Food Poisoning.
by Edwin Oakes Jordan.
CHAPTER I
INTRODUCTION
How frequently food poisoning occurs is not definitely known. Everybody is aware that certain articles of food are now and again held responsible for more or less severe "attacks of indigestion" or other physiological disturbances that have followed their consumption, but in many cases the evidence for a.s.suming a causal connection is of the slightest. That convenient refuge from etiological uncertainty, "ptomain poisoning," is a diagnosis that unquestionably has been made to cover a great variety of diverse conditions, from appendicitis and the pain caused by gallstones to the simple abdominal distention resulting from reckless gorging.
No doubt can be entertained, however, that intestinal and other disorders due to particular articles of food occur much more frequently than they are recorded. There are few persons who have not experienced gastro-intestinal attacks of moderate severity which could be reasonably attributed to something eaten shortly before. It is often possible to specify with a fair degree of certainty the offending food. The great majority of such attacks are of a mild character, are quickly recovered from, and are never heard of beyond the immediate family circle. Only when the attack is more serious than the average or when a large number of persons are affected simultaneously does knowledge of the occurrence become more widely spread. A small proportion of food-poisoning cases receives notice in the public press and a still smaller proportion is reported in the medical journals. Very few indeed are ever completely investigated as to their origin.
Although most attacks of food poisoning are usually of a slight and apparently temporary nature, it does not follow that they are to be considered negligible or of trivial importance from the standpoint of public health. The human organism is always more or less weakened by such attacks, many of them, as we shall see, genuine infections; and, as is known to be the case with many infectious diseases, some permanent injurious impression may be left on the body of the affected individual.
Under certain conditions it is possible that degenerative changes are initiated or accelerated in the kidneys or blood vessels by the acute poisoning which is manifested for a short time in even the milder cases.
In yet greater degree these changes may follow those insidious forms of food poisoning due to the frequent ingestion of small quant.i.ties of mineral or organic poisons, which in each dose may cause little or no measurable physiological change, but whose c.u.mulative effect may be vicious. In view of the grave situation evidenced by the increase in the degenerative diseases affecting early middle life in the United States,[1] the extent, causes, and means of prevention of food poisoning seem pressing subjects for investigation.
THE EXTENT OF FOOD POISONING
Since cases of food poisoning, "ptomain poisoning," and the like are not required by law to be reported, public health authorities in general possess no information respecting their occurrence. Very indirect and imperfect indications of the prevalence of certain kinds of food poisoning are afforded by casual press reports. Such as they are, these accounts are the only available material. Tables I and II summarize data I have gathered through a press-clipping bureau and other sources during the period October, 1913, to October, 1915. They serve to show at least the universality and complexity of the problem.
The 375 group and family outbreaks together involved 5,238 persons.
While it is not probable that all the instances reported as due to food poisoning can properly be so considered, there is no doubt that the number recorded in the tables falls far short of the actual occurrences.
In the past few years the writer has investigated several large food-poisoning outbreaks which have never been reported in the press nor received public notice in any way. There is reason to think that the majority of cases escape notice. Probably several thousand outbreaks of food poisoning in families and larger groups, affecting at least 15,000-20,000 persons, occur in the United States in the course of a year.
The a.s.signment of causes indicated in Table I is of limited value. The tendency to incriminate canned food is here manifest. Proper investigation of the origin of an outbreak is so rarely carried out that the articles of food ordinarily accused are selected rather as the result of popular prejudice and tradition than of any careful inquiry.
TABLE I
FOOD POISONING IN THE UNITED STATES, OCTOBER, 1913, TO OCTOBER, 1915
================================================================= a.s.signed cause | Group | | |and Family|Individual| | Outbreaks| Cases | Total -----------------------------------+----------+----------+------- Meat | 40 | 35 | 75 Canned fish | 29 | 35 | 64 Canned vegetables | 27 | 34 | 61 Ice cream | 31 | 22 | 53 Fish, oysters | 17 | 31 | 48 Cheese | 31 | 9 | 40 Sausage and canned meat | 18 | 18 | 36 Milk | 14 | 13 | 27 Mushrooms | 12 | 7 | 19 Fruit | 8 | 11 | 19 Vegetables | 11 | 7 | 18 Fowl | 12 | 4 | 16 Salad | 9 | 5 | 14 Contact of food or drink with metal| 12 | 1 | 13 Miscellaneous | 29 | 55 | 84 -----------------------------------+----------+----------+------- | 300 | 287 | 587 No cause a.s.signed | 357 | 88 | 445 -----------------------------------+----------+----------+------- | 657 | 375 | 1,032 -----------------------------------------------------------------
TABLE II
SEASONAL DISTRIBUTION OF FOOD POISONING CASES, 1914-15 (GROUP, FAMILY, AND INDIVIDUAL)
========================================== January | 90 ||May | 63 ||September| 76 February| 66 ||June |108 ||October | 96 March | 75 ||July | 99 ||November | 96 April | 79 ||August| 96 ||December | 88 ------------------------------------------
There is no very striking seasonal incidence apparent in the figures here gathered (Table II). The warmer months seem to have a slight preponderance of cases, but general conclusions from such data are hardly warranted.
VARIOUS KINDS OF FOOD POISONING
Cases of poisoning by articles of food may be distinguished as: (1) those caused by some injurious const.i.tuent in the food itself, and (2) those caused by a peculiar condition of the individual consuming the food, by virtue of which essentially wholesome food substances are capable of producing physiological disturbance in certain individuals.
The latter group includes persons, apparently normal in other respects, who are more or less injuriously affected by some particular article of diet, such as eggs or milk, which is eaten with impunity by all normal individuals. This is the so-called food sensitization or food allergy.
Food poisoning, as more commonly understood, is due to the composition, contents, or contamination of the food itself. It is not within the scope of this book to consider any of those cases in which definite poisonous substances are added to food with criminal intent. The term food poisoning is here taken to include the occasional cases of poisoning from organic poisons present in normal animal or plant tissues, the more or less injurious consequences following the consumption of food into which formed mineral or organic poisons have been introduced by accident or with intent to improve appearances or keeping quality, the cases of infection due to the swallowing of bacteria and other parasites which infest or contaminate certain foods, and the poisoning due to deleterious substances produced in food by the growth of bacteria, molds, and similar organisms. As already pointed out, little is known about the relative frequency of occurrence of these different causes or the extent to which they are separately and collectively operative.
THE ARTICLES OF FOOD MOST COMMONLY CONNECTED WITH FOOD POISONING
In addition to the definitely poisonous plants or animals, certain everyday articles of food have been frequently a.s.sociated with the more serious outbreaks of food poisoning. Meat in particular has been implicated so often that the term meat poisoning is used about as commonly as the term food poisoning in general discussions of this subject. Certain it is that the great majority of the best-studied and most severe outbreaks of food poisoning have been attributed on good grounds to the use of meat or meat products. Other animal foods, and especially milk and its derivatives, cheese and ice-cream, have likewise been held responsible for extensive and notable outbreaks.
Perhaps the most significant feature of food poisoning attacks is the frequency with which they have been traced to the use of raw or imperfectly cooked food. The probable interpretation of this fact will be discussed in the later chapters. Especially have the use of uncooked milk, either by itself or mixed with other food substances, and the eating of raw sausage brought in their train symptoms of poisoning in a disproportionately large number of cases.
Canned goods of various sorts have likewise been repeatedly accused of causing injurious effects, but the evidence adduced is not always convincing. The actual degree of danger from this source is far from being determined. The National Canners a.s.sociation publishes in the annual report of the secretary a brief list of "libels on the industry"
or instances in which canned foods of various sorts were regarded as the cause of illness. The 1916 report contains fifty-one cases of this character, none of which was considered by the investigator of the a.s.sociation to be based on sound evidence. A still more searching investigation of all such cases would seem to be desirable, not with a view to incriminating or exculpating any particular product, but simply for the purpose of ascertaining and placing on record all the facts.
FOOTNOTES:
[1] Tables A and B show that the "expectation of life" for adults of forty years and over is shorter in New York City now than it was thirty years ago (Table A), and that this increase in the death-rate in the higher-age groups is manifested in recent years in a wide area in this country (Table B). This increased mortality is due chiefly to diseases of the heart, arteries, and kidneys, and to cancer.
TABLE A[1a]
APPROXIMATE LIFE TABLE, TRIENNA 1879-81 AND 1909-11, BASED ON NEW YORK CITY STATISTICS
================================================== |Expectation|Expectation| Gain (+) or | of Life, | of Life, |Loss (-) in Years Ages | 1879-81 | 1909-11 | of Expectancy --------+-----------+-----------+----------------- Under 5 | 41.3 | 51.9 | +10.6 5 | 46.3 | 51.1 | + 4.8 10 | 43.8 | 46.9 | + 3.1 15 | 39.7 | 42.5 | + 2.8 20 | 35.8 | 38.3 | + 2.5 25 | 32.6 | 34.3 | + 1.7 30 | 29.6 | 30.5 | + 0.9 35 | 26.7 | 26.9 | + 0.2 40 | 23.0 | 23.4 | - 0.5 45 | 21.1 | 20.0 | - 1.1 50 | 18.3 | 16.8 | - 1.5 55 | 15.4 | 13.9 | - 1.5 60 | 13.0 | 11.3 | - 1.7 65 | 10.5 | 9.1 | - 1.4 70 | 8.9 | 7.2 | - 1.7 75 | 7.3 | 5.5 | - 1.8 80 | 6.4 | 4.3 | - 2.1 85 | 5.5 | 2.2 | - 3.3 Balance | | | +26.6 | | | -16.6 | | |----------------- | | | +10.0 --------------------------------------------------
TABLE B[1b]
COMPARISON OF MORTALITY OF MALES AND FEMALES, BY AGE GROUPS. DEATH-RATES PER 1,000 POPULATION (REGISTRATION STATES AS CONSt.i.tUTED IN 1900)
============================================================ Ages | Males |Percentage | Females |Percentage |-----------|Increase or|-----------|Increase or | 1900| 1911| Decrease | 1900| 1911| Decrease ------------+-----+-----+-----------+----------------------- Under 5 | 54.2| 39.8| -26.27 | 45.8| 33.3| -27.29 5-9 | 4.7| 3.4| -27.66 | 4.6| 3.1| -32.61 10-14 | 2.9| 2.4| -17.24 | 3.1| 2.1| -32.26 15-19 | 4.9| 3.7| -24.49 | 4.8| 3.3| -31.25 20-24 | 7.0| 5.3| -24.29 | 6.7| 4.7| -29.85 25-34 | 8.3| 6.7| -19.28 | 8.2| 6.0| -26.83 35-44 | 10.8| 10.4| -3.70 | 9.8| 8.3| -15.31 45-54 | 15.8| 16.1| +1.90 | 14.2| 12.9| -9.15 55-64 | 28.9| 30.9| +6.92 | 25.8| 26.8| +0.78 65-74 | 59.6| 61.6| +3.36 | 53.8| 55.1| +2.42 75 and over|146.1|147.4| +0.89 |139.5|139.2| +0.22 All ages | 17.6| 15.8| -10.23 | 16.5| 14.0| -15.15 ------------------------------------------------------------
[1a] _Monthly Bull., Dept. of Health, City of New York_, III (1913), 113.
[1b] Dublin, _Amer. Jour. Public Health_, III (1915), 1262.
CHAPTER II
SENSITIZATION TO PROTEIN FOODS
The first introduction under the skin of a guinea-pig of a minute quant.i.ty of egg-white or other apparently harmless protein substance is itself without visible injurious effect, but if this is followed by a second injection of the same substance after an interval of about ten days, the animal will die in a few minutes with symptoms of violent poisoning. Whatever be the physiological explanation of the remarkable change that thus results from the incorporation of foreign protein into the body, there can be no doubt that the phenomenon known as protein sensitization or anaphylaxis is relatively common.[2] Sensitization to proteins came to light in the first instance through the study of therapeutic sera, and has been found to have unexpectedly wide bearings.
It is now known that not only the rash and other symptoms which sometimes follow the administration of horse serum containing diphtheria ant.i.toxin, but the reaction to tuberculin and similar accompaniments of bacterial infection, are probably to be explained on the principle of anaphylactic change. The sensitiveness of certain individuals to the pollen of particular plants (hay fever) is also regarded as a typical instance of anaphylaxis, accompanied as it is by asthma and other characteristic manifestations of the anaphylactic condition.
Among the reactions usually cla.s.sed as anaphylactic are the occasional cases of sensitivity to particular food substances. It is a familiar fact that certain foods that can be eaten with impunity by most persons prove more or less acutely poisonous for others. Strawberries and some other fruits and some kinds of sh.e.l.lfish are among the articles of food more commonly implicated. Unpleasant reactions to the use of eggs and of cow"s milk are also noted. The severity of the attacks may vary from a slight rash to violent gastro-intestinal, circulatory, and nervous disturbances.
Coues[3] has described a rather typical case in a child twenty-one months old and apparently healthy except for some eczema. When the child was slightly over a year old egg-white was given to it, and nausea and vomiting immediately followed. About eight months later another feeding with egg-white was followed by sneezing and all the symptoms of an acute coryza. Extensive urticaria covering most of the body also appeared, and the eyelids became edematous. The temperature remained normal and there was no marked prostration. The symptoms of such attacks vary considerably in different individuals, but usually include p.r.o.nounced urticaria along with nausea, vomiting, and diarrhea. The rapidity with which the symptoms appear after eating is highly characteristic.
Schloss[4] has reported a case of an eight-year-old boy who evinced marked sensitiveness to eggs, almonds, and oatmeal. Experiments in this instance showed that a reaction was produced only by the proteins of these several foods, and that extracts and preparations free from protein were entirely inert. It was further found that by injection of the patient"s blood serum guinea-pigs could be pa.s.sively sensitized against the substances in question, thus showing the condition to be one of real anaphylaxis.
Idiosyncrasy to cow"s milk which is observed sometimes in infants is an anaphylactic phenomenon.[5] The subst.i.tution of goat"s milk for cow"s milk has been followed by favorable results in such cases.