Identification of zoonotic Giardia duodenalis in Korean native calves with normal feces

Multilocus genotyping of Giardia duodenalis in pre-weaned calves with diarrhea in the Republic of Korea

Giardia duodenalis is a protozoan parasite that infects humans, companion animals, livestock, and wildlife. Infections in cattle caused by this parasite are often asymptomatic, but such infections can cause diarrhea, reduced weight gain, and ill-thrift in young calves. Although G. duodenalis causes diarrhea in calves, only a few studies have been conducted on calves in the Republic of Korea (ROK). Here, we aimed to determine the prevalence and distribution of G. duodenalis assemblages in pre-weaned calves with diarrhea in the ROK, identify the association between the occurrence of G. duodenalis and the age of calf, and perform molecular characterization of G. duodenalis. We collected 455 fecal samples from pre-weaned native Korean calves (≤60 days old) with diarrhea in four different regions. G. duodenalis was detected using nested PCR targeting the beta-giardin (bg) gene, and positive samples were further genotyped for the glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi) genes. The overall prevalence of G. duodenalis in calves with diarrhea was 4.4% (20/455) based on the analysis of bg. The highest prevalence was observed in calves aged 11-30 days (7.5%; 95% confidence interval: 3.7%-11.3%), whereas the lowest prevalence was observed in neonatal calves. From the 20 samples that were positive for bg, 16, 5, and 6 sequences were obtained following genotyping of bg, gdh, and tpi, respectively. Sequencing analysis of the bg gene revealed the presence of assemblage E (n = 15) and sub-assemblage AⅠ (n = 1) in the samples. Moreover, we detected mixed infections with assemblages E and A in two calves for the first time. Among the sequences obtained herein, two new subtypes of assemblage E were detected in gdh and tpi sequences each. The results suggest that G. duodenalis is an infectious agent causing diarrhea in calves, and pre-weaned calves are at a higher risk of infection than neonatal calves. Multilocus genotyping should be performed to confirm the presence of potentially zoonotic genotypes. These results highlight the importance of cattle as a source of zoonotic transmission of G. duodenalis to humans.

Prevalence and multilocus genotyping of Giardia duodenalis in Holstein cattle in Yunnan, China

Giardia duodenalis is an important zoonotic protozoon, which can infect a variety of animals, causing diarrhea and even death of animals or humans. Dairy cattle have been implicated as important sources of human G. duodenalis. However, the information about the prevalence and genetic diversity of G. duodenalis in dairy cattle in China's Yunnan Province remains limited. This study investigated the occurrence and multilocus genotyping of G. duodenalis of Holstein cattle in Yunnan Province, China. A total of 524 fresh fecal samples of Holstein cattle were randomly collected from 8 farms in Yunnan. In this study, 27.5% (144/524) of tested samples were positive for G. duodenalis infection. The highest infection ratio was found in preweaned calves (33.7%), and the infection rates of postweaned calves, growing cattle, and adult cattle were 24.5%, 23.0%, and 17.3%, respectively. The sequence analysis of SSU rRNA gene showed that the predominant assemblage of G. duodenalis in this study was assemblage E (97.9%, 141/144), whereas assemblage A was identified only in three samples (2.1%, 3/144). All G. duodenalis-positive samples were further assayed with nested polymerase chain reaction (PCR) targeting β-giardin (bg), triosephosphate isomerase (tpi), and glutamate dehydrogenase (gdh) genes, and 87, 41, and 81 sequences were obtained, respectively. Mixed infection of assemblages A and E of G. duodenalis was detected in three samples. Multilocus genotyping yielded 23 multilocus genotypes (MLGs). This is the first study that reveals the prevalence data of G. duodenalis in Holstein cattle in Yunnan Province, and the results of this study provided baseline data for the prevention and control of G. duodenalis infection in Holstein cattle in Yunnan Province, China.

Multilocus Genotyping of Giardia duodenalis Occurring in Korean Native Calves

Giardia duodenalis is one of the most widely occurring zoonotic protozoan parasites causing diarrheal disease in calves. This study aimed to investigate the prevalence of G. duodenalis in Korean native calves and elucidate the causal factors associated with giardiasis in these animals. We investigated the sequences of three genes (ssu, bg, and gdh) of G. duodenalis in fecal samples collected from 792 Korean native calves during 2019–2020. Data were analyzed with regard to age, sex, sampling season, and the fecal sample type (based on its physical characteristics). The samples were screened for the three genes mentioned above, and 44 samples (5.6%) were G. duodenalis-positive. Polymerase chain reaction results showed a significantly higher prevalence of the infection in calves aged ≥1 month and in those with watery diarrhea in spring season. Screening for the gene sequences ssu (87.5%), bg (96.2%), and gdh (96.7%) revealed that most of the G. duodenalis-positive samples belonged to assemblage E. Four of the G. duodenalis-positive samples belonged to the zoonotic assemblage A. This study highlights the importance of continuous surveillance of genetic mutations in G. duodenalis for the detection of emerging variants of zoonotic G. duodenalis in calves.

Prevalence and Multilocus Genotyping of Giardia lamblia in Cattle in Jiangxi Province, China: Novel Assemblage E Subtypes Identified

Giardia lamblia is a common enteric pathogen associated with diarrheal diseases. There are some reports of G. lamblia infection among different breeds of cattle in recent years worldwide. However, it is yet to know whether cattle in Jiangxi province, southeastern China is infected with G. lamblia. The objectives of the present study were to investigate the prevalence and examine the multilocus genotypes of G. lamblia in cattle in Jiangxi province. A total of 556 fecal samples were collected from 3 cattle breeds (dairy cattle, beef cattle, and buffalo) in Jiangxi province, and the prevalence and genotypes of G. lamblia were determined by the nested PCR amplification of the beta-giardin (bg) gene. A total of 52 samples (9.2%) were positive for G. lamblia. The highest prevalence of G. lamblia was detected in dairy cattle (20.0%), followed by that in beef cattle (6.4%), and meat buffalo (0.9%). Multilocus sequence typing of G. lamblia was performed based on sequences of the bg, triose phosphate isomerase and glutamate dehydrogenase loci, and 22, 42, and 52 samples were amplifiable, respectively, forming 15 MLGs. Moreover, one mixed G. lamblia infection (assemblages A and E) was found in the present study. Altogether, 6 novel assemblage E subtypes (E41*–E46*) were identified for the first time. These results not only provided baseline data for the control of G. lamblia infection in cattle in this southeastern province of China, but also enriched the molecular epidemiological data and genetic diversity of G. lamblia in cattle.

Multilocus genotyping of Giardia duodenalis from pigs in Korea

Giardia duodenalis (syn. G. intestinalis, G. lamblia) is an important zoonotic parasite infecting livestock (including pigs) through ingesting cysts in contaminated food or water. This parasite has been classified into eight different genetic assemblages, A to H. Here, we examined the individual-level prevalence of G. duodenalis in domestic pig farms and confirmed host specificity by genotype comparisons. Samples were collected from southern and central Korea, between May 2017 and January 2019. DNA directly extracted from 745 pig fecal specimens were tested by PCR for G. duodenalis small subunit ribosomal RNA (ssu rRNA), glutamate dehydrogenase (gdh), and β-giardin gene sequences. Based on ssu rRNA PCR, 110 (14.8%) were positive for G. duodenalis. Infection risk was the highest in the fattener group (31/139, 22.3%) and during the autumn season (52/245, 21.2%: p < .001). No statistically significant differences in risk for infection were observed between fecal types (normal versus diarrheal). Fifty ssu rRNA samples, three gdh samples, and five β-giardin samples were successfully sequenced and genotyped. Ssu rRNA assemblage sequence analysis identified E (40.0%, 20/50), D (34.0%, 17/50), C (24.0%, 12/50), and A (2.0%, 1/50). The gdh locus identified three samples as assemblage E, and the β-giardin locus identified four samples as assemblage E and one as assemblage C. Assemblage A sequences obtained (ssu rRNA; MK430919) had 100% identity with Giardia sequences isolated from a Korean individual (AJ293301), indicating the potential of zoonotic transmission. Continuous management and monitoring for prevention of transmission and protection of animal and human health are essential.

Multilocus genotyping and risk factor analysis of Giardia duodenalis in dogs in Korea

Giardia duodenalis (syn. G. intestinalis, G. lamblia), a protozoan parasite that infects most mammals (including humans), has recently been classified into eight different groups/assemblages (A to H) based on host range and genetic characteristics. Assemblages A and B have been reported in humans and in many other animals, including dogs. This study analyzed Giardia infections, implementing multilocus genotyping, including the 18S rRNA, gdh, and β-giardin genes, in sheltered, companion, and special-purpose dogs throughout Korea. Of 640 dog stool samples, 99 (15.5%) were G. duodenalis-positive; this prevalence was similar to that previously reported in Korean calves. In addition, the prevalence was significantly higher in the southern region, and lower in non-sheltered dogs, older dogs, and in the autumn season. Phylogenetic analysis revealed that all G. duodenalis-positive samples belonged to assemblages C and D. Although no G. duodenalis assemblages A and B (mainly found in humans) were identified in this study, assemblage C was detected in the main types of dogs in contact with humans. Assemblage C, thought to be dog-specific, was recently identified in humans. As Giardia (including zoonotic assemblages) is distributed throughout Korea, dog living environments and the potential for dog-human transmission should be monitored.

Prevalence and molecular characterization of Cryptosporidium and Giardia in pre-weaned native calves in the Republic of Korea

Cryptosporidium spp. and Giardia duodenalis are protozoan parasites that cause diarrhea in humans and animals. Molecular data on Cryptosporidium spp. and G. duodenalis in calves in the Republic of Korea (ROK) is limited; thus, we investigated the prevalence of Cryptosporidium and Giardia in pre-weaned calves, analyzed the association between these parasites and diarrhea, and identified their zoonotic potential for human infection. Fecal samples were collected from 315 pre-weaned calves aged 1-60 days from 10 different regions in the ROK and screened for Cryptosporidium spp. and G. duodenalis using PCR. Overall prevalence of Cryptosporidium spp. and G. duodenalis was 4.4% (n = 14) and 12.7% (n = 40), respectively. Co-infection was not detected. All Cryptosporidium-positive samples were identified as C. parvum after sequence analysis of a small subunit rRNA fragment and further subtyped into zoonotic IIaA15G2R1 (n = 13) and IIaA18G3R1 (n = 1) by DNA sequencing of the 60-kDa glycoprotein gene. To our knowledge, this is the first report of C. parvum IIaA15G2R1 subtype in calves in the ROK. Based on β-giardin (bg) gene, G. duodenalis-positive samples belonged to assemblages E (n = 36) and A (n = 4), with the latter belonging to subtype A1, the zoonotic genotype. Six subtypes of assemblage E were identified at the bg locus: E1 (n = 6), E2 (n = 3), E3 (n = 13), E5 (n = 1), E8 (n = 1), and E11 (n = 1). The occurrence of C. parvum and G. duodenalis was not associated with diarrhea in pre-weaned Korean native calves. The present results suggest that the prevalence of C. parvum is not related to calf age; in contrast, the prevalence of G. duodenalis was significantly higher in 41-50-day-old calves (odds ratio = 9.90, 95% confidence interval 2.37-41.34; P = 0.001) than in 1-10-day-old calves. Therefore, calves are a potential source of zoonotic transmission, which may have significant public health implications.

Infection patterns, clinical significance, and genetic characteristics of Enterocytozoon bieneusi and Giardia duodenalis in dairy cattle in Jiangsu, China

The infection patterns and clinical significance of Enterocytozoon bieneusi and Giardia duodenalis in dairy cattle remain poorly investigated despite their common occurrence. Data on the genetic diversity are also needed to understand the transmission and human-infective potential of the two pathogens. In this study, fecal specimens from 1366 dairy cattle on a large farm were examined for the presence and genotype distribution of E. bieneusi and G. duodenalis by PCR and DNA sequencing. The overall infection rates of E. bieneusi and G. duodenalis were 13.0% and 20.6%, respectively. Pre-weaned calves had significantly higher infection rates of both pathogens than post-weaned and adult cattle (P < 0.001), with peak occurrence of the pathogens in animals of 7-12 weeks. In both pre- and post-weaned calves, animals with diarrhea were 2.1-3.0 times more likely to be infected with either pathogen than those without diarrhea (P < 0.01). The E. bieneusi identified belonged to five genotypes, including J (n = 138), I (n = 21), BEB4 (n = 10), Type IV (n = 1), and a novel genotype CHC17 (n = 1). Genotype J was the dominant one in all age groups, whereas genotype I was only identified in calves of 6-11 weeks. Genotyping of G. duodenalis at three genetic loci identified assemblage E (n = 278), assemblage A (n = 2), and concurrence of the two (n = 1). Altogether, 13, 7 and 10 subtypes of assemblage E were detected at the bg, gdh, and tpi loci, respectively, forming 65 multilocus genotypes. The formation of two major clusters of MLGs in eBURST analysis indicated that intra-assemblage genetic recombination of two dominant MLGs could have led to the high genetic heterogeneity within assemblage E on a single farm. Results of this study provide much needed data on the pathogenicity of E. bieneusi and G. duodenalis in pre- and post-weaned calves. The clinical significance of the two pathogens in dairy cattle warrants further investigations.

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.

Molecular characterization of Giardia intestinalis and Cryptosporidium parvum from calves with diarrhoea in Austria and evaluation of point-of-care tests

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Giardia intestinalis (48/177) and Cryptosporidium parvum (98/177) occur in Austrian calves.

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C. parvum genotypes IIaA15G2R1, IIaA19G2R2, IIaA21G2R1 and IIaA14G1R1 were found.

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Giardia intestinalis assemblage E and a single sample of assemblage A were found.

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Cryptosporidium was detected mostly in the first two weeks of age (72/102).

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Point-of-care test validity varied greatly for Giardia and Cryptosporidium.

To obtain information about the occurrence and genotype distribution of G. intestinalis and C. parvum in Austrian cattle, faecal samples from diarrhoeic calves younger than 180 days of age originating from 70 farms were examined. Of the 177 faecal samples, 27.1% were positive for Giardia cysts (immunofluorescence microscopy) and 55.4% for Cryptosporidium oocysts (phase-contrast microscopy). Positive samples were characterized by nested PCR for Giardia, 83.3% (triosephosphate isomerase; tpi) and 89.6% (β-giardin; bg) were positive, while the Cryptosporidium nested PCR returned 92.5% (60-kDa glycoprotein) positive results. Sequence analysis revealed one assemblage A-positive sample and 30 (bg) respectively 29 (tpi) assemblage E-positive samples for G. intestinalis. For C. parvum four subtypes within the IIa family (IIaA15G2R1, n = 29; IIaA19G2R2, n = 3; IIaA21G2R1, n = 2; IIaA14G1R1, n = 1) could be differentiated. Validation of two immunochromatographic point-of-care tests resulted in a sensitivity of 29.2% and 77.6%; a specificity of 98.4% and 91.1% for the detection of Giardia intestinalis and Cryptosporidium parvum, respectively. Results confirm the widespread occurrence of both protozoa in diarrhoeic calves in Austria.

Effects of some natural products from fungal and herbal sources on Giardia lamblia in vivo

Giardia lamblia (G. lamblia) is the most widely known protozoan parasite that causes human gastrointestinal infection worldwide. Some natural compounds exhibited pivotal effects against different infectious diseases. In this research, the antigiardial activity and cytotoxicity of fungal chitosan, nano-chitosan, Rhamnus cathartica (R. cathartica) and emodin were evaluated in Balb/c mice. Genotyping of G. lamblia was assessed by PCR-RFLP technique. Different concentrations of mentioned compounds were used to check their antigiardial and cytotoxicity effects on human intestinal epithelial cells (HT-29) after 24, 48 and 72 h. The G. lamblia strain used in the current work was genotyped and revealed as an AII assemblage. All the concentration showed acceptable activity against G. lamblia cysts and trophozoites in comparison to the negative and positive controls (furazolidone and metronidazole) in vitro (P 0.05). The maximum mortality rate (100%) was achieved at 100 and 50 µg kg-1 concentrations after 48 and 72 h of exposure time, respectively. Our results provide significant information about the new antigiardial agent and proposed the nano-chitosan and emodin for the development of new drugs against G. lamblia in the future.