Spotlight on avian pathology: aspergillosis

Aspergillosis in 41 wild bird species in the eastern United States: a 22-year retrospective review

Aspergillosis is the most commonly and widely reported fungal infection in birds. Disease development is often secondary to stressors that cause immunocompromise, and it is typically regarded as a disease of captivity. We retrospectively evaluated data from 133 birds diagnosed with aspergillosis at the Southeastern Cooperative Wildlife Disease Study from 2001-2023 to assess diversity and relative frequency across avian taxa, gross and histologic lesion patterns, and comorbidities. Of 10 taxonomic orders represented, Charadriiformes (shorebirds; n = 35) and Accipitriformes (raptors; n = 32) were most common. Among them, the laughing gull (Leucophaeus atricilla; n = 20) and bald eagle (Haliaeetus leucocephalus; n = 14) were infected most commonly. Gross lesions were most frequent in lung (n = 80), air sac (n = 71), or celomic cavity lining (n = 42). Four distinct gross lesion patterns were identified: 1) tan caseous plaques (n = 106), 2) hollow masses lined with mold (n = 26), 3) red pulmonary nodules (n = 15), and 4) necrotic brown plaques (n = 3). Histologically, fungal hyphae were most common in lung (n = 107) and air sac (n = 49). Comorbidities were diagnosed in 67 birds with a spectrum of viral (n = 19), bacterial (n = 11), parasitic (n = 6), other fungal (n = 4), and non-infectious (n = 50) causes. Six birds each were diagnosed with highly pathogenic avian influenza or salmonellosis. Twenty-two birds were emaciated. Free-ranging birds are susceptible to myriad stressors that can predispose them to the development of aspergillosis.

Disseminated Infection with Aspergillus fumigatus in a Scarlet Macaw Parrot (Ara macao)-A Case Report

A 3-year-old male scarlet macaw parrot (Ara macao) was presented to the Exotic Animal Clinic at the Faculty of Veterinary Medicine, Iași University of Life Sciences (Iași, Romania) for its postmortem examination. According to the owner, the parrot had been raised only in captivity and after 5 days of inappetence, lethargy, and mild respiratory clinical signs, the parrot died. The post mortem examination revealed various-sized granulomas and caseous plaques in the lungs, air sacs, spleen, intestinal serosa, and liver. Microscopically, the granulomas were characterized by a necrotic center and the infiltration of numerous multinucleated giant cells and epithelioid-like cells and by the presence of hyphae typical of Aspergillus spp. Moreover, in the liver tissue, a diffuse inflammation, with numerous fungal hyphae, was noted. The fungal culture and the PCR assay allowed for the isolation and identification of Aspergillus fumigatus from the lung and liver samples. The macroscopical lesions and the histopathological findings, with the fungal isolation and molecular confirmation of Aspergillus fumigatus by nested PCR, provided the basis for the diagnosis of disseminated aspergillosis. To the authors' best knowledge, this is the first report of disseminated infection caused by Aspergillus fumigatus in a scarlet macaw parrot (Ara macao).

Epidemiological characteristics and financial losses due to avian aspergillosis in households in the Almaty region, Republic of Kazakhstan

Aspergillosis is a severe fungal disease that affects all species and ages of poultry and leads to significant economic losses within the poultry industry. The economic significance of aspergillosis is associated with direct losses due to poultry mortality, a decline in the production of meat and eggs, feed conversion, and poor growth of recovering poultry. Although a decrease in the production of poultry meat and eggs in Kazakhstan due to this fungal disease has been widely reported, studies on the consequent financial losses on affected farms (households) have not been carried out. This study aimed to estimate the financial losses and epidemiological parameters of avian aspergillosis among households affected by the disease in the Almaty region. To achieve the objectives of the research, a survey was conducted involving affected households from February 2018 to July 2019. The affected poultry were diagnosed based on clinical, macroscopical, and microscopical procedures, and once the infection was confirmed, household owners were interviewed. Data were collected from 183 household owners. The median incidence risk and fatality rates were 39 and 26% in chickens, 42 and 22% in turkeys, and 37 and 33% in geese, respectively, with young poultry having a higher incidence risk and fatality rate than adults. Approximately 92.4% of the household owners treated the affected poultry using natural folk methods and 7.6% of household owners used antifungal drugs and antibiotics, spending a median of US $35.20 (min US $0; max US $400) per household throughout the course of the infection. Egg production was reduced by a median of 58.3% when households were affected. The price of poultry fell by a median of 48.6% immediately after recovery due to weight loss. The median of the overall financial losses of households was US $198.50 (min US $11; max US $1,269). The majority of household owners (65%) did not replace their poultry, 9.8% of household owners replaced all their poultry, and the remaining 25.1% replaced only a proportion of the poultry lost at the time of the study. Newly acquired poultry were purchased from neighbors (10.9%), fellow villagers (50%), and state poultry farms (39.1%). This study demonstrates that aspergillosis has an immediate impact on subsistence household owners' livelihoods in the Almaty region of Kazakhstan.

Aspergillus spp. Isolated from Lungs of Poultry (Gallus gallus) at the Mycology Laboratory, School of Veterinary Medicine, Universidad Nacional, Heredia, Costa Rica between 2008 and 2021 and Associated Factors

Aspergillosis is a disease caused by some species of the fungus Aspergillus, occurring in both mammals (including humans) and birds, the latter being the most susceptible group. Aspergillus must be considered a public health concern as it affects the poultry industry economically and is an occupational risk to its workers. A retrospective study of fungal isolates from the lungs of chickens (Gallus gallus), analyzed between 2008 and 2021 at the Mycology Laboratory, School of Veterinary Medicine, Universidad Nacional, Heredia, Costa Rica was performed to report the prevalence of Aspergillus spp. in poultry farms in Costa Rica and their associated factors. A total of 1113 cases were received, of which 31% (n = 392; 95% CI: 28.3−33.7) were positive for fungal isolation. Aspergillus was the most frequently detected genus, and the most frequent sections were Fumigati (n = 197/392, 50.3%), Flavi (n = 90/392, 22.9%), and Nigri (n = 50/392, 12.7%). Significant effects (p < 0.05) related to the year, geographical origin, purpose, and age were identified in relation to the Aspergillus infection. The identified factors are explained by climatic variations in the tropics and the particularities of the birds. Future research including molecular characterization and antifungal susceptibility tests in animals, humans, and the environment, are needed to better understand the risks of the diseases caused by those fungi in this country.

Histopathological Findings in the Cardiovascular System of Psittacidae in Routine Diagnostics

Samples of 363 Psittacidae were included in this study with a focus on cardiovascular diseases. These were identified in 28.9% of the animals, with pericarditis and/or epicarditis and myocarditis representing approximately half of all lesions and bacteria being the most common infectious cause. Cardiac lymphoma was only seen in 5 birds, whereas degenerative vascular lesions were diagnosed in 26.7% of the cases. Histopathology in the context of clinical findings and complementary examination results is the most useful tool for the evaluation of cardiac diseases.

Aerosol Concentrations and Fungal Communities Within Broiler Houses in Different Broiler Growth Stages in Summer

Fungal aerosols in broiler houses are important factors that can harm the health of human beings and broiler. To determine the composite characteristics and changes in fungal aerosols in broiler houses during different broiler growth stages in summer. We analyzed the species, concentration and particle diameter distribution characteristics of the aerosols in poultry houses using an Andersen sampler and internal transcribed spacer 1 (ITS1) high-throughput sequencing technology. The concentration of fungal aerosols in the poultry houses increased as the ages of the broiler increased, which was also accompanied by gradual increases in the variety and diversity indices of the fungal communities in the air of the poultry houses. During the entire broiler growth period, the dominant genera in the fungal aerosols in the poultry houses included Trichosporon, Candida, Aspergillus, Cladosporium and Alternaria. These fungi may be harmful to the health of poultry and human beings, so permanent monitoring of microbial air quality in chicken houses is necessary.

Molecular epidemiology of aspergillosis in Magellanic penguins and susceptibility patterns of clinical isolates

Aspergillus section Fumigati is reported in up to 99% of aspergillosis cases in penguins. So far, no data regarding molecular epidemiology and azole resistance are available for A. fumigatus isolates collected from Magellanic penguins. The aim of this work was to perform molecular identification of Aspergillus section Fumigati at species level, to genotype those isolates using microsatellite markers, to evaluate the in vitro susceptibility patterns of A. fumigatus sensu stricto, and to characterize the cyp51A gene in clinical A. fumigatus strains isolated from Magellanic penguins with proven aspergillosis. All 34 isolates included in the study were identified as A. fumigatus sensu stricto. Analyzing the genetic diversity of the isolates of A. fumigatus sensu stricto, we identified two possible outbreaks in the rehabilitation center and we also observed the maintenance of clonal strains through the years. One A. fumigatus sensu stricto isolate was resistant to posaconazole, but the mutations found in the cyp51A gene of this isolate have not been described as conferring phenotypic resistance, suggesting that other mechanisms of resistance could be involved in the resistance of this isolate. With this study we were able to understand the molecular diversity of Aspergillus fumigatus isolates collected from Magellanic penguins, to characterize them and to associate them with the described global population of Aspergillus fumigatus.

Aspergillosis in Wild Birds

The ubiquitous fungi belonging to the genus Aspergillus are able to proliferate in a large number of environments on organic substrates. The spores of these opportunistic pathogens, when inhaled, can cause serious and often fatal infections in a wide variety of captive and free-roaming wild birds. The relative importance of innate immunity and the level of exposure in the development of the disease can vary considerably between avian species and epidemiological situations. Given the low efficacy of therapeutic treatments, it is essential that breeders or avian practitioners know the conditions that favor the emergence of Aspergillosis in order to put adequate preventive measures in place.

Pulmonary Artery Aneurysm in a Greater Flamingo (Phoenicopterus roseus) Associated with Aspergillus fumigatus Infection

We report necropsy findings in a captive 60-year-old female greater flamingo (Phoenicopterus roseus) that died suddenly following rupture of a pulmonary artery aneurysm. Histologically, there was focally extensive, intramural granulomatous inflammation with intralesional fungal hyphae, and adjacent severe mixed-cell inflammation and acute haemorrhage at the rupture site. Aspergillus fumigatus was identified as the aetiological agent following DNA PCR amplification and sequencing from paraffin-embedded pulmonary artery tissue sections. The most likely explanation is that this lesion was a consequence of haematogenous spread, secondary to mycotic pneumonia or aerosacculitis, following aspiration of A. fumigatus conidiospores. However, no further fungal-related lesions were observed on gross or histopathological examination.

Aspergillosis, Avian Species and the One Health Perspective: The Possible Importance of Birds in Azole Resistance

The One Health context considers health based on three pillars: humans, animals, and environment. This approach is a strong ally in the surveillance of infectious diseases and in the development of prevention strategies. Aspergillus spp. are fungi that fit substantially in this context, in view of their ubiquity, as well as their importance as plant pathogens, and potentially fatal pathogens for, particularly, humans and avian species. In addition, the emergence of azole resistance, mainly in Aspergillus fumigatus sensu stricto, and the proven role of fungicides widely used on crops, reinforces the need for a multidisciplinary approach to this problem. Avian species are involved in short and long distance travel between different types of landscapes, such as agricultural fields, natural environments and urban environments. Thus, birds can play an important role in the dispersion of Aspergillus, and of special concern, azole-resistant strains. In addition, some bird species are particularly susceptible to aspergillosis. Therefore, avian aspergillosis could be considered as an environmental health indicator. In this review, aspergillosis in humans and birds will be discussed, with focus on the presence of Aspergillus in the environment. We will relate these issues with the emergence of azole resistance on Aspergillus. These topics will be therefore considered and reviewed from the “One Health” perspective.

Use of Essential Oils in Veterinary Medicine to Combat Bacterial and Fungal Infections

Essential oils (EOs) are secondary metabolites of plants employed in folk medicine for a long time thanks to their multiple properties. In the last years, their use has been introduced in veterinary medicine, too. The study of the antibacterial properties of EOs is of increasing interest, because therapies with alternative drugs are welcome to combat infections caused by antibiotic-resistant strains. Other issues could be resolved by EOs employment, such as the presence of antibiotic residues in food of animal origin and in environment. Although the in vitro antimicrobial activity of EOs has been frequently demonstrated in studies carried out on bacterial and fungal strains of different origins, there is a lack of information about their effectiveness in treating infections in animals. The scientific literature reports some studies about in vitro EOs' activity against animal clinical bacterial and fungal isolates, but in vivo studies are very scanty. The use of EOs in therapy of companion and farm animals should follow careful studies on the toxicity of these natural products in relation to animal species and route of administration. Moreover, considering the different behavior of EOs in relation to both species and strain pathogen, before starting a therapy, an aromatogram should be executed to choose the oil with the best antimicrobial activity.

Antifungal drugs-low-susceptibility in Aspergillus flavus isolated from a captively reared Okinawa rail (Hypotaenidia okinawae)

A four-month old female Okinawa rail (Hypotaenidia okinawae) presented with respiratory distress. Despite antifungal treatment with voriconazole (VRZ), micafungin (MCF), and itraconazole (ITZ), respiratory distress did not improve and the bird died 167 days after initiating treatment. Necropsy revealed multifocal pyogranulomatous necrotic nodular lesions with numerous whitish-green fungal hyphae in the left air sac. Aspergillus flavus was isolated from the left air sac lesion. Antifungal susceptibility tests indicated that the isolate showed low susceptibility to amphotericin B (AMB), fluconazole (FLZ), VRZ and MCF.