Evidence of disseminated infection by Mycobacterium avium subspecies hominissuis in a pet ferret (Mustela putorius furo)

Ferrets as a model for tuberculosis transmission

Even with the COVID-19 pandemic, tuberculosis remains a leading cause of human death due to a single infectious agent. Until successfully treated, infected individuals may continue to transmit Mycobacterium tuberculosis bacilli to contacts. As with other respiratory pathogens, such as SARS-CoV-2, modeling the process of person-to-person transmission will inform efforts to develop vaccines and therapies that specifically impede disease transmission. The ferret (Mustela furo), a relatively inexpensive, small animal has been successfully employed to model transmissibility, pathogenicity, and tropism of influenza and other respiratory disease agents. Ferrets can become naturally infected with Mycobacterium bovis and are closely related to badgers, well known in Great Britain and elsewhere as a natural transmission vehicle for bovine tuberculosis. Herein, we report results of a study demonstrating that within 7 weeks of intratracheal infection with a high dose (>5 x 10³ CFU) of M. tuberculosis bacilli, ferrets develop clinical signs and pathological features similar to acute disease reported in larger animals, and ferrets infected with very-high doses (>5 x 10⁴ CFU) develop severe signs within two to four weeks, with loss of body weight as high as 30%. Natural transmission of this pathogen was also examined. Acutely-infected ferrets transmitted M. tuberculosis bacilli to co-housed naïve sentinels; most of the sentinels tested positive for M. tuberculosis in nasal washes, while several developed variable disease symptomologies similar to those reported for humans exposed to an active tuberculosis patient in a closed setting. Transmission was more efficient when the transmitting animal had a well-established acute infection. The findings support further assessment of this model system for tuberculosis transmission including the testing of prevention measures and vaccine efficacy.

Pathology of Diseases of Geriatric Exotic Mammals

The review covers select disease conditions most frequently described in aging rodents (rats, mice, hamsters, guinea pigs), rabbits, and ferrets. The conditions are categorized by general organ systems, infectious diseases, and neoplasms. Two data systems, the Veterinary Medical Teaching Hospital and Comparative Pathology Laboratory at the University of California, Davis and Zoo/Exotic Pathology Service, Citrus Heights, California were used in the determining disease conditions to describe.

Case of mycobacteriosis in a pet ferret in Poland

A seven-year-old dead pet ferret (Mustela putorius furo) was brought to the National Veterinary Research Institute, Department of Microbiology, to have the disease diagnosed and cause of death determined. Significant loss of fur and various numerous skin lesions—such as nodules, bruises and small scabs— were found. A prominent subcutaneous cyst filled with semiliquid mass was observed on the right hindlimb, and the left eyelid was slightly swollen left eyelid with symptoms of conjunctivitis. On the basis of combined findings, the authors concluded that the ferret’s death was caused by a generalized Mycobacterium aviumsubspecies avium infection. Some immunodeficiency resulting from ferret’s age could be a predisposing factor. A feral cat, which was the only animal the ferret had contacted several weeks before the appearance of the first clinical symptoms, was a possible source of infection.

The Role of Myofibroblasts in Granulomatous Lymphadenitis in Pigs Naturally Infected with M. Avium Subsp. Hominissuis

The most important morphological characteristic of infections caused by M. avium subsp. hominissuis (MAH) is granuloma formation. The growth of mycobacteria is in accordance with anti-bacterial effector mechanisms of the host within granuloma. The most important cytokines for „orchestrating“the host defense are interferon γ (INF-γ), tumor necrosis factor α (TNF-α) and transforming growth factor β1 (TGF-β1). Myofibroblasts that make up a peripheral layer of granuloma largely express receptors for TGF-β1. This cytokine is believed to affect the induction of myofibroblast proliferation. The aim of this paper is to point out the importance of myofibroblasts in the formation and sustainability of granuloma during natural infection of pigs with M. avium subsp. hominissuis. Examinations have been performed on the samples of Lnn. jejunales, Lnn. ileocolici and Lnn. colici of 100 pigs with a positive tuberculin skin test. The molecular method confirmed the presence of a genome M. avium subsp. hominissuis. The microscopic examination of lymph node samples stained by the routine hematoxyilin-eosin (HE) method, showed the presence of granulomatous lymphadenitis. The method of double immunohistochemical staining revealed that myofibroblasts which express TGF-β1 receptor type I (TGF-β1RI) and α smooth muscle actin (α SMA) have an important role in the morphogenesis of granulomatous lymphadenitis in pigs infected with MAH.

Mycobacteriosis in Pigs – An Underrated Threat

Although Mycobacterium avium subspecies are generally not considered food pathogens, the infections caused by these particular nontuberculous mycobacteria (NTM) can represent a serious threat to immunocompromised population. Additionally, infections with a member of Mycobacterium Avium Compex (MAC) can affect the efficiency of BCG vaccines used for the humans. In infected animals, M. avium may be present in different tissues without apparent clinical symptoms and macroscopic lesions. Veterinary meat inspection would then fail to recognize infected animals and such meat and meat products thereof could enter the human diet. The aim of this paper is also to analyze the current control policy in Europe according to infections of pigs with the members of MAC, and point out the risks for public health. By analyzing a large number of meat samples and other dietary nutrients, different groups of authors have provided evidence to support the hypothesis that M. avium is present in the everyday environment. Therefore, food as a source of infection with mycobacteria should not be ignored. The control of mycobacteria requires a better diagnostic approach, having in mind recent positive cases of M. avium subspecies hominissuis (MAH) in an increasing number of exported pigs from EU countries to Serbia. The introduction of reliable diagnostic methods for MAH could result in decreasing the occurrence of infection in pigs, as well as in humans, having in mind that WHO reported 10 million new cases of tuberculosis-mycobacteriosis in the human population in 2015 with 21% of these cases occurring in immunocompromised individuals and children.