Occurrence of a Cryptosporidium xiaoi-like genotype in peafowl (Pavo cristatus) in China

The risk of wild birds contaminating source water with zoonotic Cryptosporidium and Giardia is probably overestimated

Cryptosporidium and Giardia are important waterborne protozoan parasites that are resistant to disinfectants commonly used for drinking water. Wild birds, especially wild migratory birds, are often implicated in the contamination of source and wastewater with zoonotic diseases, due to their abundance near water and in urban areas and their ability to spread enteric pathogens over long distances. This review summarises the diversity of Cryptosporidium and Giardia in birds, with a focus on zoonotic species, particularly in wild and migratory birds, which is critical for understanding zoonotic risks. The analysis revealed that both avian-adapted and zoonotic Cryptosporidium species have been identified in birds but that avian-adapted Cryptosporidium species dominate in wild migratory birds. Few studies have examined Giardia species and assemblages in birds, but the non-zoonotic Giardia psittaci and Giardia ardeae are the most commonly reported species. The identification of zoonotic Cryptosporidium and Giardia in birds, particularly C. parvum and G. duodenalis assemblages A and B in wild migratory birds, is likely due to mechanical carriage or spillback from birds co-grazing pastures contaminated with C. parvum from livestock. Therefore, the role of wild migratory birds in the transmission of zoonotic Cryptosporidium and Giardia to source water is likely overestimated. To address knowledge gaps, it is important to conduct more extensive studies on the prevalence of Cryptosporidium and Giardia in a broader range of migratory wild birds. There is also a need to investigate the extent to which zoonotic infections with C. hominis/C. parvum and G. duodenalis assemblages A and B are mechanical and/or transient, and to assess the load and viability of zoonotic oo/cysts shed in avian faeces. Understanding the contribution of birds to zoonoses is essential for effective disease surveillance, prevention, and control.

Dominance of the zoonotic pathogen Cryptosporidium meleagridis in broiler chickens in Guangdong, China, reveals evidence of cross-transmission

Background

Cryptosporidium is one of the most prevalent parasites infecting both birds and mammals. To examine the prevalence of Cryptosporidium species and evaluate the public health significance of domestic chickens in Guangdong Province, southern China, we analyzed 1001 fecal samples from 43 intensive broiler chicken farms across six distinct geographical regions.

Methods

Individual DNA samples were subjected to nested PCR-based amplification and sequencing of the small subunit of the nuclear ribosomal RNA gene (SSU rRNA). Analysis of the 60 kDa glycoprotein gene (gp60) was performed to characterize the subtypes of C. meleagridis.

Results

The overall prevalence of Cryptosporidium was 13.2% (95% CI 11.1–15.3) (24 of 43 farms), with C. meleagridis (7.8%), C. baileyi (4.8%) and mixed infections (0.6%). Using the gp60 gene, three subtype families, IIIb, IIIe and IIIg, were identified, including six subtypes: one novel (IIIgA25G3R1a) and five previously reported (IIIbA23G1R1c, IIIbA24G1R1, IIIbA21G1R1a, IIIeA17G2R1 and IIIeA26G2R1). Within these subtypes, five known subtypes were genetically identical to those identified in humans.

Conclusions

This is the first report of C. meleagridis in chickens from Guangdong. The frequent occurrence of C. meleagridis in domestic chickens and the common C. meleagridis subtypes identified in both humans and chickens is of public health significance. Our study indicates that broiler chickens represent a potential zoonotic risk for the transmission of Cryptosporidium in this region.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05267-x.

Case of necrotic enteritis associated with campylobacteriosis and coccidiosis in an adult Indian peacock (Pavo cristatus)

Background

To date, Campylobacter jejuni has not been found to be pathogenic to peafowl. The available publications show that out of a total of 44 samples tested from peafowl, this bacterium was isolated only in two cases. Eimeria pavonina infestations in the peafowl have been described, but no fatal cases have been reported yet.

Case presentation

The four-year-old peacock was presented with chronic diarrhea, emaciation and weakness. Post mortem examination revealed enlarged and pale kidneys, small intestinal mucosal necrosis and thickening of intestinal wall, and pericardial effusion. The histopathological examination revealed necrotic enteritis with marked mononuclear cells infiltration associated with the presence of coccidia, additionally there was histological evidence of septicemia in liver and kidneys. Bacteria identification was based on light microscopy of the small intestine sample, culture, and biochemical tests. Further identification was based on PCR. Antimicrobial susceptibility profile was created by determination of minimal inhibitory concentration (MIC) values for 6 antimicrobial agents from 5 different classes. PCR assays were performed to detect virulence factors genes responsible for motility, cytolethal distending toxin production, adhesion and internalization. Bacteriology of the small intestine sample showed abundant growth almost exclusively of Campylobacter jejuni, resistant to ciprofloxacin, gentamycin and ampicillin. Bacteria was sensitive to Amoxicillin + clavulanic acid, tetracycline, and erythromycin. All tested virulence factors genes have been detected. The parasitological examination was performed by microscopic examination of fresh faeces and intestinal content, and revealed the moderate number of Eimeria pavonina, Histomonas meleagridis, single Capillaria spp. eggs as well Heterakis spp. like parasites.

Conclusion

The above case shows that a virulent isolate of Campylobacter jejuni in combination with a parasitic invasion may cause chronic enteritis in peafowl, which most likely led to extreme exhaustion of the host organism and death.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03260-1.

Validation of a one-tube nested real-time PCR assay for the detection of Cryptosporidium spp. in avian fecal samples

The aim of this study was to validate a one-tube nested real-time PCR assay followed by genetic sequencing to detect and identify Cryptosporidium species and genotypes in birds. A total of 443 genomic DNA extracted from avian fecal samples were analyzed by one-tube nested real-time PCR and conventional nested PCR. By one-tube nested real-time PCR, 90/443 (20.3%) samples were positive for Cryptosporidium spp. In contrast, 36/443 (8.1%) samples were positive for Cryptosporidium spp. by conventional nested PCR. The analytical sensitivity test showed that one-tube nested real-time PCR detects approximately 0.5 oocyst (2 sporozoites) per reaction. An evaluation of analytical specificity did not reveal amplification of microorganisms that commonly present nonspecific amplification with primers used for the diagnosis of Cryptosporidium spp. The repeatability analysis showed the same result in 27 out of 30 samples (90%). As for the reproducibility of one-tube nested real-time PCR, 24 of the 30 samples examined (80%) showed the same result. All the 90 samples amplified by one-tube real-time nested PCR were successfully sequenced, leading to the identification of C. baileyi, C. galli, C. meleagridis, C. proventriculi, and Cryptosporidium avian genotype I. Genetic sequencing of conventional nested PCR amplicons was successful in 10/36 (27.8%) of positive samples.

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.

Molecular Identification of Cryptosporidium spp., Enterocytozoon bieneusi, and Giardia duodenalis in Captive Pet Birds in Henan Province, Central China

Cryptosporidium spp., Enterocytozoon bieneusi, and Giardia duodenalis are common enteric pathogens that are capable of infecting humans and animals. Total of 1,005 fecal samples from captive pet birds were collected from seven locations in Henan Province, China. The results demonstrated that 9.9% (99/1,005) of the captive birds were infected with one of these three pathogens. Enterocytozoon bieneusi was the most prevalent species among the birds (45/1,005, 4.5%) followed by G. duodenalis (33/1,005, 3.3%) and Cryptosporidium spp. (21/1,005, 2.1%). Five Cryptosporidium species were identified, namely, C. baileyi (10), C. galli (5), C. meleagridis (4), C. andersoni (1), and C. parvum (1). Two known E. bieneusi genotypes were identified: Peru 6 (44) was identified in pigeons (34) and European turtle doves (10); whereas, the genotype PtEb I (1) was only identified in a pigeon. Only G. duodenalis assemblage E (33) was identified in some pet birds. To the best of our knowledge, this study is the first to undertake the molecular identification of G. duodenalis in birds in China. The identification of potentially zoonotic species/genotypes of the pathogens suggests that exposure to the excreta of these birds, either directly or via food and water, may pose a threat to human health.