SUMMARYThis study investigates the course of tuberculosis in a naturally infected badger population, its impact on the population and the risk of spread to other species in the light of capture data and post-mortem findings from 47 tuberculous badgers, stratified by age group and sex, accrued since 1975. The findings are compared with those for 260 badgers from the same population in whom no evidence of infection was detected. Detailed estimates of seasonal variations in bodyweight for uninfected male and female cub, yearling and adult badgers are presented and compared to the weights at post-mortem examination of the tuberculous badgers, in whom poor condition and weight loss were the principal presenting signs. Lesions were seen especially in the lungs and associated lymph nodes, and in the kidneys. Organisms were detected intermittently in faeces, urine, sputum and discharging bite wounds. Infected animals could survive for nearly 2 years and produce cubs successfully.
T h e dynamics of bovine tuberculosis infection in a wild Badger population have been studied since 1981. Faeces are sampled regularly to determine the distribution of infection in the study area. Badgers in known infected social groups, plus the neighbouring groups, are periodically caught and subjected to full clinical and bacteriological examination to monitor the progression of infection within and between groups of Badgers. The interim results of this study are presented and discussed. During 5 years (1981)(1982)(1983)(1984)(1985), the temporal spread of infection between social groups in the study area was slow and restricted. Some clinically affected Badgers have survived for long periods. Evidence of infection in individual Badgers indicates that pseudo-vertical (mother to cub) transmission may be important in the maintenance of infection in the Badger population. There is also evidence of horizontal transmission by bite wounding and aerosol infection. Badger mortality due to Mycobacterium bovis infection was low, and the prevalence of infection in male Badgers is greater than in females. T h e data accumulated so far show no apparent relationship between Badger population density and the prevalence of M . bovis infection, nor is there any evidence to support the hypothesis that M . bovis infection acts to depress Badger population density significantly below diseasefree levels. Cattle and infected Badgers can co-exist for long periods without the disease necessarily being transmitted to cattle.
The data accumulated from 1972 to 1987 on the distribution and prevalence of tuberculosis in the badger population in Great Britain is reviewed. The current information on the influence of Mycobacterium bovis infection on badger population dynamics and its clinical effect on badgers is also summarized. The results of these reviews indicate that M. bovis is endemic in the British badger population and that the badger is an ideal maintenance host for M. bovis. The studies in progress to obtain a fuller understanding of the epidemiology of tuberculosis in badgers are also described.
SUMMARYFollowing epidemiological and ecological studies of a defined badger population in an area of East Sussex, removal of all badgers by cage trapping was attempted. Trapping was incomplete due to the activities of protesters. Forty-seven badgers were caught from the eight social groups. All badgers were examined clinically and samples offaeces, urine and tracheal aspirate were taken, together with swabs from any bite wounds, for bacteriological examinations. Forty-five animals were skin tested using whole killed cells of Mycobacterium bovis strain AN5, bovine PPD Weybridge and new human tuberculin. Skin test results were recorded after 24 and 72 h. All badgers were killed and subjected to a post-mortem and bacteriological examination.M. bovis was detected in 10 (21-3 %) badgers at post-mortem and in 2 badgers from clinical samples. Four social groups were infected. Positive skin test results were recorded at 72 h with bovine PPD (2 ,ug and 20 ,ug/ml), strain AN5 (1 mg/ml) and human tuberculin (2 jug/ml), but not with human tuberculin at 20 jug/ml. Histological sections of the skin test reactions showed the cellular types typical of delayed-type hypersensitivity. The skin test reactions observed were neither sensitive nor specific enough to be of practical value.
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