Zentralblatt fur Bakteriologie, Mikrobiologie und Hygiene. 1. Abt. Originale B, Hygiene最新文献

Today we distinguish 4 forms of viral hepatitis: hepatitis A, hepatitis B, hepatitis non-A, non-B and hepatitis occurring in the course of other viral diseases. The viruses of hepatitis A and hepatitis B have been identified but the agent(s) of hepatitis non-A, non-B remain unknown. Inoculation of normal pooled human immunoglobulin provides passive immunity for 2-3 months against hepatitis A but not against hepatitis B or hepatitis non-A, non-B. For passive protection against hepatitis B a special immunoglobulin with a high anti-HBs titer must be used whereas the protection against hepatitis non-A, non-B with immunoglobulin is uncertain. Live attenuated and noninfectious polypeptide vaccines for active immunisation against hepatitis A are currently developed and first clinical trials have begun with the live attenuated vaccine. A vaccine consisting of noninfectious highly purified HBsAg derived from the plasma of HBV carriers is in general use since two years and has proved safe and highly effective and vaccines are now developed from HBsAg obtained through molecular cloning of the HBsAg genome in plasmids and expression of the genome with HBsAg production in yeast cells. First clinical studies with this vaccine are encouraging and these as well as purely synthetic vaccines will in time replace the currently used vaccines. No vaccines could be developed so far against hepatitis non-A, non-B because the agent(s) of this disease are unknown.

Besides acute virus diseases, persistent virus infections have attracted increasing attention during the last few years. In the case of such infections, the infecting virus may remain in the host organism for months or even years, before symptoms appear. These persistent virus infections can be caused by different viruses and may lead to a variety of pathogenic reactions and clinical manifestations. As far as knowledge goes, the mechanisms underlying a virus persistance are equally different. Within the space limitations, an attempt is made to present such mechanisms and to derive from them the pathogenesis of the follow-up diseases.

The wide-spread ubiquitous occurrence of molds and great masses of aerial spores (conidia, arthrospores etc.) as well as of yeast species with facultative pathogenicity, renders prophylaxis of respective human infections caused by such opportunists, rather difficult. Suppression of such fungi and continuous surveillance of endangered patients require considerable efforts and costs. Adequate control is particularly cumbersome in Candida infections, since the causative yeasts may be considered as "normal" commensals of the mucous membranes in many individuals. Overt secondary infections are frequently of endogenous origin, hence the name "endomycoses" as introduced by Gemeinhardt (1976). Under particular conditions such as care for patients with extended burns, or patients after bone-marrow transplantation or irradiation of the whole body, or patients after joint surgery, the complete elimination of yeasts is just as essential as the antibacterial decontamination over a limited period of time. In other groups of individuals similar drastic measures of control against Candida albicans are not deemed necessary. Reduction of local Candida cell counts to amounts below the individual level of tolerance may be deemed sufficient. Since the level of tolerance is, however, extremely low in infants and in many patients of the intensive care wards, especially in cases of malignant immunocytomas and leukemias of various nature, prophylaxis by proper hygienic measures and eventual preventive antimycotic treatment is an integral part of proper control.

The investigation is aimed at analysing from different aspects the complex nature of the barriers against vaccination and with this the prerequisites for the development of adequate motivations among the population. The pilot study is based on the detailed interviewing of 80 persons (30 parents or mothers with infants aged up to 15 months; 30 parents or mothers with children aged from six to ten years; 20 physicians). The group interviewed was additionally broken down into persons favouring vaccination (50%) and others skeptical about or opposed to vaccination (50%). The barriers against vaccination likely to influence the attitude of the population in the Federal Republic of Germany are mentioned below: In the general consciousness of health, health education and preventive medicine the idea of vaccination does not play an important role. Vaccination is not seen as a preventive means against the central risks of life (environmental burden, stress factors, road traffic, semiluxuries). The body is not expected to suffer lasting damage from infectious diseases in childhood; the knowledge of the risks resulting from childhood diseases or infectious diseases is minimal. Childhood ailments and infectious diseases successfully overcome by the sufferer tend to weaken the motivating insight into the necessity of vaccination. The general outbreak of infectious diseases and epidemics in the Federal Republic of Germany is considered rather unlikely. The probability of being attacked by infectious diseases regarded as dangerous is deemed negligible.

Physical preservation procedures are mostly aimed at prolonging the durability of foods by slowing down or repressing the spoilage mechanisms by the alteration of relevant parameters. Of these mechanisms of microbiological, enzymatic, chemical and mechanical type, especially the first-named are dealt with. Growth and multiplication of micro-organisms can be influenced by temperature, water activity and high-energy radiation. Depending on the susceptibility to deterioration of the products and the intensity of the processes based on these parameters, different degrees of durability are obtained. Micro-organisms are killed by the application of high temperatures in conjunction with the treatment times required in a given case. Relatively mild treatments affect only the vegetative forms (pasteurization), whereas more aggressive treatments are required to kill spores as well (sterilization). Recontamination of the products which were subjected to the two procedures must be avoided. Pasteurized foods require additional cold storage to prevent the spores from sprouting. Low temperatures reduce and repress the growth of micro-organisms (refrigeration) or prevent any activity of the micro-organisms (deep-freezing). The latter deprives the micro-organisms of the water they need for their growth. The same principle applies to another method of preservation where so much water is extracted from the product that the residual humidity no longer allows the micro-organisms to be active (drying). Ionising radiation can be used to reduce a potential risk to hygiene, to influence physiological processes, to control insects and to lengthen the durability of fresh food in the short term. Finally optimum product quality can be maintained by combining various procedures. If such methods cope with controlling the microbiological situation, attention must nevertheless be given to the other spoilage mechanisms as well, as they may prove to be limiting factors with respect to product quality.

Preservation of foodstuffs has always been a necessity for a number of reasons: the durability of food is limited, numerous foodstuffs are only available during a short harvesting season, the transport routes of food or raw materials from the production site to the consumers are continuously increasing in length and the consumers in modern society characterized by division of labor and changed shopping habits increasingly insist on buying durable products. Beyond this, there are medical-hygienic efforts aimed at inhibiting the growth of micro-organisms in food. The hazard to health which many bacteria carry, has been long known. Recently, a number of fungi have been shown to form toxins during their growth on foodstuffs. There are two methods of food preservation: the physical and the chemical. The greater proportion of foodstuffs is rendered durable by physical procedures: drying, cooling, deep-freezing and heating. But chemical preservation also plays a prominent role. The use of preservatives is often combined with physical methods. The application of preservatives has a long history, such as the use of common salt, smoke or sulfur dioxide. Some of these agents, such as benzoic acid, are achievements of the last century. Others, such as propionic acid and sorbic acid, result from research during the last few decades. The preservatives now in use have been thoroughly tested for their toxicological properties. Their use in the food industry is subject to stringent legal regulations. The consumer can be certain of not running any risk by partaking foods which contain preservatives.

While making allowance for the changes in defining the term disinfection during the last few decades the present understanding of this term is explained. Moreover the prerequisites to be satisfied for proper disinfection, especially in the light of the new guidelines of the DGHM, are dealt with. This covers both the types of germs to be affected by the methods and the various modes of disinfection. As known routes of transmission obtaining with infectious hospitalism are also included in the discussion, an attempt is made to assign priorities to certain methods of disinfection, depending on the extend to which they are capable of preventing the transmission of microorganisms. The same criteria are applied to the areas outside the hospital (medical and dental practices, residential quarters, kitchen etc.) Finally it is attempted ro provide a forecast of the future importance of disinfection, with special emphasis on chemical disinfection. Known limitations and others to be expected, such as those imposed by the toxicity of the substances used, the resistance to such substances developed by micro-organisms, material incompatibilities, irreconcilable relationships between concentration and time of action and the like, are discussed.

In the developing countries diarrhoea ranks among the most frequent diseases: 5-18 million children are estimated to die annually from gastro-intestinal infections. But also in Europe and the USA diarrhoea is of utmost medical importance, especially among children and infants. It was only twelve years ago that 2 viral groups, the Norwalk and the rotavirus group, were discovered to be etiological agents responsible for a large proportion of gastro-intestinal infections. Whilst viruses of the Norwalk group cause primarily gastro-intestinal infections in schools and families (school-children and adults), rotaviruses attack mainly infants. In our latitudes rotaviruses are important agents responsible for nosocomial infections. A rapid diagnosis is crucial if the chain of infections is to be interrupted. Uncontrolled spread may not only lead to severe disease in infants and young children, but also burdens health insurance - plans considerably. Experiments intended to develop a rotavirus vaccine are under way.

Pest control measures in rooms serving the production, treatment or marketing of foods have to be executed according to the principles laid down in the food hygiene regulations of the Länder of the Federal Republic of Germany. However, a proper pest control following these rules can only be realized if such control is performed by persons experienced and qualified in the field of hygiene. Corresponding knowledge includes diagnostic and accessory equipment, morphology, biology, sensitivity including resistance and vector function of the pest to be controlled, suitable pesticides, formulations according to the type of action, possible residual effect and indoor air exposure, the respective technique of application, decontamination procedures, structure and pH value of the materials used for the application, methods for the determination of the concentrations of the active substances and solvents in indoor air as well as of climatic factors in the resting and hatching area of pests, the shelf-life of foods, their protection against pesticides and their safe removal in the case of contamination.

Hygiene problems that arise in connection to sanitation procedures in civil aviation are described; the relevant international regulation and recommendation are explained. The particular problems that arise in connection to prophylaxis to infections, food hygiene, sanitation, refuse disposal and the maintenance lavoratory facilities are emphasized. Relevant rules and recommendations are quoted.