Common occurrence of divergent Cryptosporidium species and Cryptosporidium parvum subtypes in farmed bamboo rats (Rhizomys sinensis)

BACKGROUND

Bamboo rats are widely farmed in southern China for meat, but their potential in transmitting pathogens to humans and other farm animals remains unclear.

METHODS

To understand the transmission of Cryptosporidium spp. in these animals, 709 fecal samples were collected in this study from Chinese bamboo rats (Rhizomys sinensis) on nine farms in Jiangxi, Guangxi and Hainan provinces, China. They were analyzed for Cryptosporidium spp. using PCR and sequence analyses of the small subunit rRNA gene. Cryptosporidium parvum, C. parvum-like and C. ubiquitum-like genotypes identified were subtyped by sequence analysis of the 60 kDa glycoprotein (gp60) gene.

RESULTS

Altogether, Cryptosporidium spp. were detected in 209 (29.5%) samples. The detection rate in samples from animals under two months of age (70.0%,105/150) was significantly higher than in samples from animals above 2 months (18.6%, 104/559; χ² = 150.27, df = 1, P < 0.0001). Four Cryptosporidium species/genotypes were identified: C. parvum (n = 78); C. occultus (n = 1); a new genotype that is genetically related to C. ubiquitum (n = 85); and another new genotype that is genetically related to C. parvum (n = 44). Among them, C. parvum (27,610 ± 71,911 oocysts/gram of feces) and the C. parvum-like genotype (38,679 ± 82,811 oocysts/gram of feces) had higher oocyst shedding intensity than the C. ubiquitum-like genotype (2470 ± 7017 oocysts/gram of feces) and the C. occultus (1012 oocysts/gram of feces). The C. parvum identified belonged to three subtypes in two rare subtype families, including IIpA9 (n = 43), IIpA6 (n = 6) and IIoA15G1 (n = 9), while the C. parvum-like and C. ubiquitum-like genotypes generated very divergent gp60 sequences.

CONCLUSIONS

Results of the present study suggest that bamboo rats on the study farms were infected with diverse Cryptosporidium species and divergent C. parvum subtypes, which probably had originated from their native habitats. As similar C. parvum subtypes have been recently detected in humans and farmed macaques, attentions should be paid to the potential role of these new farm animals in the transmission of zoonotic pathogens.

in bamboo rats (Rhizomys sinensis) in South Central China

Cryptosporidium is one of the most prevalent zoonotic parasites and is responsible for the high burden of diarrheal disease across the globe. Rodents are globally overpopulated and are reservoirs for a variety of zoonotic pathogens. Bamboo rats are a common species of rodent that are bred for meat and wool in China. However, the genetic characterization of Cryptosporidium in bamboo rats in China is limited. The aim of this study was to determine the occurrence and genetic characterization of Cryptosporidium in bamboo rats from South Central China. From February2017to February 2018, 435 fecal samples were collected from bamboo rats in 13 farms located in 12 cities in South Central China. All fecal specimens were examined for Cryptosporidium by PCR, and through sequencing the partial small subunit of ribosomal DNA (SSU rRNA). C. parvum-positive samples were further subtyped through analysis of the 60-kDa glycoprotein (gp60) gene sequence. Meanwhile, all the new Cryptosporidium genotypes samples were selected for further sequence characterization at the 70-kDa heat shock protein (HSP70) gene and oocyst wall protein (COWP) gene as well as gp60 gene. Infection rates of 2.1% (9/435) were recorded for Cryptosporidium. Sequence analysis confirmed the presence of two Cryptosporidium species including C. parvum (n = 2), C. occultus (n = 1) and two new Cryptosporidium genotypes termed Cryptosporidium bamboo rat genotype I (n = 5) and Cryptosporidium bamboo rat genotype II (n = 1). Two subtypes of C. parvum were identified including IIdA15G1 and IIpA19 (one each).The discovery of zoonotic Cryptosporidium species/genotypes in bamboo rats suggests they have significant zoonotic potential and pose a threat to human health. The novel sequences discovered provide new insight into genotypic variations in Cryptosporidium in bamboo rats.

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This is the first report of the identification of Cryptosporidium in farmed bamboo rats in South Central China.

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2.1% (9/435) bamboo rats were PCR-positive for Cryptosporidium.

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Cryptosporidium parvum, C. occultus, Cryptosporidium bamboo rats I and II were identified.

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

First report of Giardia duodenalis infection in bamboo rats

Background

The zoonotic parasite, Giardia duodenalis (syns. G. lamblia and G. intestinalis), has been widely reported in humans and animals, including rodents. The bamboo rat, a rodent species belonged to the subfamily Rhizomyinae, is farmed in China because of its medicinal and edible values. However, no information of G. duodenalis infection was available in bamboo rats prior to the present study. Here, the prevalence and genetic diversity of G. duodenalis in bamboo rats from Hunan Province of China were investigated.

Results

Of 480 faecal samples collected from six farms located in four cities (Wugang, Chenzhou, Huaihua and Jishou) of Hunan Province, 52 (10.8%) were positive for G. duodenalis infection by using a nested PCR approach targeting the beta giardin (bg) gene. Significant differences (P < 0.01) in prevalence were found among different age groups and geographical localities, and among different farms in Wugang city. Sequence analysis revealed existence of the zoonotic assemblage B and genetic diversity of G. duodenalis in these animals. Multilocus genotyping analysis also indicated broad genetic diversity of assemblage B isolates in these bamboo rats.

Conclusions

This is the first report of the infection and genetic variations of G. duodenalis in bamboo rats. These findings will provide basic data for implementing effective strategies to control giardiasis in bamboo rats.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3111-2) contains supplementary material, which is available to authorized users.

Characterization of Akabane virus from domestic bamboo rat, Southern China

To identify the causative agents in 3 large-scale outbreaks of encephalitis and death among farmed bamboo rats (Rhizomys pruinosus). The routine bacterial culture and identification were performed. There were no significant pathogenic bacteria isolated from the brain, heart, liver, spleen, lung, or kidney of diseased bamboo rats. Using PCR-based methods, we excluded the following as causative agent: pox virus, herpesvirus, adenovirus, lymphocytic choriomeningitis virus, rabies virus, and sendai virus. Furthermore, the homogenate from the diseased bamboo rats was subjected to viral metagenomic analysis which revealed 48506 filtered viral reads annotated to Akabane virus (AKAV) with >75% nucleotide identity, suggesting the presence of AKAVs in bamboo rats. Five novel AKAV isolates were successfully isolated and characterized. Furthermore the newly isolated AKAV isolate was used to demonstrate that it can reproduce the severe encephalitic and pneumonic disease in bamboo rats and mice. The findings add to the better understanding of AKAV epidemiology and to the prevention and control of Akabane diseases in China.

Occurrence of novel and rare subtype families of Cryptosporidium in bamboo rats (Rhizomys sinensis) in China

This report is the first to describe Cryptosporidium infection in bamboo rats (Rhizomys sinensis). Ninety-two fresh fecal specimens were collected from a pet market in Ya'an City, China. One Cryptosporidium isolate from an asymptomatic host and two isolates from separate hosts with diarrhea were obtained by using Sheather's sucrose flotation technique and modified acid-fast staining. The Cryptosporidium spp. were genotyped by nested PCR and nucleotide sequencing of the small subunit rRNA (SSU rRNA), 70-kDa heat shock protein (HSP70), oocyst wall protein (COWP), and actin genes: isolates were identified as Cryptosporidium parvum with minor nucleotide differences at all four loci. Further subtyping was performed by PCR amplification and DNA sequence analysis of the 60-kDa glycoprotein (gp60) gene: two subtype families were detected, including a novel C. parvum subtype IIpA9 and a rare subtype IIoA13G1 (only reported in diarrheal patients of Sweden). Our results suggest that the bamboo rat is a reservoir host of C. parvum. Significantly, we discovered that the rare C. parvum subtype family IIo is also a zoonotic subtype and confirmed C. parvum subtype IIpA9 as a novel subtype family.

Mitochondrial genome of bamboo rat Rhizomys pruinosus

Abstract Bamboo rats are a group of subterranean rodents some of which feed on the roots and shoots of bamboo and other plants. In this study, we sequence the mitochondrial genome of a hoary bamboo rat Rhizomys pruinosus from the south of China. The genome is 16,575 bp in length, and had a gene content of 13 protein coding, 22 tRNAs and 2 rRNAs. The overall base composition is 30.94% T, 24.83% C, 32.21% A and 12.02% G, with an A+T bias of 63.15%. The cytochrome genes were the most conservative genes compared with plateau zokor (Eospalax baileyi) and blind mole rats (Spalax carmeli) in the family Spalacidae. These mitochondrial data are potentially important for the study of molecular evolution, conservation genetics, agricultural technology and epidemiology.