1Royal Zoological Society of Antwerp, K. Astridplein, Antwerp, Belgium; 2Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan, Merelbeke, Belgium; 3Animal Health, Institute of Tropical Medicine, Nationalestraat, Antwerp, Belgium
Following mortalities of confiscated turacos (Corythaeola cristate) in our quarantine section due to Cryptosporidium baileyi and a recent international report of lethal infections in mixed-bred falcons (Falco rusticolus x Falco cherrug), every individual aviary in the Antwerp Zoo was examined for this parasite. Pooled fecal samples were analyzed by modified Ziehl-Neelsen, rapid immunomigration, immunofluorescence and PCR. Only by PCR, one sample was found positive, suggestive for the low presence of Cryptosporidium in our captive bird population. Additionally, samples of trachea, lung and small intestine were taken at necropsies, but so far no evidence for Cryptosporidium spp. was found.
Material and Methods
From August 2008 until March 2009 pooled fecal samples and individual organs were analyzed for Cryptosporidium spp. Feces were collected in all 94 aviaries of the Antwerp Zoo, comprising 686 birds, in total 86 species and 22 orders. A modified Ziehl-Neelsen (mZN), an immunofluorescent assay (MeriFluor® Cryptosporidium/Giardia immunofluorescence assay, Meridian Diagnostics Inc., Cincinnati, OH 45244 USA), and an immunomigration dipstick assay (Crypto-Strip, Coris BioConcept, Belgium) were used for all fecal samples, and a PCR4 targeting the 18S rRNA was used for 50 samples. Since this parasite has been found in the respiratory and intestinal tract,5 tracheae, lungs and small intestines of 16 birds were sampled at necropsy.
Discussion and Conclusion
Although avian cryptosporidiosis has been reported worldwide1 in more than 30 avian species,5 data on its prevalence in zoos are lacking. In one Japanese zoo, all 173 samples of 46 avian species belonging to 11 orders were negative,2 yet a nucleic acid recognition method was not used. The detection limit of mZN is reported to stand at 106 oocysts per ml unconcentrated fecal smears, whereas PCR is reported to be more sensitive than conventional and immunologic assays.3 The immunologic assays have each a similar level of sensitivity, but whether these assays are performing better than staining methods remains a matter of discussion.3 The rapid immunomigration assay for copro-antigen can be useful when the oocysts are lacking in the feces.3
Our results indicate a low presence of Cryptosporidium in our collection and a higher sensitivity for PCR than mZN or immunoassays, but warrants a continuous search for this protozoan.
1. Coles, B. H. 2007. Parasitic diseases of birds. In: Coles, B. H. (ed.). Essentials of Avian Medicine & Surgery, 3rd ed., Blackwell Publishing Ltd., Oxford, UK. 313–333.
2. Matsubayashi, M., K. Takami, I. Kimata, T. Nakanishi, T. Hiroyuki, S. Kazumi, and B. Eiichiroh. 2005. Survey of Cryptosporidium spp. and Giardia spp. infections in various animals at a zoo in Japan. J. Zoo Wildl. Med. 36: 331–335.
3. World Organization for Animal Health. 2008. Cryptosporidiosis. Manual of Diagnostic Tests and Vaccines for Terrestrial Animals; Chapter 2.9.4. 1192–1215.
4. Ryan, U. M., L. Xiao, I. M. Sulaiman, P. Montis, A. A. Lal, R. Fayer, and I. Pavlasek. 2003. A redescription of Cryptosporidium galli Pavlasek, 1999 (Apicomplexa: Cryptosporidiidae) from birds. J. Parasitol. 89: 809–813.
5. van Zeeland, Y. R. A., N. J. Schoemaker, M. J. L. Kik, and W. J. B.van der Giessen. 2008. Upper respiratory tract infection caused by Cryptosporidium baileyi in three mixed-bred falcons (Falco rusticolus x Falco cherrug). Avian Dis. 52: 357–363.