IIaA17G2R1 and C. canis subtypes XXa4 and XXa5 will be helpful to explore the source attribution of infection/contamination and assess the transmission dynamics of C. parvum and C. canis in the investigated areas in the future.

Molecular characterization and zoonotic potential of Cryptosporidium spp. and Giardia duodenalis in humans and domestic animals in Heilongjiang Province, China

BACKGROUND

Cryptosporidiosis and giardiasis are significant parasitic diseases shared between humans and domestic animals. Due to the close contact between humans and domestic animals in rural areas, it is important to consider the potential transmission of zoonotic parasites from infected domestic animals to humans. This investigation aimed to determine the prevalence and molecular characteristics of Cryptosporidium spp. and Giardia duodenalis in domestic animals and villagers.

METHODS

A total of 116 fecal samples from villagers and 686 fecal samples from domestic animals in Heilongjiang Province, China, were analyzed for two parasites using nested polymerase chain reaction (PCR) targeting various genetic loci and DNA sequence analysis of the PCR products.

RESULTS

By sequence analysis of the SSU rRNA gene, the prevalence of Cryptosporidium in humans was 0.9% (1/116), with one species of C. parvum (n = 1) detected; among domestic animals, the prevalence was 2.6% (18/686), with five species identified: C. suis (n = 7) and C. scrofarum (n = 7) in pigs, C. meleagridis (n = 1) in chickens, C. andersoni (n = 1) in cattle, and C. canis (n = 2) in foxes. C. parvum and C. canis were further subtyped as IIdA19G1 and XXa4 on the basis of gp60 gene. Regarding G. duodenalis, based on the SSU rRNA, bg, gdh, and tpi genes, the prevalence in domestic animals was 5.1% (31/608), with three assemblages identified: A (n = 1) in pigs, D (n = 1) in foxes, and E (n = 27) in geese, cattle, pigs, ducks, and sheep, along with mixed infection of A + E (n = 1) in one pig and B + E (n = 1) in one sheep. No G. duodenalis was detected in humans (0/116).

CONCLUSIONS

The present results show that no overlap of subtypes between animals and villagers was found in Cryptosporidium spp. and G. duodenalis, indicating a minor role of domestic animals in infecting humans in this population. However, the presence of zoonotic protozoa in domestic animals highlights the need for special attention to high-risk individuals during close contact with domestic animals.

The Occurrence of Cryptosporidium spp. in Wild-Living Carnivores in Poland-A Question Concerning Its Host Specificity

Cryptosporidium is an apicomplexan protozoan parasite that primarily infects the gastrointestinal epithelium in humans and domestic and wild animals. The majority of studies have been focused on human, livestock, and pet infections. Hence, Cryptosporidium spp. in wildlife, including wild carnivores, remained neglected. There are several studies reporting the occurrence of Cryptosporidium spp. in wild foxes, but these are only a few molecular surveys; no data is available concerning the occurrence of this parasite in raccoon dogs and martens in Europe, and to the best of our knowledge to date, only one study has reported Cryptosporidium from badgers in Spain. Therefore, we used molecular analyses to identify and genotype Cryptosporidium spp. in wild-living mesocarnivores in Poland. A total of 322 individual fecal samples from six carnivore species, i.e., raccoon, raccoon dog, red fox, European badger, pine, and beech martens were collected and then analyzed for the presence of Cryptosporidium spp. using the nested PCR method. The appearance of PCR products in the reaction with Cryptosporidium-specific primers against the 18S rRNA and actin genes demonstrated that Cryptosporidium spp. occurred in 23.0% of all examined species of animals. Performed sequence analyses showed the presence of the Cryptosporidium skunk genotype, Cryptosporidium vole genotype II, Cryptosporidium canis dog and fox genotypes, as well as Cryptosporidium erinacei, Cryptosporidium ditrichi, Cryptosporidium suis, and Cryptosporidium alticolis, in these hosts. Molecular data presented here indicate that examined mesocarnivores may be a significant reservoir of specific and non-specific Cryptosporidium species, including those with zoonotic potential. Most studies of carnivores have described the presence of non-specific Cryptosporidium spp. in carnivore hosts, and this is probably the result of the transfer of these parasites from prey species through the digestive tract or the transfer of the parasite from a contaminated environment.

Divergent Cryptosporidium species and host-adapted Cryptosporidium canis subtypes in farmed minks, raccoon dogs and foxes in Shandong, China

Cryptosporidium spp. are common parasitic pathogens causing diarrhea in humans and various animals. Fur animals are widely farmed in Shandong Province, China, but the prevalence and genetic identity of Cryptosporidium spp. in them are unclear. In this study, 1,211 fecal samples were collected from 602 minks, 310 raccoon dogs and 299 foxes on two farms in Shandong and analyzed for Cryptosporidium spp. by nested PCR and sequence analyses of the small subunit rRNA gene. The overall infection rate of Cryptosporidium spp. was 31.5% (381/1,211), with a higher infection rate in raccoon dogs (37.7%, 117/310) than in foxes (32.4%, 97/299) and minks (27.7%, 167/602). By age, the highest infection rates of Cryptosporidium spp. were observed in raccoon dogs of 1-2 months, minks of 5-6 months, and foxes of > 12 months. Three Cryptosporidium species and genotypes were detected, including C. canis (n = 279), C. meleagridis (n = 65) and Cryptosporidium mink genotype (n = 37). Among the three major host species, raccoon dogs were infected with C. canis only (n = 117), while foxes were infected with both C. canis (n = 32) and C. meleagridis (n = 65), and minks with C. canis (n = 130) and Cryptosporidium mink genotype (n = 37). Subtyping of C. canis by sequence analysis of the 60 kDa glycoprotein gene identified eight subtypes. They belonged to two known subtype families, XXa and XXd, and two novel subtype families XXf and XXg, with host adaptation at the subtype family level. Notably, C. canis from foxes was genetically distant from those in other hosts. Further subtyping analysis identified three subtypes (IIIeA21G2R1, IIIeA19G2R1 and IIIeA17G2R1) of C. meleagridis and two novel subtype families Xf and Xg of the Cryptosporidium mink genotype. The presence of zoonotic C. canis subtypes in raccoon dogs and C. meleagridis subtypes in foxes suggests that these fur animals might be potential reservoirs for human-pathogenic Cryptosporidium spp.

Prevalence of Toxoplasma gondii and Cryptosporidium in Feral and Farmed American Mink (Neovison vison) in Denmark

PURPOSE

To investigate the prevalence of Cryptosporidium spp. infection and Toxoplasma gondii antibodies in farmed and feral mink in Denmark.

METHODS

We examined meat juice from 235 feral mink and 306 farmed mink for T. gondii antibodies, and faecal samples from 113 feral mink and 166 farmed mink for Cryptosporidium oocyst excretion. Meat juice was analysed using a commercial indirect enzyme-linked immunosorbent assay and oocyst excretion was identified by a modified Ziehl-Neelsen method.

RESULTS

All farmed mink tested sero-negative, while 53.6% of feral mink were T. gondii sero-positive. The probability of being sero-positive for T. gondii was not associated with recent escapes from farms (p = 0.468), but was significantly higher for male feral mink (64.2%) than female feral mink (42.5%) (p = 0.0008). Only one feral mink and four farmed mink (2.4%) excreted Cryptosporidium oocysts.

CONCLUSION

Farmed mink were all T. gondii sero-negative, whereas approximately half the feral mink were sero-positive. Cryptosporidium prevalence in farmed and feral mink were low. Overall, the public health risk of transmission of these two parasites via mink in Denmark is low.

An Update on Zoonotic Cryptosporidium Species and Genotypes in Humans

The enteric parasite, Cryptosporidium is a major cause of diarrhoeal illness in humans and animals worldwide. No effective therapeutics or vaccines are available and therefore control is dependent on understanding transmission dynamics. The development of molecular detection and typing tools has resulted in the identification of a large number of cryptic species and genotypes and facilitated our understanding of their potential for zoonotic transmission. Of the 44 recognised Cryptosporidium species and >120 genotypes, 19 species, and four genotypes have been reported in humans with C. hominis, C. parvum, C. meleagridis, C. canis and C. felis being the most prevalent. The development of typing tools that are still lacking some zoonotic species and genotypes and more extensive molecular epidemiological studies in countries where the potential for transmission is highest are required to further our understanding of this important zoonotic pathogen. Similarly, whole-genome sequencing (WGS) and amplicon next-generation sequencing (NGS) are important for more accurately tracking transmission and understanding the mechanisms behind host specificity.

Molecular prevalence and characterization of Cryptosporidium in domestic free-range poultry in Anhui Province, China

Free-range chickens might mediate the spread of Cryptosporidium oocysts to humans and other animals. Few studies have evaluated the prevalence of Cryptosporidium species in domestic free-range poultry in China. Here, we characterized the prevalence and distribution of species and genotypes of Cryptosporidium in domestic free-range chickens, ducks, and geese in Anhui Province, China. A total of 1910 fresh fecal samples from three poultry species were examined from 18 free-range poultry farms by nested PCR and analysis of the Cryptosporidium SSU rRNA gene. The overall prevalence of Cryptosporidium species was 2.9% (55/1910), with infection rates of 1.3% (11/829) in chickens, 7.3% (36/487) in ducks, and 1.4% (8/594) in geese. C. baileyi (0.6%), C. meleagridis (0.2%), C. galli (0.2%), and C. xiaoi-like genotype (0.2%) were identified in chickens, and only C. baileyi was identified in ducks and geese, with infection rates of 7.4% and 1.3%, respectively. C. baileyi was the most prevalent species. Sequencing of the GP60 gene revealed that the C. meleagridis isolates belonged to the IIIbA26G1R1b subtype. This is the first study to document C. galli and C. xiaoi-like genotype in domestic free-range chickens in China. These findings expand the range of avian hosts known for Cryptosporidium and highlight the need for additional studies to characterize the diversity of Cryptosporidium in avian species.

Zoonotic parasites in farmed exotic animals in China: Implications to public health

Several species of wild mammals are farmed in China as part of the rural development and poverty alleviation, including fur animals, bamboo rats, and macaque monkeys. Concerns have been raised on the potential dispersal of pathogens to humans and other farm animals brought in from native habitats. Numerous studies have been conducted on the genetic identity and public health potential of Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi in these newly farmed exotic animals. The data generated have shown a high prevalence of the pathogens in farmed wildlife, probably due to the stress from the short captivity and congregation of large numbers of susceptible animals. Host adaptation at species/genotype and subtype levels has reduced the potential for cross-species and zoonotic transmission of pathogens, but the farm environment appears to favor the transmission of some species, genotypes, and subtypes, with reduced pathogen diversity compared with their wild relatives. Most genotypes and subtypes of the pathogens detected appear to be brought in from their native habitats. A few of the subtypes have emerged as human pathogens. One Health measures should be developed to slow the dispersal of indigenous pathogens among farmed exotic animals and prevent their spillover to other farm animals and humans.

Discrimination of meat from fur-producing and food-providing animals using mass spectrometry-based proteomics

Non-edible meat from fur-producing animals entering into meat consumption chain could pose a serious threat to public health. For the purpose of risk prevention and control of meat safety, in this study, marker peptides for discriminating non-edible meat of fur-producing animals (including fox, silver fox, blue fox, raccoon dog, ussuri raccoon dog, mink and American mink) from meat of food-providing animals (including pig, cattle, sheep and donkey) were explored by shot-gun proteomics and verified by target approach. Two mass spectrometry platforms combined with bioinformatic and chemometric tools were integratedly emloyed for method development. Meat samples were first subjected to in-solution protein digestion and the subsequently tryptic peptides were profiled and quantitated by ultra-high pressure liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q/TOF MS) with sequential windowed acquisition of all theoretical fragment ion mass spectra (SWATH-MS) mode. Candidate marker peptides screened by chemometric tools were further filtered for their biological specificity and detectability through bioinformatics analysis as well as multiple reaction monitoring (MRM) verification with UHPLC-triple quadrupole mass spectrometry (UHPLC-QQQ MS). As a result, 9 peptides, out of 104 candidates, were selected as markers for discriminating analysis, of which DQTLQEELAR was validated as primary indicator of non-edible meat from the concerned fur-producing animals. An MRM method based on the developed marker peptides for routine use was finally proposed for risk alarming of non-edible meat from fur-producing animals in food safety control.

Molecular characterization of Cryptosporidium spp. in minks (Neovison vison), blue foxes (Vulpes lagopus), and raccoon dogs (Nyctereutes procyonoides) in farms from Xinjiang, Northwest China

The objective of this study was to determine the infection rate and genetic diversity of Cryptosporidium spp. in minks, foxes, and raccoon dogs, farmed in the Xinjiang Uygur Autonomous Region, Northwest China. Fresh fecal specimens were collected from individual cages of farmed minks (n = 214), blue foxes (n = 35), and raccoon dogs (n = 39) and examined using nested PCR based on the Cryptosporidium spp. small subunit rRNA gene. Cryptosporidium spp. was detected in 35 cages (12.2%, 35/288), with a higher infection rate detected in raccoon dogs (20.5%) compared with minks (12.1%) and blue foxes (2.9%). Sequence analysis showed that Cryptosporidium canis was the only species identified in blue foxes and raccoon dogs, while in the 26 Cryptosporidium-positive mink specimens, Cryptosporidium mink genotype (n = 17), C. canis (n = 7), and Cryptosporidium parvum (n = 2) were identified. Further analysis based on the 60-kDa glycoprotein (gp60) gene determined that both C. parvum isolates belonged to the subtype IIdA15G1, while eight of the 17 Cryptosporidium mink genotype isolates were a novel subtype that we have named XeA5G1. To the best of our knowledge, this is the first report of C. parvum subtype IIdA15G1 infection in minks. Since all the Cryptosporidium species/genotypes identified in minks, foxes, and raccoon dogs from Xinjiang have been previously found in humans, our results suggest that these fur animals may play a role in the transmission of zoonotic Cryptosporidium.

A retrospective epidemiological analysis of human Cryptosporidium infection in China during the past three decades (1987-2018)

Background

Cryptosporidiosis is an emerging infectious disease of public health significance worldwide. The burden of disease caused by Cryptosporidium varies between and within countries/areas. To have a comprehensive understanding of epidemiological status and characteristics of human Cryptosporidium infection in China since the first report in 1987, a retrospective epidemiological analysis was conducted by presenting differences in the prevalence of Cryptosporidium by province, year, population, living environment and season and possible transmission routes and risk factors as well as genetic characteristics of Cryptosporidium in humans.

Methodology/Principal findings

A systematic search was conducted to obtain epidemiological papers of human Cryptosporidium infection/cryptosporidiosis from PubMed and Chinese databases. Finally, 164 papers were included in our analysis. At least 200,054 people from 27 provinces were involved in investigational studies of Cryptosporidium, with an average prevalence of 2.97%. The prevalence changed slightly over time. Variable prevalences were observed: 0.65–11.15% by province, 1.89–47.79% by population, 1.77–12.87% and 0–3.70% in rural and urban areas, respectively. The prevalence peak occurred in summer or autumn. Indirect person-to-person transmission was documented in one outbreak of cryptosporidiosis in a pediatric hospital. 263 Cryptosporidium isolates were obtained, and seven Cryptosporidium species were identified: C. hominis (48.3%), C. andersoni (22.43%), C. parvum (16.7%), C. meleagridis (8.36%), C. felis (3.04%), C. canis (0.76%) and C. suis (0.38%).

Conclusions/Significances

This systematic review reflects current epidemiological status and characteristics of Cryptosporidium in humans in China. These data will be helpful to develop efficient control strategies to intervene with and prevent occurrence of human Cryptosporidium infection/cryptosporidiosis in China as well as have a reference effect to other countries. Further studies should focus on addressing a high frequency of C. andersoni in humans and a new challenge with respect to cryptosporidiosis with an increasing population of elderly people and patients with immunosuppressive diseases.

Cryptosporidium is a major cause of diarrheal disease in humans globally. Due to the lack of effective drug treatment and vaccine prevention against cryptosporidiosis, it is particularly important to develop efficient control strategies to intervene with and prevent Cryptosporidium infection in humans. The present review presented and analyzed epidemiological status and characteristics of Cryptosporidium infection in humans in China since the first report in 1987. To date, epidemiological investigations of Cryptosporidium infecion have been carried out in different populations in 27 provinces, autonomous regions, and municipalities. Average prevalence of Cryptosporidium was 2.97% (5,933/200,054). Like other infectious disease, due to poor sanitation conditions in rural areas, people living in rural areas had a significantly higher prevalence of Cryptosporidium (1.77–12.87%) than those living in urban areas (0–3.70%). Seven Cryptosporidium species were identified, including C. hominis, C. andersoni, C. parvum, C. meleagridis, C. felis, C. canis and C. suis. This retrospective epidemiological analysis indicates wide geographical distribution of human Cryptosporidium infection/cryptosporidiosis in China.

Occurrence and genetic characteristics of Cryptosporidium spp. and Enterocytozoon bieneusi in pet red squirrels (Sciurus vulgaris) in China

Cryptosporidium spp. and Enterocytozoon bieneusi are two well-known protist pathogens which can result in diarrhea in humans and animals. To examine the occurrence and genetic characteristics of Cryptosporidium spp. and E. bieneusi in pet red squirrels (Sciurus vulgaris), 314 fecal specimens were collected from red squirrels from four pet shops and owners in Sichuan province, China. Cryptosporidium spp. and E. bieneusi were examined by nested PCR targeting the partial small subunit rRNA (SSU rRNA) gene and the ribosomal internal transcribed spacer (ITS) gene respectively. The infection rates were 8.6% (27/314) for Cryptosporidium spp. and 19.4% (61/314) for E. bieneusi. Five Cryptosporidium species/genotypes were identified by DNA sequence analysis: Cryptosporidium rat genotype II (n = 8), Cryptosporidium ferret genotype (n = 8), Cryptosporidium chipmunk genotype III (n = 5), Cryptosporidium rat genotype I (n = 4), and Cryptosporidium parvum (n = 2). Additionally, a total of five E. bieneusi genotypes were revealed, including three known genotypes (D, SCC-2, and SCC-3) and two novel genotypes (RS01 and RS02). Phylogenetic analysis revealed that genotype D fell into group 1, whereas the remaining genotypes clustered into group 10. To our knowledge, this is the first study to report Cryptosporidium spp. and E. bieneusi in pet red squirrels in China. Moreover, C. parvum and genotype D of E. bieneusi, previously identified in humans, were also found in red squirrels, suggesting that red squirrels may give rise to cryptosporidiosis and microsporidiosis in humans through zoonotic transmissions. These results provide preliminary reference data for monitoring Cryptosporidium spp. and E. bieneusi infections in pet red squirrels and humans.

Dietary probiotics have different effects on the composition of fecal microbiota in farmed raccoon dog (Nyctereutes procyonoides) and silver fox (Vulpes vulpes fulva)

BACKGROUND

The abuse of antibiotics in animal husbandry imposes a serious threat to both animal health and the environment. As a replacement for antibiotics, probiotic products have been widely used in livestock farming to promote growth of animals. However, no products specifically developed for farmed raccoon dogs and foxes are commercially available at the moment. This study was conducted to investigate the effects of mixed probiotics on farmed raccoon dogs and foxes.

RESULTS

Two feeding trials on farmed raccoon dogs and foxes were performed. A mixed probiotic preparation composed of Bifidobacterium bifidum, Clostridium butyricum, Bacillus subtilis and Bacillus licheniformis was fed to these two canine species in order to assess whether such a mixed probiotics can be an alternative to antibiotics (control group). The body weight of raccoon dogs exhibited an increasing tendency with mixed probiotics administration, while that of foxes did not. The serum antioxidant activity was evaluated, and a significantly increase of total antioxidative capacity (T-AOC) was observed in both species. Illumina MiSeq was used for the sequencing of 16S rRNA genes to compare the composition of fecal microbiota between the control and mixed probiotics groups. Although α-diversity did not change, β-diversity of the fecal microbiota showed a distinct dissimilarity between the control and probiotics groups of both raccoon dogs and foxes. Dietary mixed probiotics increased the abundance of the genus Bifidobacterium in the fecal samples of raccoon dogs, and the genus Bacillus in the fecal samples of foxes. The different responses of raccoon dogs and foxes to probiotics might be the result of differences in the composition of the native gut microbiota of the two species.

CONCLUSIONS

The mixed probiotics preparation composed of Bifidobacterium bifidum, Clostridium butyricum, Bacillus subtilis and Bacillus licheniformis could be an effective feed additive for the improvement of the health of farmed raccoon dogs, but it may not be suitable for foxes.