Transmammary transmission of Troglostrongylus brevior feline lungworm: a lesson from our gardens.

Feline lungworms such as Aerulostrongylus abstrusus and Troglostrongylus brevior are snail-borne pathogens causing respiratory disease in domestic cats. Paratenic hosts such as rodents and reptiles have also been implicated in the epidemiology of these parasites. Although A. abstrusus has been recognized for a long time as the most prevalent lungworm among cats worldwide, T. brevior is of major concern in kittens. Bearing in mind that disease due to T. brevior occurs mainly in pediatric patients younger than 6 months of age, the diagnosis of this parasite in two kittens presenting severe respiratory disease from the garden of one of the authors inspired us to investigate the potential routes of transmission for T. brevior in domestic cats. Of the three queens (A, B and C) that delivered kittens (n = 8), only cat A was positive for T. brevior, presenting her two kittens severe respiratory clinical signs, which lead to the exitus in one of them, 18 days of age. In addition, three kittens, the offspring of queen B, turned to be positive at the coprological examination after suckling from queen A, whereas those from queen C (that suckled only on their own mother) remained negative. A series of coprological, histological and molecular tests were conducted to confirm the presence of T. brevior in the patients as well as in the other cats cohabiting the same garden. Adult nematodes were retrieved from the trachea and bronchi of the dead kitten (kitten 1A), and larvae at the histology of the lung and liver parenchyma associated with bronco pneumonitis and lymphocytic pericholangitis, respectively. Cornu aspersum (n = 60), Eobania vermiculata (n = 30) snails (intermediate hosts) as well as lizards and rats (potential paratenic hosts) were collected from the same garden and processed through tissue digestion and molecular detection. Troglostrongylus brevior larvae were recovered through tissue digestion from two C. aspersum (3.33 %) and it was confirmed by PCR-sequencing approach, which also detected T. brevior DNA in the liver and lungs of one rat and in the coelomatic cavity of one gecko lizard. During the COVID-19 lockdown, when scientists spent more time at home, we grasp the opportunity to decipher T. brevior biology and ecology starting in a small ecological niche, such as the garden of our house. Data herein presented led us to suggest: i) the transmammary transmission of T. brevior in domestic cats; ii) the role of intermediate and paratenic hosts (including reptiles) in the epidemiology of the infection which they transmit; as well as iii) the importance of observational parasitology in studying any event that certainly occurs in small ecological niches, as it could be in our home gardens.

Pulmonary infections due to brucellosis in childhood.

INTRODUCTION: Brucellosis is widely distributed zoonotic infection. Brucellosis is a multisystemic disease but pulmonary infection due to brucellosis is very rarely reported. MATERIALS AND METHODS: We retrospectively evaluated our pediatric brucellosis cases between February 2014 and December 2015. The brucellosis patients with and without pulmonary infection were compared with each other. RESULT: We detected pulmonary infection in 18 of the 98 brucellosis patients. There was no statistical significant difference between the brucellosis patients with and without a pulmonary infection as regards age, gender, and animal husbandry history. The laboratory findings including the Brucella Coombs agglutination titers were also similar. The most common chest X-ray findings were interstitial infiltration and hilar lymphadenopathy. All of our cases with pulmonary infection recovered with the usual anti-brucella treatment. CONCLUSIONS: Brucellosis may cause a pulmonary infection more often than thought. The prognosis of respiratory brucellosis is good and the classic treatment regimen is appropriate.

Correlates of pathological lesions associated with respiratory cryptosporidiosis prevalence in shot red grouse Lagopus lagopus scotica from moors in northern England.

Infection of wild red grouse Lagopus lagopus scotica by Cryptosporidium baileyi was first diagnosed in 2010. Within three years, signs of infection were reported from grouse on half of all grouse moors in northern England, bringing severe concerns of economic losses to grouse shooting. A total of 45,914 red grouse shot from 10 moors in northern England between 2013 and 2018 were visually screened for signs of respiratory cryptosporidiosis. Prevalence varied with age, being twice as high in juveniles (4.5%) as in adults (2.4%). It also varied nine-fold between moors and three-fold between years. Prevalence was highest in grouse shot later in the shooting season. Our results are consistent with the concept that disease incidence is highest in naïve juveniles that have previously not been exposed to infection, with prevalence dropping as birds develop immunity. We found no evidence of increased prevalence over time, and fears of escalated disease prevalence, bringing with it increased mortality and lowered productivity, that may have significant impacts on the economic viability of shoots, have not yet been realized. We recommend continued annual screening for clinical signs amongst shot birds, better hygiene associated with potential reservoirs of infection, and practices that both improve the detection and selective culling of diseased individuals and generally reduce overall grouse densities.

Efficacy of a moxidectin/imidacloprid spot-on formulation (Advocate®) for the treatment of Troglostrongylus brevior in naturally infected cats in a field study in Greece.

BACKGROUND: Troglostrongylus brevior is a lungworm of wild felids that recently has been recognized as agent of severe respiratory disease in domestic cats in Mediterranean and Balkan countries. Nevertheless, the information on treatment options for feline troglostrongylosis is still poor. The aim of this pilot field trial was to evaluate the efficacy of the spot-on formulation containing 1% w/v moxidectin and 10% w/v imidacloprid (Advocate® spot-on solution for cats, Bayer Animal Health GmbH) in the treatment of T. brevior infection in naturally infected cats in Greece. METHODS: The trial was a negative control, multicentre, clinical efficacy study conducted according to the standards of Good Scientific Practice (GSP). Sixteen cats in two study sites, naturally infected with T. brevior, were allocated to an untreated control group (G1, n = 8) or a treatment group (G2, n = 8), according to a randomization list. Animals assigned to G2 were treated with Advocate® for cats on days 0 and 28 at the recommended dose rate and animals assigned to G1 received a rescue treatment with the same product on days 56 and 84. Efficacy was assessed on days 28 and 56 in G2 and on days 84 and 112 in G1 by faecal larval counts. The primary efficacy criterion was the absence of T. brevior first-stage larvae (L1) following treatment. Other efficacy parameters were the quantitative comparison of L1 presence before (baseline) and after one or two treatments in both groups. RESULTS: All G2 cats were negative for T. brevior L1 at the first post-treatment evaluation (100% efficacy) while G1 cats were persistently shedding L1. The difference of the mean number of L1 per gram between G2 and G1 was statistically significant (P < 0.001). All G1 cats were negative (100% efficacy) for T. brevior L1 at the first post-rescue-treatment evaluation. Therefore, treatment efficacy at study completion was 100% in both groups in terms of stopping the L1 shedding in the faeces of the animals. No adverse effects were observed during the study. CONCLUSIONS: These results indicate that Advocate® spot-on solution for cats represents an option for treating cats naturally infected with T. brevior.

Evaluating respiratory cryptosporidiosis in pediatric diarrheal disease: protocol for a prospective, observational study in Malawi.

BACKGROUND: Cryptosporidium is among the most common causes of severe diarrhea in African children 0-23 months old. It is associated with excess mortality, stunting and malnutrition. The most common manifestation of cryptosporidium is intestinal diarrheal disease. However, respiratory cryptosporidiosis has been documented in up to a third of children presenting with diarrhea. It is unclear whether respiratory involvement is a transient phenomenon or a reservoir for gastrointestinal (GI) disease. This study aims to evaluate the role of respiratory cryptosporidiosis in pediatric diarrheal disease. METHODS: This is a prospective, observational study conducted at Queen Elizabeth Central Hospital (QECH) in Blantyre, Malawi. Young children aged 2-24 months hospitalized with diarrhea will be enrolled. Enrolled children will have induced sputum, nasopharyngeal (NP) swab and stool samples collected. All participants positive for cryptosporidium on sputum/NP/stool PCR testing will be followed up fortnightly after discharge from the hospital up to 8 weeks post-discharge. Sputum/NP/stool sample collection will be done at each visit. The primary outcomes will be presence of Cryptosporidium spp. in sputum/NP/stool. The secondary outcome will be presence of respiratory and GI symptoms, mortality and stunting. Ethical approval was obtained from the University of Malawi College of Medicine Research Ethics Committee (COMREC) and the Liverpool School of Tropical Medicine (LSTM) research ethics committee. DISCUSSION: The study began recruitment activities at QECH in February 2019. The protocol allows for expansion of recruitment to secondary sites within Blantyre and Chikwawa districts in the event that targets are not met at QECH. Study recruitment is expected to continue until early 2020.

Shedding of feline lungworm larvae and their infectivity to snail intermediate hosts after anthelmintic treatment.

Aelurostrongylus abstrusus and Troglostrongylus brevior are snail-transmitted helminths causing respiratory diseases in infected cats. The shedding of feline lungworm L1s and their infectivity to the snail intermediate host, after administration of anthelminthic products to cats, are poorly documented. To assess the efficacy of 8.3% fipronil, 10% (S)-methoprene, 0.4% eprinomectin and 8.3% praziquantel (i.e. eprinomectin formulation) and 10% imidacloprid/1% moxidectin (i.e. moxidectin formulation) against these nematodes and to determine the number of days post-treatment until viable L1s are released in the faeces, 384 animals were screened by faecal examination. Of the 54 positive animals (i.e., 14.1%; 7.3% A. abstrusus, 6.2% T. brevior and 0.5% coinfected), 36 were randomly allocated to four groups. Groups A and B were composed of cats positive for T. brevior and treated with the eprinomectin and with the moxidectin formulations, respectively, whereas cats in groups C and D were positive to A. abstrusus and treated with the eprinomectin and the moxidectin formulations, respectively. Prior to and every day after treatment, faecal samples were analysed by the Baermann technique and the number of larvae per gram of faeces determined, and again four weeks after treatment, to assess the efficacy of a single administration of the products. In addition, to evaluate the pre- and post-treatment infectivity of L1s to snail intermediate hosts, one/two snails per cat were infected with 100 L1s collected from the faeces of enrolled animals and then digested 28 days p.i. Based on L1s faecal counts, the efficacy of the eprinomectin and the moxidectin formulations at 28 days was 100% for both A. abstrusus and T. brevior, with a mean number of days of 7.9 ±â€¯1.2 in group A, 7.8 ±â€¯1.9 in B, 6.9 ±â€¯1.6 in C and 8.9 ±â€¯2.0 in D to become negative. Following the artificial digestion, active L3s of T. brevior and A. abstrusus were found in 160 (87.4%) experimentally infected snails. The results of this study demonstrate that a single administration of the two formulations is effective in the treatment of A. abstrusus and T. brevior infections and that during the post-treatment period live L1s are shed for up to 8.9 ±â€¯2.0 days. L1s of both lungworm species released in the faeces after drug administration are still able to reach the infective larval stage in the infected snails. Hence, preventative measures after the treatment of infected animals should include keeping cats indoors and disposal of their faeces for approximately 10 days to avoid environmental contamination and infection of gastropod intermediate hosts.

Air Sac Nematode ( Serratospiculum tendo) Infection in an Austral Peregrine Falcon ( Falco peregrinus cassini) in Argentina.

We report a case of air sac nematode ( Serratospiculum tendo) infection in an adult male Austral Peregrine Falcon ( Falco peregrinus cassini) admitted to a rehabilitation center in Mendoza Province, Argentina, in September 2017. This case of air sac nematodes reported in an Argentine raptor is only the second report of S. tendo in South America. We recommend examination of all raptors, especially those falcon species that include insects in their diet and inhabit open lands and those in rehabilitation centers or kept for falconry, education, or captive breeding. Fecal analysis and microscopic examination of oral swabs for evidence of parasites are simple noninvasive diagnostic procedures that allow easy detection of these parasites under field and captive circumstances.

Helminth and respiratory mite lesions in Pinnipeds from Punta San Juan, Peru.

The tissues and parasites collected from Peruvian fur seals (Arctocephalus australis) and South American sea lions (Otaria byronia) found dead at Punta San Juan, Peru were examined. The respiratory mite, Orthohalarachne attenuata infected 3 out of 32 examined fur seals and 3 out of 8 examined sea lions, however caused moderate to severe lymphohistiocytic pharyngitis only in fur seals. Hookworms, Uncinaria sp, infected 6 of the 32 examined fur seals causing variable degrees of hemorrhagic and eosinophilic enteritis. This parasite caused the death of 2 of these pups. In fur seals and sea lions, Corynosoma australe and Contracaecum osculatum were not associated with significant tissue alterations in the intestine and stomach respectively. Respiratory mites and hookworms have the potential to cause disease and mortality among fur seals, while parasitic infections do not impact significatively the health of sea lions at Punta San Juan, Peru.

Acidic mammalian chitinase tuning after enteric helminths eradication in inflammatory respiratory disease patients.

AIM: This study aimed at investigating the presence of intestinal parasitic infections in inflammatory respiratory diseases patients during the disease attack, and measuring the acidic mammalian chitinase (AMCase) gene expression in blood before and after infection eradication. METHODOLOGY: This case-control study included 123 inflammatory respiratory diseases patients and 120 apparently healthy individuals. Repeated stool examination was done, while total and specific IgE were measured. AMCase gene expression was analysed by real time-polymerase chain reaction (RT-PCR). RESULTS: Infection was detected in 32.5% of the diseased and 23.25% of the healthy individuals. Higher rate of the helminthic infection was detected (23.57) in comparison to the protozoal (12.19%) in the patients. A significantly higher rate of infection with the chitin-rich helminths "Enterobius vermicularis & Hymenolepis nana" and level of anti-Dermatophagoide-IgE were reported in the patients (14.63%, 6.5% and 23.57%, respectively). AMCase expression was significantly higher in helminths-infected patients than the noninfected, or protozoa infected. After infection eradication, AMCase expression significantly declined in the previously helminth-infected patients (mean ± SD = 13.9 ± 3.918 before and 4.515 ± 1.93 after), but insignificantly affected in the protozoa infected (mean ± SD = 2.095 ± .285 before and 2.675 ± 1.181 after). CONCLUSION: Chitin-rich intestinal helminths are suspected to precipitate Th2-immune response in remote tissues by enhancing systemic AMCase expression through intestinal mucosa and macrophages irritation.

Aberrant and accidental trichomonad flagellate infections: rare or underdiagnosed?

The clinical significance and frequency of human infections with trichomonad flagellates in aberrant locations (locations other than the predilection sites) and accidental infections (infections with non-human trichomonads) are unclear. The total number of case reports in the literature is low, with the identification of the infection largely the outcome of investigations for the cause of clinical signs. At least seven species have been identified in either aberrant or accidental infections, with these infections occurring worldwide. Results of prospective and retrospective surveys of adults with respiratory disease suggest that aberrant and accidental trichomonad infections are less rare than the number of case reports suggest, with Trichomonas tenax being the most frequent. Surveys of neonates and infants suggest that aberrant Trichomonas vaginalis infections can be higher and more serious than suggested by the few case reports. The density and location of infection might be as important, if not more so, than species in determining pathogenicity. Molecular diagnostic methods including DNA sequencing can be used to better diagnose infections and enable identification to assist in determining the clinical significance of different species. Raising awareness of these infections among clinicians and adding them to their differential lists are strongly suggested.

Altitude above 1500 m is a major determinant of asthma incidence. An ecological study.

BACKGROUND: Previous studies suggest an inverse correlation between asthma and altitude. In the present work, we performed an in-depth analysis of asthma incidence in the 758 Mexican counties covered by the largest medical institution in the country (∼37.5 million insured subjects), and evaluated its relationships with altitude and other factors. METHODS: Asthma incidence in each county was calculated from new cases diagnosed by family physicians. Other variables in the same counties, including selected diseases, geographical variables, and socioeconomic factors, were also obtained and their association with asthma was evaluated through bivariate and multivariate analyses. RESULTS: Median asthma incidence was 296.2 × 100,000 insured subjects, but tended to be higher in those counties located on or near the coast. When asthma incidence was plotted against altitude, a two-stage pattern was evident: asthma rates were relatively stable in counties located below an altitude of ∼1500 m, while these rates progressively decreased as altitude increased beyond this level (rS = -0.51, p < .001). Multivariate analysis showed that, once each variable was adjusted by the potential influence of the others, asthma incidence was inversely correlated with altitude (standardized ß coefficient, -0.577), helminthiasis (-0.173), pulmonary tuberculosis (-0.130), and latitude (-0.126), and was positively correlated with acute respiratory tract infection (0.382), pneumonia (0.289), type 2 diabetes (0.138), population (0.108), and pharyngotonsillitis (0.088), all with a p ≤ .001. CONCLUSION: Our study showed that altitude higher than ∼1500 m comprises a major factor in determining asthma incidence, with the risk of new-onset asthma decreasing as altitude increases. Other less influential conditions were also identified.

Heartworm-associated respiratory disease (HARD) induced by immature adult Dirofilaria immitis in cats.

BACKGROUND: A controlled, blind research study was conducted to define the initial inflammatory response and lung damage associated with the death of immature adult Dirofilaria immitis in cats as compared with cats developing adult heartworm infections and cats on preventive medication. METHODS: Three groups of cats were utilized, 10 per group. All cats were infected with 100 third-stage (L3) larvae by subcutaneous injection. Group A cats were treated topically with selamectin (Revolution®; Zoetis) per label directions at 28 days post infection (PI) and once monthly for 8 months. Group B cats were treated orally with ivermectin (Ivomec®; Merial) at 150 µg/kg at 70 days PI, then every 2 weeks for 5 months. Group C cats were untreated PI. At baseline (Day 0) and on Days 70, 110, 168, and 240 PI, peripheral blood, serum, bronchial lavage, and thoracic radiographic images were collected on all cats. Upon completion of the study (Day 245), cats were euthanized and necropsies were conducted. RESULTS: Results were analyzed statistically between groups by ANOVA and by paired sample T testing for changes within the group over time. The selamectin-treated cats (Group A) did not develop radiographically evident changes throughout the study and were free of adult heartworms or worm fragments at necropsy. The heartworm life cycle was abbreviated with oral doses of ivermectin (Group B), shown by the absence of adult heartworms or worm fragments at necropsy. The early stage of immature adult worm in Group B cats, however, did induce severe pulmonary airway, interstitial, and arterial lung lesions, revealing that the abbreviated infection is a significant cause of respiratory pathology in cats. Cats in Groups B and C could not be differentiated based on radiographic changes, serologic antibody titers, complete blood count, or bronchoalveolar lavage cytology at any time point throughout the study. Eighty percent of cats in Group A and 100% of cats in Groups B and C became heartworm antibody positive at some time point post infection. CONCLUSIONS: The clinical implications of this study are that cats that become infected with immature adult heartworms may not develop fully mature heartworms and are only transiently heartworm antibody positive, but do develop Heartworm-Associated Respiratory Disease (HARD).

The progression of heartworm associated respiratory disease (HARD) in SPF cats 18 months after Dirofilaria immitis infection.

BACKGROUND: Heartworm-associated respiratory disease (HARD) in cats is induced by the arrival and death of immature adult Dirofilaria immitis in the pulmonary system and is indistinguishable from mature adult heartworm infection. METHODS: A controlled, blind research study investigated the long-term (18 months post infection, PI) consequences of the inflammatory response associated with the death of immature adult heartworms in cats. Three groups of cats, 10 per group, were infected with 100 third-stage (L3) larvae by subcutaneous injection. Group A cats were treated with selamectin (Revolution®; Zoetis) per label directions at 28 days PI and once monthly for 17 months. Group B cats were treated orally with ivermectin (Ivomec®; Merial) at 150 µg/kg) at 70 days PI, then every 2 weeks for 15 months. Group C cats were untreated PI. At baseline (Day 0) and on Days 70, 110, 168, 240, 309, 380, and 505 PI, peripheral blood, serum, bronchial lavage, and thoracic radiographic images were collected. RESULTS: The selamectin-treated cats (Group A) and ivermectin-treated cats (Group B) were free of heartworms or heartworm fragments at necropsy. All cats became heartworm antibody positive at some time point in the study except for one cat in Group A. Only cats in Group C (all with adult heartworms) were heartworm antigen positive. The heartworm antibody titer for Group B was highest on Days 110 to 168 and then decreased over time and 50% were serologically antibody negative on Day 240. Eosinophilic bronchoalveolar lavage (BAL) cytology and peripheral eosinophilia were most pronounced on Day 110 in all cats. Randomly distributed myofibrocytes in the lungs of some Group A cats suggest that precardiac larval stages were affecting the lungs. Radiographs in Group B cats demonstrated partial resolution of the initial HARD reaction but chronic myofibrocyte proliferation was histologically evident 18 months after infection. CONCLUSION: HARD was induced by immature adult worm infection with progressive improvement starting 6 to 8 months after infection but histologic lesions were evident in some cats 18 months after infection. The serologic antibody assay was negative in 50% of cats at 8 months and 100% of cats at 18 months post infection. Abnormal radiographic lung patterns continued in a subset of Group B cats for months after heartworm antibody serology and BAL cytology returned to normal.

[Mycological and parasitological examinations in the management of lung infections]. / Examens mycologiques et parasitologiques dans la prise en charge des infections pulmonaires.

Pulmonary parasitic diseases are rare whereas pulmonary fungal infections are increasing. The diversity of clinical presentations requires laboratory tests to confirm the diagnosis. Direct examination of lung samples and antibody detection are the basis of parasitological diagnosis. With regard to mycoses, the range of biological tests is broader. The conventional mycological examination allows identification of any type of fungus except Pneumocystis jirovecii. Its specificity is excellent but it lacks sensitivity. Detection of antibodies, antigens or nucleic acid complements the diagnostic tools. With regard to aspergillosis, there is a broad nosological set with variable prognosis. The choice of appropriate laboratory procedures depends on the clinical presentation and patient risk factors. The search for galactomannan antigen is effective and a new technique, "Lateral Flow Device", seems very promising. The detection of antibodies is also informative but various techniques are used. A good knowledge of the performance and limitations of these techniques allows targeted prescription. The use of PCR for the diagnosis of pulmonary fungal infections has limited indications. Biological and clinical co-operation is essential for the choice and interpretation of laboratory tests for parasitic or fungal pulmonary disease.

Parasites and vector-borne diseases in client-owned dogs in Albania. Intestinal and pulmonary endoparasite infections.

From March 2010 to April 2011 inclusive, feces from 602 client-owned dogs visiting four small animal clinics in Tirana, Albania, were examined using standard coproscopical techniques including Giardia coproantigen ELISA and immunofluorescent staining of Giardia cysts. Overall, samples of 245 dogs (40.7 %, 95 % CI 36.6-45.6) tested positive for at least one type of fecal endoparasite (protozoan and/or helminth and/or pentastomid) stage, of which 180 (29.9 %, 95 % CI 26.3-33.7) and 129 (21.9 %, 95 % CI 18.2-24.9) tested positive for protozoan or nematode endoparasites, respectively. Fecal forms of at least 14 endoparasites were identified. The most frequently identified stages were those of Giardia (26.4 %), Trichuris (9.5 %), Toxocara (8.0 %), hookworms (7.1 %), Cystoisospora ohioensis (4.3 %), and Cystoisospora canis (3 %). For the first time for dogs in Albania, fecal examination indicated the occurrence of Hammondia/Neospora-like (0.2 %), Angiostrongylus lungworm (0.3 %), capillariid (2.8 %), and Linguatula (0.2 %) infections. Single and multiple infections with up to seven parasites concurrently were found in 152 (25.2 %, 95 % CI 21.8-28.9) and 93 dogs (15.4 %, 95 % CI 12.7-18.6), respectively. On univariate analysis, the dog's age, the dog's purpose (pet, hunting dog, working dog), the dog's habitat (city, suburban, rural), and environment (mainly indoors, indoors with regular outside walking, yard, kennel/run), presence/absence of other dogs and/or cats, history of anthelmintic use, and season of examination were identified as significant (p < 0.05) factors predisposing dogs to various types of endoparasitism while the variables breed (pure breed dogs vs. mixed-breed dogs), gender, and type of food were not significant predictors. Multivariate logistic regression analysis for factors associated with overall endoparasitism revealed that dogs >1 year of age (odds ratio [OR] = 0.64), dogs dewormed at least once per year (OR = 0.35), and dogs tested during spring, summer, and autumn (OR = 0.51, 0.15, and 0.20, respectively) had a significantly lower risk compared with ≤1 year old dogs, dogs not dewormed, or dogs tested during winter. The odds of a dog to be diagnosed positive for endoparasites was 1.56 times higher for dogs living together with other pets than that for a dog without other dogs or cats.

Effects of different inoculation routes on the parasitic sites of Cryptosporidium baileyi infection in chickens.

Cryptosporidiosis is prevalent in domesticated, caged, and wild birds. Cryptosporidium baileyi, an ascendant species of avian Cryptosporidium, is an important pathogen. It causes respiratory disease in chickens, especially chickens younger than 50 days. In this study, SEM, histological, semi-quantitative PCR, and nested PCR techniques were used to explore the impact of different inoculation routes on sites of C. baileyi infection in chickens. Results showed that inoculation with sporozoites or oocysts via the rectum was an effective means of causing infection. This may provide an important reference for the development of the transfection system of C. baileyi in chickens. Numerous endogenous stages of C. baileyi were observed in the bursas of Fabricius (BF) and cloacas of chickens inoculated with sporozoites or oocysts via the rectum, but no parasite was seen in the tracheas of any of these chickens. In chickens infected with oocysts via the crop, the number of parasites in the BF was approximately 23-fold more than in the trachea. All blood samples collected after inoculation were negative for C. baileyi. These data show that C. baileyi was not transferred by blood circulation between the BF and respiratory tract. Different routes of inoculation were here found to distinctly affect sites of parasitism in chickens. These findings may facilitate further understanding of the biology of C. baileyi and efforts to control avian cryptosporidiosis.