PubMed Health⌕ Search

Biomedical subjects

D Strauch

Publications and source records attributed to D Strauch.

At least 37 records · Page 2Linked to original sources
PubMed1991

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.

Animals↗
PubMed1991

[Kinetics of the inactivation of Salmonella during thermal disinfection of liquid manure].

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.

Animals↗
PubMed1991

[Livestock manure as a vector for infectious agents].

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.

Animals↗
PubMed1989

[Comparison of the sporocidal effects of two different disinfectants i a model experiment with pathogenic and nonpathogenic clostridial spore as well as with Bacillus cereus].

Official methods concerning the examination of sporocidal effects of disinfectants are presently lacking in the Federal Republic of Germany. Spore resistance of selected clostridial species towards formaldehyde and peracetic acid was examined by suspension tests and germ-carrier tests in comparison to spores of Bacillus cereus. Formaldehyde in concentrations between 5% and 20% as well as peracetic acid in concentrations between .004% and .125% were tested. Spore concentration of 10(6) spores/ml in the suspension-tests and 10(4) spores/ml in the germ-carrier tests with wooden germ-carriers were used. Against formaldehyde spores of Cl. septicum had the lowest resistance in the suspension tests followed by Cl. difficile, Cl. tertium, Cl. bifermentans and Cl. perfringens. Cl. sporogenes strain NCTC 532 had the most resistant spores. Concerning peracetic acid the situation was nearly the same. The resistance of all spores of pathogenic species under investigation towards chemical disinfectants was covered by those of Cl. sporogenes NCTC 532 treated with isopropanol. Isopropanol treated spores of B. cereus offer an alternative solution for practical disinfectant testing because spore production as well as growth of clostridia entail great expense. In order to cover the resistance of spores of Cl. perfringens A, the most resistant pathogenic clostridial species tested here, increased spore concentrations of B. cereus would be necessary.

Bacillus cereus↗
PubMed1988

[Advice as to the safety precautions for handling infectious material in a veterinary practice laboratory].

The number of microbiological investigations with infectious material increases in veterinary practice. Frequently the working space is cramped so that special security measures are imperative. These measures are discussed in detail. Their disregard can result in laboratory infections with zoonotic agents and in unpleasant lawsuits with bad consequences. The German regulations pertaining to security in laboratories are listed. They should be observed in any case.

Animals↗
PubMed1988

[Disease agents in feces and their epidemiologic significance].

The causative agents of nearly all infectious diseases are excreted either directly or indirectly by the infected animals. In many cases they leave the animals' body with the faeces. In most cases the pathogenic agents end up on the floor of the animal housing. Thus they can be found in the farm-yard manure or in the slurry. The danger of infection by slurry is only assumed but not yet sufficiently quantified. To reduce the assumed risk of any slurry an expert group of the European Communities has elaborated recommendations for long-term storage and agricultural utilization of slurry. Provable infected slurry comes within the provisions of the animal epidemics law. The problem of an acceptable risk in connection with infected slurry is discussed, when it was not or not sufficiently disinfected but only long-term stored to wait for the natural die-off of the pathogens concerned. A transfer of such considerations into the practice of notifiable disease eradication is rejected. A regular disinfection of infected animal excrements is considered to be unrenouncable.

Animals↗
PubMed1987

[The behavior of viruses in conventional and 2-step anaerobic-mesophilic stabilization of clarified sludge with pre- and postpasteurization].

In a pilot-plant of semi-technical scale for the digestion of sewage-sludge with two single operated reactors and five coupled reactors investigations about the influence of anaerobic mesophilic sludge digestion and pasteurisation of raw and digested sludge on viruses were carried out. Following test-viruses were used: bovine enterovirus ECBO strain LCR-4, bovine parvovirus strain "Haden" and reovirus type I. In the case of a daily addition of virus-contaminated raw sludge both ECBO-virus LCR 4 and Reovirus--with one exception--were inactivated by a conventional single stage sludge digesting process with a mean hydraulic retention time (t/R) of 20 d as well as by a two-stage digesting process with 2 d tR in the anaerobic pretreatment and 8 d tR in the main-digestion process with and without prepasteurisation of the raw-sludge. Bovine Parvovirus was inactivated completely by a single-stage sludge digesting process with 20 d tR and pasteurisation of the digested sludge. All other investigated processes did not inactivate Parvovirus completely.

Anaerobiosis↗
PubMed1987

[Aerosol disinfection of bacterial spores].

The present investigations are divided into two parts. First it is tested which commercial disinfectants are efficient in aerosol disinfection of bacterial spores. This part is carried out in an aerosol chamber with airborne spores (laboratory experiments). The best results are obtained with peracetic acid, hydrogen peroxide and formaldehyde are effective with some restrictions. With these disinfectants it is tested in the second part if the aerosol disinfecting-method is capable for disinfecting rooms with electronic equipment. This part is carried out in a vessel under open air conditions (field experiments). Bacterial spores dried on germ carriers of limewood, aluminium and rusty iron are exposed to disinfectant aerosols under those temperature and relative humidity conditions which are representative for the four seasons in Germany. In these investigations there are also included germ carriers with spores, that have been lyophilized without any protective substances respectively with Bentonite, Mixtura desiccans and Silicagel + Serum as protective substances. To check the corrosive effect of disinfectant aerosols electronic pocket calculators and pocket transistor receivers have been exposed to the aerosols. The best results are obtained with formaldehyde at temperatures above 10 degrees C and relative humidities within 65% to 95%. At temperatures and relative humidity conditions outside of this optimal range the effectiveness of formaldehyde tends to zero. Hydrogen peroxide is capable for disinfecting spores on germ carriers of limewood and aluminium at all temperature and relative humidity conditions; on germ carriers of rusty iron the effectiveness is reduced strongly. Same results could be obtained with peracetic acid respectively a mixture of peracetic acid and hydrogen peroxide. With these disinfectants a decontamination of rusty iron surfaces is impossible too except the germ concentration on the surface is below 10(4) CFU/cm2. As to the protective substances used in the lyophilization process Bentonite and Mixtura desiccans cause hardly any change in the disinfectant resistance of bacterial spores. Silicagel + Serum in comparison to that protects the imbedded spores that far, that no disinfection of these germ carriers was achieved with the oxidizing agents. As about 15 disinfection runs with each disinfectant did not cause permanent damages to the pocket calculators and transistor receivers it can be emphasized as result of these investigations that aerosol disinfection is an effective method in disinfecting rooms with electronic equipment under middle European climate conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Aerosols↗
PubMed1986

[Animal hygiene and environmental hygiene].

Animal Hygiene has developed historically from the field of Animal Health Care and is as a part of Veterinary Hygiene now about 100 years old. From her very beginning Animal Hygiene has dealt with the influences of the live and inanimate environment on the health of animals an also investigated the reverse developments. From a historical point of view it can be stated that Animal Hygiene has done active research in the field of environmental hygiene ever since. This tendency was intensified by the modern developments of keeping animals in confinements, enlargement of livestock, new kinds of residues like slurry which demanded a change in the management of arable and forage land combined with an increase in the agricultural utilization of residues form the municipal area like sewage sludge and compost made from refuse. Based on selected examples from the field of production and processing of animals the research on Animal Hygiene in the framework of environmental hygiene is described. This refers especially to emissions and other environmental problems (malodor, dust, airborne microbes) which derive from keeping animals in confinements as well as such which are caused by storage and utilization of animal residues (farm-yard manure, urine, slurry). The most serious problems are caused by production and utilization of slurry (transmission of infectious agents, malodors, damages of soils, plants, surface and ground waters by excess fertilization of arable and forage land). It was Animal Hygiene which made most valuable contributions for solving such problems of environmental hygiene. It was also Animal Hygiene which warned of the possible negative environmental influences of disinfectants. Respective investigations were made and recommendations to avoid damages to the environment given. Also in the field of the agricultural utilization of residues from the municipal area (sewage, sewage sludge, refuse composts) Animal Hygiene has developed basic investigation methods whose results were reflected in several legal regulations for environmental protection.

Agriculture↗
PubMed1985

[The occurrence of Salmonellae in organic fertilizer].

Out of 24 samples of organic and organic-chemical fertilizers which were bought in retail stores ("Bio-Fertilizers") in 25% salmonellas and in 12.5% Clostridium perfringens were isolated. In each of the fertilizers, from which these pathogens were cultivated, products from animal origin were part of the ingredients. In the majority of the cases these were animal fecal residues but also blood meal and horn shavings. The epidemiological importance of these findings is discussed. It is appealed to the legislature to bring the ordinance on fertilizers to bear which demands "rendering to hygienically safe products". It is further necessary to lay down relevant executive orders for the hygienic control of the fertilizers and the supervision of the production plants. This is especially important in the context of the aim to check salmonellosis of man and animals.

Animals↗