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388828 32888 000 a =] p 885 B S828: e numbers emerging ‘ t e py mfrcaylag SALISBURY MEDICAL BULLETIN - SPECIAL SUPPLEMENT NO. 87 Incidence of anthrax, and environmental detection of Bacillus anthracis in the UK P.C.B. TURNBULL’, JANE E. BOWEN’, J.S. GILLGAN? and N.J. BARRETT? ‘Anthrax Section, Centre for Applied Microbiology and Research, Porton Down, Salisbury, Wiltshire SP4 0JG, UK; *Notifiable Diseases Section, Ministry of Agriculture, Fisheries, and Food, Government Buildings, Tolworth, Surrey KT6 7NF, UK; *PHLS Communicable Disease Surveillance Centre, 61 Colindale Avenue, London NW9 SEO, UK Notifications of human cases of anthrax remain exceedingly rare while small but troublesome outbreaks continue to occur in livestock. The last confirmed human incident was a case of cutaneous anthrax in a casual labourer in London in August 1995'. The source of the infection was not established. The confirmed human case prior to that was a case of cutaneous anthrax in a worker in a woollen mill in Scotland in October 1991‘. The case notified in 1992 remained unconfirmed. Figures 1 and 2 and Table 1 are updated versions of those presented at the last International Workshop on Anthrax’. Perhaps most noteworthy among the livestock incidents was the outbreak in an intensive pig-rearing unit in 1989*° which led to the study reported elsewhere.in these proceedings’. 120 o 100 === Factories Acts 5 s+* Public Health Act g 80 = ca 2 60 so 8 40 —E =) = 20 0 = 1900 10 20 30 40 50 60 70 80 9094 Year Figure 1. Human anthrax. Notifications under Factories Acts and Public Health Act United Kingdon 1900-1994 1600 1400 1200 1000 800 600 400 200 0 1880 90 1990 10 20 30 40 50 60 70 80 9094 Year Outbreaks Figure 2. Reported cases of animal anthrax in Britain 1888-1994 (CVO reports [MAFF]) Although only 19 deaths were confirmed as cases of anthrax, the outbreak created husbandry problems which resulted in the Fumate slaughter and incineration of all 4492 animals on the arm. The less anthrax is seen, the more emotive its occasional appearances become. Recent outbreaks in livestock have Tesulted in official obstacles to the disposal of the wastes reflecting concern which is out of proportion to the real hazards posed. Furthermore, as with the outbreak in pigs, interest from the media frequently raises public anxiety. The finding of anthrax spores in environmental specimens similarly results in considerable public and official concern. Some perspective can be gained from Table 2, which summarises an analysis of 1342 environmental samples from 95 sites examined in the 8-year period, October 1987 to August 1995. In all, 43 (3.2 %) samples from 14 (15 %) sites yielded virulent Bacillus anthracis. Spore numbers exceeded an estimated 100 cfu/g in 13 of the positive samples, but 9 of these were from a single troublesome carcase burial site*. In the majority of samples, numbers were clearly very low and, in our view, represented no hazard to site workers taking sensible hygienic precautions. Risks for subsequent users of the site are also regarded as vanishingly small in these instances, but consideration is obviously given to either removal of the contamination or the most suitable subsequent use of such sites, for example, car parks. An attempt at providing guidance on assessing risks associated with environments known to be, or suspected of being contaminated with anthrax spores has been made elsewhere®. The isolation from environmental sites of avirulent B. anthracis that have lost one or both plasmids continues to be of interest since our formal report on this’. A dilemma exists over whether to report these to clients; while of no hazard in themselves, it is presumed they represent virulent parents and, as seen in Table 2, they are periodically isolated together with virulent counterparts. A molecular explanation of the point at which they lose their plasmid(s) in the germination, multiplication and sporulation cycle is looked forward to. Table 1. Reported cases of human and animal anthrax in Britain 1989-95 Year Human Animal Notifications* Incidents Deaths Animals Numbert 1989 1 3 Cattle 3 1 Pigs 19 1990 3 5 Cattle 6 1991 1 2 Cattle 2 1992 1 2 Cattle 2 1993 0 2 Cattle 5 1994 0 3 Cattle 5 1995 1 1 Cattle 1 1 Ferrets 2 *No deaths reported b7c ' Confirmed cases and not including animals which were treated and lived 47 Sources: Human: notifications and reports to OPCS, SHHD and HSE. Animal: CVO reports (MAFF).