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Biomedical subjects

R S Morris

Publications and source records attributed to R S Morris.

At least 73 records · Page 4Linked to original sources
PubMed1998

Effect of time on liver clearance of technetium-99m-tetrofosmin in patients with acute chest pain: when should imaging begin?

OBJECTIVE: Due to stable myocardial retention and technetium imaging characteristics, 99mTc-tetrofosmin has been considered potentially useful for acute chest pain imaging. Tetrofosmin also has favorable biokinetics with reported rapid liver clearance, 5 min poststress and 30-45 min post-rest injection. Since comparable data are not available, the effect of time on liver clearance was evaluated in patients with acute chest pain. METHODS: One hundred six patients received an intravenous injection of 25-30 mCi 99mTc-tetrofosmin to evaluate acute chest pain. SPECT imaging was performed 15-120 min after injection of the tracer. Patient images were grouped according to the time of acquisition after acute injection: 15-30 min, 31-45 min, 46-60 min, 61-90 min and > 90 min. Quantitative analysis was performed of a similar anterior projection for each patient consisting of 6 X 6-pixel region of interest over the myocardium and adjacent liver. Average counts per pixel were determined and a heart/liver (H/Li) ratio was calculated. RESULTS: The mean H/Li ratio was < 1.0 for patient images acquired 15-45 min after injection, and > 1.0 for patient images acquired after 45 min. The difference was statistically significant (p < 0.05). CONCLUSION: Quantitative analysis suggests that the optimal imaging time should be at least 45 min after the injection of 99mTc-tetrofosmin to allow adequate liver clearance before image acquisition of acute chest pain syndromes.

Aged↗
PubMed1997

What is the radiation exposure to patients during a gynecoradiologic procedure?

OBJECTIVE: To evaluate the risk of radiation exposure to infertility patients during a gynecoradiologic procedure. DESIGN: Retrospective clinical study. SETTING: Medical school-affiliated infertility center. PATIENT(S): Three hundred thirty-two consecutive infertility patients undergoing a gynecoradiologic procedure. INTERVENTION(S): Patients underwent a gynecoradiologic procedure as part of their infertility workup and the fluoroscopic exposure time was analyzed. MAIN OUTCOME MEASURE(S): The fluoroscopic exposure (rad time) during gynecoradiologic procedures, including hysterosalpingogram (HSG), selective salpingography, tubal catheterization, and others. RESULT(S): The rad time (mean +/- SD) was 63 +/- 54 seconds for normal HSG (n = 94, range 17 to 404 seconds), 100 +/- 61 seconds for abnormal HSG (n = 53, range 28 to 272 seconds), 111 +/- 57 seconds for unilateral selective salpingography (n = 36, range 31 to 324 seconds), 142 +/- 74 seconds for bilateral selective salpingography (n = 87, range 40 to 430 seconds), 176 +/- 77 seconds for unilateral tubal catheterization (n = 27, range 70 to 342 seconds), and 239 +/- 82 seconds for bilateral tubal catheterization (n = 30, range 110 to 381 seconds). Five patients had other procedures, such as lysis of intrauterine adhesions (n = 2) and resection of an uterine septum (n = 3), for which the rad time was in a range of 180 to 300 seconds. CONCLUSION(S): The radiation exposure of patients during a gynecoradiologic procedure, using previously described standard techniques, is well within established margins of safety.

Environmental Exposure↗
PubMed1997

Natural infection of red deer with bovine tuberculosis.

Six bovine tuberculosis-free red deer hinds were introduced in October 1993 to a 1.8 ha enclosure, within a larger field study site known to contain tuberculous possums, and kept there for 9 months. A Mycobacterium bovis-infected possum was found in the vicinity of the deer enclosure 3 weeks after the introduction. Subsequently, a further eleven infected possums were found in the area. The deer were monitored by repeated composite antibody detection ELISA and lymphocyte transformation assays for tuberculosis, interpreted in parallel, by skin testing and by routine culturing of samples collected from potential excretion sites. Lymphocyte transformation assay evidence of M. bovis infection in four hinds was first observed 4 months after introduction. One other hind became bovine tuberculin lymphocyte transformation assay positive in the 5th month. Positive or equivocal bovine reactivity remained evident at most test episodes. A comparative cervical skin test performed in July 1994, shortly before slaughter, was positive in these five hinds. Mycobacterium bovis was recovered off swabs from the oropharyngeal tonsils of two hinds during routine sampling. Detailed necropsy of the six deer revealed a single typical tuberculous lesion in only one, but culturing of various tissue specimens ascertained that the five blood test and comparative cervical skin test-positive animals were all infected. Mycobacterium bovis was cultured from the oropharyngeal tonsils of four and medial retropharyngeal lymph nodes of two of the deer with no typical gross lesions. Six additional tuberculosis-free hinds were introduced to the enclosure in April 1994 and kept there for 12 months. Four of these animals showed a positive lymphocyte transformation assay response to M. bovis after 9 weeks, but no significant reactivity thereafter. Concurrent observational studies suggest that five of the first six deer probably became infected through close inspection and investigation of the tuberculous possums, although the possibility of deer-to-deer transmission cannot be totally excluded. The likely deer-possum contact, and thus exposure to M. bovis, was related to the curiosity and social ranking of the hinds. The second group appear to have had transient exposure to M. bovis, possibly caused by direct contact with the infected hinds introduced earlier. This group never showed any curiosity toward, or interaction with, possums during the periods of observation.

Journal Article↗
PubMed1997

Elucidating the risk factors of feline lower urinary tract disease.

A questionnaire-based case-control study investigating the association of a range of host-related, owner-related and environmental risk factors with feline lower urinary tract disease was conducted in New Zealand over a 2-year period from 1991 to 1993. The study was subsequently extended in two ways, to examine the influence of the use of litter trays and to correlate weather records with the appearance of the disease in one particular region of the country. A range of statistical techniques was employed to analyse the data, including univariate odds ratio and chi-squared calculations, time series analysis, Poisson regression and conditional and unconditional logistic regression. Variables that were positively associated with lower urinary tract disease included low activity levels, the use of a litter tray coupled with restriction indoors, a high number of rainfall days in the month preceding the appearance of clinical signs, stress factors such as moving house within the last 3 months or the presence of more than one cat in the household, and a diet high in dry cat food. There was some indication that high levels of fluid consumption reduced the effect of a diet high in dry cat food. Other variables that appeared to have some protective effects included a routine visit to the veterinarian in the last 12 months and the use of alternative food sources such as rodents and birds.

Journal Article↗
PubMed1997

Epidemiology of Mycobacterium bovis infection in feral ferrets (Mustela furo) in New Zealand: I. Pathology and diagnosis.

Necropsies from 228 ferrets captured from eight areas in the North and South Islands provided material for an investigation into the epidemiology of tuberculosis in feral ferrets. Mycobacterial culture of pooled lymph nodes (retropharyngeal, respiratory and jejunal) identified the prevalence of infection to be much higher than that estimated from gross lesions only. Seventy-three of the 228 animals examined (32%) were diagnosed as tuberculous. Fifty-three culture-positive ferrets and 18 seemingly uninfected animals were subjected to detailed histopathological examination. The outcomes of these investigations, including the characteristics of the disease, distribution of lesions and aids to diagnosis, are presented. Of the feral carnivores found in New Zealand, the disease persists at high prevalence only in ferrets, and is probably the maintained principally by ingestion of tuberculous carrion. The course of the disease may be prolonged in some ferrets, but tuberculosis eventually causes death of many infected animals. Microscopic hepatic granulomas may be considered pathognomonic of the disease, and have potential to be used as a rapid diagnostic tool in ferrets with no gross lesions.

Journal Article↗
PubMed1997

Epidemiology of Mycobacterium bovis infection in feral ferrets (Mustela furo) in New Zealand: II. Routes of infection and excretion.

Detailed necropsies of 228 ferrets captured from eight areas in the North and South Islands provided material for an investigation into the epidemiology of tuberculosis in wild ferrets. Seventy-three of the 228 (32%) animals examined were diagnosed as tuberculous, by culture of pooled lymph nodes and detailed histopathological examination. The prevalence of bovine tuberculosis was 96% in 24 ferrets taken from areas in which tuberculous possums were common. None of 35 animals under 4 months of age were found to be infected, and the prevalence of infection was shown to rise with age, such that for each 6 month age increment there was a 2.8 times greater risk of becoming infected. The most common route of infection appeared to be via the alimentary tract, as 79% of 38 animals, in which the initial lesions could be reasonably determined, had these lesions associated with the digestive tract. Samples from potential sites of excretion from infected ferrets were submitted for culturing. The most common route of excretion was via the oral cavity, with M. bovis recovered from 15 of 64 (23%) oral swabs. Mycobacterium bovis was also isolated from four of 64 (6%) tracheobronchial lavage samples, ten of 63 (16%) faecal samples, two of 29 (7%) urine samples and one of 8 (12.5%) mammary glands. The disease in ferrets appears to be principally maintained by ingestion of tuberculous carrion. Although a moderate number of ferrets excrete M. bovis orally, there appears to be only minor intraspecific transmission by bite wounding. The findings provided no evidence to support the occurrence of pseudo-vertical transmission.

Journal Article↗
PubMed1997

Clinical comparison of circular versus noncircular acquisition using technetium-99m myocardial perfusion SPECT imaging.

UNLABELLED: The optimal orbit for myocardial SPECT imaging has not yet been determined. In order to evaluate differences in image quality and reader interpretation between orbiting methods, 50 patients scheduled for routine stress/rest 99mTc-sestamibi imaging had both a circular and a noncircular study using an ADAC Vertex dual-head imaging system. METHODS: Each study was acquired using a 64 x 64 matrix, 64 stops at 25 sec per stop. Images were processed using a Butterworth filter with a frequency cutoff of 0.6 and an order of 5.0. Studies were interpreted by three experienced readers without knowledge of patient name or orbiting technique for normal and abnormal segments and overall image quality. RESULTS: There was no significant difference in the semi-quantitative assessment of either defect extent or reversibility or in the quantitative assessment of defect size between the two types of orbits. However, while all 50 noncircular studies were read as good or fair quality, 23 circular studies were read as fair or poor (p = < 0.0002). CONCLUSION: Qualitative and quantitative analysis revealed similar size and extent of perfusion defects using either circular or noncircular orbit, but images with the noncircular orbit were of significantly better image quality and may be preferable to a circular orbit with 99mTc-sestamibi.

Adrenergic beta-Agonists↗
PubMed1996

Biologic effects of 17 alpha-dihydroequilin sulfate.

OBJECTIVE: To determine the independent biologic effects of 17 alpha-dihydroequilin sulfate. DESIGN: Prospective randomized study. SETTING: University of Southern California Medical Center. PATIENTS(S): Twenty-one postmenopausal women, mean age 50 +/- 2 (+/-SEM) years, and mean body mass index 27 +/- 2. INTERVENTION(S): Women were randomized to receive daily oral doses of either 1.25 mg of estrone sulfate (E1S), 0.2 mg of 17 alpha-dihydroequilin sulfate, or a combination. Three blood and urine samples were obtained before and after 30 and 90 days of treatment. RESULT(S): After 30 and 90 days of treatment, E1S alone increased sex hormone-binding globulin (SHBG) levels significantly, 19.7% +/- 6.0% and 61.3% +/- 13.0%, whereas 17 alpha-dihydroequilin sulfate reduced SHBG levels, 20.8% +/- 68% and 12.4% +/- 7.5%, respectively. Nevertheless, the combination of E1S and 17 alpha-dihydroequilin sulfate significantly increased SHBG levels, 103% +/- 27.9% and 98.2% +/- 19.1%, compared with baseline at 30 and 90 days. Fewer changes were evident with corticosteroid-binding globulin (CBG). After 90 days of treatment, CBG levels significantly increased 30.9% +/- 5.5% with E1S, decreased by 7.2% +/- 5.0% with 17 alpha-dihydroequilin sulfate, and, with the combination, significantly increased by 10.5% +/- 2.4% compared with baseline. Changes in lipids and lipoproteins were more variable. However, high-density-lipoprotein cholesterol increased significantly with E1S at 30 and 90 days compared with baseline, 96.5% +/- 39% and 91.5% +/- 22.6%, and with the combination increased 66.4% +/- 13.3% and 79.2% +/- 24.4%, respectively. Fewer changes were evident with 17 alpha-dihydroequilin sulfate alone, decreasing 4.4% +/- 22% and 2.6% +/- 21.3%. Urinary ratios of bone collagen equivalents-creatinine and calcium-creatinine decreased in all three groups. However, the combination group resulted in a significantly greater percentage decrease in bone collagen equivalents-creatinine than with E1S alone. CONCLUSIONS(S): 17 alpha-Dihydroequilin sulfate could modify some of the first-pass effects of conjugated equine estrogens and act synergistically with other conjugated equine estrogens to reduce bone resorption.

Calcium↗
PubMed1996

A study of the topography of the lymphatic system of the Australian brushtail possum (Trichosurus vulpecula).

The superficial and deep lymphatic systems of the Australian brushtail possum (Trichosurus vulpecula) are described. In common with other marsupials studied to date and in contrast with most eutherians, there were no popliteal lymph nodes and efferent drainage from the inguinal lymph centre passed directly to the deep axillary group of lymph nodes via an inguinoaxillary trunk. Efferent vessels from the tonsil passed directly to the deep cervical lymph node, which was drained by the tracheal trunk. The mandibular and parotid lymph nodes drained independently to the superficial cervical lymph node. All subcutaneous lymph drainage passed either through the superficial cervical or the axillary lymph centres before entering the venous system, an arrangement which is also found in kangaroos. The significance of the patterns of lesion distributions in possums with naturally occurring tuberculosis caused by Mycobacterium bovis is discussed.

Abdomen↗
PubMed1995

Angiotensin converting enzyme inhibition of the gonadotropin-stimulated rabbit: effect on estradiol production.

PURPOSE: Our purpose was to determine whether angiotensin converting enzyme (ACE) inhibitors affect gonadotropin-stimulated estradiol (E2) production. DESIGN: This was a prospective, masked, randomized, placebo-controlled animal trial. Twenty female New Zealand White rabbits were hyperstimulated with gonadotropins. One-half of the rabbits received concomitant treatment with the ACE inhibitor, enalapril; one-half received concomitant treatment with a placebo. RESULTS: Baseline peripheral E2 (13 +/- 4 vs 11 +/- 2 pg/ml) and angiotensin II (Ang II) (22 +/- 5 vs 27 +/- 7 pg/ml) levels were similar in both groups. Significant inhibition of peripheral Ang II levels was achieved in the enalapril group (32 +/- 6 vs 93 +/- 15 pg/ml; P = 0.005). E2 was significantly higher in the rabbits receiving enalapril versus placebo (369 +/- 58 vs 183 +/- 35 pg/ml, P < 0.03), respectively. By day 10, peripheral E2 had returned to normal levels in both groups (13 +/- 1 vs 13 +/- 1 pg/ml). However, E2 levels in the ovarian effluent were 2.8 times higher in the enalapril rabbits. CONCLUSION: Peripheral Ang II levels increase after gonadotropin stimulation and ACE inhibitors are able to blunt this increase significantly. ACE inhibition has a significant stimulatory effect on ovarian E2 production. This implies that Ang II may normally inhibit ovarian E2 production in stimulated cycles.

Angiotensin II↗
PubMed1995

Alterations in the sensitivity of serum insulin-like growth factor 1 and insulin-like growth factor binding protein-3 to octreotide in polycystic ovary syndrome.

OBJECTIVE: To determine if the somatostatin analog, octreotide, affects insulin and related peptides and, hence, androgen levels differently between polycystic ovary syndrome (PCOS) patients and controls. DESIGN: Prospective controlled trial. SETTING: Reproductive endocrinology clinic of our medical center. PATIENTS: Eleven women with PCOS and six matched ovulatory controls. INTERVENTIONS: Octreotide (100 micrograms) was administered subcutaneously in the midfollicular phase. Serum was obtained before and at 60, 120, 180, and 240 minutes after octreotide. MAIN OUTCOME MEASURES: Fasting insulin, insulin-like growth factor 1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3), T, androstenedione (A), and LH. RESULTS: In PCOS, baseline levels of T, A, LH, and fasting insulin were significantly higher than in controls. Pretreatment IGF-1 and IGFBP-3 levels were similar in PCOS and controls. Octreotide reduced fasting insulin levels significantly but to a similar degree in control and PCOS patients (77% and 90%, respectively). Both groups also experienced a significant decrease in LH levels after octreotide administration, but no significant changes were demonstrated in serum T or A. However, serum IGF-1 suppression in PCOS was greater (63% versus 8% in controls). Serum IGFBP-3 levels increased after octreotide administration in both groups with a larger increase (40%) occurring in the PCOS patients. CONCLUSIONS: These data suggest that women with PCOS may be more sensitive to the effects of octreotide in decreasing IGF-1 and increasing IGFBP-3. Although no significant changes could be demonstrated in ovarian androgens after a single dose, octreotide effectively reduced serum LH and insulin and, as such, may prove useful in treating some patients with PCOS.

Adolescent↗
PubMed1995

Prorenin is elevated in polycystic ovary syndrome and may reflect hyperandrogenism.

OBJECTIVE: To examine the null hypothesis that women with polycystic ovary syndrome (PCOS) produce similar levels of prorenin and other components of the ovarian-derived prorenin to angiotensin cascade (ODPAC) at baseline and after stimulation with clomiphene citrate (CC) or hMG when compared with normal age- and weight-matched ovulatory controls. DESIGN: Prospective controlled clinical trial. SETTING: Infertility clinic in a university-based county hospital and a hospital-based private infertility practice. PATIENTS: Twenty-eight infertile women aged 18 to 35 years. Thirteen patients were diagnosed with PCOS. Fifteen normal ovulatory patients who were matched for age and weight served as controls. INTERVENTIONS: Twenty patients were stimulated with CC and eight were stimulated with hMG. MAIN OUTCOME MEASURES: Serum E2, P, T, androstenedione (A), DHEAS, LH, FSH, and plasma prorenin, active renin, and angiotensin II (Ang II) were measured at baseline and during the preovulatory and midluteal phases of the stimulation cycles. RESULTS: Baseline plasma prorenin in PCOS was higher than that of follicular phase controls. Plasma prorenin correlated significantly with peripheral androgen levels. Prorenin, active renin, and Ang II increased in response to gonadotropins with the largest increases occurring in control patients receiving CC. An association was seen between ovulation with CC and lower baseline levels of active renin. CONCLUSIONS: The null hypothesis was rejected. Infertile women with PCOS have higher baseline prorenin levels when compared with age- and weight-matched ovulatory controls. There is a significant correlation between prorenin and the peripheral levels of androgens produced during ovarian stimulation. Baseline active renin levels may be predictive of ovulation with CC.

Adolescent↗
PubMed1995

Directions and issues in bovine tuberculosis epidemiology and control in New Zealand.

Current knowledge on the epidemiology of bovine tuberculosis in New Zealand is reviewed, with emphasis on recent findings. It would appear that the epidemiology of the disease is determined by the behaviour of both wildlife and domestic stock, and environmental influences on the development of the infectious state in wildlife. The central cause of persistent disease nationally remains the possum, although other species may play a subsidiary role locally. Current understanding provides much improved prospects for control, which will be based on implementing individual farm control strategies to complement current regional control, with additional later prospects of vaccination of wildlife and possibly reproductive control of possums.

Journal Article↗
PubMed1995

The epidemiology of Mycobacterium bovis infection in brushtail possums (Trichosurus vulpecula Kerr) in the Hauhungaroa Ranges, New Zealand.

The prevalence of Mycobacterium bovis infection in the wild possum population around the perimeter of the Hauhungaroa Ranges, New Zealand, was determined by a cross-sectional study, and risk factors associated with tuberculosis were identified. Of 6083 possums necropsied, 128 (2.1%) showed gross lesions suggestive of tuberculosis infection, and 76 (1.25%) were subsequently confirmed as tuberculous on histopathological examination. Considering only traplines where tuberculosis was detected, adult possums were 1.9 times as likely to be infected as immature animals, and the total prevalence was 5.4% in males compared with 3.9% in females. Adult females were 3.64 times as likely to be infected as immature females, whereas there was no significant age difference for males (odds ratio = 1.46, p=O.29). Immature males were 3.12 times as likely to be infected as immature females. Possums in poor condition were more likely to be found infected than possums in good condition. Tuberculous possums were found in 27 local clusters of infection. The correlation between the prevalence of tuberculosis in possums in zones and the incidence of tuberculosis in cattle on adjoining properties was 0.4 (p<O.05).

Journal Article↗
PubMed1995

Foraging and denning patterns of brushtail possums, and their possible relationship to contact with cattle and the transmission of bovine tuberculosis.

Radio-tracking and direct observation were used over 18 months in 1990-92 to investigate both the use of sleeping dens and foraging activity by possums (Trichosurus vulpecula) on a 21 ha site in the Wairarapa used for a longitudinal study of bovine tuberculosis. Males had larger home ranges than females, and both sexes had larger activity areas during the autumn mating season than at other times of the year. Possums typically foraged in only a small area of their home ranges (termed an activity area) on any one night, and the areas used by individuals were commonly very similar over a series of nights. Activity areas overlapped extensively among possums. Possums used a limited number of dens, commonly in a small and in most cases a circumscribed part of their home range. No simultaneous den-sharing was found, with the exception of mother-joey pairs. The mortality of juveniles after independence was 36%. Only two of 25 juveniles under surveillance to detect dispersal dispersed more than 500 m off the study site, and both subsequently died. Grazing patterns of cattle meant that almost all accessible areas of the paddock were covered by at least some grazing cattle, and so all activity areas of possums within the paddock were covered by areas where cattle foraged. However, possums avoided contact with cattle, and when some cattle were excluded from access to the part of the paddock principally used by both tuberculous and healthy possums for denning, transmission of Mycobacterium bovis from possums to these cattle ceased, although there was subsequent transmission to deer. Cattle which grazed the area used principally for possum denning continued to become infected, and these denning areas appeared to be of importance in the transmission of tuberculosis.

Journal Article↗
PubMed1995

Interactions between beef cattle and simulated tuberculous possums on pasture.

Brushtail possums (Trichosurus vulpecula) were sedated with ketamine and placed within a fenced observation area with 17 Hereford cross steers. The behaviour of the sedated possums simulated that of terminally ill possums. Behavioural analysis was carried out during eight observation periods in which sedated possums were successfully released and interactions occurred. Cattle were attracted from over 50 m away by the movements of the possums, and for 34% of observation time cattle investigated the possums. Inactive animals engendered far less interest, and cattle investigated them for 3% of observation time. An average of seven to eight cattle came in physical contact with the possum in each of the observation periods. Cattle actively investigated the possum while following it as it moved, commonly close enough to be within aerosol transmission distance, and some sniffed the possum, touched it with their noses, and in many cases licked it extensively. All of these activities would expose the cattle to high risk of receiving an infective dose of Mycobacterium bovis, especially via the respiratory route. The type and duration of contact between individual steers and the possum varied between animals and observation period. The cattle exposed themselves to greater risk, overall, during the first week of observations, and there was evidence of habituation with increased contact. Although all 17 steers came within 5 metres of the possum at some point during the observation periods, some individual cattle behaved in ways which would put them at greater risk of contracting tuberculosis than did others. Cattle showed little interest in possum carcasses placed on pasture. These were unlikely to be a significant source of infection for cattle, although they could be for scavenger species.

Journal Article↗
PubMed1995

Behavioural studies on the potential for direct transmission of tuberculosis from feral ferrets (Mustela furo) and possums (Trichosurus vulpecula) to farmed livestock.

Studies were conducted to evaluate the response of cattle and deer to ferrets which were sedated so they behaved like terminally tuberculous animals, and to compare this with the response of cattle, deer and sheep to sedated possums. Six groups of deer and two groups of cattle were exposed to a sedated ferret and to a sedated possum. Both livestock species showed interest in the possum by sniffing and licking it, but they only briefly touched the ferret and no licking or extended investigation was observed. The proportion of available time spent in physical contact with the possum by cattle was 7.7 times as high as for the ferret, and for the deer was 5.7 times as high. The behavioural response of three groups of sheep to a sedated possum was investigated, and sheep showed limited interest beyond viewing the possum from a distance. The amount of time spent by sheep investigating the possum was very low and the intensity of exploration was also low. For possums, at least one deer was within 1.5 m (an estimate of the distance that tuberculosis can be transmitted by aerosol) for 50.9% of observation time, and in physical contact with the possum for 9.5% of time. The figures for cattle were 69.3% and 17.3%, while those for sheep were 6.9% and 0.3%. In interactions with ferrets, the equivalent figures were 29.8% within 1.5 m and 2.2% in physical contact for cattle, and 20.8% and 1.1% for deer. Tuberculous possums commonly and tuberculous ferrets less commonly have lung lesions and/or discharging sinuses, and may excrete Mycobacterium bovis intermittently or continuously in aerosols or discharges. The exploratory behaviour of deer and cattle in this study would provide opportunities for them to become infected with M. bovis if they had contact with infectious possums, and less probably with ferrets. The response of sheep to possums suggests that they would be much less likely to contract the disease.

Journal Article↗