June   2003   VOLUME 56: Number 6 Veterinary Ireland Journal Page CONTENTS Peer review articles are available in full as  Acrobat PDF files You will need to download the Acrobat reader    which can be got free at this web site

EDITORIAL   

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They haven’t gone away, you know

Nobody is in any doubt about the challenges that the health sciences face in dealing with the many newly recognised pathogens and syndromes that have emerged recently: amongst others, HIV, BSE, nvCJD, Sars, Escherichia coli O157. On the other hand, we may have become somewhat more complacent about the threat and the significance of some of the “old” diseases. As one commentator put it: dramatic changes in society, technology, travel and the environment have created new opportunities for the re-emergence of some microbes and the recrudescence of diseases once expected to be eliminated. In recent decades the scientific community has made tremendous advances in elucidating the aetiology, pathogenesis and molecular pathology of a vast range of infectious diseases that have long been recognised as threats to the well-being of human and/or animal populations. As a consequence the expectation has been fostered that the health professions have been well on the way to effective control of many of the maladies that have posed serious problems for previous generations. Sadly, the pages of this issue of the Journal carry a number of news items that reveal such expectation as a false dawn; in veterinary medicine, as in human medicine, many of the menacing “old diseases” are still with us, on occasion still causing havoc. In the words of the immortal aphorism: “they haven’t gone away, you know.”

In the following pages we reprint announcements by the Department of Agriculture and Food on the publication of a contingency plan and operations manual for the handling of any future foot-and-mouth disease outbreak, on the significant progress made by the National Aujeszky’s Disease Control and Eradication Programme, on a review of the policy and practice in relation to Johne’s disease in the light of increased numbers of reported cases, and on developments in the genotyping of sheep with the aim of producing a national flock that is resistant to scrapie.

The developments with reference to Johne’s disease are particularly interesting. Shortly, literature on the disease and its control will be sent to every farmer and every veterinary surgeon in the country. In the meantime,the Department of Agriculture and Food has initiated a series of consultations with the several “stakeholders” with a view to developing an effective approach to the control of the disease that “… will have direction, momentum, and the commitment of all concerned.” In that context, we reprint in this issue an article by George Caldow and his colleagues on the different approaches to the control of Johne’s disease adopted by a number of countries; there are lessons to be learned from the experiences they record. We particularly draw attention to their statement that “…there is agreement that it is the clear responsibility of the veterinary adviser to point out to herd owners the long-term nature of the process of eradication: it may take many years, depending on the procedures.”

It is equally true that the advisory role of the veterinarian also is, of necessity, a long-term process. The first task may be to convince the herdowner that the long haul to eradication should be embarked upon; that once the disease has taken root on the farm, each year increasing numbers of calves will be exposed and acquire the infection and some will, in turn, pass it on to succeeding crops of calves; that in due course a variable proportion of the infected female animals will have to be culled prematurely because of poor milk production and/or infertility, causing unsustainable financial losses. Thus, the earlier the intervention, the lower the ultimate cost.

Thereafter, veterinary advice on biosecurity, on management of calves, on management of slurry and on general hygiene will be central to the progress and to the success of the eradication programme. The current upsurge in the diagnosis of paratuberculosis has been attributed to the arrival from continental Europe of large numbers of subclinically infected carrier animals of high genetic merit that were imported to improve milk production in the dairy herd. The infection is acquired in calfhood, principally from ingestion of pooled colostrum, from suckling contaminated teats, or from contact with contaminated faeces in the environment. In a sense, veterinary advice will serve to counter the detrimental consequences of modern practices of intensive animal husbandry

that have been adopted for pragmatic reasons without any thought for the inherent risks to animal health; for instance, the labour-saving and convenient practice of feeding pooled colostrum has been found to be a major factor in the dissemination of the causal agent of paratuberculosis(Map) within herds.

In essence, the involvement of the veterinarian in such an advisory role will give ample evidence of the practical benefit that might accrue from a more comprehensive herd health management programme. If it is accepted that Map may be involved in Crohn’s disease, the benefit to be gained may be expressed in terms of animal health, public health, and animal welfare.

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