Tuberculosis Caused byMycobacterium microtiin South American Camelids

A Literature Review of Selected Bacterial Diseases in Alpacas and Llamas-Epidemiology, Clinical Signs and Diagnostics

The breeding of South American Camelids (SACs), particularly llamas and alpacas, is becoming increasingly popular in regions that are not their natural habitat, including Europe. These animals are considered to be relatively disease resistant. However, due to their growing popularity, special attention should be given to infections in llamas and alpacas. Knowledge of bacterial infections is very important to veterinarians and breeders. Many of these diseases also have zoonotic potential, so these animals must be considered as sources of potential zoonotic infections. Due to the limited information on many diseases occurring in llamas and alpacas, veterinarians often rely on data collected in other animal species, focusing on cattle, sheep and horses. This work aims to summarise the knowledge of diseases caused by Clostridium spp., Mycobacterium tuberculosis complex, Mycobacterium avium subsp. paratuberculosis, Streptococcus spp., Escherichia coli, Pasteurella multocida, Manheimia haemolytica and Corynebacterium pseudotuberculosis in llamas and alpacas, with particular attention to epidemiology, clinical signs and diagnostics.

The puzzle of the evolutionary natural history of tuberculosis

Several pieces of the puzzle of the natural history of tuberculosis are assembled in this review to illustrate the potential reservoirs and sources of the Mycobacterium tuberculosis complex (MTBC) mycobacteria, their transmission to animals and humans, and their fate in populations, in a co-evolutionary perspective. Millennia-old companions of mammalian and human populations, MTBC are detected in the soil, in which they infect and survive within vegetative amoebae and cysts, except for Mycobacterium canettii. Never detected in the sphere of plants, they are transmissible by transcutaneous, digestive and respiratory routes and cause an infection of the lymphatic system with secondary dissemination in most tissues, in which they determine a specific and non-pathognomonic granulomatous inflammatory reaction; in which MTBC survives in dormant form irrespective of MTBC species and mammalian species; indicating that the current epidemiology in mammalian populations is essentially governed by the probabilities of contact between mammalian species and MTBC species. Individual variabilities in clinical expression of tuberculosis are related to MTBC species, strain and inoculum; host genetic factors; acquired modulations of the inflammatory response; and probably human microbiota. This review of the literature suggests an evolutionary natural history of telluric environmental mycobacteria, satellites of unicellular eukaryotes, transmissible to mammals via the digestive and then respiratory tracts, in which they determine a fatal contagious infection that is primarily lymphatic and a quiescence-mimicking encysted form. This review opens perspectives for microbiological and translational medical research.

Pathogenomic analyses of Mycobacterium microti, an ESX-1-deleted member of the Mycobacterium tuberculosis complex causing disease in various hosts

Mycobacterium microti is an animal-adapted member of the Mycobacterium tuberculosis complex (MTBC), which was originally isolated from voles, but has more recently also been isolated from other selected mammalian hosts, including occasionally from humans. Here, we have generated and analysed the complete genome sequences of five representative vole and clinical M. microti isolates using PacBio- and Illumina-based technologies, and have tested their virulence and vaccine potential in SCID (severe combined immune deficient) mouse and/or guinea pig infection models. We show that the clinical isolates studied here cluster separately in the phylogenetic tree from vole isolates and other clades from publicly available M. microti genome sequences. These data also confirm that the vole and clinical M. microti isolates were all lacking the specific RD1mic region, which in other tubercle bacilli encodes the ESX-1 type VII secretion system. Biochemical analysis further revealed marked phenotypic differences between isolates in type VII-mediated secretion of selected PE and PPE proteins, which in part were attributed to specific genetic polymorphisms. Infection experiments in the highly susceptible SCID mouse model showed that the clinical isolates were significantly more virulent than the tested vole isolates, but still much less virulent than the M. tuberculosis H37Rv control strain. The strong attenuation of the ATCC 35872 vole isolate in immunocompromised mice, even compared to the attenuated BCG (bacillus Calmette-Guérin) vaccine, and its historic use in human vaccine trials encouraged us to test this strain's vaccine potential in a guinea pig model, where it demonstrated similar protective efficacy as a BCG control, making it a strong candidate for vaccination of immunocompromised individuals in whom BCG vaccination is contra-indicated. Overall, we provide new insights into the genomic and phenotypic variabilities and particularities of members of an understudied clade of the MTBC, which all share a recent common ancestor that is characterized by the deletion of the RD1mic region.

Mycobacterium microti: Not Just a Coincidental Pathogen for Cats

Public interest in animal tuberculosis is mainly focused on prevention and eradication of bovine tuberculosis in cattle and wildlife. In cattle, immunodiagnostic tests such as the tuberculin skin test or the interferon gamma (IFN-γ) assay have been established and are commercially available. Feline tuberculosis is rather unknown, and the available diagnostic tools are limited. However, infections with Mycobacterium tuberculosis complex members need to be considered an aetiological differential diagnosis in cats with granulomatous lymphadenopathy or skin nodules and, due to the zoonotic potential, a time-efficient and accurate diagnostic approach is required. The present study describes 11 independent cases of Mycobacterium microti infection in domestic cats in Switzerland. For three cases, clinical presentation, diagnostic imaging, bacteriological results, immunodiagnostic testing, and pathological features are reported. An adapted feline IFN-γ release assay was successfully applied in two cases and appears to be a promising tool for the ante mortem diagnosis of tuberculosis in cats. Direct contact with M. microti reservoir hosts was suspected to be the origin of infection in all three cases. However, there was no evidence of M. microti infection in 346 trapped wild mice from a presumptive endemic region. Therefore, the source and modalities of infection in cats in Switzerland remain to be further elucidated.

Tuberculosis caused by Mycobacterium caprae in a camel (Camelus dromedarius)

BACKGROUND

Animal tuberculosis (TB) is distributed worldwide and has a wide range of wild and domestic reservoirs. Few studies concerning TB in camelids have been published in the last decade, particularly as regards Old World Camelids (OWC), but the increase in reports of TB outbreaks in these species in recent years suggests a high susceptibility to the infection.

CASE PRESENTATION

We studied a dromedary camel (Camelus dromedarius) herd (n = 24) in which a Mycobacterium caprae infection was detected. The TB infection was confirmed in one animal at necropsy through the detection of TB lesions, mainly in the abdominal organs, and the subsequent isolation of M. caprae (SB0157 spoligotype). The whole herd was additionally tested using cellular and humoral based diagnostic techniques. The intradermal tuberculin test results were compared with those obtained using P22 ELISA for the detection of specific antibodies against the M. tuberculosis complex. The TB infected animal was a positive reactor to both the intradermal tuberculin tests and P22 ELISA, while the others were negative to all the diagnostic tests.

CONCLUSION

The present study found M. caprae infection in OWC. This is the first report of M. caprae infection in an OWC not living in a zoo. Since the animal was born in the herd and fed with goat's milk, this practice was suspected to be the potential source of TB infection, which was not confirmed in the other animals present in the herd. Moreover, our results highlight that the intradermal tuberculin test and the P22 ELISA could be valuable tools for the diagnosis of TB in OWC.

Examining variation in skeletal tuberculosis in a late pre-contact population from the eastern mountains of Peru

OBJECTIVE AND MATERIALS

This research evaluates the presence and chronology of tuberculosis (TB) in the northeastern highlands of Peru (CE 800-1535) through the analysis of osseous lesions from Pre-Contact Kuelap, Chachapoyas.

METHODS

We examined macroscopic lesion morphology and distribution from the skeletal series (MNI = 207).

RESULTS

We determined that skeletal evidence was highly consistent with advanced multifocal and spinal tuberculosis in 13 individuals. Destructive lesions of the lower thoracic and/or lumbar vertebra bodies and sacroiliac joints are evident in most cases, but we also observed lesions within the manubriosternal, hip, and knee joints. Both adult males (n = 7) and females (n = 6) present skeletal lesions from young adult to older adults, but there is only one late adolescent. Only three individuals demonstrate similar lesion distributions.

CONCLUSIONS

Variation in lesion distribution in this population-based study shows the importance of identifying extra-vertebral tuberculosis and suggests that the disease may have manifested differently than at other coastal sites. These cases confirm the presence of tuberculosis both before and after Inca occupation across this central Andean highlands region.

SIGNIFICANCE

This evidence for the likely endemic presence of TB in the New World prior to European Contact furthers our understanding of the distribution of this infectious disease across the region as well as elucidating lesion distribution.

LIMITATIONS

The diagnosis of tuberculosis is based on skeletal lesions and it should be confirmed by molecular analysis.

FUTURE RESEARCH

Additional examination of vertebral bodies (including juvenile remains) for evidence of earlier manifestations of infection.

Transboundary tuberculosis: Importation of alpacas infected with Mycobacterium bovis from the United Kingdom to Poland and potential for serodiagnostic assays in detecting tuberculin skin test false-negative animals

The present study highlights the transboundary nature of tuberculosis (TB) in alpacas and the failure of current antemortem testing protocols to identify TB-free alpaca herds and individuals for exportation. The tuberculin skin test (TST) failed to identify Mycobacterium bovis-infected animals prior to movement from the United Kingdom (UK) to Poland. This study describes the use of four serological assays [Enferplex Camelid TB, dual-path platform (DPP) VetTB and BovidTB assays, and multi-antigen print immunoassays (MAPIAs)] to detect TB in an alpaca herd with negative TST results. The breeding in Poland purchased alpacas for several years from the UK with the last group arriving in May 2018. In July 2018, two sick alpacas from the centre were hospitalized in a veterinary clinic and both died of TB a few weeks later. In November 2018, 20 alpacas remaining in this M. bovis-affected herd were euthanized and samples were collected. The study population included 20 M. bovis-infected and 20 uninfected alpacas, but only 15 infected animals were tested by all serology tests. The DPP VetTB and DPP BovidTB assays detected antibodies in 14 of the 20 infected alpacas, with results confirmed by MAPIA, and in none (MAPIA and DPP BovidTB) or one (DPP VetTB) of the 20 uninfected animals. None of the infected alpacas tested positive using the Enferplex assay. In addition, the group included three orphans and two cria-dam pairs, which provided an opportunity to analyse immune aspects of cria-mother relationships in this herd. The results suggest high susceptibility of this host species to M. bovis infection and rapid progression to disease. The serological tests used in this study offer useful tools for the detection of M. bovis infection in TST and Enferplex test non-reactive alpacas. These tests should be further evaluated for implementation into TB management and control strategies for camelid species.

Bronchioalveolar carcinoma in an adult alpaca (Vicugna pacos)

BACKGROUND

This report describes a case of a bronchiolar adenocarcinoma in a 6-year old alpaca mare. For the first time in an alpaca, neoplasia was classified by histopathology as a lepidic-predominant bronchiolar adenocarcinoma.

CASE PRESENTATION

The mare was referred to the Clinic for Ruminants after a 6-week period of forced breathing and weight loss. The clinical examination included complete blood count, blood chemistry, ultrasound, radiographs and a CT-scan of the thorax. A bilateral pneumothorax and several, structures within the lung parenchyma were diagnosed. Differential diagnosis included neoplasia, tuberculosis and fungal granulomas. The owner requested euthanasia due to the mare's ongoing deterioration. At postmortem examination, the granulomatous changes in the lungs were histopathologically classified as lepidic dominant bronchiolar adenocarcinoma.

CONCLUSIONS

Neoplastic diseases are more often seen in South American camelids compared to other farm animal species. The use of a CT scan was helpful in classifying the lung lesions and give a clear prognosis.

Development and Evaluation of a Serological Assay for the Diagnosis of Tuberculosis in Alpacas and Llamas

South American camelids are susceptible to tuberculosis, caused mainly by Mycobacterium bovis and M. microti. Despite the tuberculin skin test being the official test for tuberculosis, it has a very low sensitivity in these species (14–20%). Serological tests present the advantages of being rapid, easy to perform and facilitate analysis of large numbers of samples in a short period of time. Novel antigen discovery and evaluation would provide enhanced detection of specific antibodies against members of M. tuberculosis complex. Here, we describe the development and evaluation of an ELISA-type immunoassays to use in the diagnosis of tuberculosis in llamas and alpacas based on P22, a multiprotein complex obtained by affinity chromatography from bovine Purified Protein Derivative (bPPD), that showed high sensitivity and specificity in mice, cattle and goats. This work was performed in two stages. First, a preliminary panel of samples collected from tuberculosis-free (n = 396) and M. bovis-infected herds (n = 56) was assayed, obtaining high specificity (100%) and sensitivity ranging from 63 to 96%. Subsequently, the use of the serological assay was tested using samples from two herds suffering from clinical M. bovis (n = 88) and M. microti (n = 25) infection to evaluate the ability of the ELISA to detect infected animals. 11 out of 88 alpacas were positive to the ELISA in a M. bovis outbreak and 7 out of 25 in a M. microti outbreak. The P22 ELISA potentially provides a sensitive and specific platform for improved tuberculosis surveillance in camelids.

Skin as a marker of general feline health: Cutaneous manifestations of infectious disease

Practical relevance: Infectious disease in feline patients often presents a diagnostic challenge. This article reviews the most relevant viral, bacterial and protozoal diseases and their cutaneous manifestations. Many of the diseases discussed have overlapping presentations or may mimic more common noninfectious disease processes. The purpose of the article is to reinforce knowledge of common and uncommon infectious diseases, help practitioners identify possible infectious dermatoses, create a comprehensive and prioritized differential list, and provide guidance for the diagnosis of these diseases. A working knowledge of these clinical syndromes is important if what is thought to be a case of a common disease does not respond to conventional management.

AUDIENCE

This review is aimed at veterinarians who treat cats and especially those with an interest in feline dermatology. Tables are included to allow the reader to formulate a concise list of differential diagnoses for clinically similar presentations. The diagnostic approach to a case of ulcerative facial dermatitis is reviewed in a Case Notes quiz. Evidence base: This article includes up-to-date information regarding dermatologic manifestations of less commonly encountered feline cutaneous infectious diseases. Information has been drawn from the published, peer-reviewed literature and the most recent textbook chapters with a particular aim of describing and differentiating clinical lesions and the diagnostic approach to cutaneous disease, especially in unusual cases.

Spatiotemporal and Ecological Patterns of Mycobacterium microti Infection in Wild Boar (Sus scrofa)

Mycobacterium microti has recently been described as the causative agent of tuberculosis-like lesions in wild boar (Sus scrofa), a reservoir specie of Mycobacterium tuberculosis complex (MTBC) in some European Mediterranean ecosystem. Through a five-year survey on tuberculosis in free-living wild boars, the epidemiological trend of M. microti infections and the host and population risk factors linked with its occurrence were described. Retropharyngeal and mandibular lymph nodes of 3041 hunted wild boars from six different districts were macroscopically inspected. The sex and age of each animal were registered, as well as the animal abundance in each district. Lesions compatible with tuberculosis (190) were collected and analysed using a gyrB PCR-RFLP assay. M. microti was identified directly in 99 tissue samples (Prev = 3.26%; 95% CI: 2.67-3.97%), while neither Mycobacterium bovis, nor other members of the MTBC were detected. The probability of being M. microti positive showed spatio-temporal variability, with 26% of increase of risk of being infected for each year. Moreover, a positive effect of wild boar abundance and age on the prevalence was detected. The generalized increase in the European wild boar population, coupled with its sensitivity to M. microti infection, poses a future concern for the identification and management of MTBC members in wild boar.

Detection and molecular characterization of Mycobacterium microti isolates in wild boar from northern Italy

Approximately 23,000 hunter-harvested wild boars from the pre-Alpine area of northern Italy were examined for tuberculosis over a 9-year period (2003 to 2011). Retropharyngeal and mandibular lymph nodes from the wild boars were examined grossly, and 1,151 of the lymph nodes were analyzed in our laboratory by histology (728 samples) and culture isolation (819 samples). Mycobacterium tuberculosis complex (MTBC)-specific PCR (1,142 samples) was used for molecular-level detection in tissue samples, as was a gyrB restriction fragment length polymorphism (RFLP) assay (322 samples). Lesions compatible with tuberculosis and indistinguishable from those described in cases of Mycobacterium bovis infection had been observed since 2003. Mycobacterium microti was identified directly in 256 tissue samples by the adopted molecular approaches. However, only 26 M. microti strains were obtained by culture isolation due to the well-known difficulties in isolating this slow-growing mycobacterium. During 2006, a prevalence study was performed in two provinces of the area, and the diffusion of M. microti was calculated to be 5.8% (95% confidence intervals surrounding the estimated prevalences [CIP95%], 3.94 to 7.68%). Over the following years (2007 to 2011), the presence of M. microti appeared to be stable. All isolates were genotyped by spoligotyping and exact tandem repeat analysis (ETR types A to F). In addition to the typical vole type (SB0118), a new spoligotype lacking the 43 spacers was found. Spoligotyping was also applied directly to tissue samples, and a geographical cluster distribution of the two spoligotypes was observed. This is the first report studying the diffusion and genetic variability of M. microti in wild boar.

Overview and phylogeny of Mycobacterium tuberculosis complex organisms: implications for diagnostics and legislation of bovine tuberculosis

Members of the Mycobacterium tuberculosis complex (MTBC) cause a serious disease with similar pathology, tuberculosis; in this review, bovine tuberculosis will be considered as disease caused by any member of the MTBC in bovids. Bovine tuberculosis is responsible for significant economic loss due to costly eradication programs and trade limitations and poses a threat to both endangered and protected species as well as to public health. We here give an overview on all members of the MTBC, focusing on their isolation from different animal hosts. We also review the recent advances made in elucidating the evolutionary and phylogenetic relationships of members of the MTBC. Because the nomenclature of the MTBC is controversial, its members have been considered species, subspecies or ecotypes, this review discusses the possible implications for diagnostics and the legal consequences of naming of new species.

Computed tomographic characterization of the pulmonary system in clinically normal alpacas

OBJECTIVE

To characterize and quantitatively assess the typical pulmonary anatomy of healthy adult alpacas with multidetector row CT.

ANIMALS

10 clinically normal adult female alpacas.

PROCEDURES

CT examination of the thorax was performed before and after IV administration of iodinated contrast medium in sedated alpacas in sternal recumbency. Measurements of the trachea, bronchi and related blood vessels, and selected vertebrae as well as the extent and density of lung parenchyma were performed with a Digital Imaging and Communications in Medicine (DICOM) viewer. Morphometric and quantitative data were summarized.

RESULTS

Separation of individual lung lobes could not be identified, except for the accessory lung lobe. In all alpacas, both lungs extended farther caudally at the medial aspect than at the lateral aspect. The right lung extended farther in both cranial and caudal directions than did the left lung. The branching pattern of the bronchial tree varied only slightly among alpacas and consisted of 1 cranial bronchus and 3 caudal bronchi bilaterally, with a right accessory bronchus. Luminal diameters of first-generation bronchi ranged from 3 to 9 mm. Mean ± SD parenchymal lung density was -869 ± 40 Hounsfield units (HU) before contrast injection and -825 ± 51 HU after contrast injection. Mean difference in diameter between bronchi and associated arteries or veins was 0.8 ± 0.9 mm.

CONCLUSIONS AND CLINICAL RELEVANCE

Knowledge of the typical anatomy of the lungs and bronchial tree in healthy alpacas as determined via CT will aid veterinarians in clinical assessment and bronchoscopic evaluation of alpacas.

Evaluation of the performance of cellular and serological diagnostic tests for the diagnosis of tuberculosis in an alpaca (Vicugna pacos) herd naturally infected with Mycobacterium bovis

Tuberculosis (TB) in llamas and alpacas has gained importance in recent years since they are imported into the European Union mainly for serving as pets and for production of natural fibre. The intradermal tuberculin test has been widely used for diagnosis of TB in these species showing lack of sensitivity (Se) although little information has been previously reported evaluating the effect on its performance of different PPD inoculation sites and time of readings. Moreover, different cost-effective serological assays have been developed in the recent years for TB diagnosis in camelids obtaining a variety of results and, for this reason, new assays still being developed. The main objectives of this study were: (1) to evaluate the performance of the intradermal tuberculin test using different inoculation sites (axillary, prescapular and cervical) and times of reading (72 and 120 h) and (2) to test a novel serological assay based on MPB83 antigen in a Mycobacterium bovis naturally infected alpaca herd in Spain. In regards to skin test, single intradermal tuberculin (SIT) test at the prescapular site and reading at 72 h showed the highest proportion of test-positive-culture positive animals among all culture positive animals (T+/C+), ranging from 53.8% (95% CI, 37.2-69.9) to 80% (95% CI, 44.4-97.5) using a more stringent interpretation than typically prescribed although, in general, low T+/C+ was achieved using both SIT and single comparative intradermal tuberculin (SCIT) tests alone. T+/C+ of the serological assay increased using samples collected 15-30 days after PPD injection [76.9% (95% CI, 60.7-88.9) - 100% (95% CI, 69.2-100)]. The best results of T+/C+ were obtained applying in parallel the most sensitive SIT test and serology using samples collected 15-30 days after PPD inoculation [90% (95% CI, 55.5-99.7)-100% (95% CI, 69.2-100)]. Therefore implementation of serology in parallel with the most sensitive skin test could maximize the detection of infected animals.

Surveillance of bovine tuberculosis and risk estimation of a future reservoir formation in wildlife in Switzerland and Liechtenstein

Bovine tuberculosis (bTB) caused by Mycobacterium bovis or M. caprae has recently (re-) emerged in livestock and wildlife in all countries bordering Switzerland (CH) and the Principality of Liechtenstein (FL). Comprehensive data for Swiss and Liechtenstein wildlife are not available so far, although two native species, wild boar (Sus scrofa) and red deer (Cervus elaphus elaphus), act as bTB reservoirs elsewhere in continental Europe. Our aims were (1) to assess the occurrence of bTB in these wild ungulates in CH/FL and to reinforce scanning surveillance in all wild mammals; (2) to evaluate the risk of a future bTB reservoir formation in wild boar and red deer in CH/FL. Tissue samples collected from 2009 to 2011 from 434 hunted red deer and wild boar and from eight diseased ungulates with tuberculosis-like lesions were tested by direct real-time PCR and culture to detect mycobacteria of the Mycobacterium tuberculosis complex (MTBC). Identification of suspicious colonies was attempted by real-time PCR, genotyping and spoligotyping. Information on risk factors for bTB maintenance within wildlife populations was retrieved from the literature and the situation regarding identified factors was assessed for our study areas. Mycobacteria of the MTBC were detected in six out of 165 wild boar (3.6%; 95% CI: 1.4-7.8) but none of the 269 red deer (0%; 0-1.4). M. microti was identified in two MTBC-positive wild boar, while species identification remained unsuccessful in four cases. Main risk factors for bTB maintenance worldwide, including different causes of aggregation often resulting from intensive wildlife management, are largely absent in CH and FL. In conclusion, M. bovis and M. caprae were not detected but we report for the first time MTBC mycobacteria in Swiss wild boar. Present conditions seem unfavorable for a reservoir emergence, nevertheless increasing population numbers of wild ungulates and offal consumption may represent a risk.

Evaluation of gamma interferon and antibody tuberculosis tests in alpacas

We describe the performance of cell-based and antibody blood tests for the antemortem diagnosis of tuberculosis (TB) in South American camelids (SAC). The sensitivity and specificity of the gamma interferon (IFN-γ) release assay, two lateral flow rapid antibody tests (Stat-Pak and Dual Path Platform [DPP]), and two enzyme-linked immunosorbent assay (ELISA)-based antibody tests (Idexx and Enferplex) were determined using diseased alpacas from Mycobacterium bovis culture-confirmed breakdown herds and TB-free alpacas from geographical areas with no history of bovine TB, respectively. Our results show that while the sensitivities of the IFN-γ and antibody tests were similar (range of 57.7% to 66.7%), the specificity of the IFN-γ test (89.1%) was lower than those of any of the antibody tests (range of 96.4% to 97.4%). This lower specificity of the IFN-γ test was at least in part due to undisclosed Mycobacterium microti infection in the TB-free cohort, which stimulates a positive purified protein derivative (PPD) response. The sensitivity of infection detection could be increased by combining two antibody tests, but even the use of all four antibody tests failed to detect all diseased alpacas. These antibody-negative alpacas were IFN-γ positive. We found that the maximum sensitivity could be achieved only by the combination of the IFN-γ test with two antibody tests in a "test package," although this resulted in decreased specificity. The data from this evaluation of tests with defined sensitivity and specificity provide potential options for antemortem screening of SAC for TB in herd breakdown situations and could also find application in movement testing and tracing investigations.

Respiratory mechanics and results of cytologic examination of bronchoalveolar lavage fluid in healthy adult alpacas

OBJECTIVE

To evaluate respiratory mechanical function and bronchoalveolar lavage (BAL) cytologic results in healthy alpacas.

ANIMALS

16 client-owned adult alpacas.

PROCEDURES

Measurements of pulmonary function were performed, including functional residual capacity (FRC) via helium dilution, respiratory system resistance via forced oscillatory technique (FOT), and assessment of breathing pattern by use of respiratory inductive plethysmography (RIP) in standing and sternally recumbent alpacas. Bronchoalveolar lavage was performed orotracheally during short-term anesthesia.

RESULTS

Mean ± SD measurements of respiratory function were obtained in standing alpacas for FRC (3.19 ± 0.53 L), tidal volume (0.8 ± 0.13 L), and respiratory system resistance at 1 Hz (2.70 ± 0.88 cm H(2)O/L/s), 2 Hz (2.98 ± 0.70 cm H(2)O/L/s), 3 Hz (3.14 ± 0.77 cm H(2)O/L/s), 5 Hz (3.45 ± 0.91 cm H(2)O/L/s), and 7 Hz (3.84 ± 0.93 cm H(2)O/L/s). Mean phase angle, as a measurement of thoracoabdominal asynchrony, was 19.59 ± 10.06°, and mean difference between nasal and plethysmographic flow measurements was 0.18 ± 0.07 L/s. Tidal volume, peak inspiratory flow, and peak expiratory flow were significantly higher in sternally recumbent alpacas than in standing alpacas. Cytologic examination of BAL fluid revealed 58.52 ± 12.36% alveolar macrophages, 30.53 ± 13.78% lymphocytes, 10.95 ± 9.29% neutrophils, 0% mast cells, and several ciliated epithelial cells.

CONCLUSIONS AND CLINICAL RELEVANCE

Pulmonary function testing was tolerated well in nonsedated untrained alpacas. Bronchoalveolar lavage in alpacas yielded samples with adequate cellularity that had a greater abundance of neutrophils than has been reported in horses.

Molecular epidemiology of mycobacteriosis in wildlife and pet animals

The ecology of mycobacteria is shifting in accordance with environmental change and new patterns of interaction between wildlife, humans, and nondomestic animals. Infection of vertebrate hosts throughout the world is greater now than ever and includes a growing prevalence in free ranging and captive wild animals. Molecular epidemiologic studies using standardized methods with high discriminatory power are useful for tracking individual cases and outbreaks, identifying reservoirs, and describing patterns of transmission and are used with increasing frequency to characterize disease wildlife. This review describes current features of mycobacteriosis in wildlife species based on traditional descriptive studies and recent molecular applications.

Diagnostic value of animal-side antibody assays for rapid detection of Mycobacterium bovis or Mycobacterium microti infection in South American camelids

Tuberculosis (TB) in South American camelids (SAC) is caused by Mycobacterium bovis or Mycobacterium microti. Two serological methods, rapid testing (RT) and the dual-path platform (DPP) assay, were evaluated using naturally infected SAC. The study population included 156 alpacas and 175 llamas in Great Britain, Switzerland, and the United States. TB due to M. bovis (n = 44) or M. microti (n = 8) in 35 alpacas and 17 llamas was diagnosed by gross pathology examination and culture. Control animals were from herds with no TB history. The RT and the DPP assay showed sensitivities of 71% and 74%, respectively, for alpacas, while the sensitivity for llamas was 77% for both assays. The specificity of the DPP assay (98%) was higher than that of RT (94%) for llamas; the specificities of the two assays were identical (98%) for alpacas. When the two antibody tests were combined, the parallel-testing interpretation (applied when either assay produced a positive result) enhanced the sensitivities of antibody detection to 89% for alpacas and 88% for llamas but at the cost of lower specificities (97% and 93%, respectively), whereas the serial-testing interpretation (applied when both assays produced a positive result) maximized the specificity to 100% for both SAC species, although the sensitivities were 57% for alpacas and 65% for llamas. Over 95% of the animals with evidence of TB failed to produce skin test reactions, thus confirming concerns about the validity of this method for testing SAC. The findings suggest that serological assays may offer a more accurate and practical alternative for antemortem detection of camelid TB.

Mycobacterium microti infection in two meerkats (Suricata suricatta)

Mycobacterium microti is a member of the Mycobacterium tuberculosis complex (MTC). M. microti is generally considered a pathogen of small rodents, although sporadic infections in a range of other mammals, including domestic animals and man, have been reported. While many human infections have been associated with immunosuppression, an increasing number of cases are being reported in immunocompetent patients. Two cases of M. microti infection in meerkats (Suricata suricatta) are reported. These are the first cases of mycobacterial disease to be described in meerkats outside Africa.

Controlling tuberculosis in a llama (Lama glama) herd using clinical signs, tuberculin skin testing and serology

An outbreak of tuberculosis (TB), caused by Mycobacterium bovis, was investigated in a small herd of llamas (Lama glama). Based on three ante-mortem diagnostic methods (clinical signs, tuberculin skin test reactions, and 'Rapid Test' serology), 12 llamas were selected for examination post-mortem. Grossly visible lesions suspicious of TB were observed in eight animals, four of which had exhibited clinical signs, one was a skin test 'reactor', and three had been seropositive. M. bovis was isolated from seven of these eight animals. Clinical signs combined with serology were found to be useful in identifying infected animals, but tuberculin skin testing had limited negative predictive value as four llamas that were subsequently confirmed as infected were not detected using this assay.

Mycobacterium microti infection in the cat: a case report, literature review and recent clinical experience

OVERVIEW

Mycobacterium microti infection is infrequently described in cats in the veterinary literature. It can be one of a large number of possible differential diagnoses in a feline patient with dermal nodules and non-healing draining ulcers, and can occasionally spread to involve the lungs and/or other areas of the body.

CASE SUMMARY

This report describes the clinical signs, eventual diagnosis and variable response to treatment in a cat in Switzerland with recurrent cutaneous M microti infection. Only after several diagnostic and therapeutic attempts, over more than 2 years, was the species of Mycobacterium finally identified and targeted therapy given.

PRACTICAL RELEVANCE

For any cat in which there is even a low suspicion of mycobacterial infection, the authors recommend that an aggressive diagnostic approach is taken. Tissue specimens should be collected and frozen early on, and, as soon as acid-fast bacilli are detected, samples should be sent to a mycobacterial reference laboratory for definitive identification.

LITERATURE REVIEW

A review of the literature relating to the aetiopathogenesis, diagnosis and management of M microti infection in cats and dogs is included. This is supplemented with clinical and therapeutic experience gained from this case and other, unpublished cases managed over the past 15 years by one of the authors (DGM).