TUBERCULOSIS.
CONSUMPTION AND OTHER TUBERCULAR DISEASES.
Consumption (also called _phthisis_ or _phthisis pulmonalis_) in
the year 1899 caused a recorded death-rate of 1,336, and tubercular
diseases of other parts of the body a death-rate of 575 per million
of the population. In the same year the chief infectious diseases,
including small-pox, measles, scarlet fever, whooping cough, typhus,
and enteric fever, and diphtheria, were together responsible for a
death-rate of 1,248 per million. In the five years, 1861-65, the mean
death-rate from consumption was 2,527 per million, so that a reduction
of nearly 50 per cent. has apparently occurred. Notwithstanding this
great decline, consumption and other consumptive diseases, which
may together be classed under the name =tuberculosis=, still cause
more deaths than all the acute infectious diseases put together. Its
importance is emphasised by the fact that between the ages of 20 and
45, one-third of all the deaths of males, and between one-third and
one-fourth of all the deaths of females occurring at these ages are due
to consumption of the lungs.
Formerly great stress was laid on the =hereditary character= of
consumption. It would appear, however, that what is inherited is
simply an increased vulnerability of tissues. Judging by the analogy
of other animals it may be said that infants are rarely, if ever, born
tuberculous. Bang examined 6,000 head of cattle with the tuberculin
test (see page 311), and found that in calves under 6 months old only
10·7 per cent. reacted, _i.e._ showed evidence of tuberculosis, between
6 and 12 months old 18·7 per cent., 1 to 2 years 23·2 per cent., and
over this age 31·3 per cent. reacted; from which it may be inferred
that the infection is nearly always received after birth.
The real cause of tuberculosis was shewn by Koch, in 1881, to be
the =tubercle bacillus=. This is a minute bacillus, the length of
which is from a quarter to half the size of a blood corpuscle.
These bacilli, obtained from tuberculous growths in the body, Koch
was able to cultivate on glycerine agar at blood-heat outside the
body. By sub-culturing he obtained pure cultures, and after growing
the bacilli for as long as fifty-four days, he inoculated various
animals, producing tuberculosis in every case, while in similar check
experiments in which all the conditions were the same, barring the
absence of bacilli, no tuberculosis resulted.
The tubercle bacilli are easily distinguished from most other bacilli
by the fact that after being stained by aniline dyes, such as
carbol-fuchsin, the colouration is not removed when the preparation
is soaked in dilute acid. By this means the presence of tubercle
bacilli in the sputum (expectoration) of a phthisical patient is easily
discovered, and a valuable means of early recognition of the disease
secured. This is most important, as in its early stages consumption is
an easily curable disease. Tubercle bacilli are discharged from the
lungs in consumption of the lungs, from the bowels in consumption of
the bowels, and so on. Hence the essential necessity for disinfecting
these discharges. Such discharges while in a moist condition have,
unless they are actually swallowed, little or no capacity for evil.
It is when they become dry that they become dangerous. Thus the
expectoration of a consumptive patient spat on to the floor or
deposited in a pocket handkerchief is, so long as it remains moist,
perfectly innocuous. What is evaporated from the wet surface is simply
steam, harmless as the steam escaping from the domestic tea-kettle.
But when it becomes dry, then comes danger. Dust is formed, which
contains the living tubercle bacilli, and with the mere shaking of
the handkerchief or the disturbance of the dust on the floor these
are inhaled, and often cause consumption. The person thus infected
may be a new patient. Often also it is the consumptive patient who is
thus re-infected. Consumptive patients tend to recover. But if the
patient’s disease is daily recruited by fresh doses of the tubercle
bacilli inhaled with the dust of previous expectoration, fresh centres
of disease are produced, and thus the patient is unwittingly helping to
cause his own death.
The =infectious character= of tuberculosis has been long suspected. In
the 18th century, in Naples, there were enactments insisting on the
isolation of consumptive patients and disinfection of their furniture,
books, etc. We now know, however, that these were counsels of panic,
and that for practical purposes the infection may be regarded as
confined to the sputum. The _expired breath is free from infection_
except during coughing. That the sputum is infectious can be easily
proved by feeding guinea-pigs or the domestic fowl on it. These rapidly
become affected by generalised tuberculosis. The simple character of
the precautions against infection which are required may be gathered
from the following copy of a card which is given to consumptive
patients in Brighton:—
Precautions for Consumptive Persons.
Consumption is, to a limited extent, an infectious disease. It is
spread chiefly by inhaling the expectoration (spit) of patients which
has been allowed to become dry and float about the room as dust.
+_Do not spit except into receptacles, the contents of which are to
be destroyed before they become dry. If this simple precaution is
taken, there is practically no danger of infection._+ The breath of
consumptive persons is free from infection.
The following detailed rules will be found useful, both to the
consumptive and to his friends:—
1.—Expectoration indoors should be received into small paper bags and
afterwards +burnt+.
2.—Expectoration out of doors should be received into a suitable
bottle, to be afterwards washed out with +boiling water+; or into a
small paper handkerchief, which is afterwards +burnt+.
3.—If ordinary handkerchiefs are ever used for expectoration, they
should be +put into boiling water before they have time to become
dry+; or into a solution of a disinfectant, as directed by the doctor.
4.—+Wet+ cleansing of rooms, particularly of bedrooms occupied by sick
persons, should be substituted for “dusting” and sweeping.
5.—+Sunlight+ and +fresh air+ are the greatest enemies of infection.
Every patient should sleep with his bedroom window +open+ top and
bottom, a screen being arranged, if necessary, to prevent direct
draught; and, if possible, occupy a separate bedroom. The patient need
not fear going out of doors in any weather, if warmly clad.
N.B.—The patient +himself+ is the +greatest gainer+ by the above
precautions, as his recovery is retarded and frequently prevented by
renewed infection derived from his own expectoration.
6.—Persons in good health have little reason to fear the infection of
consumption. Over-fatigue, intemperance, bad air, dusty occupations,
and dirty rooms favour consumption.
The most common source of infection is undoubtedly the dried
expectoration. Infection may, however, probably be derived from
infected food, as milk or meat.
The danger from meat is much less than that from milk, because the
former is more generally cooked than the latter, and because the
diseased portions of the former would be at least partially removed
before it was sold. The conditions under which the =meat= derived
from tuberculous cattle should be destroyed are given on page 24. The
abolition of private slaughter-houses, the general establishment of
public abattoirs, and efficient meat inspection would do much towards
aiding in eliminating tuberculous cattle from herds; because it would
no longer be found remunerative to keep tuberculous cows until they
become seriously diseased.
The danger from infected =milk= is probably very great. This has
been repeatedly proved experimentally for bovine tuberculosis by
experimenting on calves and pigs. A cow may suffer from tuberculosis
of its udder, and yet go on freely secreting milk. The milk from such
an udder readily produces tuberculosis in calves or pigs drinking it;
but if another animal be fed during the same period with boiled milk
obtained from the same udder, it remains well.
The presence of tuberculosis in cattle can be determined with almost
complete certainty by the =tuberculin test=. A glycerine extract of
pure cultivations of tubercle bacilli (filtered so as to be free from
bacilli) was found by Koch to contain substances which, when injected
into guinea-pigs suffering from tuberculosis, produced a febrile
reaction, and appeared likely to cure the disease. So far as man and
larger animals are concerned the hope of cure by this means has
not been realised; but _as a means of diagnosis_, _i.e._ detection
of tuberculosis, injection of a small quantity of tuberculin under
the skin, has been found most valuable. If the cow thus injected is
suffering from the slightest tuberculosis, it becomes feverish for
a few days; if it is healthy no “febrile reaction” occurs. By using
this test tuberculous cattle can be detected, they can then be kept
in separate sheds, the former sheds cleansed and disinfected; the
milk of these cattle kept separate from that of the rest of the herd,
and boiled before being drunk, or the infected cattle sent to the
butcher. If the disease is strictly localised the carcases can be
utilised for food, after careful destruction of all diseased portions.
If these means were generally adopted, tuberculosis might gradually
be eliminated from the cattle of the entire country, and a serious
source of loss to farmers, as well as of danger to children drinking
the infected milk, removed. The presence of tubercle bacilli in cow’s
milk is detected by microscopic examination and by injection of small
quantities of the suspected milk into guinea-pigs. The proportion of
infected samples found when examinations of milk supplies have been
made in different towns has varied from 10 to over 50 per cent.
It is probable that tuberculosis is conveyed by cow’s milk only when
the tuberculous disease affects the udder. But inasmuch as the udder
of a tuberculous animal may become tuberculous very rapidly and
without being detected for a considerable time, it is evident that
_no tuberculous animal of any kind should be allowed to remain in any
cowshed where milch cows are kept_.
Recently (July, 1901) Koch has thrown doubt on the identity of bovine
and human tuberculosis, which was previously accepted, because (unlike
some other observers) he has been unable to produce in 19 cattle,
on which he experimented, tuberculosis by mixing with their food
expectoration of consumptive persons, or inoculating under their skins
similar material. Even if these negative results should subsequently
be confirmed, the converse proposition does not follow, that bovine
tuberculosis cannot be communicated to man; and apart from this
possibility milk containing the bacilli of bovine tuberculosis cannot
be regarded as wholesome.
The boiling of milk destroys tubercle bacilli. So does a temperature
considerably below 212° F. In Denmark, where butter and cheese are
manufactured on a large scale, and the raw milk is collected in central
dairies, a law was passed in 1898, obliging every proprietor of a dairy
to heat all skimmed milk, or butter milk, to a temperature of 85° C.
(185° F.) before returning it to the farms. _Pasteurization_, _i.e._
the heating of milk in a special apparatus to a temperature of 70° C.
(158° F.), and keeping it at this temperature for 30 minutes kills
tubercle bacilli. If it is rapidly cooled, the nutritive value and
taste of the milk are not spoilt. It is safer, however, to go beyond
this point, and the use of an apparatus like the Aylmer or Sentinel
Sterilizer can be recommended. More recent experiments have made it
doubtful whether tubercle bacilli in milk are always killed in milk at
a temperature of 70° C., the pellicle formed on milk when it is heated
appearing to shield the bacilli from the effect of the heat. Hence it
is desirable that “no sterilizer should be looked upon as thoroughly
efficient for the purpose in which a temperature of at least 85° C.
(185° F.) is not attained.”
The following test may be used to determine whether milk has been
efficiently pasteurized:—
Natural milk contains a ferment or enzyme, which is destroyed at a
temperature of 176° F. This enzyme splits up hydrogen peroxide (H₂O₂)
into water and oxygen, but this effect is not produced in milk heated
above 176° F. Take one drop of a dilute aqueous solution of hydrogen
peroxide, add it to one teaspoonful of the milk. Next add two drops
of a watery solution of paraphenyldiamine. A dark indigo colour is
produced with uncooked milk, no change of colour if the milk has been
pasteurized. The same test can be used for determining whether butter
has been made with pasteurized milk.
Infection is not the sole determining cause of tuberculosis. Certain
conditions of environment may determine whether the infection will
succeed in “taking root” or not. Of these the following are important:
The _nutrition of the individual_ if defective favours infection.
Probably one chief reason why consumption has declined nearly 50 per
cent. in the last 50 years is the better, more varied and more abundant
food of the population.
_Improved housing of the population_ has greatly helped in the same
direction. Tubercular diseases increase with density of population,
and are most prevalent in overcrowded tenements. Probably overcrowding
chiefly acts by favouring direct infection, but it must also lower the
health and power of resistance of the individual against infection.
The _drying of the subsoil_ has been regarded as a chief cause of the
reduction of consumption (page 226). It is probable, however, that the
wet soil merely predisposed to consumption, because it was commonly
associated with cold and wet houses, which would favour catarrhs, and
open the way for the infection of consumption.
The _dryness of the house_ is a most important matter. If a damp soil
means also a damp house it must favour consumption and other chest
affections. Damp air, like water, rapidly abstracts heat from the body.
Compare, for instance, the discomfort of sitting clad in water at a
temperature of 65° F. with the comfort of sitting clad in a dry room at
the same temperature! The domestic fowl is naturally immune to anthrax;
but by being kept for a few hours with its feet in cold water, it can
be rendered susceptible to inoculation with this disease.
The _effects of breathing foul air_ are clearly shewn by the varying
death-rate from phthisis in different occupations. Thus, if the
comparative mortality figures of agriculturists be represented as 100,
that of a commercial clerk = 176, of a draper = 200, of a tailor = 211,
of a printer = 244, of a bookbinder = 246.
The _effects of breathing dust-laden air_ are even more marked. Thus,
if the comparative mortality figures from phthisis of agriculturists =
100, that of a coal-miner = 166, of a mason = 215, of a chimney-sweep
= 249, of a file-maker = 373, of a cutler = 407, of a potter = 453.
The last figure probably also shows the influence of alcoholism, which
greatly favours tuberculosis.
=Means for Preventing Tuberculosis.=—The means for preventing
tuberculosis from infected milk and meat have been already indicated.
They comprise—
(_a_) Means of eradicating tuberculosis from cattle;
(_b_) Means of preventing harm from tubercle bacilli in milk or meat;
Under the first head improved conditions of housing of cattle, greater
air-space, improved ventilation, a larger proportion of out-door life
are important. The use of the tuberculin test, the separation of
healthy from diseased cattle; the disinfection of sheds occupied by
infected cattle are also essential.
Under the second head come efficient sterilization of suspected food
(see p. 13), and the rejection of diseased meat. (See p. 24).
The most important measure against tuberculosis is the prevention of
infection from patients with consumption. Under this head are comprised
the following steps:—
A. _Means of ascertaining the existence of the disease_—
1. Bacteriological diagnosis.
2. Notification of cases, voluntary or compulsory.
B. _Direct preventive measures_—
1. Law against expectoration in places of public resort.
2. Disinfection and cleanliness.
3. Isolation.
4. General sanitary improvement.
C. _Education of the public and of patients as to the importance of
the preceding measures._
_The gratuitous examination of suspected sputum_ is now being
undertaken in certain towns. The earlier the infectious condition of
expectoration is detected, the sooner can the necessary precautions be
taken.
The _notification_ to the medical officer of health of all cases of
consumption I have repeatedly advocated. This is already carried out
for the chief acute infectious diseases, and although the difficulties
of acting on the information received in regard to a chronic disease
like consumption are considerable, they can be overcome with tact and
discretion. Voluntary notification is already practised in Brighton,
Manchester, and a few other towns. Notification gives increased
and more exact opportunities of preventing phthisis by—1. Enabling
disinfection and cleansing of affected rooms to be effected; 2.
Enabling instructions to be given to the patient and his relatives as
to the exact precautions required; and by 3. Facilitating the removal
of the insanitary conditions of home and work which may have caused the
case or favoured its untoward progress.
The following scheme of measures of disinfection was prepared by Drs.
Niven and Newman and myself for the National Association for the
Prevention of Consumption, and is issued by them in pamphlet form:—
In preventing a consumptive person from spreading the disease,
two sets of preventive measures are required:—1st, The removal
or destruction of the infective matter already disseminated by
the patient’s discharges, especially by his phlegm; and, 2nd, the
prevention of future dissemination. For the latter purpose the main
object is not to permit any discharge to become dry before being
destroyed. Before the consumptive person has learned the personal
precautions which must be taken, and up to the time when he has been
trained to carry them out carefully, he has probably distributed a
considerable amount of infective matter. This is especially liable
to accumulate in a dangerous form at home, where the space is small,
and light and ventilation are defective. Infective particles will be
found in greater abundance on and near the floors, on ledges, and in
room-hangings. But the personal clothing and bedclothes will also have
become infected. Hence it is necessary to disinfect the floor, walls,
and ceiling of the rooms occupied by the patient, as well as the
furniture, carpet, bedclothes, &c.
When this has been done, if the personal precautions advised are
carried out by the consumptive, further disinfection should not be
needed.
It is, however, difficult to make sure that personal precautions are
fully carried out, and rooms should therefore be subsequently cleaned
at least once in six months, the floors being scrubbed with soft soap,
the furniture washed, the walls cleaned down with dough, and the
ceiling whitewashed.
Confined workshops in which a consumptive has worked for some time
should be cleansed, and a notice in reference to spitting should be
suspended in all workshops. The latter precaution should also be
observed in all public-houses and common lodging houses, both of which
require special attention to cleansing.
Disinfection of rooms which have been occupied by consumptive patients
may be secured in various ways, but the following are the practical
rules which must underlie any methods adopted:—
1. Gaseous Disinfection of Rooms, or “Fumigation,” as it is termed, by
whatever method it is practised, is inefficient in such cases.
2. In order to remove and destroy the dried infective discharges, the
Disinfectant must be applied _directly to the infected surfaces_ of
the room.
3. The Disinfectant may be applied by washing, brushing, or spraying.
4. Amongst other chemical solutions used for this purpose a solution
of Chloride of Lime (1 to 2 per cent.) has proved satisfactory and
efficient.
5. In view of the well-established fact that it is the dust from dried
discharges which is chiefly infective, emphasis must be laid upon the
importance of thorough and wet cleansing of infected rooms.
6. Bedding, carpets, curtains, wearing apparel, and all similar
articles belonging to or used by the patient, which cannot be
thoroughly washed, should be disinfected in an efficient steam
disinfector.
7. After all necessary measures of Disinfection have been carried out,
the essential principle governing the subsequent control of a case
of consumption is that all discharges, of whatever kind (especially
expectoration from the lungs), should under no circumstances be
allowed to become dry. #/
Besides measures of disinfection and cleanliness, the patient must be
placed under the best conditions for overcoming the disease. The same
measures tend to prevent infection. Thus abundant food, an open-air
life, sleeping with bedroom windows widely open, avoidance of dust,
abundance of sunshine, are all important. The importance of _sunlight_
in the prevention of consumption can scarcely be exaggerated. Koch
found that tubercle bacilli were killed in from a few minutes to some
hours, according to the thickness of the layer in which they were
exposed to the sunlight. He found that even ordinary daylight produced
the same effect, if it lasted long enough; cultures of tubercle bacilli
dying in from five to seven days if exposed at the window in compact
masses. These experimental facts emphasise the importance of abundant
open space about dwelling-houses (see p. 203), the provision of a large
window-area (see pages 202 and 216), of staircase ventilation, and
lighting, &c.
=Scrofula= means a tubercular affection of the lymphatic glands. It
occurs most commonly in the neck. The infection is usually received
from some neighbouring mucous surface, as from the throat, being
derived from dried expectoration or diseased milk. The same indications
as for the prevention of phthisis hold good for scrofula.