Food Infections

FOOD INFECTIONS, POISONINGS, diseases in which, as a rule, food is the main method of transmission of the infection or poisoning principle to man, or at least gives the disease a special character associated with the transmission of the disease-causing agent specifically through food. Therefore, the concept of "food infection" does not apply to cholera, typhoid fever, dysentery, and other similar diseases, where food plays far from a primary role, and sometimes even a secondary one, as a transmitter of contagion. On the contrary, one can speak of anthrax of food origin, since its intestinal forms are exclusively of food origin (see Anthrax). If the clinical picture of the resulting disease is dominated by phenomena characterizing the infectious process (incubation, temperature, corresponding changes in organs, reproduction and excretion of pathogens), then such a food-borne disease is termed a "food infection." Conversely, in cases where phenomena of body intoxication come to the foreground (sudden onset, stormy course, absence of a specific pathogen, phenomena from the central nervous system, etc.), the disease is classified in the category of "food poisonings." It is not always possible to draw such a strict boundary, since sometimes a human food infection depends not only on the reproduction of a pathogenic microbe in his body, but also on the absorption from food of the toxins contained therein produced by the given microbe. One must therefore reckon with the presence of a special group of toxin-infectious diseases, which is transitional between food infections and food poisonings. Practically, these specified groups of diseases are narrowed down even further, since it is only possible to register those cases where the severity of the disease or a large number of victims draws attention. Thus, it must be recognized that isolated and mild cases of food infections and poisonings often escape the attention of both the patients themselves and statistical institutions. The question of the nature of acute diseases caused by food was not resolved with sufficient clarity immediately. Thus, in the pre-bacteriological period, the opinion of Hübener predominated for a time, who believed that meat poisonings, for example, arise due to hydrocyanic acid, which is formed in meat under some unexplained conditions. Jean-Jacques Rousseau considered copper, passing from utensils into the food product, to be the cause of food poisonings. These one-sided views were refuted by all data of everyday observations and therefore did not last long. The experiments of Albrecht von Haller, Panum, Bergman, and Schmiedeberg, who studied the toxic properties and nature of chemical bodies formed during meat putrefaction, acquired great significance. Selmi first introduced the term ptomaines (see) for these substances, which possessed alkaloid properties and chemically were bases. This theory gained special popularity as a result of the works of Nencki, Brieger, and other authors who chemically studied many poisonous ptomaines isolated from putrefying products. In addition, a whole series of scientists led by Gautier established that the cells of animal organisms themselves (independently of the microbe) produce various chemical substances, many of which are bases, possess alkaloid properties, and are unusually poisonous to animals. These bodies were named leukomaines at Gautier's suggestion. Recently, however, this ptomaine theory has begun to arouse great doubts, since, contrary to the opinion of the indicated authors, facts were constantly observed testifying to the frequent harmlessness of putrefying products, and, on the other hand, it became definitely clear that sometimes food, completely flawless in appearance and taste, was the cause of fatal diseases. In the further development of the question of the essence of food poisonings (infections), a major role was played by Bollinger, who spoke at the Union of Public Hygiene in Düsseldorf in 1876 and in Munich in 1880 with a report on the connection between pyemic and septicemic diseases of domestic animals, on the one hand, and mass diseases observed after the consumption by people of the meat of such animals, on the other. He based his opinion on observations of 17 epidemics of meat poisoning with 2,400 cases of individual diseases and 35 deaths. Thus, this author first drew attention to the importance of the antemortem condition of the animal. Although Bollinger himself understood the problem he touched upon somewhat narrowly, nevertheless his view contained a large share of truth and served as the basis for the further development of this issue. After Bollinger, other authors also tried to connect food poisonings with some disease-producing pathogen located in the meat, but this doctrine was quite firmly established since the discovery by Gaertner of a microorganism isolated by him during an outbreak of meat poisoning in Frankenhausen in 1880 in a case of fatal human poisoning from meat. This microorganism was isolated both from the human organism and from the organs of the animal from which the meat originated, and was named Bacillus enteritidis. Soon, namely in 1895, in Belgium, van Ermengem, while studying an outbreak of food poisoning in Ellezelles, managed to isolate from the spleen and stomach contents of the deceased a special anaerobic microbe named by him Bacillus botulinus. These discoveries shed new light on the question of food poisonings and showed that bacteria entering a food product and developing in it under the most diverse conditions can be the cause of the disease-producing properties of food. It cannot be said that even at the present time all this is completely clear, but nevertheless the question of food poisonings and infections is now understood in a much more definite way. All related diseases can be represented in the following scheme. I. Food poisonings of chemical nature: 1) poisoning by a food product toxic by its nature, 2) poisoning by a temporarily toxic food product, 3) poisoning due to an admixture of a toxic substance to a food product.—II. Food poisonings of bacterial nature: 1) toxic poisonings—botulism, 2) toxin-infectious diseases: a) diseases caused by proteus (Bacillus proteus), b) diseases caused by the colon bacillus group (Bacterium coli and Bacterium paracoli), c) diseases caused by the paratyphoid microorganisms group (Bacterium paratyph. B. Breslau, Bacterium enteritidis Gaertneri, Bacterium suipestifer).—III. Food infections: a) tuberculosis of food origin, b) septic inflammation of the fauces of milk origin, c) Malta fever, d) anthrax of food origin, etc.—IV. Food poisonings of unknown nature.—V. Food idiosyncrasies.—VI. Psychogenic food diseases. I. Chemical food poisonings are understood to mean the following categories of cases. 1. Poisoning by a food product toxic by its nature: for example, poisoning by a toxic fish that is edible under certain conditions (the marinka fish in Lake Balkhash), unroasted beech nuts containing the harmful substance fagin (chemical nature not yet elucidated), and the like. 2. Poisoning by a food product that has temporarily acquired toxic properties which as a rule are usually absent. This includes cases of poisoning by fish that only temporarily during some interval of their life (most often during spawning) produce toxic substances within themselves, and in these fish usually only individual internal organs are poisonous: roe, blood, liver. Such fish include burbot, haddock, pike, etc., in which the roe can be poisonous; perch, mackerel, etc., in which the liver can be poisonous. To the same category of cases should be attributed poisonings from sprouted potatoes containing a large amount of the toxic glycoside solanine in their skin and sprouts (see Potatoes). 3. Poisonings arising due to the presence of toxic impurities in the food product itself, such as poisoning by bread baked from flour containing a large amount of ergot, darnel, and other toxic plant impurities.—Sometimes a toxic substance gets into food during the process of its processing; in these cases, the poison can pass into the food product either through utensils (lead in canned food contents if the tin can is improperly manufactured, copper from poorly tinned cauldrons, lead from improperly manufactured glaze, zinc when preparing acidic dishes in galvanized utensils) or due to insufficient purity of auxiliary substances used in processing the food product (arsenic together with acetic acid or impure molasses, amyl alcohol together with pear essence, etc.). Poisonings due to the accidental ingress of chemical poison into food (for example, in the control of rodents) can also be attributed here. If chemical food poisoning is sufficiently pronounced, establishing its nature is in most cases possible, although not entirely easy. Less pronounced symptoms often pass unnoticed or under other names.

The element of mass incidence and suddenness of diseases is noted in this category of cases quite frequently (poisoning of children in a children's home with kissel made in galvanized utensils, poisoning with ice cream containing a large amount of improperly prepared pear essence, etc.). A striking example of mass chemical poisoning is the illness in Liverpool in 1901 of 6,000 workers (with 70 deaths) who drank beer containing arsenic due to impurity of the raw product—molasses. The clinical picture and treatment in chemical poisonings are diverse (see Poisoning, Poisons). II. A large group of food poisonings of bacterial nature can be divided at present into several subgroups according to the etiological factor and clinical picture (see above). Microbes figuring in food poisonings and infections are quite widely distributed in nature and are found both in the intestines of animals themselves used for food (microbes of the paratyphoid group in the intestines of cattle) and in the environment contaminating the food product (the botulism microbe in the soil). For not every food product are both paths of contamination equivalent. In meat, for example, one or another pathogenic intestinal inhabitant may appear due to dissemination in the animal's organism during any of its illnesses, even during prolonged agony, and only in much rarer cases can it be passively transferred by man, a piece of contaminated carcass, or other material to a completely healthy food product. Upon contamination of canned vegetables with botulinus spores, conversely, the transfer of infection occurs passively through the soil and the contaminated surface of the vegetables. As can be seen, the number of causative agents capable of causing food poisoning is quite large, and nevertheless, among all cases of food poisoning (of a bacterial nature) there is something in common that makes it possible to isolate them into a special group. Below are some features of the outbreaks of these diseases. It must be said, however, that these features are expressed to varying degrees, and therefore they should be understood to a certain extent conditionally. They are most sharply noticeable in cases of outbreaks caused by highly pathogenic and toxic causative agents (Bact. botulinus, Bact. enteritidis Gärtner), and less sharply in the presence in the food product of less dangerous microorganisms (Bac. proteus, Bact. paracali). In general, outbreaks of food poisoning of a bacterial nature are distinguished in the majority of cases by the following features: 1) suddenness of occurrence, 2) mass incidence of diseases, with the majority of individuals falling ill simultaneously or almost simultaneously, 3) all cases of illness in a single epidemic are linked by a homogeneous food product, and sometimes even by a single sample that caused the poisoning, 4) territorially, the diseases are concentrated in a district, street, enterprise, hostel served by a store or other institution (canteen) that distributed the pathogenic food product, 5) the contact method does not figure as a route of spread of diseases among the population, 6) after the elimination of the object that caused the poisoning, the appearance of new cases abruptly ceases, in accordance with which the curve of the entire food poisoning epidemic has a sharp rise and a sharp fall. Ordinary gastrointestinal epidemics, conversely, spread more or less widely depending on the mode of transmission of the contagion (wide dissemination in water epidemics and more limited in other routes of spread); it is often possible in this case to note a contact origin; finally, epidemic gastrointestinal diseases yield a decaying curve, gradually descending to nothing. The food product that may have been the occasion for the first cases of contagious diseases may subsequently not figure at all. The epidemic may also spread by other routes (see Infection). If we compare bacterial food poisonings among themselves in various countries, we can note some difference between them; thus, in America the main object causing poisoning is vegetables, in Europe—meat, and in the USSR—fish. Such a difference is explained by several reasons. In America, the influence of two factors is combined: a highly developed vegetable canning industry and a high degree of soil contamination by the botulism microbe (about 30% of all examined samples). Spores of B. botulinus, withstanding in some cases the sterilization of cans with vegetable preserves, germinate during further storage of the preserves and form a potent toxin. In Western Europe, the reason for more frequent poisonings due to meat is the fairly widespread custom of consuming meat in a semi-raw state. Finally, in the USSR, fish is most often consumed in the same semi-raw state. Although the scientific classification of food poisonings of a bacterial nature according to the etiological factor is the most well-founded, nevertheless, from a practical point of view, it is important to characterize these food poisonings also by individual products, since each of the products can impart its own features to the resulting outbreak of acute diseases. In this regard, the most interesting and important are meat, fish, and vegetable poisonings. Meat poisonings (see) are best studied in Germany, and on German material a number of interesting details can be revealed. If in describing meat poisonings one has to base oneself on German material, then for characterizing fish poisonings one can rely to a significant extent on Russian material. Since 1885, a total of 60 cases of fish poisoning have been described, which are grouped in the following table: [Table data omitted in translation per historical preservation without structural alteration] From these data it is seen, firstly, that the reason for fish poisonings is such fish as can be eaten in an undercooked form (salted, dried, and smoked samples), and secondly, poisonings arise more often due to the consumption of red fish. The etiology of fish poisonings has become clear since the discovery by Konstantsov in 1913 in white salmon, which served as the cause of two fatal diseases, of a microbe very close to B. botulinus described by van Ermengem. At present, the majority of authors consider that fish poisonings are the result of the formation of toxins in fish due to a microbe either identical to the causative agent of botulinus or very close to it (see Botulinism). The works of Ruchkovsky have elucidated with high probability the reason for the particular frequency of fish poisonings due to the meat of red fish. It turned out that sturgeons are especially resistant to botulinus toxin (surviving up to 250,000 doses lethal to a guinea pig), and the meat of poisoned sturgeons that remained completely healthy is capable of causing death upon introduction of an infusion into the peritoneal cavity of a guinea pig. Lesser fish do not possess such resistance and die from 500 to 15,000 lethal doses. It also turned out that botulinus toxin can be formed both upon contamination of red fish through the mouth (with washed spores), both during its life (not always) and after death, and in the latter case, the toxin in the meat can be discovered by a biological experiment only after 24 hours of storage of the fish together with the contaminated intestine. Hence Ruchkovsky justly puts forward the theory of the emergence of toxicity after the catching of fish due to its prolonged stay in an uneviscerated state. Poisonings by fish belong to the category of the most severe ones and give a very high lethality (up to 67%). The clinical picture completely coincides with what is observed in botulism in general. The third type of poisonings of a bacterial nature having great significance are poisonings due to vegetables, or rather canned vegetables. They are especially widespread in America due to the heavy contamination of American soil by the botulism microbe (type A). Especially often, poisonings by canned vegetables arise upon the consumption of home-canned preserves. Of all cases of food poisoning, according to Knorr, in America vegetable poisonings account for 68%, while in Germany about 4%. Depending on the etiology (the botulism microbe), the lethality observed in poisoning by canned vegetables is very high (up to 60%). Mention should also be made here of cases of food poisoning caused by vegetables consumed in the form of salad, vinaigrette, etc. Potatoes sometimes figure as the contaminated object. Bacteriological investigation has shown that potatoes are in these cases contaminated with proteus.

Savage believes that this kind of potato contamination can occur particularly often when potatoes are stored in a peeled state, since such potatoes serve as an excellent nutrient medium. III. Food infections. As stated above, the concepts of food poisoning and food infections are difficult to delineate. An example of such a situation can be meat poisonings, where following the typical poisoning effect of the toxin, a secondary infection by developed enteric bacilli may sometimes ensue, which, according to Standfuss, can lead to a complication of the process. Nevertheless, one can cite a number of infections that do not cause phenomena of poisoning, and therefore it is conceivable to speak of their delimitation. These should include: food-borne tuberculosis, septic inflammation of the throat caused by milk, Malta fever, food-borne anthrax, and others. Although not all microorganisms causing these food infections are specific only to the food product, the peculiar clinical picture of the disease arising depending on the transmission of the infection through food makes it possible to call these special infections food-borne. IV. Food poisonings of unknown nature. Much less data can be cited in characterizing food poisonings arising from the consumption of cheese, as well as oyster meat. Until now, the exact cause of poisoning for these products has not been clarified. Brieger suggested that cheese acquires its toxicity due to the presence of a large amount of trimethylamine; Vaughan considered the poisonous principle of toxic cheese to be a special substance isolated by him (tyrotoxin), which does not belong to the alkaloids. Even less data are available for judging the nature of poisonings arising from the consumption of oyster meat. A number of authors have suggested that the poisonous properties of oysters should be attributed to various harmful substances adhering to them from the outside or eaten by the mollusks. According to Brieger, mollusks become poisonous as a result of the putrefactive process to which they allegedly succumb even during their lifetime in the hot summer months during the period of their reproduction. Schmidtmann noticed that poisonous mollusks multiply predominantly in the stagnant water of harbors. Completely healthy mollusks, when transplanted into this water, become highly poisonous after some time. Damon believes that this circumstance depends rather on the infection of mollusks with bacteria that have formed toxins poisonous to humans consuming the mollusks as food. V. Food idiosyncrasies. This category includes diseases arising in connection with the hypersensitivity of certain individuals to the normal composition of certain food products (crayfish, wild strawberries, and so on). These diseases at first can sometimes simulate mild food poisonings (see Idiosyncrasy). VI. Psychic food poisonings are cases of the emergence, on the soil of special hypochondria, of a symptom complex characterizing food poisoning after the consumption of completely harmless food. As is known, the pathogenic state of a food product is discovered most often after its toxicity has been proven on humans. The difficulty of preliminary establishment of harmfulness often lies in the absence of any indications for research, as well as in the complexity of the research itself. Therefore, prophylaxis in this field must be shifted not only to the places of sale of the product, but mainly to the places of its procurement. Slaughterhouses, sausage factories, canning factories, salting plants, and fisheries must be under constant and vigilant supervision. The role of slaughterhouses and fisheries, on the sanitary condition of which the release of a fresh, flawless food product depends, should be especially emphasized. Along with the controlling organizations monitoring operations in the indicated institutions, it is necessary to rely on sufficiently knowledgeable sanitary personnel who could in each individual case specifically resolve the issue of necessary measures to eliminate an arisen outbreak, as well as the possibility or impossibility of allowing certain suspected food products into food. Their conclusions should be built by the sanitary physician on the basis of sanitary and laboratory study of the food market, and therefore they must be provided with a sufficiently well-equipped chemical and bacteriological laboratory. Finally, food legislation serves and must increasingly serve to aid the cause of food poisoning prophylaxis, both along the lines of public health authorities and the veterinary administration and other departments (see Food legislation).

The object of attention of food legislation must be not only production itself, not only raw materials, semi-finished products, and the final product, but also the conditions for admission to processing, and consequently to food, of various so-called conditionally marketable and less valuable products. Clarification in this area and revision of old provisions on the basis of the latest scientific data are an immediate and urgent necessity. A huge role in the fight against food poisonings must be played by correctly organized registration of these diseases, which is still insufficiently organized. In 1931, the People's Commissariat of Health of the RSFSR gave corresponding instructions to its organs. When the need arises to investigate a food product regarding food poisoning, it is necessary to keep in mind three lines of investigation of the suspected object, namely: chemical, bacteriological research, and biological testing on animals. Sometimes the product itself, accompanying circumstances (typical poisoning picture), and other circumstances make it possible to simplify the task and deal with two or even one aspect of the study, but in cases where these facilitating circumstances are absent, one has to study the product comprehensively. And yet, even with such a comprehensive study of the object, only positive cases can be probative. A negative result of the study by itself does not resolve the question in the vast majority of cases. Such a situation depends on the great difficulty of correctly selecting a sample for study (the poisonous part may already be absent), as well as on insufficiently perfected research methodology. All cases of death from food infections or food poisonings, as well as those suspicious in this sense, must be the occasion for a forensic medical autopsy to establish the true cause of death, in particular to rule out other poisonings, for example for the purpose of suicide or murder (see Poisoning).