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During two falcon seasons (2020/21 and 2021/22) we investigated Serratospiculum samples from 112 falcons and examined a total of 760 nematodes. Of the 112 falcons, there were 62 Saker (Falco cherrug), 15 Peregrine (Falco peregrinus), 11 Gyr (Falco rusticolus), 7 Lanner falcons (Falco biarmicus) and 17 hybrid falcons. In 47 samples the origin of the birds was not mentioned, 49 were from Mongolia, 6 from the UAE, 3 from the USA, 2 from Russia, 2 from the UK and one each from Kazakhstan, Uzbekistan and Germany. Three different Serratospiculum species were identified: S. seurati from 100 falcons (62 Saker, 11 Gyr, 10 Peregrine, 5 Lanner, 12 hybrid falcons, S. tendo from 10 falcons (4 Peregrine, 2 Lanner, 1 Gyr, three hybrid falcons) and S. guttatum from two falcons (one Peregrine and one hybrid falcon). The main morphological features of the three parasite species were described briefly and hosts and countries where Serratospiculum spp. were found were listed according to references., Competing Interests: Declaration of Competing Interest The authors have no relevant financial or non-financial interests to disclose., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Air sac nematodes from birds are known for more than 200 years now and Filaria attenuata was the first described species from falcons, owl and corvid birds. The superficial description and the loss of the original material made F. attenuata a species inquirenda. Seurat (1915) redescribed the species with material from lanner falcon and pallid harrier from Algeria and based on this description Bain and Mawson, Rec S Aust Mus 18:265-28, (1981) created a new species, Serratospiculum seurati, by adding some, slightly divergent, measurements. The current paper is based on light and scanning electron microscopy of five male and 10 female S. seurati specimens from a Peregrine falcon that acquired the infection in Pakistan. The length of the slender male and female nematodes varied between 42-70 and 165-221 mm, respectively, spicules of unequal shape and length measured 292-325 and 638-785 μm. S. seurati was also found in Saker, Barbary and crossbreed falcons.

Pitted darkling beetles (Adesmia cancellata) were infected with nematode eggs found in the alimentary tract of a gyrfalcon (Falco rusticolus) naturally infected with Paraspiralatus sakeri. Third-stage larvae in numbers between 1 and 84 were removed from the beetles 5 weeks postinfection and were used for morphological studies as well as to infect domestic chicken, yellow-bellied geckos (Hemidactylus flaviviridis) and fringe-toed lizards (Acanthodactylus schmidti). All experimental animals, necropsied 4-38 weeks later, were positive for spirally coiled nematode larvae located under the skin and in the interstitium of skeletal muscles. Despite similarities in general morphology, larvae from beetles and reptiles and chicken differed strikingly in the total body length and body width. Differences in length of the muscular oesophagus and distances of cervical papillae, nerve ring and excretory pore from the anterior end were less distinct. Morphology of these larvae matched with larvae found in subcutaneous cysts in naturally infected houbara bustards (Chlamydotis macqueeni) from Pakistan and UAE as well as with those detected in the muscles of an ocellated skink (Chalcides ocellatus).

Philophthalmus aweerensis, a new eye fluke species, was discovered in the conjunctival cavities of a rhea in the UAE. This fluke was described and differentiated from other eye flukes that had been found in birds in the Middle East such as Philophthalmus palpebrarum, Philophthalmus nocturnus, Philophthalmus gralli, Philophthalmus lucipetus, Philophthalmus distomatosa, and Philophthalmus hegeneri. The new species lacks spination and is characterized by a long cirrus pouch extending behind the caudal margin of the acetabulum, long vitellaria of tubular type reaching the midbody, and a genital opening situated anteriorly to the bifurcation of the caeca.

We describe an outbreak of cryptosporidiosis in Stone curlews kept in a mixed-species rearing unit in Dubai. Cryptosporidium was the predominant intestinal pathogen detected, although microbiological investigations revealed a concurrent Salmonella infantis infection in two of the 29 Stone curlew chicks that died. Nineteen of 29 birds had catarrhal enteritis associated with histopathological findings of numerous Cryptosporidium developmental stages at the mucosal surface. Catarrhal enteritis was present without associated Cryptosporidium oocysts in five cases. Histology of the intestine, faecal examination by direct microscopy and antigenic detection by immunochromatography revealed the presence of Cryptosporidium spp. associated with catarrhal enteritis in intestinal sections and faeces. Clinical and histopathological outcomes of infection were severe, including disruption of intestinal epithelial integrity, the presence of numerous endogenous Cryptosporidium stages in intestinal epithelia and the excretion of large numbers of sporulated oocysts. The application of polymerase chain reaction and restriction fragment length polymorphism techniques at two 18S rRNA and one Cryptosporidium oocyst wall protein gene locus confirmed the presence of Cryptosporidium parvum DNA in faecal samples.

Four falcons from a private collection of 137 falcons in Abu Dhabi (UAE) died suddenly in summer 2005. In order to screen for a possible disease among the remaining falcons in the aviary, all other birds were caught, examined and treated if necessary. Most of the falcons suffered from massive lice infestation and 74 falcons additionally from a heavy Caryospora sp. burden. Endoscopy revealed yellowish plaques on intestines, livers or kidneys in 70 birds (51.1% morbidity). Proliferative serositis was seen in 17 out of 24 necropsied birds with plaques on intestines, livers or kidneys, which did not resemble any known disease in falcons. However, apart from 20 falcons, which died within a 6-week period after the initial examinations due to advanced disease stages, all other falcons responded well to the treatment with dimetridazole (Emtryl), indicating protozoal disease. Immunohistochemistry confirmed the presence of microsporidial antigen. The final diagnosis of Enterocytozoon (E.) bieneusi genotype D was confirmed with materials from 6 birds by PCR and sequencing. To our knowledge this is the first report of microsporidiosis caused by E. bieneusi in raptors in general and in falcons in particular. However, it is still unclear for how long E. bieneusi was present in the falcon flock, and which role it played in the development of the disease. Predisposing factors such as high temperature and overcrowding in the aviary induced immune suppression causing massive lice infestation as well as coccidiosis, thus paving the way for invasion with microsporidial spores.