Prevalence and molecular characterisation of Giardia duodenalis in calves with diarrhoea

The detection and phylogenetic characterization of Cryptosporidium, Cystoisospora, and Giardia duodenalis of cats in South Korea

Introduction

Cryptosporidium, Cystoisospora, and Giardia duodenalis are gastrointestinal protozoa parasites that cause diarrhea in various animals. However, information regarding the detection and phylogenetic characterization of gastrointestinal protozoa parasites in cats is limited throughout South Korea. Therefore, this study aimed to determine the detection and identify subspecies of gastrointestinal protozoa parasites in cats from South Korea.

Methods

A total of 290 fecal samples were collected from stray, companion, and shelter cats in six provinces. Cryptosporidium, Cystoisospora, and G. duodenalis were identified by PCR. All positive samples were subtyped by PCR and sequencing of gp60, ITS-1, tpi, bg, and gdh.

Results

The overall detection of gastrointestinal protozoan parasitic infection was 17.93%. G. duodenalis was the most prevalent, with 7.93%, followed by Cystoisospora spp. (7.24%) and Cryptosporidium spp. (4.48%). In addition, C. felis (n=10), C. parvum (n=2), C. ryanae (n=1), Cystoisospora felis (n=14), Cystoisospora suis (n=5), Cystoisospora ohioensis (n=1), Cystoisospora spp. were identified in subspecies analysis of positive samples. C. felis showed a significant association with diarrhea (7.81%) and living condition (6.04%), and Cystoisospora felis in diarreha (9.38%) according to detection. Through phylogenetic analysis of the tpi, bg, and gdh genes from 23 G. duodenalispositive samples, it was confirmed that the samples of present study belonged to assemblage A, B, C, and D.

Discussion

South Korean cats have a high rate of gastrointestinal protozoan parasites infection with cat-specific Cryptosporidium and Cystoisospora, which are associated with living conditions and diarrhea symptoms. Moreover, zoonotic and other animal-specific subtype of protozoan parasites have been detected in cat 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.

Molecular detection and assemblage analysis of the intestinal protozoan Giardia duodenalis in wild boars in Korea

Giardia duodenalis (syn. G. intestinalis, G. lamblia) is the only Giardia species that infects humans and most other mammals. Wild boars are a reservoir of many viruses, bacteria, and parasites that can be transmitted to livestock and humans. This study examined the infection rate of G. duodenalis in wild boars and confirmed its specificity by comparing assemblages through PCR amplification of the 18S rRNA, gdh, and β-giardin genes. Fecal samples were collected from roadkilled or trapped wild boars from April 2016 to December 2021 in Korea. DNA was extracted directly from 612 wild boar fecal specimens using a commercial kit. PCR was performed targeting the 18S rRNA region, β-giardin, and glutamate dehydrogenase genes of G. duodenalis. Some PCR-positive samples were selected for sequencing analysis. The obtained sequences were subsequently used for phylogenetic tree construction. Of the 612 samples tested, 125 (20.4%) were positive for G. duodenalis. The highest infection rate was detected in the central region (12.0%) and in autumn (12.7%). Among the risk factors, the seasonal factor was statistically significant (p = 0.012). Phylogenetic analysis revealed three genetic assemblages: A, B, and E. Assemblages A and B exhibited 100% identity with Giardia sequences isolated from human and farmed pigs in Korea and Japan. This result cannot be ignored because it indicates the possibility of zoonotic transmission. Therefore, continuous management and monitoring of this pathogen are necessary to prevent transmission and protect animal and human health.

Meta-Analysis of the Prevalence of Giardia duodenalis in Cattle in China

Giardia duodenum (G. duodenalis) can cause giardiasis and infect a variety of hosts. So far, there have been no detailed data regarding the positive rate of G. duodenalis in cattle in China. Here, a systematic literature review was carried out to investigate the epidemiology of bovine G. duodenalis in China. To perform the meta-analysis, the databases China National Knowledge Infrastructure, VIP Chinese Journal Databases, WanFang Databases, PubMed, and ScienceDirect were employed for screening studies related to the prevalence of G. duodenalis in cattle in China. The total prevalence of G. duodenalis in cattle was estimated to be 8.00% (95% confidence interval [CI]: 5.51-11.62). In the age subgroup, the prevalence of G. duodenalis in calves (11.72%; 95% CI: 7.75-17.73) was significantly higher than that in cattle of other age groups. An analysis based on seasons showed that the prevalence of G. duodenalis in cattle was higher in summer (9.69%; 95% CI: 2.66-35.30) than that in other seasons. The prevalence of G. duodenalis in cattle in 2016 or later was 11.62% (95% CI: 6.49-20.79), which was significantly higher than that before 2016 (3.65%; 95% CI: 2.17-6.12). The highest prevalence of G. duodenalis in cattle was 74.23% (95% CI: 69.76-78.45) recorded in South China. The NOAA's National Center for Environmental Information (https://gis.ncdc.noaa.gov/maps/ncei/cdo/monthly) was used to extract relevant geoclimatic data (latitude, longitude, elevation, temperature, precipitation, humidity, and climate). By analyzing the data of each subgroup, it was shown that age of cattle, sampling year, province, region, temperature, and climate were potential risk factors for giardiasis prevalence in cattle. Based on the analysis of common factors and geographical factors, it is recommended to strengthen effective management measures (e.g., ventilation and disinfection in warm and humid areas) and formulate relevant policies according to local conditions. Breeders should pay more attention to the detection of G. duodenalis in calves, to prevent giardiasis prevalence in cattle of different ages, thereby reducing the economic losses of animal husbandry in China.

Distribution of Gastrointestinal Parasitic Infection in Domestic Pigs in the Republic of Korea: Nationwide Survey from 2020-2021

This study aimed to examine the distribution of gastrointestinal parasitic infections in domestic pigs in the Republic of Korea. From May 2020 to October 2021, 364 pig fecal samples were collected from 75 farms in 7 Provinces and microscopically examined. A total of 170 (46.7%) pigs were infected with at least one of the following parasites: Balantioides coli, strongyles, Ascaris suum, Trichuris suis, and coccidia. By parasite species, B. coli, strongyles, A. suum, T. suis, and coccidia oocysts or eggs were detected in 144 (39.6%), 24 (6.6%), 14 (3.8%), 4 (1.1%), and 1 (0.3%) samples, respectively. One hundred fifty-four, 15, and 1 cases showed single, double, and triple infections, respectively. Of the swine fecal samples from 75 farms, 69 specimens (92.0%) were infected with 1 or more parasites. All surveyed farms across the country exhibited a positive rate of over 30%, among which the highest positive rate was 65.0% in Chungcheongnam-do, and Jeollabuk-do was followed by 61.9%. Winter showed a statistically lower prevalence than other seasons. This study showed that gastrointestinal parasites are prevalent in pigs in Korea, although the diversity of parasites is low.

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.

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.

Causative agents and epidemiology of diarrhea in Korean native calves

Calf diarrhea caused by infectious agents is associated with economic losses in the cattle industry. The purpose of this study was to identify the causative agents and epidemiological characteristics of diarrhea in Korean native calves (KNC). In total, 207 diarrheal KNC aged less than 7 months were investigated. Fecal samples collected from the rectum were examined for causative agents using polymerase chain reaction (PCR) or real-time PCR and the number of oocysts were counted. Fourteen causative agents were detected from 164 of the 207 diarrheal KNC. Rotavirus was the most common agent (34.8%), followed by Eimeria spp. (31.7%), Escherichia coli (22.0%), Giardia spp. (14.0%), Clostridium difficile (9.8%), bovine viral diarrhea virus (8.5%), coronavirus (7.9%), Cryptosporidium spp. (7.3%), torovirus (6.7%), parvovirus (5.5%), norovirus (4.9%), kobuvirus (1.8%), adenovirus (1.2%), and Salmonella spp. (0.6%). About 95 (57.9%) of 164 calves were infected with a single causative agent and 42.1% were infected by multiple agents. No significant difference was observed in mortality between calves infected with a single agent and multiple agents. The occurrence of diarrhea caused by rotavirus, Eimeria spp., kobuvirus, and Giardia spp. was significantly different based on onset age, and the prevalence of diarrhea caused by rotavirus or C. difficile was significantly different between seasons. This study help the understanding of KNC diarrhea for the development of an effective strategy for disease prevention and control, especially in Eastern provinces of South Korea.

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.

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.

First Molecular Detection and Phylogenetic Analyses of Zoonotic Giardia intestinalis in Horses in Turkey

The goal of our study was to investigate the molecular prevalence of Giardia intestinalis in naturally infected horses in Kayseri, Central Anatolia Region in Turkey, to determine the molecular characterization of the obtained isolates and to exhibit the potential role of horses in zoonotic transmission of G. intestinalis. Fecal samples were randomly collected from totally 150 horses with clinically healthy between March and June of 2018. After the genomic DNA extractions, 25 (16.6%) of the 150 fecal samples, were found positive for G. intestinalis by nested PCR analyses of β-giardin gene. Phylogenetic analysis of the β-giardin gene sequences of G. intestinalis showed that the sequences detected in this study belonged to assemblage A that is regarded as zoonotic. Our study is the first report on the presence of G. intestinalis in horses in Turkey. The findings of the present study indicate that future research studies are required to determine molecular epidemiology and geographical distribution of G. intestinalis infections in horses nationwide. In addition, this study also may be helpful to assess the zoonotic potential for public health of G. intestinalis infections.

Morphological and molecular diagnosis of Eimeria sp. that caused fatality in a red-necked wallaby (Macropus rufogriseus) in Korea

A red-necked wallaby (Macropus rufogriseus) in the Republic of Korea, introduced from Australia, died in 12 d after exhibiting anorexia and diarrhea. Postmortem examination revealed that the wallaby died due to coccidiosis by Eimeria sp. Morphologically, Eimeria sp. identified closely resembled E. mykytowyczi. The 18S rRNA sequence analysis showed that Eimeria sp. identified in this study has a 98.5% identity with that in Australian red kangaroo (M. rufus). However, owing to insufficient molecular information on marsupial-specific Eimeria, exact species could not be determined. Phylogenetically, Eimeria sp. identified in this study belonged to clade five of the marsupial group.

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

Giardia duodenalis is an important zoonotic protozoan parasite that infects humans and other animals. This study was conducted to investigate the prevalence and molecular characterization of G. duodenalis infection in the feces of normal and diarrheic pre-weaned calves aged 1-60 days. Fecal samples were collected from 90 Korean native calves in 7 different regions in the central region of the Republic of Korea (ROK). Of the 90 fecal samples, 9 (10%, 9/90) were positive for G. duodenalis by PCR using the β-giardin gene. Phylogenetic analysis identified G. duodenalis assemblages A and E in the farms examined and G. duodenalis with both assemblage A and E was detected in one farm. Assemblage A was detected in calves with normal feces, while assemblage E was frequently identified in calves with diarrhea. This is the first report of the identification of assemblage A in pre-weaned calves with normal feces in the ROK. These results suggest that G. duodenalis infection is closely associated with calf age and management systems including overcrowding, age-mixed grouping, and hygiene. Thus, giardiasis in calves is an important disease because of its zoonotic significance and should be screened in young animals. Further studies are necessary to elucidate the transmission routes of zoonotic G. duodenalis assemblages.

Cryptosporidium outbreak in calves on a large dairy farm: Effect of treatment and the association with the inflammatory response and short-term weight gain

Cryptosporidium spp. infections in neonatal dairy calves can cause diarrhoea and, in rare cases, death. The infection is usually self-limiting, but halofuginone lactate (HL) can be used prophylactically. Calves (n=144) in the study were born during a 2-month period on one farm. A total of 901 serum and 767 faecal samples were collected. Based on HL treatment, the calves were divided into 3 groups: I) not treated, II) treated incorrectly (treatment started >48h after birth, or lasted <7days), and III) treated correctly (started <48h after birth, and lasted ≥7days). Over the 3-month observation period, 14.6% (n=21) of the calves died, of which most (67%) had not been treated with HL. Correctly performed treatment of cryptosporidiosis significantly delayed the onset of oocysts shedding (P<0.001) and reduced haptoglobin (HP) and serum amyloid A (SAA) concentrations in the second week of life. HP concentration and HL treatment were negatively associated with weight gain at 3months of age. Cryptosporidium positive faecal samples were significantly (P<0.001) more likely to be diarrhoeic but Giardia or Eimeria positive samples were not. Correct prophylactic treatment with HL delayed the shedding of Cryptosporidium oocysts and improved survival, but was negatively associated with weight gain. Incorrect treatment had a low impact on mortality and resembled no treatment regarding the proportion of calves shedding oocysts. Acute phase response (APR) in the second week of life seemed to be positively associated with shedding high amounts of Cryptosporidium oocysts.

Prevalence and multilocus genotyping of Giardia duodenalis in pigs of Shaanxi Province, northwestern China

Background

Giardiasis, caused by Giardia duodenalis (syn. Giardia intestinalis, Giardia lamblia), is a significant zoonotic parasitic disease of animals and humans worldwide. Accurate genotyping of G. duodenalis is essential for efficient control and management of giardiasis. The objectives of the present study were to investigate the prevalence and assemblages of giardiasis in pigs in Shaanxi Province, northwestern China, and for the first time study multilocus genotypes (MLGs) in pigs using multilocus genotyping technology in this region.

Results

Of 560 faecal samples collected from five farms in Shaanxi Province, 45 were positive for G. duodenalis and significant differences in prevalence were observed among different locations. Differences in prevalence were also detected in pigs of different age groups, with the highest prevalence in sows and the lowest in boars. Two assemblages, A and E, were identified, and a mixed infection of both A and E was identified in one faecal sample. Assemblage E was predominant and widely distributed in all investigated areas and age groups. Genetic viability was detected for both assemblages, and four different multi-locus genotypes (MLGs) within assemblage E were found, MLGE1-MLGE4.

Conclusions

Giardia duodenalis was detected in pigs from Shaanxi Province, northwestern China, and genetic diversity was observed in these infections. Both assemblages A and E were detected, and four distinct MLGs within assemblage E were identified. These findings provide new data for controlling G. duodenalis infection in pigs.