[Environmental and animal hygiene--an indispensable subject for veterinary education?]. / Umwelt- und Tierhygiene--unverzichtbare Fachrichtung für die tierärztliche Ausbildung?

Based on conference reports, publications, and personal experiences in the field of veterinary environmental hygiene in Germany and abroad, the question is discussed whether the subjects environmental and animal hygiene have to be considered as indispensable subjects for the curricula in veterinary education or only play a secondary role as a fringe area of veterinary medicine. The analysis and evaluation of the relevant literature have shown that this subject has gained an extraordinary significance for science and practice during the last 4-5 decades. Due to its close interconnections with related fields of science like agriculture, human medicine, biology, ecology, engineering sciences and economics the veterinary environmental and animal hygiene has reached such a high standing that it is now an indispensable component of veterinary education in Germany.

Inactivation of viruses in liquid manure.

The stability of some viruses and methods of virus inactivation in liquid manure are reviewed. The authors discuss experimental data on the stability of foot and mouth disease virus, classical swine fever virus, Aujeszky's disease virus, African swine fever virus, swine influenza virus, porcine paramyxovirus, bovine virus diarrhoea virus and transmissible gastroenteritis of pigs virus. Recommendations and practical advice are given for the choice and application of chemical disinfectants for slurry.

Hygienic aspects of the production and agricultural use of animal wastes.

Regarding the hygienic aspects of the production and use of animal wastes, further research on the following aspects is essential: pathogenic agents present in residues of animal production in the context of transmissible multifactorial diseases and the epidemiology of pathogens under different ecological conditions; recycling of toxic agents, e.g., copper, selenium and iodine, in animal wastes in the context of the food chain from soil to humans; hygienic effects of animal wastes on water as regards the standards required by medical authorities; effects of agents used to increase animal production, or used for medicinal purposes, which are present as residues in animal excreta and may be hazardous to public health; effects of animal excreta on microbiological processes in the soil; effects of dust and airborne microbial emissions from animal production, and finally, processes of self-disinfection of manure and livestock slurry during storage as a means of reducing the amounts of chemical disinfectants used, of reducing environmental pollution, and of studying the application of biotechnological methods to disinfect manure and livestock slurry, this study being of particular importance.

[Research in veterinary environmental hygiene]. / Forschung in der veterinärmedizinischen Umwelthygiene.

The course of development of the initial subject "Veterinary Hygiene" to the reduction and specialization limited to "Animal Hygiene" and the recent extension into the broad field of environmental hygiene is described. This is done with reference to books and other publications which point the way ahead for research of veterinary medicine in environmental hygiene and thus prove the increasing importance of that subject. A survey is given over current German research in that field, future demands as well as the necessary extension of environmental hygiene in graduate and post-graduate teaching of veterinary students as well as further professional training of veterinarians.

[Kinetics of the inactivation of Salmonella during thermal disinfection of liquid manure]. / Kinetik der Inaktivierung von Salmonellen bei der thermischen Desinfektion von Flüssigmist.

Technical processes for thermal liquid manure disinfection usually reach temperatures between 50 degrees C and 70 degrees C. The destruction of important infectious micro-organisms can be expected in this temperature range. The purpose of the investigations reported here was to study the thermal resistance of Salmonellae during heat treatment of liquid manure. Salmonella senftenberg 775W survived much longer than each of 12 other strains from 8 different Salmonella serovars. Resulting from a regression analysis kinetics of thermal death were determined for this strain and decimal reduction times were calculated in cases of an exponential die-off. D60-values ranged from 47 to 138 sec depending on the type of slurry used. Further investigations on the inactivation of Salmonella senftenberg 775W at 50 degrees C, 55 degrees C, 60 degrees C, and 65 degrees C were carried out and following D-values were obtained: D50 = 56.7 min, D55 = 11.5 min, D60 = 2.3 min, D65 = 0.47 min. The resulting ZD-value was 7.2 degrees C. Minimum requirements concerning temperature and heating time can be derived from the results of this study. The given recommendations may only be applied, if technical processes work without any functional deficiencies and thermal energy is evenly distributed in the heated slurry. Combinations of temperature and heating time should not fall below the following values: 50 degrees C/15 h, 55 degrees C/3 h, 60 degrees C/30 min, 65 degrees C/5 min.

Survival of pathogenic micro-organisms and parasites in excreta, manure and sewage sludge.

The causative agents of many infectious diseases are excreted by the faecal route and also with other excretions or secretions of the body. Some pathogens are also excreted from clinically healthy animals, from those with latent infections and in cases of transmissible multifactorial diseases. In all types of livestock housing, the pathogens finally reach the floor with the installations for collecting manure as a solid or liquid. Under these conditions livestock owners do not realise that manure may contain pathogens, and therefore do not take precautions against possible spread of diseases by utilisation of manure. The pathogens do not survive very long in stored farmyard manure because of the temperatures and biological and biochemical activities prevailing in the middens. But the conditions in slurry are different because the temperature does not rise and biochemical activity is low. Therefore the pathogens survive for rather long periods in slurry. To avoid disease transfer by utilisation of manure and slurry as fertilisers, certain precautions are necessary and these are described in detail. The agricultural utilisation of municipal sewage sludge is common in many countries. However, these sludges contain pathogens which are excreted by the human population served by the sewers and sewage treatment plants. In the sewage purification processes most of the pathogens are reduced in number but not completely eliminated. They are enriched by sedimentation processes in the sewage sludge. To protect the livestock of farms utilising sewage sludge as fertiliser or for amending soils it is necessary to sanitise hygienically dubious sludges prior to their use. The epidemiological aspects of agricultural sludge utilisation are discussed and details of the available sanitation technologies are given.

[Livestock manure as a vector for infectious agents]. / Wirtschaftsdünger als Vektor für Infektionserreger.

The causative agents of nearly all bacterial and viral infectious diseases are either directly excreted by the infected animals or they reach the floor via other ways and thus end-up also in the fecal and urinary excretions of the animals. Occasionally pathogens also can be found in slurries of clinically unsuspected livestock for a short period of time while they pass through the gut of individual animals without colonization or invasion of the tissues (e.g. salmonellas). Consequently the manures are a potential for spreading infectious diseases. But their real significance as a vector for infectious agents is to a large extent still unsolved, because in the literature only very few and sometimes doubtful cases are described. During storage of manures the numbers of pathogens are reduced. This effect can be intensified by prolongation of the storage time. To assess the real epidemiological significance of the animal manures as vectors for infectious diseases further research work is urgently needed. After disinfection of animal manures in accordance with the regulations during eradication of notifiable diseases no cases of spread of disease became known in the Federal Republic of Germany. The problems of agricultural utilization of manures in water protection areas are discussed from a microbiological point of view.