Introduction Proventricular dilatation disease (PDD) is a disease of parrots which has been known for many years, but only in 2008 was it confirmed that its cause is avian bornavirus (ABV). Further disease aetiology and epidemiology information came subsequently. Later research distinguished an eight-genotype group of parrot bornaviruses (PaBV) infecting psittacines. In addition to PaBV, circoviruses (beak and feather disease viruses - BFDV) and avian polyomaviruses (APyV) also represent major viral pathogens of parrots. These may occur concurrently. This study's intent was to determine the occurrence of PaBV, BFDV and APyV in parrots in Poland between 2014 and 2024 and to compare it with extranational data.Material and Methods Samples taken from 210 naturally deceased breeder-owned and pet parrots necropsied between 2014 and 2024 were studied. Tissue samples were analysed by RT-PCR (PaBV) and nested PCR (BFDV and APyV).Results Parrot bornavirus RNA was detected in 50 parrots (23.8%), BFDV DNA in 59 (28%), and APyV DNA in 65 parrots (31%). A dilated proventriculus and gizzard - changes typical for PDD - were found in 22 (10.5%) cases and 18 were confirmed by a positive RT-PCR result. Thirty-two (15.2%) birds tested positive for PaBV despite the absence of obvious PDD lesions.Conclusion Bornavirus infections in parrots in Poland occur relatively often, but less frequently than infections with polyomaviruses and circoviruses. Only 36% of the birds with confirmed bornavirus infections had changes typical for PDD observed in necropsy.

This article investigates the causes of the sudden death of six common ravens (Corvus corax). All six birds were found on the same day in central Poland. The ravens were necropsied, and samples were collected for bacteriological, histopathological, and toxicological examinations. The presence of genetic material from common viral and some bacterial pathogens was examined using molecular methods. The ravens were found to be in good nutritional condition. Two birds had enlarged spleens with petechiae on their surface. Histopathological examination revealed multifocal hemorrhages and inflammatory infiltrates composed of mononuclear cells in the liver, and intranuclear inclusion bodies in hepatocytes. In the kidneys, inflammation, hemorrhages, parenchymal degeneration, and necrosis of the renal tubular epithelium were detected. Mild lymphocytic-plasmacytic inflammation was found in the intestines. Molecular tests were performed for circoviruses, herpesviruses, flaviviruses, adenoviruses, polyomavirus, avian bornavirus, avian paramyxovirus-1, rotavirus, avian reovirus, avian influenza viruses, Chlamydia spp., Salmonella spp., Clostridium spp., botulin toxins (A-E). Only PCR tests for circoviruses and herpesviruses yielded positive results. Toxicological tests were performed for the presence of organophosphate pesticides, rodenticides, coccidiostats, mycotoxins, and fungicides. Low and trace concentrations of brodifacoum (an anticoagulant rodenticide) and pentobarbital (a barbiturate) were detected. The remaining results were negative. There is a strong suspicion that the primary cause of death in the studied birds was raven herpesvirus, described in this case for the first time, with possible involvement of circovirus. However, other factors, including poisoning or other unknown viruses, cannot be ruled out. Although the toxicology profile was broad, it did not include all possible toxins.

Viral infections remain a major health concern in psittacine birds, with avian bornaviruses (ABV) causing proventricular dilatation disease (PDD), a chronic and often fatal condition. Ribavirin, a broad-spectrum antiviral drug widely used in human medicine, has shown in vitro (ABV) and in ovo (Newcastle disease virus) efficacy against some avian viruses, but its safety profile in birds is largely unknown. This study aimed to evaluate the safety of prolonged ribavirin administration in healthy cockatiels (Nymphicus hollandicus) aged approximately 6 months. The experiment consisted of experimental group (10 cockatiels) and negative control group (10 cockatiels). Ribavirin was administered to the experimental cockatiels according to the following protocol: orally (by gavage at dose 30 mg/kg body weight [BW]/day) two consecutive 28-day courses (course 1 & 2) separated and followed by 14-day recovery periods, then 15 mg/kg BW/day orally and 15 mg/kg BW/day intranasally for 28 days (course 3). The cockatiels were regularly weighed, clinically examined, and blood was collected for hematological and biochemical analyses. No clinical signs of adverse reactions were observed, neither during the therapy nor for 12 weeks after the therapy. BW changed significantly during the experiment, however without any link to ribavirin treatment. Only hematocrit decreased significantly after the ribavirin course 1. Our results indicate that ribavirin at 30 mg/kg BW, administered orally or in combination with intranasal dosing does not appear to cause apparent clinical or laboratory adverse reactions in cockatiels, except for potential alteration of hematocrit which is, however, too mild to be clinically meaningful. This provides an essential first step toward evaluating ribavirin as a therapeutic option for avian viral diseases.

BACKGROUND:Diseases caused by polyomaviruses and circoviruses in parrots were first described in the 1980s. Then they began to be diagnosed in other orders of birds, including Passeriformes, such as Atlantic canaries (Serinus canaria) and estrildid and fringillid finches. Over time, these viruses have also been found in an increasing number of captive and wild passerine species. The aim of the study was to assess the occurrence of these viruses in captive and wild Passeriformes in Poland, and the transmission of polyomaviruses and circoviruses through eggs in Atlantic canaries and Bengalese munias (Lonchura striata domestica). RESULTS:Nested PCR tests for avian polyomavirus (APyV) and circovirus (CV) were carried out on organ samples from 331 captive and wild birds belonging to 45 species, necropsied between 2006 and 2024. Additionally, 112 samples of eggs and dead chicks of Atlantic canaries and Bengalese munias from two aviaries with breeding problems were examined. Positive PCR results for APyV were found in 98 birds (29.6%), while CV DNA was detected in 152 birds (45.9%). In 104 wild birds examined, APyV was found in 13 (12.5%) and CV in 35 (33.7%) individuals. In 227 captive birds, APyV was found in 85 (37.4%) and CV in 117 (51.5%) individuals. Co-infections with both viruses were found in 25.1% of captive birds and 7.7% of wild birds. Negative results for both APyV and CV were found in 145 (43.8%) birds tested. In Atlantic canaries, CV DNA was identified in 79% of unfertilized eggs and 59% of embryos examined. In Bengalese munias, CV DNA was identified in 62.5% of unfertilized eggs and in all chicks examined. APyV DNA was not detected in eggs or embryos of canaries and Bengalese munias, nor in any Bengalese munia chicks or canary chicks younger than 7 days. CONCLUSIONS:Avian polyomaviruses and circoviruses are widespread in the population of captive and wild passerines in Poland, and a higher percentage of birds are infected with circovirus than with polyomavirus. Co-infections are more commonly observed in captive passerine birds than in wild passerine birds. Vertical transmission occurs for circoviruses, but not for polyomaviruses, in Atlantic canaries and Bengalese munias.

Introduction: Although the presence of rotaviruses in pigeon samples has been reported since the 1980s, its importance as an aetiological agent of the "classical" young pigeon disease (YPD) was not proven until 2020, when the Henle-Koch postulates were confirmed for pigeon-type rotavirus A (RVA) genotype G18P(17). Material and Methods: From 2011 to 2020, archived liver samples from 117 pigeons submitted by 74 individual lofts were tested for the presence of pigeon-type RVA using a VP6-specific RT-qPCR test. For four positive racing pigeons, a more detailed necropsy and histopathological analysis was performed. Results: Indicators of an acute RVA infection were found in 24 out of 117 (20.5%) samples tested, the earliest in 2014. Necropsies of the four selected RVA-positive pigeons showed changes mainly in the liver, spleen and kidneys similar to those described by other researchers. The histopathological examination revealed mainly hyperaemia and necrosis in the liver, as well as mononuclear cell infiltrates in these organs. Conclusion: Pigeon-type RVA is also a cause of YPD in Poland and is a serious challenge for racing pigeon breeders and veterinarians, especially during the training and flights of young pigeons.

This review article describes the current knowledge about the use of antiviral chemotherapeutics in avian species, such as farm poultry and companion birds. Specific therapeutics are described in alphabetical order including classic antiviral drugs, such as acyclovir, abacavir, adefovir, amantadine, didanosine, entecavir, ganciclovir, interferon, lamivudine, penciclovir, famciclovir, oseltamivir, ribavirin, and zidovudine, repurposed drugs, such as ivermectin and nitazoxanide, which were originally used as antiparasitic drugs, and some others substances showing antiviral activity, such as ampligen, azo derivates, docosanol, fluoroarabinosylpyrimidine nucleosides, and novel peptides. Most of them have only been used for research purposes and are not widely used in clinical practice because of a lack of essential pharmacokinetic and safety data. Suggested future research directions are also highlighted.

BACKGROUND:Pigeon Rotavirus A (RVA) infection has been confirmed in pigeons in the last decade as a cause of Young Pigeon Disease (YPD). Although YPD has been known for many years to date, no studies have been conducted to track the spread of RVA infection in pigeons during the racing season. The presented research aims to determine the course of RVA infection during the flights of young racing pigeons in the summer season, in one of the districts in the Mazovian Voivodeship in Poland. RESULTS:Faecal samples of pigeons collected from transport baskets in vehicles transporting pigeons to the starting point were tested. The quantitative RT-PCR (qRT-PCR) was used to detect the genetic material of RVA. Samples taken during 6 flights were analysed. The study showed a percentage increase in infections up to the fourth flight of pigeons, and then their decrease. With Cq values below 20, breeders did not participate in the next flight and/or reported disease in the flock. With positive Cq values of 20 to 30, clinical signs of disease were not reported. Of the 76 breeders participating in the races, at least one positive result was found in 46 (60.5%). Including the occurrence of the disease during the racing season was reported by 11 breeders (14.4%). The main clinical signs in sick pigeons were vomiting, diarrhea and stowed crop. The tested pigeons were not vaccinated against RVA. CONCLUSIONS:During training and racing of pigeons, it is not possible to avoid exposing them to pathogens, including RVA, regardless of whether pigeons from different breeders are placed in the same baskets or are in separate baskets. However, after four flights the number of new cases of the disease decreases which indicates the development of immunity. The qRT-PCR test is useful in the diagnosis and differentiation of clinical (Cq below 20) and subclinical RVA infections in racing pigeons.

A parrot breeder reported a problem with hand-reared chicks’ deaths. Pale skin and mucous membranes, sometimes convulsions, growth retardation and diarrhoea were observed in these birds. Post-mortem examination showed changes in the liver in two chicks, paleness or mottling of the kidneys, dilation of the proventriculus and gizzard, and bloating of the intestines in some birds. Microscopic examination of stained preparations from the intestinal content showed the presence of numerous spore-forming bacilli. Histopathological examination revealed degenerative and necrotic hepatocytes, lymphocyte depletion of spleen, bursa of Fabricius, and thymus and damage to the intestinal mucosa. Microbiological and direct molecular investigation of intestinal specimens showed the presence of Clostridium saudiense/Clostridium disporicum, in most samples tested, and Clostridium perfringens in one parrot. However, our study demonstrated that protein extract-based MALDI-TOF spectra, along with 16S rDNA sequencing, although commonly used for the reliable identification of many bacterial species, were not effective in distinguishing between C. saudiense and C. disporicum. Although the isolated clostridia, excluding C. perfringens, are not obligatory pathogenic bacteria, and they are a part of the intestinal microbiota in mammals.

An infestation of Ornithostrongylus quadriradiatus, has been found in a racing pigeon Columba livia domestica). In addition, this individual had a mild infection with Trichomonas spp. and Eimeria spp. The bird showed symptoms of increased appetite; unformed, dark- green feces; and lack of typical male behavior, but the general condition of this pigeon was good. The pigeon was euthanized because of a permanent inability to fly due to an injury to the wing. A postmortem examination revealed the presence of very small dark-pink twisted nematodes with the morphology of O. quadriradiatus in the small intestine, mainly the duodenum. Histopathology showed segmental inflammatory changes in the intestines caused by both blood-sucking nematodes and Eimeria spp. The 5.8S ribosomal ribonucleic acid polymerase chain reaction amplicons from deoxyribonucleic acid extracted from O. quadriradiatus had 82.40% identity with Australostrongylus victoriensis and 81.20% with Travassostrongylus spp. This is the first molecular characterization of O. quadriradiatus-a relatively rare pigeon parasite.

The presence of canary bornavirus (Orthobornavirus serini) genetic material was tested in organ samples from 157 Atlantic canaries (Serinus canaria) and four hybrids of Atlantic canary and European goldfinch (Carduelis carduelis). The subjects of the research were samples collected in the years 2006-2022. A positive result was obtained in 16 canaries and one hybrid (10.5%). Eleven positive canaries had neurological signs prior to death. Four of them also had atrophic changes in the forebrain, which have not previously been described in canaries and other species of birds infected with avian bornavirus. In one canary, computed tomography without contrast was performed. This study showed no changes, despite advanced forebrain atrophy found on post-mortem examination of the bird. The organs of the studied birds were also tested with PCR tests for the presence of polyomaviruses and circoviruses. There was no correlation between the bornavirus infection and the presence of the other two viruses in the tested canaries.RESEARCH HIGHLIGHTS The incidence of bornaviral infections in canaries in Poland is relatively low.Non-contrast CT is not a useful method for brain atrophy diagnostic in canaries.Neurological signs were found in the majority of birds infected with bornaviruses.Visceral ganglioneuritis was found in a minority of birds infected with bornaviruses.

Background To date, Campylobacter jejuni has not been found to be pathogenic to peafowl. The available publications show that out of a total of 44 samples tested from peafowl, this bacterium was isolated only in two cases. Eimeria pavonina infestations in the peafowl have been described, but no fatal cases have been reported yet. Case presentation The four-year-old peacock was presented with chronic diarrhea, emaciation and weakness. Post mortem examination revealed enlarged and pale kidneys, small intestinal mucosal necrosis and thickening of intestinal wall, and pericardial effusion. The histopathological examination revealed necrotic enteritis with marked mononuclear cells infiltration associated with the presence of coccidia, additionally there was histological evidence of septicemia in liver and kidneys. Bacteria identification was based on light microscopy of the small intestine sample, culture, and biochemical tests. Further identification was based on PCR. Antimicrobial susceptibility profile was created by determination of minimal inhibitory concentration (MIC) values for 6 antimicrobial agents from 5 different classes. PCR assays were performed to detect virulence factors genes responsible for motility, cytolethal distending toxin production, adhesion and internalization. Bacteriology of the small intestine sample showed abundant growth almost exclusively of Campylobacter jejuni , resistant to ciprofloxacin, gentamycin and ampicillin. Bacteria was sensitive to Amoxicillin + clavulanic acid, tetracycline, and erythromycin. All tested virulence factors genes have been detected. The parasitological examination was performed by microscopic examination of fresh faeces and intestinal content, and revealed the moderate number of Eimeria pavonina , Histomonas meleagridis , single Capillaria spp. eggs as well Heterakis spp. like parasites. Conclusion The above case shows that a virulent isolate of Campylobacter jejuni in combination with a parasitic invasion may cause chronic enteritis in peafowl, which most likely led to extreme exhaustion of the host organism and death.

Introduction Mycobacteriosis is a significant disease of companion and wild birds which causes emaciation and widely distributed lesions, as well as being a potential zoonosis. Its primary aetiological agents in birds are Mycobacterium avium subsp. avium and the fastidious Mycobacterium genavense . This study monitored the therapy of birds naturally infected with Mycobacterium genavense to gain understanding of its effectiveness and the interrelation of co-infections with the disease course and pharmacotherapy. Material and Methods Five Atlantic canaries ( Serinus canaria ) and one Bengalese finch ( Lonchura striata ) with tentative diagnoses of mycobacteriosis resulting from M. genavense infection were treated twice daily with clarithromycin at 40 mg/kg, ethambutol at 30 mg/kg, and moxifloxacin at 10 mg/kg for 6 months. Two canaries were also found to be carriers of Cryptosporidium galli . Mycobacteria in faecal samples of all birds were investigated by bacterioscopy and quantitative PCR. Results Molecular tests yielded positive results for up to four months after treatment initiation for M. genavense and Cryptosporidium , but microscopy failed to detect the latter after four weeks in specimens from one canary. Co-infections with polyomavirus (in all birds) and circovirus and bornavirus (in canaries) were diagnosed. Two birds died during treatment and one was euthanised because of other disease, 1 month after treatment completion. Three canaries were in relatively good health a year after treatment. Conclusion Canary circovirus and polyomavirus co-infection may suppress the immune system and this may facilitate the development of mycobacteriosis. The set of drugs used led to the complete cure of mycobacteriosis in three canaries. In one bird the disease returned. Clarithromycin was the active drug against C. galli . Molecular methods serve well to monitor mycobacteriosis therapy and identify M. genavense and C. galli carriage.

BACKGROUND:This study was aimed to investigate the intestinal microbiota in racing pigeons with regard to Enterococcus species distribution, virulence factors and antibiotic susceptibility. Three methods (API, Multiplex sodA-PCR, 16S rRNA sequencing) were compared for Enterococcus species identification. Cloacal samples from 179 apparently healthy pigeons of 13 different flocks were tested.RESULTS:Multiplex sodA-PCR and 16S rRNA gene sequencing showed almost perfect agreement in Enterococcus species identification. Isolates were identified as Enterococcus columbae (34.5%), Enterococcus hirae (20.7%), Enterococcus faecalis (11.7%), Enterococcus faecium (11.7%), Enterococcus gallinarum (9%), Enterococcus mundtii (4.8%), Enterococcus casseliflavus (3.4%), Enterococcus cecorum (2.1%), Enterococcus durans (2.1%). More Enterococcus species were found after the race season than before. The study showed differences between Enterococcus species in relation to 68.8% (22/32) biochemical parameters. Six out of seven virulence genes were detected: gelE (43.5%), asa1 (42.1%), efaA (30.3%), ace (30.3%), cylA (27.6%), and esp (9%). None of the isolates harboured hyl gene. Overall 15.2% of Enterococcus isolates produced gelatinase, but 66.7% gelE genes were silent. Enterococcus faecalis showed the most often efaA, ace and gelatinase activity than other enterococcal species. Nearly all isolates (93.1%) were resistant to at least one antibiotic. The most frequent resistance was to enrofloxacin (80%), doxycycline with teicoplanin (73.1%), erythromycin (49.7%). The study revealed significant differences between some enterococcal species in the antibiotic susceptibility to different antibiotics. Enterococcus columbae and E. cecorum showed significantly more frequent resistance to chloramphenicol than other enterococci. The presence of VRE (19.3%), HLGR (2.8%) and no LRE were found. Overall 30.3% of isolates were positive for vancomycin resistance genes, where vanC1 (E. gallinarum), vanC2-C3 (E. hirae, E. casseliflavus), vanB (E. columbae) predominated.CONCLUSIONS:We conclude, that intestinal microbiota in racing pigeons is composed by 9 different Enterococcus species. Given that racing pigeons are kept in close contact with humans and backyard animals, combined with their long-distance flight abilities, they can serve as potential source of virulent and antibiotic resistant Enterococcus spp. in the environment.

Mycobacteriosis caused by Mycobacterium avium subsp. avium was observed in a parental loft of 70 meat-breed pigeons. It was decided to undertake treatment as the birds represented a substantial value to the owner. A multiagent therapy using azithromycin, marbofloxacin, and ethambutol was administered. After 4 mo of therapy, the desired results were not obtained. At the end of treatment, the birds were in poor general condition, with white blood cells above 20 g/L, and after clutching, 2-yr-old and older birds were euthanatized. Overall, postmortem lesions were found in 17 out of 49 necropsied individuals. Slide agglutination tests with a M. avium subsp. avium lysate were conducted in all examined pigeons. In 28 pigeons, blood count was conducted once a month during therapy, while in 24 pigeons, a tuberculin sensitivity test was conducted before the planned euthanatization. The tuberculin sensitivity test did not prove useful in the diagnosis of ill individuals. Slide agglutination yielded positive results in only four birds, all of which also had postmortem lesions. Blood count in a large number of cases allowed distinguishing between ill and healthy individuals, which was used for subsequent selection. The comparison of cultured strains with the (CCG)4-based PCR method showed the variation of M. avium isolates up to a maximum of 30%. The described case proves that the treatment of mycobacteriosis in pigeon flocks is not effective, mainly due to the high resistance to M. avium subsp. avium. In addition, therapy may contribute to an even greater increase in mycobacterial resistance to antibiotics, which may pose a potential risk to public health.

Salmonellosis is one of the most important bacterial diseases in pigeons. The disease occurs in birds of different ages, and long-term Salmonella spp. carrier status is a major problem. The study included 499 samples from live pigeons and internal organs from 265 necropsied birds. The samples were cultured on a standard and selective media. Their antimicrobial susceptibility was carried out by the Kirby-Bauer diffusion method. Thirty one Salmonella spp. isolates were cultured. Most isolates were obtained from the internal organs of dead or euthanised pigeons, and only single isolates were obtained from droppings and cloacal swabs. A total of 4% of the samples tested were positive. The greatest percentage of isolates was susceptible to enrofloxacin (96.3%) and florfenicol (95.7%). Sulfamethoxazole and trimethoprim combination was effective against 73.9% of the isolates. Despite the fact of increasing antibiotic resistance of the investigated bacteria, it is comforting that enrofloxacin remains highly effective despite its widespread use in birds.

Mycobacterioses are a constant problem in backyard poultry, as well as pet birds. To date, no evidence of direct transmission of atypical bacilli between humans has been demonstrated, but it cannot be ruled out that sick animals can be a source of infection for people in their environment. The aim of the study was to identify mycobacteria isolated from birds with diagnosed mycobacteriosis and to determine the susceptibility of mycobacterial isolates from these animals to antituberculous drugs most commonly used in the treatment of mycobacterial infections in humans. For drug susceptibility tests, drugs such as isoniazid, rifampicin, streptomycin, ethambutol, ofloxacin, capreomycin, cycloserine and ethionamide were used. A high degree of drug resistance was demonstrated, particularly in Mycobacterium avium . Isolates of Mycobacterium xenopi showed a relatively good susceptibility to the drugs tested. The drug resistance of Mycobacterium genavense has not been determined, but this mycobacterium was identified in ten cases, which is the second most frequent occurrence in the cases studied. Mycobacterioses are a constant problem in backyard poultry, as well as pet birds. To date, no evidence of direct transmission of atypical bacilli between humans has been demonstrated, but it cannot be ruled out that sick animals can be a source of infection for people in their environment. The aim of the study was to identify mycobacteria isolated from birds with diagnosed mycobacteriosis and to determine the susceptibility of mycobacterial isolates from these animals to antituberculous drugs most commonly used in the treatment of mycobacterial infections in humans. For drug susceptibility tests, drugs such as isoniazid, rifampicin, streptomycin, ethambutol, ofloxacin, capreomycin, cycloserine and ethionamide were used. A high degree of drug resistance was demonstrated, particularly in Mycobacterium avium. Isolates of Mycobacterium xenopi showed a relatively good susceptibility to the drugs tested. The drug resistance of Mycobacterium genavense has not been determined, but this mycobacterium was identified in ten cases, which is the second most frequent occurrence in the cases studied.

Peafowl (Pavo cristatus), similarly to other Galliformes, are particularly susceptible to infection by Mycobacterium avium. Peafowl differ from other Galliformes in the clinical image of the infection, with dominating respiratory signs. Occurrence of severe and sustained dyspnoea in peafowl raises suspicion of mycobacteriosis, which, however, is not always easy to confirm. In the cases described here, mycobacteria were detected in direct swabs from the trachea of two individuals, and cultures were conducted on the Löwenstein- Jensen medium. In one individual, no mycobacteria were found in tracheal swabs stained by the Ziehl-Neelsen method, despite the presence of clear clinical signs. The fourth case was a young bird submitted for necropsy. The cause of death was a mechanical trauma, but scarce caseous nodules typical of mycobacteriosis were found in the liver, spleen and lungs. The Mycobacterium avium isolates obtained from those cases were compared using (CCG)4-based PCR. A high similarity of three isolates of Mycobacterium avium subsp. avium was observed, two of which were derived from peafowl originating from the same farm, while the isolate from the fourth bird differed significantly and was identified by sequencing as Mycobacterium avium subsp. paratuberculosis..