Comparative study of IFNγ and antibody tests for feline tuberculosis

This study describes the comparison of the cell-based interferon-gamma (IFNγ) test with serological rapid antibody tests (STAT-PAK and DPP VetTB) for the ante mortem testing of tuberculosis in domestic cats. The antibody specificities of rapid antibody test-positive cats were further discerned using multi-antigen print immunoassay. A total of 62 cats with culture-confirmed Mycobacterium bovis, Mycobacterium microti, Mycobacterium avium and Mycobacterium malmoense, as well as negative controls and dangerous-contact cats were tested. Tests were also applied longitudinally to one further cat undergoing TB chemotherapy for suspected M. bovis infection. Our data from this small study show excellent test specificity (100% for all tests) and encouraging levels of test sensitivity for M. bovis and TB Complex infections (IFNγ 70-100% depending upon test interpretation criteria; rapid tests both 90% for M. bovis infection and up to 46.2% for M. microti infection). The differential diagnosis of very pathogenic TB Complex (M. bovis, Mycobacterium tuberculosis), as opposed to less-pathogenic TB Complex (M. microti) was possible where positive responses to the protein cocktail ESAT6/CFP10 were observed (80% of M. bovis-infected cats in this study showed positive IFNγ responses to ESAT6/CFP10, while 20% had antibody responses to ESAT6/CFP10 using MAPIA). Finally, preliminary data from a longitudinal study of one M. bovis-exposed cat with a positive IFNγ test pre-treatment suggest that a decrease in bacterial burden may be reflected in the IFNγ response, and thus the IFNγ test may provide a monitor for TB chemotherapy.     

RADIOLOGIC ABNORMALITIES OF THE APPENDICULAR SKELETON OF THE LION (PANTHERA LEO): INCIDENTAL FINDINGS AND MYCOBACTERIUM BOVIS-INDUCED CHANGES

Thoracic and pelvic limbs from 15 euthanized free-ranging lions (Panthera leo), ranging in age from 16 to 144 months, underwent standard radiographic evaluation. All lions had tested positive for Mycobacterium bovis by means of a modified intradermal tuberculn test. The radiographs of six lions were normal and nine had incidental findings of which six had more than one lesion. Seven lions had lesions suspected to be associated with tuberculosis, which was confirmed in specific joints in two lions. Incidental pathology was classified as traumatic injuries and degenerative or trauma-associated joint disease. The traumatic lesions were fractures of which the most remarkable was a femur malunion. Four lions had fibula and another three lions had metacarpal/tarsal and phalangeal fractures. Joint lesions included glenoid, humeral head, and accessory carpal bone osteophytes. There was evidence of a cranial cruciate ligament rupture in an 8-year-old male. Trauma induced joint lesions were seen in four stifles (fragmented or displaced sesamoid bones, fragmented meniscal ossicle, or mineralized fragments). Radiological abnormalities believed to be caused by M. bovis were present in one stifle, one radiocarpal three tibiotarsal, and one tarsometatarsal joints. These had evidence of septic arthritis with extensive bone formation and capsular mineralization. In one 20-month-old lion, changes typical of a bone abscess were found in a proximal tibia. Radiologic evidence of elbow hygromas were seen in three elbows, all believed to be caused by M. bovis. Lions appeared to cope fairly well with a variety of traumatic injuries and were also susceptible to some of the aging/incidental radiologic findings seen in dogs and cats. The suspected M. bovis osseous lesions were more likely to involve the joints, particularly the tarsal joint and were mainly proliferative.     

Animal-side serologic assay for rapid detection of Mycobacterium bovis infection in multiple species of free-ranging wildlife

Numerous species of mammals are susceptible to Mycobacterium bovis, the causative agent of bovine tuberculosis (TB). Several wildlife hosts have emerged as reservoirs of M. bovis infection for domestic livestock in different countries. In the present study, blood samples were collected from Eurasian badgers (n=1532), white-tailed deer (n=463), brushtail possums (n=129), and wild boar (n=177) for evaluation of antibody responses to M. bovis infection by a lateral-flow rapid test (RT) and multiantigen print immunoassay (MAPIA). Magnitude of the antibody responses and antigen recognition patterns varied among the animals as determined by MAPIA; however, MPB83 was the most commonly recognized antigen for each host studied. Other seroreactive antigens included ESAT-6, CFP10, and MPB70. The agreement of the RT with culture results varied from 74% for possums to 81% for badgers to 90% for wild boar to 97% for white-tailed deer. Small numbers of wild boar and deer exposed to M. avium infection or paratuberculosis, respectively, did not cross-react in the RT, supporting the high specificity of the assay. In deer, whole blood samples reacted similarly to corresponding serum specimens (97% concordance), demonstrating the potential for field application. As previously demonstrated for badgers and deer, antibody responses to M. bovis infection in wild boar were positively associated with advanced disease. Together, these findings suggest that a rapid TB assay such as the RT may provide a useful screening tool for certain wildlife species that may be implicated in the maintenance and transmission of M. bovis infection to domestic livestock.     

Modification of the QuantiFERON-TB Gold (In-Tube) assay for the diagnosis of Mycobacterium bovis infection in African buffaloes (Syncerus caffer)

African buffaloes (Syncerus caffer) are the most significant wildlife maintenance hosts of Mycobacterium bovis, the causative organism of bovine tuberculosis (BTB). Current diagnostic tests for the detection of M. bovis infection in free-ranging buffaloes have numerous limitations and we wished to evaluate a modification to a human TB assay, the QuantiFERON-TB Gold (In-Tube) assay (QFT), as a practical diagnostic test for BTB in buffaloes. One hundred and seventy-five buffaloes were tested using the single intradermal comparative tuberculin test (SICTT) and a modified QFT (mQFT). An appropriate cut-off point for the mQFT was derived from SICTT results using receiver operator characteristic curve analysis. Twenty-six SICTT-positive buffaloes were killed and subjected to necropsy, and selected tissues were processed for mycobacterial culture and speciation. An optimal cut-off point for the mQFT was calculated as 66pg/ml. The assay correctly detected 39/40 SICTT-positive buffaloes and 129/134 TST-negative buffaloes and M. bovis was cultured from 21/26 slaughtered SICTT/mQFT-positive animals. The mQFT shows promise as a practical test for M. bovis infection in buffaloes and shows a sensitivity and specificity at least similar to that of the TST.     

Evaluation of an indirect enzyme-linked immunosorbent assay for the detection of feline lentivirus-reactive antibodies in wild felids,employing a puma lentivirus-derived synthetic peptide antigen

An enzyme-linked immunosorbent assay (ELISA) using a puma lentivirus-derived synthetic peptide as coating antigen was evaluated as a diagnostic test for infection with feline immunodeficiency virus (FIV) or related lentiviruses in free-ranging lions. The sensitivity and specificity of the ELISA was determined using two approaches. In the first approach, the results were standardized according to certain statistical criteria, and in the second, the puma lentivirus western blot was used as the gold standard. The sensitivity of the test when compared with the standardized results was 85.4% and the specificity 100%. The sensitivity of the test when using the western blot as the gold standard was 78.6% and the specificity 100%. The test would therefore be well-suited to the screening of populations of wild felids in which FIV or related lentiviruses are endemic. The results also indicate that in spite of genetic divergence between lentiviruses isolated from Panthera and Felis spp., puma lentivirus-derived antigens can be used in immunoassays for the detection of antibodies in Panthera spp. reactive to FIV or related lentiviruses. The results also indicate that the lion population in the Hluhluwe-Umfolozi Game Reserve, South Africa is lentivirus negative.     

Use of a macrophage cell line for rapid detection of Mycobacterium bovis in diagnostic samples

Mycobacterium bovis isolation on bacteriological media from suspected cases of bovine tuberculosis (TB) demands laborious and time-consuming procedures. Even polymerase chain reaction (PCR) and radiometric analyses are secondary procedures and not alternatives to bacteriological procedures. Therefore, there is a need to develop new techniques aimed at rapid M. bovis detection in diagnostic samples. The human macrophage cell line THP-1 was thus investigated in experiments of M. bovis propagation and isolation from reference lymph node suspensions. THP-1 cells were shown to support a high-titered propagation within 48h of minute amounts of both M. bovis BCG and fully pathogenic M. bovis strain 503. A semi-nested PCR for TB-complex-specific insertion sequence IS6110 revealed M. bovis infection in THP-1 cells. The same was true of a flow cytometry (FC) assay for expression of M. bovis chaperonin 10 in infected cells. The reduced time for isolation and identification of M. bovis (48-72h) and the consistency of the test results make the use of macrophage cell cultures attractive and cost-effective for veterinary laboratories involved in TB surveillance.     

Ante mortem diagnosis of tuberculosis in cattle: a review of the tuberculin tests, gamma-interferon assay and other ancillary diagnostic techniques

The early, preclinical stages of bovine TB can be detected in live animals by the use of tests of cellular immunity (the skin, gamma-interferon and lymphocyte transformation tests). Tests of humoral (antibody) immunity, Mycobacterium bovis PCR probes on early tissue cultures or live cattle specimens, and tests based on "electronic nose" technology have been developed more recently. The key measure of diagnostic test accuracy is the relationship between sensitivity and specificity, which determines the false-positive and false-negative proportions. None of the tests currently available for the diagnosis of bovine TB allow a perfectly accurate determination of the M. bovis infection status of cattle. Although various factors can reduce the sensitivity and specificity of the skin tests, these remain the primary ante mortem diagnostic tools for TB in cattle, providing a cost-effective and reliable means of screening entire cattle populations. Despite the inescapable limitations of existing diagnostic tests, bovine TB has been effectively eradicated from many developed countries and regions with the implementation of sound programmes of regular tuberculin skin testing and removal of reactors, coupled with slaughterhouse surveillance for undetected infections, repeat testing and culling of infected herds, cattle movement restrictions to prevent introduction of infected animals and occasional slaughter of entire herds with intractable breakdowns. This is likely to remain the mainstay of bovine TB control programmes for the foreseeable future. Additionally, newer ancillary in vitro diagnostic assays are now available to TB control programme managers to supplement the skin tests in defined circumstances according to the specific disease situation in each country or region. The strategic deployment of ancillary in vitro tests alongside the primary skin tests has enhanced the detection of M. bovis-infected cattle and reduced the number of animals slaughtered as false positives.     

Evaluation of an in vitro blood-based assay to detect production of interferon-gamma by Mycobacterium bovis-infected white-tailed deer (Odocoileus virginianus).

Tuberculosis due to Mycobacterium bovis in captive Cervidae was identified as an important disease in the United States in 1990 and prompted the addition of captive Cervidae to the USDA Uniform Methods and Rules for eradication of bovine tuberculosis. As well, M. bovis infection was identified in free-ranging white-tailed deer in northeast Michigan in 1995. Tuberculosis in both captive and free-ranging Cervidae represents a serious challenge to the eradication of M. bovis infection from the United States. Currently, the only approved antemortem tests for tuberculosis in Cervidae are the intradermal tuberculin skin test and the blood tuberculosis test (BTB). At present, the BTB is not available in North America. Tuberculin skin testing of Cervidae is time-consuming and involves repeated animal handling and risk of injury to animals and humans. This study evaluated the potential of a new blood-based assay for tuberculosis in Cervidae that would decrease animal handling, stress, and losses due to injury. In addition, a blood-based assay could provide a more rapid diagnosis. Twenty 6-9-month-old white-tailed deer, male and female, were experimentally inoculated by instillation of 300 colony-forming units of M. bovis in the tonsillar crypts. Seven, age-matched uninfected deer served as controls. Blood was collected on days 90, 126, 158, 180, 210, 238, 263, and 307 after inoculation and was analyzed for the production of interferon-gamma (IFN-gamma) in response to incubation with M. bovis purified protein derivative (PPDb), M. avium PPDa, pokeweed mitogen (PWM), or media alone. Production of IFN-gamma in response to PPDb was significantly greater (P < 0.05) at all time points in samples from M. bovis-infected deer as compared with uninfected control deer, whereas IFN-gamma production to PWM did not differ significantly between infected and control deer. Measurement of IFN-gamma production to PPDb may serve as a useful assay for the antemortem diagnosis of tuberculosis in Cervidae.     

BCG vaccination against tuberculosis in European badgers (Meles meles): a review

Tuberculosis (TB) is a significant animal health problem in many parts of the world, and reservoirs of infection in wild animals complicate disease control efforts in farmed livestock, particularly cattle. Badgers (Meles meles) are a significant wildlife reservoir of Mycobacterium bovis infection for cattle in the United Kingdom (UK) and Republic of Ireland (ROI). Vaccination of badgers using an M. bovis strain bacille Calmette-Guérin (BCG) vaccine could potentially be an option in the national TB eradication strategy. Wildlife vaccination has been used successfully for other diseases in wildlife species, and may have a role to play in reducing M. bovis transmission at the wildlife-livestock interface. Research to date has provided evidence that BCG is protective in badgers, and a parenteral badger BCG vaccine has been licensed in the UK. Further research is required to develop effective strategies for vaccine deployment and to determine the effect of badger vaccination on cattle TB incidence.     

A review of M. bovis BCG protection against TB in cattle and other animals species

Bovine tuberculosis (TB) causes severe economic losses in livestock due to low production, animal deaths and condemnation of carcasses. It is also an important constraint in international trade of animals and animal products. A scientific committee in Great Britain in 1997 concluded that the development of a cattle vaccine would be the best option for long-term control of TB. However, vaccination of cattle currently is not accepted because the vaccine interferes with the skin reaction to the tuberculin test in the field. Efficacy of M. bovis BCG in protecting bovine and other animal species against tuberculous infection has received much study. Vaccination of cattle prevents the spread of the disease in populations by reducing the number and size of the lesions, and the load of bacteria (rather than by preventing infection). We review the literature about the efficacy of BCG in protecting cattle and other animal species against infection with field strains of M. bovis and discusses its potential use in programs of TB control in high-prevalence populations.     

The effect of repeated tuberculin skin testing of cattle on immune responses and disease following experimental infection with Mycobacterium bovis

The comparative intradermal skin test, in which a delayed type hypersensitivity (DTH) response to purified protein derivative of tuberculin (PPD) from Mycobacterium bovis and M. avium is assessed and compared, may be used repeatedly on non-infected animals on farms where bovine tuberculosis (TB) has occurred. A skin test is known to affect subsequent skin tests in infected animals. The reported study was to determine whether repeated skin testing prior to infection with M. bovis might affect the development of the comparative skin test and IFNgamma response subsequent to exposure to virulent M. bovis. The comparative intradermal skin test was applied to one group of six calves five times at 8-week intervals. These and six control calves were subsequently inoculated intratracheally with a dose of M. bovis that produced mild disease. The development of the DTH reaction, IFNgamma, IL-10 and proliferative responses were compared in the two groups of animals. No differences in IFNgamma, IL-10 and proliferative responses were seen between the two groups of calves prior to challenge. After infection with M. bovis no differences in the development of the DTH and IFNgamma responses to PPD were noted as a consequence of the repeated skin testing prior to challenge. No differences between the groups were evident when ESAT-6 was used as antigen and IFNgamma was assayed, although two animals that responded to PPD did not respond with ESAT-6. However, there did appear to be subtle effects of repeated skin testing on the immune response post-challenge that did not affect the diagnostic tests. After challenge control animals showed greater proliferative responses than animals given repeated skin tests prior to challenge, indicating that the procedure did have consequences for immune responses following infection. In both groups a marked reduction in the intensity of the skin test and in the number of animals that would be recognized as reactors was evident when animals were tested 15 weeks post-infection compared to their responses 8 weeks earlier that could have consequences for diagnosis of TB. An antibody response was not evident as a result of repeat skin testing prior to infection but was seen in both groups of calves following skin testing performed 7 weeks after infection.     

An immunochromatographic serological assay for the diagnosis of Mycobacterium tuberculosis

A rapid serological test for tuberculosis (TB) infection was designed using antigens specific to Mycobacterium tuberculosis. Tuberculosis infection, TB vaccination and exposure to environmental Mycobacteria cannot be distinguished using skin tests based on tuberculin protein derivatives. The standard diagnostic techniques such as skin tests, X-rays and DNA techniques are time consuming, expensive, and not practical for screening large populations. We used the 38, 63, 64, 14, 59-kDa antigens of M. tuberculosis to develop a rapid immunochromatographic test kit. This study evaluates the diagnostic potential of the rapid test kit using TB positive and TB negative serum samples from various hospitals in India. The samples were obtained from patients infected with or exposed to bacteria and viral pathogens. The results demonstrated that the combination of antigens improved the diagnostic specificity and sensitivity. The specificity of the test was 99.42% with sensitivity of 98.52% (n = 241). In case of multiple infections, the specificity was 93.15% with a low sensitivity of 73.52% n = 141). The test kit may offer an improved alternative to purified protein derivative (PPD). This rapid TB test kit may be a useful tool for first-line testing of suspected cases, epidemiological studies and in designing a quality health system to reduce health hazards in resource-poor countries.     

Prevalence of Bartonella infection in wild African lions (Panthera leo) and cheetahs (Acinonyx jubatus)

Bartonella species are emerging pathogens that have been isolated worldwide from humans and other mammals. Our objective was to estimate the prevalence of Bartonella infection in free-ranging African lions (Panthera leo) and cheetahs (Acinonyx jubatus). Blood and/or serum samples were collected from a convenience sample of 113 lions and 74 cheetahs captured in Africa between 1982 and 2002. Whole blood samples available from 58 of the lions and 17 of the cheetahs were cultured for evidence of Bartonella spp., and whole blood from 54 of the 58 lions and 73 of the 74 cheetahs tested for the presence of Bartonella DNA by TaqMan PCR. Serum samples from the 113 lions and 74 cheetahs were tested for the presence of antibodies against Bartonella henselae using an immunofluorescence assay. Three (5.2%) of the 58 lions and one (5.9%) of the 17 cheetahs were bacteremic. Two lions were infected with B. henselae, based on PCR/RFLP of the citrate synthase gene. The third lion and the cheetah were infected with previously unidentified Bartonella strains. Twenty-three percent of the 73 cheetahs and 3.7% of the 54 lions tested by TaqMan PCR were positive for Bartonella spp. B. henselae antibody prevalence was 17% (19/113) for the lions and 31% (23/74) for the cheetahs. The prevalence of seropositivity, bacteremia, and positive TaqMan PCR was not significantly different between sexes and age categories (juvenile versus adult) for both lions and cheetahs. Domestic cats are thus no longer the only known carriers of Bartonella spp. in Africa. Translocation of B. henselae seronegative and TaqMan PCR negative wild felids might be effective in limiting the spread of Bartonella infection.     

Agreement between the caudal fold test and serological tests for the detection of Mycobacterium bovis infection in bison

The objective of this study was to estimate agreement between the caudal fold test (CFT) and different serological tests for the detection of Mycobacterium bovis infection in bison by using prevalence-adjusted bias-adjusted kappa (PABAK). A total of 212 of wild wood bison from Wood Buffalo National Park were tested with the CFT as well as several serological tests: fluorescent polarization assay (FPA), multiantigen print immunoassay (MAPIA), rapid lateral-flow test (RT) and dual path platform test (DPP). For RT, 3 variations were conducted using 30μl of serum (RT 30), 20μl of serum (RT 20) and 20μl of serum considering only a strong reaction as positive (RT 20 ST). The McNemar's χ(2) test was conducted to assess whether the proportion of positive test results to 2 different tests differed. Two measures of agreement between pair of tests were estimated: the Cohen's kappa statistic and PABAK. The apparent prevalence of tuberculosis in the sampled animals varied depending on the diagnostic test from 6.1% (FPA and DPP) to 47.2% (CFT). The prevalence estimated by CFT differed from the prevalence estimated by the other tests, whereas the prevalence estimated by FPA, MAPIA, RT 20 ST and DPP were not significantly different. The kappa and PABAK estimates calculated between CFT and the rest of the tests suggested poor to slight agreement between tests (k and PABAK<0.25 in all cases). The PABAK estimates for the pairwise combinations among serological tests were numerically greater than the kappa estimates (and significantly greater when FPA was compared to the rest of serological tests), and suggested substantial to almost perfect agreement (PABAK>0.75 in all cases). The disagreement between the skin and serological tests for the detection of M. bovis infection could be partly because the tests measure different immunological responses (cell-mediated vs. humoral) that are predominant at different stages of the infection, and partly due to inaccuracy of the tests. Further research is needed to evaluate the accuracy of diagnostic tests in order to establish a reliable case definition, combining different tests, to be used in the surveillance and control of tuberculosis in free-ranging bison populations.     

Occurrence of Babesia felis and Babesia leo in various wild felid species and domestic cats in Southern Africa, based on reverse line blot analysis

Reverse line blot (RLB) is a hybridization assay that can be used to detect various blood parasites and differentiate between them. Results, using the RLB, showed that Babesia felis and Babesia leo occurred as single or mixed infections in various felid species, but most frequently in domestic cats and lions, respectively. Prevalence of infection in free-ranging cheetahs in Namibia was low (7, 5%), whereas 50% of free-ranging lions in South Africa and Swaziland were infected. A large number (52, 9%) of samples tested positive only for Babesia, neither B. felis nor B. leo. This could be an indication of at least one further, as yet undescribed, Babesia species in felids.     

Epidemiology of Mycobacterium bovis in free-ranging white-tailed deer,Michigan, USA, 1995-2000

An endemic area of bovine tuberculosis (TB) (Mycobacterium bovis) currently affecting wild white-tailed deer (Odocoileus virginianus) in northern lower Michigan, USA, constitutes the first self-sustaining outbreak of the infection in free-ranging North American cervids. Given this precedent, epidemiologic insights gained from the outbreak afford the opportunity to guide not only current surveillance and intervention but also control efforts for future outbreaks involving wildlife reservoirs. Our specific objectives were to evaluate retrospective data from field surveillance conducted from 1995 to 2000 to determine apparent prevalence, trends in apparent prevalence, and the effects of various factors on the odds of being M. bovis positive.Data were gathered from post-mortem examinations of 62,560 wild deer collected from all 83 Michigan counties. Records of survey method, sex, age, geographic area and infection status as determined by mycobacterial culture were subjected to trend analysis and multivariable logistic regression. Apparent prevalence for the period was 0.54% (336/62,560) statewide. Prevalence varied widely with geographic area, but significantly decreased since 1995 in the core area of the outbreak-which coincided with implementation of control strategies. Significant risk factors were geographic area, sex, age, and the sex-by-age interaction. The survey method by which deer were obtained for testing was not a predictor of infection.Our results to date suggest an outbreak characterized by broad areas of very low prevalence surrounding focal areas where prevalence is sometimes orders-of-magnitude higher (e.g., deer originating from the core area were up to 147 times more likely to be TB positive than deer from other areas). Our results also identify older male deer as most likely to be M. bovis positive (OR=11.3, 95% CI 3.2, 40.3 for bucks > or =5 years vs. does < or =1.5 years)-an observation consistent with the biology and behavior of the species. Synthesizing these results with those of other ongoing investigations, we hypothesize a two-stage model of disease transmission where TB is maintained at very low prevalence in matriarchal groups, with primary dissemination of the disease attributable to the dispersal and movements of bucks (as well as to the large aggregations of animals created by human activities).     

结核分枝杆菌疫源追踪的基因检测分析

目的探讨牛源性人结核疫源追踪的基因分析方法。方法采用复方PCR结核杆菌快速鉴定技术,针对特征性分枝杆菌标志基因(MTP40基因、α抗原基因和IS6110),对结核病人和患牛的标本,进行检测。结果患者标本结核分枝杆菌阳性;患牛标本牛分枝杆菌和结核分枝杆菌分别阳性。结论结核病奶牛不仅是人类牛型结核的可能来源,也可能成为人类人型结核的潜在来源。     

利用聚合酶链反应技术检测牛结核杆菌病的研究

应用聚合酶链反应（ Ｐ Ｃ Ｒ） 技术检测牛结核分枝杆菌纯化 Ｄ Ｎ Ａ, 其敏感性为２５０ｆｇ 。所用引物序列对９种抗酸分枝杆菌 Ｄ Ｎ Ａ 进行扩增, 经琼脂糖凝胶电泳证实, 只有人型结核分枝杆菌、牛型结核分枝杆菌产生了３１７ｂｐ 的特异性扩增带。将 Ｐ Ｃ Ｒ 法与皮内变态反应试验（ Ｐ Ｐ Ｄ） 检测方法比较; ５４ 份血样标本中 Ｐ Ｃ Ｒ 的阳性率为１ ％ , Ｐ Ｐ Ｄ 试验的阳性率为０ 。同时对奶样标本的检测与血样结果一致。结果表明, Ｐ Ｃ Ｒ 在直接检测患牛血样、奶样标本中显示出快速、敏感、特异的优点。为今后牛结核病的检测工作提供了一条新的途径。     

Tuberculosis in cattle herds are sentinels for Mycobacterium bovis infection in European badgers (Meles meles): the Irish Greenfield Study

In Ireland badgers are removed in response to tuberculosis (TB) breakdowns in cattle herds (focal culling). Prevalence studies, conducted using a detailed post mortem and bacteriological examination, showed that 36-50% of badgers were infected with Mycobacterium bovis. Focal culling forms part of the medium term national strategy for the control of bovine TB in cattle and is based on the premise that badgers in areas with herd breakdowns have a higher prevalence of infection than the badger population at large. However, the hypothesis that cattle can be used as sentinels for infection in the badger population has never been formally tested. In this study we tested the hypothesis by determining the infection prevalence in badgers in areas where there had been historically, a consistently low prevalence of infection in cattle. Low cattle TB prevalence areas were defined as those herds with ≤ 2 standard reactors in the annual round of skin testing over the preceding 5 years (Greenfield sites). Using GIS, and adjusting for variation in land use, previous culling and cattle density, 198 Greenfield sites were identified and surveyed, and 138 areas with badger setts or signs of badger activity were identified. A single badger was removed from 87 sites and all were examined using detailed post mortem and bacteriological procedures. A prevalence of M. bovis infection of 14.9% was found in the Greenfield site badgers. This prevalence was significantly lower (P<0.001) than in badgers removed during focal culling (36.6%). The results validate the use of cattle as sentinels for TB in badgers and support the medium term national strategy for the control of bovine TB. The geographic variation in M. bovis infection prevalence in the Irish badger populations will be used when devising strategies for the incorporation of badger vaccination into the long term bovine TB control programme.     

Reversible anaesthesia of free-ranging lions (Panthera leo) in Zimbabwe

The combination of medetomidine-zolazepam-tiletamine with subsequent antagonism by atipamezole was evaluated for reversible anaesthesia of free-ranging lions (Panthera leo). Twenty-one anaesthetic events of 17 free-ranging lions (5 males and 12 females, body weight 105-211 kg) were studied in Zimbabwe. Medetomidine at 0.027-0.055 mg/kg (total dose 4-11 mg) and zolazepam-tiletamine at 0.38-1.32 mg/kg (total dose 50-275 mg) were administered i.m. by dart injection. The doses were gradually decreased to improve recovery. Respiratory and heart rates, rectal temperature and relative haemoglobin oxygen saturation (SpO2) were recorded every 15 min. Arterial blood samples were collected from 5 lions for analysis of blood gases and acid-base status. For anaesthetic reversal, atipamezole was administered i.m. at 2.5 or 5 times the medetomidine dose. Induction was smooth and all lions were anaesthetised with good muscle relaxation within 3.4-9.5 min after darting. The predictable working time was a minimum of 1 h and no additional drug doses were needed. Respiratory and heart rates and SpO2 were stable throughout anaesthesia, whereas rectal temperature changed significantly over time. Atipamezole at 2.5 times the medetomidine dose was sufficient for reversal and recoveries were smooth and calm in all lions independent of the atipamezole dose. First sign of recovery was observed 3-27 min after reversal. The animals were up walking 8-26 min after reversal when zolazepam-tiletamine doses < 1 mg/kg were used. In practice, a total dose of 6 mg medetomidine and 80 mg zolazepam-tiletamine and reversal with 15 mg atipamezole can be used for either sex of an adult or subadult lion. The drugs and doses used in this study provided a reliable, safe and reversible anaesthesia protocol for free-ranging lions.