DISEASES DUE TO FOOD.
Diseases may arise from the noxious character or from deficiency or
excess of some particular food, or of the food as a whole.
DISEASES FROM UNWHOLESOME FOOD.—I. =The Meat of Diseased Animals.=
(1) _The flesh of animals which have not been slaughtered_ should be
prohibited from sale, whether death has resulted from accident or
disease. The meat from diseased animals is also generally dangerous,
sometimes owing to the _drugs_ with which the animals have been dosed
before death, _e.g._ tartar emetic, or opium.
(2) Meat may be unwholesome from _the presence of parasites_. Of these
the most common is—
(_a_) The =cysticercus cellulosæ=, which is the undeveloped embryo of
the tape-worm; that from the pig becomes the tænia mediocanellata. The
cysticercus of the pig is the most common; it forms a cyst about the
size of a hemp-seed, commonest on the under surface of the tongue. In
hams oval holes are found or opaque white specks, which are the remains
of the cysts converted into calcareous matter. When meat containing
the cysticercus alive (as in under-cooked or raw meat) is swallowed,
it develops into the tape-worm, which consists of a number of flat
segments, each capable of producing numerous ova of new cysticerci,
with a minute head at the narrow end surrounded by hooklets. A
temperature of 174° F. kills the cysticercus. Another kind of tape-worm
common on the continent, called _bothriocephalus latus_, is derived
from the cysticercus of fish.
[Illustration: FIG. 2.
CYSTICERCUS (“MEASLES”) IN PORK.
(NATURAL SIZE.)]
(_b_) The =trichina spiralis= is not a solid worm like the tænia, but
possesses an intestine. In pork it forms a minute white speck, just
visible to the naked eye, which forms a nest, and in this one or two
coiled up worms can be seen by a magnifying glass in active movement.
They are effectually killed by the temperature of boiling water; but
no form of drying, salting, or even smoking at a low temperature is
sufficient for this purpose. Boiling or roasting does not suffice to
destroy all the trichinæ unless the joint is completely cooked in its
interior. When trichinous pork is swallowed, the eggs develop in the
alimentary canal in about a week into complete worms, and in three or
four days more each female produces over a hundred young ones. These
burrow into every part of the body, producing great irritation and
inflammation. In one case after death upwards of 50,000 worms were
estimated to exist in a square inch of muscle. Most of the cases of
trichinosis have occurred in Germany, from eating imperfectly cooked
sausages. The pig becomes trichinous by eating offal, and man is
infected by eating pork. This disease is rare in England.
[Illustration: FIG. 3.
TRICHINÆ CAPSULATED IN FLESH.
(MAGNIFIED.)]
(3) =Tuberculous Meat=, from animals suffering from tuberculosis, has
been found to cause tuberculosis in small animals experimentally fed
on it. Koch has recently thrown doubt on the communicability of bovine
tuberculosis to man; but this point must be regarded as still unsettled
(see page 312). Sheep are rarely affected by it, but it is very
common in cattle, especially in cows, and it is a serious economical
question whether the meat of all such animals should be condemned.
The ideal would be to condemn all such animals, as tuberculosis is an
infective disease, and the bacillus which causes it (as well as the
toxic products of its activity) may be present in meat which shows no
actual signs of disease, except in the lungs or other internal organs.
In practice, however, the rules laid down by the Royal Commission on
Tuberculosis, in 1898, should be followed for the present. These state
that:—
“The entire carcase and all the organs may be seized (_a_) when
there is miliary tuberculosis of both lungs, (_b_) when tuberculous
lesions are present on the pleura and peritoneum, or (_c_) in the
muscular system, or in the lymphatic glands embedded in or between
the muscles, or (_d_) when tuberculous lesions exist in any part of
an emaciated carcase. The carcase, if otherwise healthy, shall not be
condemned, but every part of it containing tuberculous lesions shall
be seized (_a_) when the lesions are confined to the lungs and the
thoracic lymphatic glands, (_b_) when the lesions are confined to the
liver, (_c_) or to the pharyngeal lymphatic glands, or (_d_) to any
combination of the foregoing, but are collectively small in extent.”
They also add that any degree of tuberculosis in the pig should secure
the condemnation of the entire carcase, owing to the greater tendency
to generalisation of tuberculosis in this animal; and that in foreign
meat, seizure should ensue in every case where the pleura has been
“stripped.” (See also page 312.)
(4) Other =Infective diseases= besides tuberculosis may render
meat wholly or partially unfit for food. Of these pleuro-pneumonia
may not require condemnation of the entire carcase; but in the
following this course should be adopted, cattle-plague, pig typhoid
(pneumo-enteritis), anthrax, and quarter ill, as well as in sheep-pox.
In puerperal fever, actinomycosis, and sheep-rot (liver flukes) each
case must be decided on its merits.
II.—=Decomposed Meat.=—Putrid meat has often produced diarrhœa and
other severe symptoms. Putrid sausages are especially dangerous, and
incipient putridity seems to be more dangerous than advanced.
=Tinned Meats= occasionally produce severe illness, which has been in
several cases fatal. It is important to secure a good brand, and to eat
the meat as early as possible after the tin is opened. Tins in which
any bulging is present, showing the presence of putrefactive gases,
must be rejected; and still more tins which have been pricked and
resoldered in a second place. All tinned meats and fruits are stated by
Hehner to contain compounds of tin in solution. These do not seem to be
perceptibly injurious, unlike lead salts, which are now rarely found.
The general subject of =Meat Poisoning= has had much light thrown on
it during the last few years. Brieger, about 1886, showed that during
the cultivation of bacteria, alkaloidal bodies known as ptomaines
and leucomaines, were formed, which were virulently poisonous. It
was commonly supposed that the poisoning occasionally produced by
eating meat pies, sausages, hams, brawn, and similar food, was due to
these ptomaines. It is now known, however, that there are far more
important =toxines= than the alkaloidal, which result from bacterial
life in meat, etc. (see page 286). These are more closely related to
substances of an albuminous or proteid nature than the ptomaines.
These toxines may be fatal when as small a dose as a fraction of a
milligramme (mgm. = about 1∕64 grain) is given subcutaneously. The
evidence now shows that neither ptomaines nor other toxines (albumoses)
or any other bacterial products besides these, cause the outbreaks of
acute poisoning occasionally traced to food, but that these are due
to bacteria. There is, in other words, actual _infection_, as well as
_poisoning_. The microbe chiefly found as the cause of these outbreaks
is the _Bacillus enteritidis of Gaertner_, and some allied microbes. In
an outbreak at Oldham, 160 pies made on a Thursday, from the veal of a
calf killed on the preceding Tuesday, were baked in several batches,
and of the persons eating these pies fifty-four became ill. That the
contamination was not introduced after cooking was shown by the fact
that several persons were made ill who ate pies still warm from baking.
The facts indicated that one batch was imperfectly cooked, the time
allowed being only twenty minutes, as compared with fifty minutes
allowed in corresponding cooking in domestic life. Experimentally it
has been found that an exposure for one minute to 70° C. kills the
_Bacillus enteritidis of Gaertner_. That this bacillus was the cause of
the outbreak was subsequently shown by the fact that the serum of blood
taken from some of the patients showed characteristic clumping with
a pure culture of this bacillus, just as happens with the blood of a
patient suffering from enteric fever when a cultivation of the microbe
of this fever is mixed with it (see page 301). In this outbreak the
symptoms were usually diarrhœa, vomiting, intense thirst, desquamation
of the skin, and a slow convalescence, lasting from three to six weeks.
(See page 26 for poisoning by _Bacillus enteritidis sporogenes_.)
III.—=Meat injuries from the food eaten before killing.=—Pheasants fed
on laurel, hares on rhododendron chrysanthemum, and other animals fed
on the lotus, wild cucumber, and wild melon of Australia, have caused
dangerous symptoms.
IV.—=Fish=, especially some kinds, occasionally produce nettlerash and
other disorders, especially in warm weather. Leprosy has been ascribed
to the eating of decomposing fish, but it occurs in countries where a
fish diet is impossible.
Shell-fish and crustaceans (as lobster, crab) are very prone to produce
evil results. Shell-fish (mollusca), such as mussels, cockles, and
oysters, are dangerous foods. They are generally grown in estuaries,
to which the sewage of towns has access; and not infrequently cases
of enteric (typhoid) fever, as well as more acute attacks of diarrhœa
and vomiting, have been traced to them. Mussels and cockles are seldom
sufficiently cooked to render them safe; and oysters are eaten raw.
They should never be eaten, unless from personal direct knowledge it is
certain that they have been derived from an estuary in which there was
no possibility of contamination by sewage.
V.—=Milk= has been a common carrier of disease. Cows eating the rhus
toxicodendron get the “trembles,” and their milk produces serious
gastric irritation in young children. The milk of goats fed on wild
herbs or spurgeworts has produced severe disorders.
The milk of animals suffering from foot-and-mouth disease, although
frequently drunk with impunity, occasionally produces inflammation of
the mouth (aphthous ulceration). The milk derived from cows fed on
grass from sewage farms is, _per se_, as wholesome as any other, and
its butter has no more tendency to become putrid than that derived from
any other source.
The great dangers in respect to milk are of its becoming mixed with
contaminated water; or of its absorbing foul odours. The absorptive
power of milk for any vapour in its neighbourhood, is shewn by exposing
it in an atmosphere containing a trace of carbolic acid vapour: the
milk speedily tastes of the acid.
Milk also tends to undergo rapid fermentative changes, especially in
warm weather, or when tainted by traces of putrefying animal matter.
Diarrhœa in children is frequently due to such a condition, or to
the rapid decomposition of milk in an imperfectly cleaned bottle.
Milk should always be boiled in warm weather; and it should never be
stored in ill-ventilated larders, or where there is a possibility of
the access of drain effluvia; nor ought it to be kept in lead or zinc
vessels.
Epidemic diarrhœa has been ascribed by Klein to a microbe called the
_Bacillus enteritidis sporogenes_. This is not killed by heating
the liquid containing it to 80°C. for twelve to fifteen minutes,
as is the typhoid bacillus and other non-spore-forming bacilli. In
an outbreak of diarrhœa among the patients in St. Bartholomew’s
Hospital, London, there was strong evidence that this microbe taken
in rice pudding had caused the mischief. Eighty-four patients and two
nurses were attacked, and the patients who had eaten rice pudding
were almost exclusively attacked. A portion of this pudding after
being kept twenty-four hours was found sour and acid. The _Bac.
enteritidis sporog._ was found in it. Furthermore it was shewn
that the temperature at which the rice puddings were cooked never
exceeded 98°C., whereas the spores of this microbe withstand 100°F. a
considerable time.
Very many epidemics of enteric fever and scarlet fever, and a smaller
number of epidemics of diphtheria have been traced to contaminated
milk. Usually in enteric fever the contamination of the milk was
traced to the use of water “for washing the milk-cans,” derived from
specifically polluted sources, and doubtless the water was the real
source of the disease. In most of the milk outbreaks of scarlet fever,
either there was scarlet fever in the dairy, or persons employed in
the dairy were in attendance on patients suffering from the disease;
but in an outbreak connected with a supply of milk from Hendon, it was
suspected that a certain eruptive disease of the udders of the cow
might have been the cause of scarlet fever in man, without infection
from a previous case of the disease. This point is still _sub judice_.
Tubercular disease of the intestines and mesenteric glands may be
produced by taking milk derived from tuberculous cows. This was proved
in the case of calves (page 311), and there are strong reasons for
thinking that the same is true for infants, though doubt has been
thrown by Koch on the communicability of bovine tuberculosis to the
human being. The only safe plan is to sterilise the milk (page 13).
VII.—=Vegetable Food= (especially greens) is indigestible if stale,
and all mouldy vegetables are dangerous. Over-ripe and rotten fruit is
liable to produce diarrhœa; but the diarrhœa prevalent in summer is due
much less to this than to other decomposing foods, particularly milk.
Poisonous symptoms have been produced by the admixture of _darnel_
(lolium temulentum) with flour.
The eating of _damaged maize_ in Italy is the cause of an endemic skin
disease, called _pellagra_, which commonly proves fatal.
_Ergotism_ is due to the growth on cereals (and most commonly on the
rye) of a poisonous fungus, the _claviceps purpurea_, which produces
a deep purple deposit on the grain. If bread made from such flour is
eaten for prolonged periods, severe symptoms result; in some cases,
a dry rotting of the limbs. There have been several epidemics on the
continent, due chiefly to eating bad rye bread.
=Starvation Diseases.=—_Simple Starvation_ causes death in a period
varying with the previous state of nutrition. Usually death occurs when
the body has lost two-fifths of its weight, whether this be after days,
months, or years (Chossat). A supply of water prolongs the duration
of life, to as much as three times what it would otherwise be. Good
nourishment doubles the power of resisting disease; while deficient
food prepares the way for many diseases. A large share of the decline
in the English death-rate during the last forty years is due to free
trade, and the great cheapening of wholesome food which has resulted
from it.
An ill-balanced is more frequent than a deficient diet. Deficiency of
fat is more serious than deficiency of carbohydrates, and deficiency of
proteid is most serious.
=Scurvy= is caused by the absence of fresh vegetables. The use of the
potato and the orange, as well as of lime juice (the juice of citrus
limetta), has led to its extinction among adults in this country. In
former times, it caused more deaths among seamen than all other causes
put together, including the accidents of war. In infants fed upon
tinned foods, whether condensed milk or patent foods, a form of scurvy
still occurs. Infants fed on new-milk never suffer in this way. If,
therefore, it is necessary to feed an infant on condensed milk for many
consecutive months, potato gruel or raw meat juice or fresh milk must
occasionally be given.
_Rickets_ is chiefly due to improper feeding in childhood. The
substitution of artificial foods (most of them containing starch) for
the natural milk is its chief cause. The lower incisor teeth of an
infant appear between the sixth and seventh months. Starchy food given
before this age is undigested. Such food likewise leads to less fat
and proteid being given, which are essential for growth. Deficiency of
lime salts in the food does not cause it, and giving them in food or
medicine will not cure it. Enrichment of the diet by cream or failing
this by cod liver oil is the best means of preventing and curing it.
Abundant fresh air and warm clothing are also necessary.
_Relapsing fever_ generally follows epidemics of typhus fever, and is
greatly favoured by starvation. Ophthalmia has been chiefly prevalent
in charity schools in which the children are underfed, though its
essential cause is contagion.
=Diseases Connected with Over-Feeding.=—A fire may go out for want of
fuel, or from becoming choked with ashes; and it is the latter state
of things which occurs in =Gout= and allied diseases. Weakness is
commonly complained of, but this is due to excess of food embarrassing
vital action; and abstinence and exercise are required to restore the
balance. Excess of nitrogenous food—especially if combined with the use
of sweet, or strong, or very acid wines, and beer—is particularly prone
to produce gout. In these cases, animal food should only be taken once
a day, and vegetable food should be allowed to preponderate.
=Obesity= is favoured by excess of starchy food and sugar, and by
copious drinking of water or other beverages. The plan of curing
obesity by restricting oneself almost entirely to meat food is
only advisable, however, under certain conditions. =Gall-stones=
are favoured by rich foods and excess of sugar; also by alcoholic
indulgence. =Dyspepsia= is commonly due to loading the stomach at too
frequent intervals; but on the other hand, it not infrequently leads to
the taking of insufficient food, because of the discomfort produced.
The result of this is that a chronic starvation results, with impaired
vital powers. Dyspeptic patients should abstain from pastry and from
tea and coffee, except in small quantities. Alcohol in any form, as a
rule, does harm. Not uncommonly mastication is imperfectly performed,
and a good dentist may cure the indigestion which has resisted all
other treatment.