Prevalence and risk factors of Giardia duodenalis in domestic rabbbits (Oryctolagus cuniculus) in Jilin and Liaoning province, northeastern China

Rabbits as reservoirs: An updated perspective of the zoonotic risk from Cryptosporidium and Giardia

Rabbits are highly abundant in many countries and can serve as reservoirs of diseases for a diversity of pathogens including the enteric protozoan parasites, Cryptosporidium and Giardia. Both parasites shed environmentally robust environmental stages (oo/cysts) and have been responsible for numerous waterborne outbreaks of diseases. Cryptosporidium hominis and C. parvum are responsible for most infections in humans, while Giardia duodenalis assemblages A and B, cause most human cases of giardiasis. Cryptosporidium cuniculus, the dominant species infecting rabbits, is the only spceies other than C. hominis and C. parvum to have caused a waterborne outbreak of gastritis, which occurred in the United Kingdom in 2008. This review examines the prevalence of Cryptosporidium and Giardia species in rabbits to better understand the public health risks of contamination of water sources with Cryptosporidium and Giardia oo/cysts from rabbits. Despite the abundance of C. cuniculus in rabbits, reports in humans are relatively rare, with the exception of the United Kingdom and New Zealand, and reports of C. cuniculus in humans from the United Kingdom have declined substantially since the 2008 outbreak. Subtyping of C. cuniculus has supported the potential for zoonotic transmission. Relatively few studies have been conducted on Giardia, but assemblage B dominates. However, improved typing methods are required to better understand the transmission dynamics of Giardia assemblages in rabbits. Similarly, it is not well understood if pet rabbits or contaminated water are the main source of C. cuniculus infections in humans. Well-planned studies using high-resolution typing tools are required to understand the transmission dynamics better and quantify the public health risk of Cryptosporidium and Giardia from rabbits.

First report of Giardia duodenalis in pet rabbits in Brazil

Giardia duodenalis is a flagellate protozoan that multiplies in the small intestine of a wide variety of hosts, animals and humans. It has a worldwide distribution, however it is considered a neglected disease by the World Health Organization (WHO). Nowadays, rabbits are being chosen as pets, especially by children. There are already reports of the occurrence of G. duodenalis in rabbits from other countries, but research has not been carried out in Brazil yet. Thus, the objective of our work was to verify the occurrence and molecularly characterize G. duodenalis that affect pet rabbits, through the polymerase chain reaction (PCR) in the northwest region of the state of São Paulo, Brazil. Fecal samples from 100 rabbits were collected, which later underwent a process of DNA extraction and amplification by nested-PCR (nPCR), using the SSU rRNA gene, and β-giardin (bg), glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi) to determine the assemblage. A questionnaire was answered by the owners with information about gender, age, deworming, diarrhea, water source, food, place of residence and contact with other animals. From those samples, 40 were positive for G. duodenalis. Good quality of the SSU rRNA gene by nPCR were obtained from two samples. For the first time, we report the occurrence of G. duodenalis assemblage A on pet rabbits in Brazil.

Iberian wild leporidae as hosts of zoonotic enteroparasites in Mediterranean ecosystems of Southern Spain

Wild lagomorphs including rabbits and hares can act as natural carriers or reservoirs of bacterial and parasitic zoonotic diseases. However, little is known on the epidemiology and potential public health significance of intestinal eukaryotes in wild leporids. We examined faecal samples from European wild rabbits (Oryctolagus cuniculus, n = 438) and Iberian hares (Lepus granatensis, n = 111) collected in the Autonomous Region of Andalusia in southern Spain during 2012-2021. We searched for the presence of DNA from the main intestinal protist and microsporidial pathogens of veterinary and public health concerns using molecular methods (PCR followed by Sanger and next-generation sequencing). Giardia duodenalis was the most prevalent species found (27.8%, 153/550; 95% CI: 24.1-31.8), followed by Cryptosporidium spp. (1.3%, 7/550; 95% CI: 0.5-2.6), Blastocystis sp. (1.1%, 6/550; 95% CI: 0.4-2.4) and Encephalitozoon intestinalis (0.2%, 1/550; 95% CI: 0.0-10.1). All samples tested negative for Enterocytozoon bieneusi. Sequence analyses revealed the presence of sub-assemblage BIV (n = 1) within G. duodenalis, and Cryptosporidium cuniculus (n = 6) and Cryptosporidium andersoni (n = 1) within Cryptosporidium. The presence of ruminant-adapted C. andersoni is indicative of a potential cross-species transmission event, although a spurious infection (mechanical carriage) cannot be ruled out. Samples assigned to C. cuniculus belonged to the gp60 subtype families Va (n = 3) and Vb (n = 2). The six Blastocystis-positive samples were identified as ST2 (n = 3) and ST1 + ST2 (n = 3). Our molecular results suggest that wild rabbits and hares were primarily infected by leporid-adapted species of eukaryotic pathogens. However, the occasional findings of zoonotic G. duodenalis sub-assemblage BIV, Blastocystis sp. ST1 and ST2, and Encephalitozoon intestinalis could be of public health relevance.

Taxonomy and molecular epidemiology of Cryptosporidium and Giardia - a 50 year perspective (1971-2021)

The protozoan parasites Cryptosporidium and Giardia are significant causes of diarrhoea worldwide and are responsible for numerous waterborne and foodborne outbreaks of diseases. Over the last 50 years, the development of improved detection and typing tools has facilitated the expanding range of named species. Currently at least 44 Cryptosporidium spp. and >120 genotypes, and nine Giardia spp., are recognised. Many of these Cryptosporidium genotypes will likely be described as species in the future. The phylogenetic placement of Cryptosporidium at the genus level is still unclear and further research is required to better understand its evolutionary origins. Zoonotic transmission has long been known to play an important role in the epidemiology of cryptosporidiosis and giardiasis, and the development and application of next generation sequencing tools is providing evidence for this. Comparative whole genome sequencing is also providing key information on the genetic mechanisms for host specificity and human infectivity, and will enable One Health management of these zoonotic parasites in the future.

Zoonotic giardiasis: an update

Giardia duodenalis is a common intestinal parasite in various hosts, with the disease giardiasis being a zoonosis. The use of molecular typing tools has improved our understanding of the distribution and zoonotic potential of G. duodenalis genotypes in different animals. The present review summarizes recent data on the distribution of G. duodenalis genotypes in humans and animals in different areas. The dominance of G. duodenalis assemblages A and B in humans and common occurrence of host-adapted assemblages in most domesticated animals suggests that zoonotic giardiasis is probably less common than believed and could be attributed mainly to contact with or contamination from just a few species of animals such as nonhuman primates, equines, rabbits, guinea pigs, chinchillas, and beavers. Future studies should be directed to advanced genetic characterization of isolates from well-designed epidemiological investigations, especially comparative analyses of isolates from humans and animals living in the same household or community. This will likely lead to better understanding of zoonotic transmission of G. duodenalis in different environmental and socioeconomic settings.

Prevalence and multi-locus genotyping of Giardia duodenalis in rabbits from Shaanxi province in northwestern China

Giardia duodenalis is an important parasite with veterinary and public health significance worldwide. The presence and zoonotic assemblages of G. duodenalis have previously been reported in rabbits. In this study, to understand the infection status of G. duodenalis in rabbits from Shaanxi province, a total of 537 fecal samples were collected from two breeds of rabbits in four age groups (<30 days, 31–90 days, 91–200 days and >200 days) from four geographical origins (Fengxiang, Yangling, Tongchuan, and Shanyang). The presence of G. duodenalis in these samples was assessed using molecular assays based on beta-giardin (bg). The glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi) loci were then amplified in the bg-positive samples for multi-locus genotype (MLG) analysis. The total prevalence of G. duodenalis in these rabbits was 3.54% (19/537). Giardia duodenalis infection was found in both breeds of rabbits, and in all farms and age groups, but with no statistically significant differences related to these factors (p > 0.05). Two assemblages, including B and E, were identified, with the former the predominant assemblage detected in both breeds, and in all age groups and farms. Sequence analysis revealed 2 (named as rbg1-2), 1 (named as rtpi1), and 2 (named as rgdh1-2) haplotypes at the gene loci of bg, tpi, and gdh, respectively, forming a multilocus genotype (MLG) of assemblage B (rbg1, rtpi1, and rgdh1). These findings reveal the significant zoonotic potential and genetic diversity of G. duodenalis in rabbits in Shaanxi Province, PR China.

Global Lysine Acetylation and 2-Hydroxyisobutyrylation Profiling Reveals the Metabolism Conversion Mechanism in Giardia lamblia

Giardia lamblia (G. lamblia) is the cause of giardiasis, a common infection that affects the general population of the world. Despite the constant possibility of damage because of their own metabolism, G. lamblia has survived and evolved to adapt to various environments. However, research on energy-metabolism conversion in G. lamblia is limited. This study aimed to reveal the dynamic metabolism conversion mechanism in G. lamblia under sugar starvation by detecting global lysine acetylation (Kac) and 2-hydroxyisobutyrylation (Khib) sites combined with quantitative proteome analyses. A total of 2999 acetylation sites on 956 proteins and 8877 2-hydroxyisobutyryl sites on 1546 proteins were quantified under sugar starvation. Integrated Kac and Khib data revealed that modified proteins were associated with arginine biosynthesis, glycolysis/gluconeogenesis, and alanine, aspartate, and glutamate metabolisms. These findings suggest that Kac and Khib were ubiquitous and provide deep insight into the metabolism conversion mechanism in G. lamblia under sugar starvation. Overall, these results can help delineate the biology of G. lamblia infections and reveal the evolutionary rule from prokaryote to eukaryote.

Cryptosporidium spp. and Giardia duodenalis emissions from humans and animals in the Three Gorges Reservoir in Chongqing, China

Cryptosporidium spp. and Giardia duodenalis are two waterborne protozoan parasites that can cause diarrhea. Human and animal feces in surface water are a major source of these pathogens. This paper presents a GloWPa-TGR-Crypto model that estimates Cryptosporidium and G. duodenalis emissions from human and animal feces in the Three Gorges Reservoir (TGR), and uses scenario analysis to predict the effects of sanitation, urbanization, and population growth on oocyst and cyst emissions for 2050. Our model estimated annual emissions of 1.6 × 10¹⁵ oocysts and 2.1 × 10¹⁵ cysts from human and animal feces, respectively. Humans were the largest contributors of oocysts and cysts, followed by pigs and poultry. Cities were hot-spots for human emissions, while districts with high livestock populations accounted for the highest animal emissions. Our model was the most sensitive to oocyst excretion rates. The results indicated that 74% and 87% of total emissions came from urban areas and humans, respectively, and 86% of total human emissions were produced by the urban population. The scenario analysis showed a potential decrease in oocyst and cyst emissions with improvements in urbanization, sanitation, wastewater treatment, and manure management, regardless of population increase. Our model can further contribute to the understanding of environmental pathways, the risk assessment of Cryptosporidium and Giardia pollution, and effective prevention and control strategies that can reduce the outbreak of waterborne diseases in the TGR and other similar watersheds.

Molecular characterization and zoonotic potential of Enterocytozoon bieneusi, Giardia duodenalis and Cryptosporidium sp. in farmed masked palm civets (Paguma larvata) in southern China

BACKGROUND

Masked palm civets are known to play an important role in the transmission of some zoonotic pathogens. However, the distribution and zoonotic potential of Enterocytozoon bieneusi, Giardia duodenalis and Cryptosporidium spp. in these animals remain unclear.

METHODS

A total of 889 fecal specimens were collected in this study from farmed masked palm civets in Hainan, Guangdong, Jiangxi and Chongqing, southern China, and analyzed for these pathogens by nested PCR and DNA sequencing.

RESULTS

Altogether, 474 (53.3%), 34 (3.8%) and 1 (0.1%) specimens were positive for E. bieneusi, G. duodenalis and Cryptosporidium sp., respectively. Sequence analysis revealed the presence of 11 novel E. bieneusi genotypes named as PL1-PL11 and two known genotypes Peru8 and J, with PL1 and PL2 accounting for 90% of E. bieneusi infections. Phylogenetically, PL4, PL5, PL9, PL10 and PL11 were clustered into Group 1, while PL1, PL2, PL3, PL6, PL7 and PL8 were clustered into Group 2. Assemblage B (n = 33) and concurrence of B and D (n = 1) were identified among G. duodenalis-positive animals. Further multilocus genotyping of assemblage B has revealed that all 13 multilocus genotypes in civets formed a cluster related to those from humans. The Cryptosporidium isolate from one civet was identified to be genetically related to the Cryptosporidium bamboo rat genotype II.

CONCLUSIONS

To the best of our knowledge, this first report of enteric protists in farmed masked palm civets suggests that these animals might be potential reservoirs of zoonotic E. bieneusi and G. duodenalis genotypes.

Longitudinal analysis of Giardia duodenalis assemblages in animals inhabiting drinking water catchments in New South Wales and Queensland - Australia (2013-2015)

Giardia duodenalis is one of the most common waterborne zoonotic parasites worldwide, and its occurrence in the environment and catchment reservoir water has serious implications for management of drinking water. The aim of the present study was to use molecular tools to identify the Giardia spp. infecting animals inhabiting five drinking water catchments across two states in Australia; New South Wales and Queensland, to better understand the potential health risks they pose. We used quantitative PCR to screen a total of 2174 faecal samples collected from dominant host species in catchment areas for the presence of G. duodenalis. All samples positive for G. duodenalis were further characterized and subtyped at tpi and gdh loci, respectively. The overall prevalence of G. duodenalis was 15.3% (332/2174, 95%CI; 13.8-16.9), and two zoonotic assemblages (assemblages A and B) and one potentially zoonotic assemblage (E) were detected in various host species. Additional subtyping of a subset of samples (n = 76) identified four human infectious sub-assemblages including AI, AII, BII-like and BIV-like, all of which have been previously reported in humans in Australia. The finding of zoonotic assemblages of G. duodenalis in the present study necessitates continued identification of the sources/carriers of human pathogenic strains in drinking water catchment areas for more accurate risk assessment and optimal catchment management.

Prevalence and Genotype Distribution of Giardia duodenalis in Rabbits in Shandong Province, Eastern China

Giardia duodenalis is a zoonotic enteric parasite that can infect humans and a number of animal species including rabbits with a worldwide distribution. Infection with G. duodenalis can cause serious public health problems and significant economic losses to animal husbandry. So accurate understanding of the prevalence and genotype distribution of G. duodenalis in rabbits is necessary. In the present study, a total of 616 fecal samples were collected from rabbits in Shandong province, eastern China, and examined in G. duodenalis prevalence and genotypes by nested PCR amplification of β-giardin (bg), glutamate dehydrogenase (gdh), and triosephosphate isomerase (tpi) gene loci of G. duodenalis. Sixty-nine (11.2%) of the examined rabbit fecal samples were G. duodenalis-positive. Of them, the prevalence of G. duodenalis is 8.4% (41/490) in Rizhao city and 22.2% (28/126) in Weihai city. Breeds, region, and feeding modes were highly correlated with G. duodenalis infection in rabbits. Moreover, three genotypes (assemblages A, B, and E) were identified in rabbits at three gene loci, and the assemblage E was the dominant genotype, while the assemblage A was reported in rabbits in China for the first time. It is noticeable that two rabbits were found to be infected with two different G. duodenalis assemblages (assemblages A and E, assemblages B and E, respectively). These findings enrich the genotype distribution of G. duodenalis in rabbits and provide baseline data for preventing and controlling G. duodenalis infection in rabbits in eastern China.

Molecular epidemiology of giardiasis from a veterinary perspective

A total of eight Giardia species are accepted. These include: Giardia duodenalis (syn. Giardia intestinalis and Giardia lamblia), which infects humans and animals, Giardia agilis, Giardia ardeae, Giardia psittaci, Giardia muris, Giardia microti, Giardia peramelis and G. cricetidarum, which infect non-human hosts including amphibians, birds, rodents and marsupials. Giardia duodenalis is a species complex consisting of eight assemblages (A-H), with assemblages A and B the dominant assemblages in humans. Molecular studies to date on the zoonotic potential of Giardia in animals are problematic and are hampered by lack of concordance between loci. Livestock (cattle, sheep, goats and pigs) are predominantly infected with G. duodenalis assemblage E, which has recently been shown to be zoonotic, followed by assemblage A. In cats and dogs, assemblages A, B, C, D and F are commonly reported but relatively few studies have conducted molecular typing of humans and their pets and the results are contradictory with some studies support zoonotic transmission but the majority of studies suggesting separate transmission cycles. Giardia also infects a broad range of wildlife hosts and although much less well studied, host-adapted species as well as G. duodenalis assemblages (A-H) have been identified. Fish and other aquatic wildlife represent a source of infection for humans with Giardia via water contamination and/or consumption of undercooked fish and interestingly, assemblage B and A predominated in the two molecular studies conducted to date. Our current knowledge of the transmission dynamics of Giardia is still poor and the development of more discriminatory typing tools such as whole genome sequencing (WGS) of Giardia isolates is therefore essential.

Seroprevalence and risk factors of Toxoplasma gondii infection in domestic raccoon dogs in four provinces in northern China

Toxoplasma gondii is an obligate intracellular apicomplexan parasite that can infect almost all homoiothermal animals, including domestic raccoon dogs (Nyctereutes procyonoides). However, related reports on T. gondii infection in domestic raccoon dogs were limited in China. Therefore, a serological investigation was undertaken to investigate the seroprevalence and risk factors for T. gondii infection in domestic raccoon dogs. A total of 962 serum samples were collected from Jilin, Liaoning, Heilongjiang and Hebei provinces, northern China between April 2016 and November 2017, and were detected by the indirect hemagglutination test (IHA). The seroprevalence of T. gondii infection was 7.28% in the overall surveyed raccoon dogs by IHA, which was different among the four provinces ranging from 6.54% to 7.57%. The seroprevalence of T. gondii infection in male and female raccoon dogs was 6.62% and 7.79%, respectively. Based on statistical analysis, age was regarded as an important risk factor for T. gondii infection in raccoon dogs in this study (P < 0.05). This study reported the seroprevalence and risk factors of T. gondii infection in domestic raccoon dogs in northern China, which provided essential data for prevention and control of T. gondii infection in raccoon dogs in Jilin province, Liaoning province, Heilongjiang province and Hebei province.

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.