Diagnosis of gastric cryptosporidiosis in birds using a duplex real-time PCR assay

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.

Cryptosporidium proventriculi in Captive Cockatiels (Nymphicus hollandicus)

Cockatiels (Nymphicus hollandicus) are among the most commonly sold psittacines pets. The aim of this study was to evaluate the occurrence of Cryptosporidium spp. in domestic N. hollandicus and identify risk factors for this infection. We collected fecal samples from 100 domestic cockatiels in the city of Araçatuba, São Paulo, Brazil. Feces from birds of both genders and older than two months were collected. Owners were asked to complete a questionnaire to identify how they handle and care for their birds. Based on nested PCR targeting the 18S rRNA gene, the prevalence of Cryptosporidium spp. in the cockatiels sampled was 9.00%, 6.00% based on Malachite green staining, 5.00% based on modified Kinyoun straining, and 7.00% when the Malachite green was combined with Kinyoun. Applying multivariate logistic regression to test the association between Cryptosporidium proventriculi positivity and potential predictors showed that gastrointestinal alterations was a significant predictor (p < 0.01). Amplicons from five samples were sequenced successfully and showed 100% similarity with C. proventriculi. In summary, this study demonstrates the occurrence of C. proventriculi in captive cockatiels.

Molecular and phylogenetic characterization of Cryptosporidium species in the saffron finch Sicalis flaveola

BACKGROUND

Cryptosporidium is the most common protozoan that can infect a wide variety of animals, including mammals and birds. Fecal samples of six saffron finches, Sicalis flaveola, from a commercial establishment were screened for the presence of Cryptosporidium by the modified Ziehl-Neelsen technique and nested PCR of the 18S rRNA gene followed by sequencing of the amplified fragments.

RESULTS

The species Cryptosporidium galli was identified in all six saffron fiches, in addition to Cryptosporidium andersoni in one of the birds, indicating a mixed infection. Only two birds had feathers that were ruffled and dirty with feces. Concomitant infection with Isospora spp. was observed in all birds.

CONCLUSIONS

Saffron finches are a possible host of C. andersoni and this is the first report of this species in a captive bird and the third report of parasitism by C. galli in Sicalis flaveola.

Cryptosporidium species in non-human animal species in Latin America: Systematic review and meta-analysis

Cryptosporidiosis is an infection caused by a protozoon that inhabits the gastrointestinal tract. More than forty valid species have been described in the genus Cryptosporidium, infecting a broad range of hosts around the world, some with zoonotic transmission and others with predominant anthroponotic transmission. Prevalence studies conducted in Latin American countries have been specific, without consolidating information on species prevalences. Thus, the aim of this study was to perform a systematic review and meta-analysis addressing the prevalence of Cryptosporidium species in animals in Latin America. The estimated pooled prevalence rate for cryptosporidiosis in animals, by means of meta-analysis with a random-effects model, based on species identification, was 18.0% (95% CI 11.0%-27.0%) with high heterogeneity. The estimated overall prevalence was 20.3% (36/177) in pets, 19.9% (1309/6573) in livestock animals and 23.9% (954/3995) in exotic/captive animals. Evidence of circulation of 16 Cryptosporidium species was found in five Latin American countries: Brazil, Colombia, Chile, Argentina and Mexico. Through meta-analysis with a random-effects model, the pooled prevalence rate for Cryptosporidium parvum was 0.7% (95% CI 0.2%-2.4%). Cryptosporidium felis (8.5%) was the most prevalent species in pets, C. parvum (10.3%) in livestock animals and Cryptosporidium galli (17.6%) in exotic/captive animals. C. parvum was the species with the greatest geographical dispersion, which can be explained by its eurixenic and zoonotic potential. Few studies on cryptosporidiosis in animals in Latin America were found, which shows that there is a need for investment in and expansion of studies on this parasite. The pooled prevalence of C. parvum in Latin America and its wide circulation are similar to what has been observed in other developing regions, which reaffirms the importance of this species as the cause of a neglected, emerging and zoonotic parasitosis.

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 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.

Cryptosporidium cf. avium in an inland-bearded dragon (Pogona vitticeps) - A case report and review of the literature

Here, we report the first case of Cryptosporidium cf. avium from an inland bearded dragon (Pogona vitticeps) from a wildlife sanctuary in Victoria, Australia. Molecular characterisation was conducted by PCR-coupled sequencing of regions in the small subunit of nuclear RNA (SSU), actin and large subunit of nuclear RNA (LSU) genes. The sequences obtained grouped with those of C. ornithophilus and other C. avium genotypes/variants originating from reptiles or birds. We discuss this case in relation to the current state of knowledge of C. avium of birds and reptiles, considering provenance and environment (agricultural, pet industry, wildlife, zoo or wildlife park) as well as clinical context, and pathological changes associated with cryptosporidiosis in these host animals.

•

Characterisation of Cryptosporidium cf. avium from an inland bearded dragon (Pogona vitticeps).

•

Molecular differentiation of C. cf. avium from other members of the C. avium clade.

•

Pathogenicity of C. cf. avium seems higher than other members of this clade.

Cryptosporidium proventriculi sp. n. (Apicomplexa: Cryptosporidiidae) in Psittaciformes birds

Cryptosporidiosis is a common parasitic infection in birds that is caused by more than 25 Cryptosporidium species and genotypes. Many of the genotypes that cause avian cryptosporidiosis are poorly characterized. The genetic and biological characteristics of avian genotype III are described here and these data support the establishment of a new species, Cryptosporidium proventriculi. Faecal samples from the orders Passeriformes and Psittaciformes were screened for the presence of Cryptosporidium by microscopy and sequencing, and infections were detected in 10 of 98 Passeriformes and in 27 of 402 Psittaciformes. Cryptosporidium baileyi was detected in both orders. Cryptosporidium galli and avian genotype I were found in Passeriformes, and C. avium and C. proventriculi were found in Psittaciformes. Cryptosporidium proventriculi was infectious for cockatiels under experimental conditions, with a prepatent period of six days post-infection (DPI), but not for budgerigars, chickens or SCID mice. Experimentally infected cockatiels shed oocysts more than 30 DPI, with an infection intensity ranging from 4,000 to 60,000 oocysts per gram (OPG). Naturally infected cockatiels shed oocysts with an infection intensity ranging from 2,000 to 30,000 OPG. Cryptosporidium proventriculi infects the proventriculus and ventriculus, and oocysts measure 7.4 × 5.8 μm. None of the birds infected C. proventriculi developed clinical signs.

Revisiting the infectivity and pathogenicity of Cryptosporidium avium provides new information on parasitic sites within the host

Background

Cryptosporidium spp. are protozoans that cause diarrheal illness in humans and animals, including birds, worldwide. The present study was aimed to revisit the infectivity and pathogenicity of C. avium, recently considered to be a valid avian-infecting species of Cryptosporidium, and foster further understanding of its biological characteristics.

Results

Results showed that no Cryptosporidium oocysts were detected in the feces of experimentally inoculated BALB/c mice, Mongolian gerbils, quail or budgerigars within 30 days post-infection (dpi). Oocysts were first detected in feces of 3-day-old and 40-day-old hens at 8 and 9 dpi, respectively. In ducks infected with C. avium, oocysts were first detected at 9 dpi. Oocysts of infected animals were studied using a nested-polymerase chain reaction (PCR) technique for the SSU rRNA gene, actin gene, HSP70 gene and Cryptosporidium oocyst wall protein gene (COWP) detection. Restriction fragment length polymorphism (RFLP), using SspI and VspI restriction enzymes, was carried out to genotype the species and obtained amplification products were sequenced. Cryptosporidium developmental stages were found in the longitudinal plica of the bursa fabricii (BF) of hens, with high levels observed in histological sections and scanning electron microscopy. No pathological changes were observed.

Conclusions

These findings indicate that the bursa fabricii may be the primary site of C. avium infection. More biological data are needed to support the establishment of new species and contribute to the taxonomy of Cryptosporidium.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3088-x) contains supplementary material, which is available to authorized users.

A new avian Cryptosporidium genotype in a 1-month-old caged brown wood owl (Strix leptogrammica) with severe dehydration and diarrhea

A 1-month-old brown wood owlet (Strix leptogrammica) purchased from a wholesaler and housed as a companion bird by an individual owner in Japan showed severe dehydration and anorexia following a week of vomiting and severe diarrhea. A great number of approximately 5 × 4-μm-sized Cryptosporidium oocysts were found in the feces by microscopy. The owlet was administered subcutaneous fluid and intragastric tube feeding for 2 weeks, resulting in improvement of the condition with a decreased number of oocysts in the feces. At days 51 and 119, no oocysts were found in the feces by microscope and PCR detection. These results suggested that this parasite was a possible agent of severe diarrhea in the affected bird. Molecular analysis of DNA extracted from oocysts based on the 18SrRNA loci identified C. avium; however, analysis of actin and hsp (heat shock protein) genes identified a novel genotype indicating a mixed infection with C. avium and a novel genotype.

Molecular characterization of Cryptosporidium spp. in poultry from Brazil

Cryptosporidiosis is an important zoonotic disease caused by Cryptosporidium. Infections in birds are mainly caused by C. meleagridis, C. baileyi, and C. galli. C. meleagridis is the third most common cause of cryptosporidiosis in humans and the only Cryptosporidium species known to infect both birds and mammals. One hundred and fifty-five fecal specimens from different poultry species (chicken, turkey, ostrich, helmeted guinea fowl, quail, pheasant, and emu) were collected at local markets in the state of Minas Gerais, Brazil. Twenty-three (14.8%) birds (20 chickens, 2 quails, and 1 turkey) were found Cryptosporidium-positive. This constitutes the first report of Cryptosporidium in turkeys from Brazil. Nucleotide sequence analysis identified C. meleagridis in chickens (15), a turkey (1), and a quail (1), C. baileyi in chickens (4) and a quail (1), and a mixed infection C. meleagridis/C. baileyi in a chicken (1). This is the first report of C. meleagridis in turkeys and quails from Brazil. Using the gp60 gene, three subtype families were identified, IIIa, IIIb and IIIg. Within subtype family IIIg, four subtypes were identified in chickens, two novel (IIIgA25G3R1 and IIIgA21G3R1) and two previously reported (IIIgA22G3R1 and IIIgA24G2R1). Within subtype family IIIb two subtypes were identified, IIIbA24G1R1 in a chicken and IIIbA23G1R1 in a quail. A novel subtype in the family IIIa was identified (IIIaA22G3R1) in a turkey. The finding of C. meleagridis subtypes previously identified in humans (IIIgA22G3R1, IIIbA24G1R1 and IIIbA23G1R1) indicates that they can be potentially zoonotic. Further subtyping studies that clarify genetic diversity of C. meleagridis are required to better understand host specificity, source of infection, and transmission dynamics of C. meleagridis.

Detection and molecular characterization of Cryptosporidium spp. in captive canaries (Serinus canaria) using different diagnostic methods

This study used several diagnostic methods to examine the occurrence of and molecularly characterize Cryptosporidium spp. in captive canaries (Serinus canaria) in southern and southeastern Brazil. A total of 498 fecal samples were purified by centrifugal-flotation using Sheather's solution. Cryptosporidium spp. diagnosis was performed using three diagnostic methods: malachite green negative staining, nested PCR targeting the 18S rRNA gene, followed by sequencing the amplified fragments, and duplex real-time PCR targeting the 18S rRNA specific to detect Cryptosporidium galli and Cryptosporidium avian genotype III. The overall positivity for Cryptosporidium spp. (total samples positive in at least one protocol) from the microscopic analysis, nested PCR and duplex real-time PCR protocol results was 13.3% (66/498). The positivity rates were 2.0% (10/498) and 4.6% (23/498) for Cryptosporidium spp. by microscopy and nested PCR, respectively. Sequencing of 20 samples amplified by nested PCR identified C. galli (3.0%; 15/498), Cryptosporidium avian genotype I (0.8%; 4/498) and Cryptosporidium avium (0.2%; 1/498). Duplex real-time PCR revealed a positivity of 7.8% (39/498) for C. galli and 2.4% (12/498) for avian genotype III. Malachite green negative staining differed significantly from nested PCR in detecting Cryptosporidium spp. Duplex real-time PCR was more sensitive than nested PCR/sequencing for detecting gastric Cryptosporidium in canaries.

Cryptosporidium spp. in caged exotic psittacines from Brazil: Evaluation of diagnostic methods and molecular characterization

The aim of this study was to evaluate the prevalence of and diagnostic methods for Cryptosporidium spp. in caged adult exotic parrots from Southern and Southeastern Brazil. Oocysts were purified from fecal samples from 463 psittacines by centrifugal-flotation in Sheather's sugar solution. Cryptosporidium spp. were detected by malachite green negative staining and nested PCR targeting the 18S rRNA gene. Cryptosporidium species were identified by sequencing nested PCR amplicons. Samples were also tested by duplex real-time PCR targeting the 18S rRNA gene of Cryptosporidium galli and Cryptosporidium avian genotype III. The prevalence rates of Cryptosporidium spp. determined by microscopy and nested PCR were 3.0% (14/463) and 5.0% (23/463), respectively. The nested PCR/sequencing identified avian genotype III (1.7%; 8/463), Cryptosporidium parvum (0.9%; 4/463) and Cryptosporidium canis (0.2%; 1/463). Duplex real-time PCR was positive for gastric Cryptosporidium in 9.5% (44/463) of the samples. Among them, 1.9% (9/463) were positive for C. galli, 5.8% (27/463) were positive for avian genotype III and 1.7% (8/463) showed mixed infections with C. galli and avian genotype III. With regards to the positive detection of Cryptosporidium spp., there was no statistically significant difference between nested PCR and microscopic analysis (p = .1237), and a fair agreement existed between them (Kappa = 0.242). A statistically significant difference (p < .0001) and fair agreement (Kappa = 0.317) were obtained between nested PCR/sequencing and duplex real-time PCR for the detection of gastric Cryptosporidium. We determined that nested PCR and duplex real-time PCR are the best options for the detection of Cryptosporidium spp. and gastric Cryptosporidium, respectively, and that avian genotype III is the most common Cryptosporidium genotype/species in psittacines.

Cryptosporidium baileyi in wild captive psittacines in Brazil

Cryptosporidiosis in birds manifests as an acute or chronic disease of the respiratory or digestive tracts. The objective of our study was to perform the molecular characterization of Cryptosporidium spp. in wild psittacines kept in captivity at the Araçatuba Municipal Zoo, São Paulo, Brazil. A total of 47 fecal samples were collected from Amazona aestiva, Psittacara leucophthalma, and Ara ararauna. All samples were collected at the time the birds defecated. DNA extraction was performed using the ZR Fecal DNA MiniPrep™ kit (Zymo Research). Screening for Cryptosporidium spp. was accomplished using nested PCR targeting the 18S RNA gene and sequencing of amplified fragments. Positivity for Cryptosporidium spp. (10.64%; 5/47) was found in A. ararauna (4) and P. leucophthalma (1) samples. The amplified fragments were sequenced and showed 100% genetic similarity with Cryptosporidium baileyi.

Infectious Diseases

The chapter describes bacerial, viral, parasitic and fungal infections commonly detected in pet birds. The chapter includes history, etiology, susceptible hosts, transmission, pathogenesis, clinical symptoms, lesion, diagnosis, zoonosis, Treatment and control strategy of Tuberculosis, Salmonellosis, Chlamydiosis, Campylobacteriosis, Lyme disease, other bacterial infection, Newcastle disease, Avian Influenza infection, West Nile Virus infection, Usutu virus infection, Avian Borna Virus infection, Beak and feather disease, other viral infection, Toxoplasmosis, Giardiasis, Cryptosporidiosis, other parasitic infection, Cryptococcosis, Aspergillosis, Other fungal infections.

Molecular identification of Enterocytozoon bieneusi, Cryptosporidium, and Giardia in Brazilian captive birds

A total of 85 fecal samples from captive birds collected from October 2013 to September 2014 in Uberlândia and Belo Horizonte in the state of Minas Gerais (Brazil) were evaluated for the presence of Enterocytozoon bieneusi, Cryptosporidium, and Giardia by PCR. Of these, three birds were found positive for E. bieneusi (3.5%), two for Cryptosporidium (2.3%), and one for Giardia (1.2%). Two genotypes of E. bieneusi were detected by nucleotide sequence analysis of the ITS region, genotypes D and Peru 6 in a swan goose and in two rock pigeons, respectively. For Cryptosporidium and Giardia, nucleotide sequence analysis of the SSU rRNA identified Cryptosporidium baileyi and Duck genotype in a swan goose and a mandarin duck, respectively, and Giardia duodenalis assemblage A in a toco toucon. Our results demonstrate that human-pathogenic E. bieneusi genotypes D and Peru6 and G. duodenalis assemblage A are present in captive birds in Brazil, corroborating their potential role as a source of human infection and environmental contamination.

Cryptosporidium avium n. sp. (Apicomplexa: Cryptosporidiidae) in birds

The morphological, biological, and molecular characteristics of Cryptosporidium avian genotype V are described, and the species name Cryptosporidium avium is proposed to reflect its specificity for birds under natural and experimental conditions. Oocysts of C. avium measured 5.30-6.90 μm (mean = 6.26 μm) × 4.30-5.50 μm (mean = 4.86 μm) with a length to width ratio of 1.29 (1.14-1.47). Oocysts of C. avium obtained from four naturally infected red-crowned parakeets (Cyanoramphus novaezealandiae) were infectious for 6-month-old budgerigars (Melopsittacus undulatus) and hens (Gallus gallus f. domestica). The prepatent periods in both susceptible bird species was 11 days postinfection (DPI). The infection intensity of C. avium in budgerigars and hens was low, with a maximum intensity of 5000 oocysts per gram of feces. Oocysts of C. avium were microscopically detected at only 12-16 DPI in hens and 12 DPI in budgerigars, while PCR analyses revealed the presence of specific DNA in fecal samples from 11 to 30 DPI (the conclusion of the experiment). Cryptosporidium avium was not infectious for 8-week-old SCID and BALB/c mice (Mus musculus). Naturally or experimentally infected birds showed no clinical signs of cryptosporidiosis, and no pathology was detected. Developmental stages of C. avium were detected in the ileum and cecum using scanning electron microscopy. Phylogenetic analyses based on small subunit rRNA, actin, and heat shock protein 70 gene sequences revealed that C. avium is genetically distinct from previously described Cryptosporidium species.

RENAL AND CLOACAL CRYPTOSPORIDIOSIS (CRYPTOSPORIDIUM AVIAN GENOTYPE V) IN A MAJOR MITCHELL'S COCKATOO (LOPHOCHROA LEADBEATERI)

A 7-yr-old male Major Mitchell's cockatoo (Lophochroa leadbeateri) presented with a recent history of lethargy and anorexia. Physical examination revealed poor body condition and cloacal prolapse. Abnormalities on serum chemistry included severe hyperuricemia and hyperphosphatemia with a low calcium-to-phosphorus ratio. Symptomatic treatment was initiated including intravenous fluids and antibiotics. The bird continued to decline and died within a few days. Visceral gout and renal and cloacal pathology were observed on gross necropsy. Histopathology revealed chronic inflammation within the kidney, ureter, and cloaca in association with protozoal organisms and an invasive cloacal adenocarcinoma tumor. The location and morphology was consistent with Cryptosporidium sp., confirmed by immunohistochemistry and molecular testing. Direct sequencing identified Cryptosporidium avian genotype V. To the author's knowledge, this is the first reported infection of Cryptosporidium avian genotype V associated with clinical disease in birds and the first renal Cryptosporidium infection in a psittacine.

Public health significance of zoonotic Cryptosporidium species in wildlife: Critical insights into better drinking water management

Cryptosporidium is an enteric parasite that is transmitted via the faecal-oral route, water and food. Humans, wildlife and domestic livestock all potentially contribute Cryptosporidium to surface waters. Human encroachment into natural ecosystems has led to an increase in interactions between humans, domestic animals and wildlife populations. Increasing numbers of zoonotic diseases and spill over/back of zoonotic pathogens is a consequence of this anthropogenic disturbance. Drinking water catchments and water reservoir areas have been at the front line of this conflict as they can be easily contaminated by zoonotic waterborne pathogens. Therefore, the epidemiology of zoonotic species of Cryptosporidium in free-ranging and captive wildlife is of increasing importance. This review focuses on zoonotic Cryptosporidium species reported in global wildlife populations to date, and highlights their significance for public health and the water industry.

Cryptosporidium infections in birds - a review

Cryptosporidiosis is one of the main protozoan infections in birds. It manifests as either a respiratory or a digestive illness, and it affects a very large number of avian species across several continents. The aim of this review is to report on the main results of studies on cryptosporidiosis among birds and the importance of these results to veterinary medicine and public health.

Ascaridia nymphii n. sp. (Nematoda: Ascaridida) from the alimentary tract of a severely emaciated dead cockatiel Nymphicus hollandicus

This report describes Ascaridia nymphii n. sp., a new species isolated from the alimentary tract of cockatiel Nymphicus hollandicus in Japan. More than 63 nematodes were found in the formalin-fixed small intestine, ventriculus, proventriculus and crop of a 48-day-old young cockatiel that died after exhibiting severe emaciation. No nematode eggs were observed in the faecal examination performed while the cockatiel was alive, but Cryptosporidium oocysts were found. The intestinal mucosa was damaged considerably. Male worms had two alate spicules, well-developed precloacal sucker and a tail with ventrolateral caudal alae and mainly 11 pairs of papillae. Nuclear partial (813 bp) 18S ribosomal RNA gene (18S rDNA) sequences obtained from two female samples were mutually identical. They respectively showed 99.1 and 98.6% identities to those from Ascaridia numidae and Ascaridia galli. Phylogenetic analysis using this locus indicated the present nematode as Ascaridia species. The mitochondrial NADH dehydrogenase subunit 2 gene (nad2) sequences obtained for four samples were mutually identical. They respectively showed 98.7, 85.7 and 82.2% identities with those from Ascaridia columbae, Ascaridia sp. and A. galli. Combining the morphological and sequencing data from two loci, the present nematode was identified as A. nymphii n. sp., which is closely related with A. columbae. This report is the first of a study examining the distribution of Ascaridia species in captive parrots in Japan. This study also identified the trachea and cloaca, like Cryptosporidium baileyi, as the possible location of Cryptosporidium avian genotype V in avian hosts.