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Avian haemosporidian parasites are widespread and infect birds from a broad variety of avian families with diverse consequences ranging from subclinical infections to severe and fatal disease. This study aimed to determine the occurrence and diversity of avian haemosporidia including associated clinical signs and pathomorphological lesions in captive and free-ranging, wild birds from two zoos and the near environment in Switzerland. Blood samples from 475 birds, including 230 captive and 245 free-ranging, wild individuals belonging to 42 different avian species from 15 orders were examined for the presence of avian haemosporidian DNA by a one-step multiplex PCR designed to simultaneously detect and discriminate the genera Plasmodium , Haemoproteus and Leucocytozoon by targeting mitochondrial genome sequences. Positive samples were additionally tested using a nested PCR targeting the cytochrome b gene of Plasmodium and Haemoproteus . The obtained amplicons were bidirectionally sequenced. This study revealed haemosporidian DNA in 42 samples, belonging to ten host species. The most commonly detected lineage was Plasmodium relictum SGS1, which was identified in 29 birds ( Phoenicopterus roseus : n = 24, Alectoris graeca : n = 1, Lamprotornis superbus : n = 1, Somateria mollissima : n = 1, Spheniscus demersus : n = 1, Tetrao urogallus crassirostris : n = 1), followed by Haemoproteus sp. STRURA03 in six avian hosts ( Bubo bubo : n = 5, Bubo scandiacus  = 1), Plasmodium relictum GRW11 in four individuals ( Phoenicopterus roseus : n = 3, Spheniscus demersus : n = 1) and Plasmodium elongatum GRW06 in one Alectura lathami lathami . A Phalacrocorax carbo was infected with Plasmodium relictum , but the exact lineage could not be determined. One mixed infection with P. relictum and Haemoproteus sp. was detected in a Bubo scandiacus . Only five individuals ( Spheniscus demersus : n = 2, Somateria mollissima : n = 1, Bubo scandiacus : n = 1, Alectoris graeca : n = 1) showed clinical and pathomorphological evidence of a haemosporidian infection., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Authors.)

Syngamosis is a disease caused by the strongylid nematode Syngamus trachea, which infects the respiratory tract of various bird species around the world. The parasite appears to be harmful for a wide variety of avian orders, occasionally leading to a fatal outcome, particularly in young birds. The aim of this study was to examine the parasitic fauna in deceased or euthanized, free-ranging white storks nesting at the Zoo Basel in 2019 and 2020; and to assess the extent to which these parasites contributed to the wild birds' death. In five out of 24 necropsied white storks, an infection with S. trachea was diagnosed based on morphological analysis of adult nematode stages and eggs, in combination with PCR amplification and sequencing of DNA extracted from female worms. The main pathological changes affected the white storks' respiratory tract and a mixed cell tracheitis was diagnosed in the histopathological examination of three of the five infected birds. Some birds displayed additional lesions compatible with syngamosis, namely partially degenerated parasitic structures with concurrent granulomatous inflammation in the lung and multifocal acute hemorrhages in the bronchi and parabronchi. Coprological examinations (fecal flotation technique, fecal sedimentation technique, sodium acetate acetic acid formalin procedure and Ziehl-Neelsen staining) from the intestinal content as well as a PCR for Toxoplasma gondii on brain, lung, heart, liver, and spleen tissue yielded negative results in all examined individuals. In the absence of further major pathological findings, S. trachea was assumed to have significantly contributed to the death of the infected birds., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Authors.)

Avian malaria is a vector-borne disease caused by Plasmodium species , which may affect a broad spectrum of bird families worldwide. In most endemic and migratory birds, Plasmodium infections seem not to cause severe harm; however, non-indigenous species kept in human care such as penguins may experience high morbidity and mortality rates. Fatal avian malaria may also occur in other non-native seabirds such as puffins ( Fratercula spp.), but reported cases are scarce. The aim of this study was to analyze seven cases of sudden death in captive Atlantic puffins ( Fratercula arctica ) at Berne Animal Park in Switzerland between 2010 and 2020, and to determine the involvement of haemosporidian parasites in the fatal outcome. In all cases, lymphoplasmacytic inflammation, necrotic lesions in several organs and presence of protozoan stages within tissues/erythrocytes or accumulation of iron-based pigment were observed histologically. A one-step multiplex PCR designed to simultaneously detect and discriminate haemosporidia belonging to the genera Plasmodium , Haemoproteus and Leucocytozoon, and a nested PCR detecting Plasmodium and Haemoproteus infections were performed on DNA extracted from formalin-fixed and paraffin-embedded (FFPE) or fresh liver and spleen tissues from five and two birds, respectively. Plasmodium spp. DNA was detected in the tissues from six of seven birds by the one-step multiplex PCR and in five of seven individuals by the nested PCR protocol. Direct sequencing of the amplification products allowed the molecular identification of Plasmodium relictum SGS1 as the involved species in three individuals and Plasmodium matutinum LINN1 in two of these fatal cases. In one bird, no haemosporidian DNA could be amplified from FFPE tissues despite of suggestive histopathological findings. These results indicate that avian malaria represents an important cause of death in captive puffins and it should be considered as a differential diagnosis in unclear or fatal cases in this threatened bird species., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2021 The Authors.)