Tuberculosis outbreak caused by Mycobacterium caprae in a rabbit farm in Spain

A humoral diagnostic test outperforms cellular tests in a farm with a latent tuberculosis outbreak caused by a new Mycobacterium tuberculosis complex spoligotype that affected sheep but not goats

Tuberculosis (TB) is a disease caused by members of the M. tuberculosis complex (MTC) that affects numerous species. M. caprae, a member of the complex which is close to M. bovis, is emerging and affects several different hosts that include goats, cattle, sheep, pigs, rabbits, wild boar, red deer, foxes and also humans. A new M. caprae spoligotype (SB2737) was isolated from an outbreak of sheep tuberculosis affecting a mixed sheep (323)-goat (29) farm in 2021. The index case was detected by the La Rioja slaughterhouse veterinary inspection. Tracing back to the farm of origin, both species were submitted to Comparative Intradermal Tuberculin Test (CITT) and M. bovis-specific antibody ELISA tests. A subsample was also examined by IFN-γ release assay (IGRA) and all positives were slaughtered and pathologically and microbiologically investigated. Only 1.2% of sheep and no goat were positive in the CITT, and 11.4% in the IGRA sheep subsample, while up to 36.8% were positive in two consecutive M. bovis-specific antibody ELISA tests. Goats had always tested negative in annual intradermal follow-up since 2013. Upon confirmation of the immunologically positive sheep at slaughter, all the remaining negative animals were killed and 29.2% of sheep were still found infected. This raised the final overall prevalence to 37.5%. Antibody ELISA was the most sensitive (81.4%) in vivo detection method still showing a 85.0% specificity relative to pathological and microbiological tuberculosis status. It was nearly 10 times more sensitive than skin test and had an 86.8% positive predictive value. Notwithstanding a possible singular pathogenesis of the new spoligotype, this outbreak adds up to previous reports suggesting that sheep tuberculosis could be huge reservoir of infection worldwide overlooked by skin test low sensitivity or simply lack of investigation. This makes it urgent to extend the use antibody tests to address the Trojan horse of hidden M. tuberculosis complex infections on bovine TB control programs.

Respiratory Disorders in Rabbits

Respiratory disorders are very common in rabbits. Rabbits are obligate nasal breathers, so "simple" rhinitis can cause severe respiratory distress and patient collapse. Causes of dyspnea could be of primary origin or secondary, whereby diseases primarily affecting other organs can result in respiratory embarrassment even if the respiratory system is healthy (eg, anemia, cardiac disease). Diagnosis is based on radiography, ultrasonography, endoscopy, computed tomography, and/or pathogen isolation. Once the diagnosis has been completed, treatment options should be discussed with the owner. The article describes the anatomy of the respiratory tract, diagnostics, and therapy for selected respiratory disorders in rabbits.

Antibody responses in European bison (Bison bonasus) naturally infected with Mycobacterium caprae

Mycobacterium caprae, a member of the Mycobacterium tuberculosis complex, infects humans and animals causing lesions and disease like that of Mycobacterium bovis. The aim of this study was to evaluate antibody responses in European Bison (EB, Bison bonasus; a vulnerable species) naturally infected with M. caprae using dual path platform (DPP) BovidTB test and multi-antigen print immunoassay (MAPIA). Study cohorts consisted of naturally M. caprae-infected EB (n = 4), M. caprae-exposed but uninfected (n = 3), EB infected with non-tuberculous mycobacteria or other respiratory pathogens (n = 3), and negative controls (n = 19). M. caprae-infected EB were seropositive by both DPP and MAPIA; 3/4 were seropositive by DPP; and 4/4 were seropositive by MAPIA. One M. caprae-infected animal that developed generalized disease with most advanced gross lesions in the group produced the most robust antibody response. All 25 EB with no culture-confirmed M. caprae infection, including three animals exposed to M. caprae and three other animals infected with non-tuberculous pathogens, were seronegative on both tests. Antibody responses to M. caprae infection included IgM antibodies against MPB70/MPB83 and IgG antibodies to both MPB70/MPB83 and CFP10/ESAT-6. This study demonstrates the potential for use of serological assays in the ante-mortem diagnosis of M. caprae infection in EB.

Emerging Infectious Diseases of Rabbits

Recently, multiple infectious organisms have been identified as the cause of emerging diseases in lagomorphs. The most important of these emerging diseases is rabbit hemorrhagic disease virus (RHDV) type 2, a new variant with differences in pathogenicity to classical RHDV. Hepatitis E is considered an emerging zoonotic infectious disease, with widespread prevalence in many different rabbit populations. Mycobacteriosis has been recently reported in other captive domestic rabbit populations. This article provides a recent review of the published literature on emerging infectious diseases in rabbits, including farmed, laboratory, and pet rabbits, some of which have zoonotic potential.