Verification of immunosuppression in chicks caused by Cryptosporidium baileyi infection using Brucella abortus strain 1119-3

Outbreak of cryptosporidiosis in African penguins Spheniscus demersus

Cryptosporidium spp. are parasitic intracellular protozoa that infect the digestive, respiratory, and urinary tracts of vertebrates. The disease affects many different avian species across all continents, and >25 species and genotypes of Cryptosporidium have been documented infecting birds. We report on an outbreak of cryptosporidiosis in African penguin Spheniscus demersus chicks admitted to a rehabilitation center in South Africa from February 2012 to October 2013. Eighteen cases were confirmed through histopathology. The most frequent clinical signs were regurgitation (78%), dyspnea (72%), decreased weight gain or weight loss (72%), and lethargy (50%). Clinical signs began 8-46 d after hatching or admission (median: 13 d), and death followed 1-41 d after the onset of clinical signs (median: 13.5 d). The most frequent necropsy findings were stomach distended with undigested food or gas (78%), mildly reddened lungs (56%), spleen petechial hemorrhage (44%), and kidney congestion (39%). The most frequent histopathological findings were necrotic bursitis (89%), necrotic enteritis (83%), and bursal atrophy (67%). Small round or oval basophilic bodies (3-5 µm diameter) consistent with Cryptosporidium sp. were closely associated with the surface of the epithelial cells or in the lumen of the bursa (89%), large intestine (61%), small intestine (44%), trachea (22%), and ventriculus (6%). Transmission electron microscopy of 1 case confirmed that these organisms were Cryptosporidium sp. To our knowledge, this is the first report of cryptosporidiosis in penguins, raising concern of the potential implications for the conservation of these species.

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.

Avian Immunosuppressive Diseases and Immunoevasion

Subclinical immunosuppression in chickens is an important but often underestimated factor in the subsequent development of clinical disease. Immunosuppression can be caused by pathogens such as chicken infectious anemia virus, infectious bursal disease virus, reovirus, and some retroviruses (e.g., reticuloendotheliosis virus). Mycotoxins and stress, often caused by poor management practices, can also cause immunosuppression. The effects on the innate and acquired immune responses and the mechanisms by which mycotoxins, stress and infectious agents cause immunosuppression are discussed. Immunoevasion is a common ploy by which viruses neutralize or evade immune responses. DNA viruses such as herpesvirus and poxvirus have multiple genes, some of them host-derived, which interfere with effective innate or acquired immune responses. RNA viruses may escape acquired humoral and cellular immune responses by mutations in protective antigenic epitopes (e.g., avian influenza viruses), while accessory non-structural proteins or multi-functional structural proteins interfere with the interferon system (e.g., Newcastle disease virus).

Cryptosporidiosis in birds--a review

The morphology, life cycle, maintenance, host specificity, incidence of Cryptosporidium species infecting birds, as well as the epidemiology, clinical signs, pathology, immunology, diagnosis, therapy, and control of avian cryptosporidiosis are reviewed. Based on the accepted criteria used for differentiation of Cryptosporidium isolates into valid species, this review places the validity of C. meleagridis in doubt and suggests that C. meleagridis isolated from birds is very closely related to, or identical with C. parvum infecting more than 100 species of mammals.