to find none whatever; on mountains and even hills of humble elevation
the paucity of bacteria is very marked if there are no abnormal or
untoward circumstances contributing to their distribution. In
illustration of this the recent investigations of the air on the
summit of Mont Blanc by M. Jean Binot are of especial interest,
inasmuch as the altitude at which they were carried out is the highest
at which the search after bacteria has so far been pursued. This
intrepid investigator spent no less than five days in the observatory,
which is situated on the top of the mountain. As was to be
anticipated, frequently no bacteria at all were found, and it was only
when such comparatively large volumes of air as one thousand litres
(about 200 gallons) were explored that microbes in numbers varying
from four to eleven were discovered. The air of the country is far
freer from microbial life than that of cities; whilst open spaces,
such as those afforded by the London parks, are paradises of purity
compared with the streets with their attendant bacterial slums.
That it is no exaggeration to describe streets from the bacterial
point of view as slums is to be gathered from the fact that much less
than a thimbleful of that dust which is associated with the blustering
days of March and the scorching pavements of summer may contain from
nine hundred to one hundred and sixty millions of bacteria. But
investigators have not been content to merely quantitatively examine
street dust; in addition to estimating the numerical strength of these
bacterial dust-battalions, the individual characteristics of their
units have been exhaustively studied, and the capacity for work,
beneficent or otherwise, possessed by them has been carefully
recorded. The qualitative discrimination of the bacteria present in
dust has resulted in the discovery of, amongst other disease germs,
the consumption bacillus, the lock-jaw or tetanus bacillus, bacteria
associated with diphtheria, typhoid fever, pulmonary affections, and
various septic processes. Such is the appetising menu which dust
furnishes for our delectation.
There can be no doubt, therefore, that dust forms a very important
distributing agent for micro-organisms, dust particles, aided by the
wind, being to bacteria what the modern motor-car, with its benzine or
electric current, is to the ambitious itinerant of the present day.
Attached to dust, bacteria get transmitted with the greatest facility
from place to place, and hence the significance of their presence in
dust.
Mention has been made of the fact that the germs of typhoid fever have
been discovered in dust, and the belief in the possibility of this
disease being spread by dust is gaining ground.
An interesting case in point is afforded by an outbreak of typhoid
fever which occurred in Athens a few years ago, and in which the
starting-point or nucleus was discovered to be a group of labourers
who were engaged upon excavating the soil in a street through which a
sewer had once been taken. The epidemic subsequently spread to those
districts of the city swept by the prevailing wind, which passed over
the place where the soil had been turned up and exposed. M. Bambas,
who brought his observations before the International Congress of
Hygiene at Buda-Pesth, was convinced from the inquiries he made that
this outbreak of typhoid was due to the disturbance of the soil and
the dissemination by means of the wind of typhoid-dust-particles to
certain parts of the city.
That this hypothesis is by no means without experimental justification
is shown by the properties possessed by the typhoid bacillus in regard
to its vitality in soil which have been discovered. Thus numerous
investigators have studied the important question of the behaviour of
this micro-organism in soil, and have found that it can exist over
periods extending from three to twelve or more months in the ground.
This property of the typhoid bacillus may possibly explain the
appearance over and over again of typhoid fever in particular
localities, suggesting that the bacteria had become indigenous in the
soil.
Dr. Mewius, of Heligoland, describes an epidemic of typhoid fever in
the island, concerning which he made a most searching and elaborate
inquiry. It appears that a case of typhoid occurred and was concealed
from the medical authorities, so that no steps for disinfection could
be taken in the first instance; and, following the primitive custom
which prevails on the island, the dejecta was thrown over and upon the
cliffs, this being the usual method of disposing of sewage. Ample
opportunity was thus given for its desiccation and subsequent
distribution as dust. That this typhoidal matter did subsequently
become pulverised and spread the infection Dr. Mewius has no doubt,
the germs having been conveyed to the open rain-water cisterns which
constitute the water-supply of the majority of the inhabitants. His
theory is again supported by the coincidence between the prevailing
direction of the wind and the quarter where the outbreak occurred.
That diphtheria germs can remain for a long time in a living and, what
is more, virulent condition in dust has been clearly demonstrated by
Germano, amongst other investigators, this organism being specially
endowed with the capacity for resisting the, to other microbes, lethal
effect of getting dried up.
Bacteria, however, survive this desiccation process much better when
they are herded together in large numbers than when they have to face
such untoward conditions as isolated individuals. This has been well
illustrated in the case of diphtheria bacilli, and the difference in
their powers of endurance under these respective conditions is very
striking. Thus when a few only were exposed to a very dry atmosphere
on silken threads they disappeared after eight days; but when somewhat
larger numbers were taken they contrived to exist for eighteen days,
whilst when great multitudes of them were herded together even one
hundred and forty days' starvation in these desert-like surroundings
could not entirely stamp out their vitality.
This dangerous property possessed by the germs of diphtheria should,
if possible, increase the vigilance with which the outbreaks of this
disease are watched and dealt with. Abel cites an instance in which a
wooden toy in the sickroom of a child suffering from diphtheria was
found six months later to have _virulent_ diphtheria bacilli upon it.
This reminds me of a case in which tetanus or lock-jaw ensued from the
use of some old cobwebs in stopping the bleeding of a cut. The wound
was a perfectly clean one, and nothing need have resulted from this
obedience to a superstitious prejudice had not the cobwebs
unfortunately arrested some tetanus germs, and these getting access to
the wound set up the typical symptoms of lock-jaw. That this
implication of the cobweb was no idle accusation was subsequently
proved by portions of the same web, on being inoculated into animals,
inducing in the latter well-defined symptoms of tetanus.
That cobwebs readily catch dust is familiar to everyone who has the
mortification of seeing them adorn ceilings and corners; that they
also arrest bacteria follows as a natural consequence of the presence
of dust, and hence these delicate filaments may become veritable
bacterial storehouses, more especially as it is usually in the dark
and remote corners that they best succeed in eluding the vigilance of
the domestic eye, and are thus also out of reach of the lethal action
of sunbeams; and hence their unwelcome lodgers may manage to maintain
a very comfortable existence over long periods of time.
That the bacillus of consumption should have been very frequently
found in dust by different investigators is hardly surprising when it
is realised that the sputum of phthisical persons may contain the
tubercle germ in large numbers, and that until recently no efforts
have been made in this country to suppress that highly objectionable
and most reprehensible practice of indiscriminate expectoration.
Considering that the certified deaths from phthisis in 1901, in
England and Wales only, reached the enormous total of 42,408, and
bearing in mind the hardy character of the _bacillus tuberculosis_
when present in sputum, it having been found alive in the latter even
when kept in a dry condition after ten months, it is not too much to
demand that vigorous measures should be taken by the legislature to
cope with what is now regarded as one of the most fruitful means of
spreading consumption. We know that in some of the states of America
public opinion has permitted the enactment of laws penalising this
practice. Local rules to the same effect exist in our Australian
colonies. On the Continent the trend of public opinion is evident by
the prohibition found in the railway carriages and the notices to that
effect conspicuously posted in public places. In this country public
opinion moves so slowly that we are not yet ripe for any such strong
step, and so far one of the few attempts at official activity in this
respect is to be found in a circular issued by the Local Government
Board of Ireland to the various local authorities stating that
"tuberculous sputum is the main agent for the conveyance of the virus
of tuberculosis from man to man, and that indiscriminate spitting
should therefore be suppressed." The public exhibition of notices
calling attention to the danger accruing from expectoration in public
resorts is, as already pointed out, one means of educating the people,
and it has been stated that such a notice is posted in every beerhouse
in Manchester. The question has also been raised of the inspection of
beerhouses and the suggestion made that licences should be withdrawn
in the case of those holders who did not wash the floors of their
public rooms and keep them in a sanitary state. At the present time,
in this country, it is perhaps more to the private conscience of the
individual and the pressure of public opinion than to penal enactments
that we must look for effective reform in this direction, for the
objection of the English to official sanitary control is deeply
rooted. It is to be hoped, however, that with the spread and
popularisation of the knowledge acquired through the arduous labours
of so many scientific authorities, it may come to be regarded as a
matter for both public and private morality that every step should be
taken which lies in the power of each member of society to minimise
the opportunities for the spread of a disease which by its very
familiarity we have until the last few years accepted as incurable and
the ravages of which as inevitable.[1]
[1] Since the above was written, the first international
conference of the Central Committee for the Prevention of
Consumption has been held in Berlin. The official report of
the English National Association for the Prevention of
Tuberculosis was presented to the Congress, and the
encouraging announcement was made that the Corporations of
Glasgow, Manchester, and Liverpool had made expectoration in
tramcars a punishable offence; and that the Glamorganshire
County Council had passed a bye-law providing as penalty for
expectoration in public buildings a fine of £5, which
enactment had been sanctioned by the Secretary for the Home
Department.
Now that we are considering the status of street dust in bacterial
circles, it will not perhaps be out of place to inquire into the
character of another waste product of streets, _i.e._ the discarded
ends of cigars and cigarettes. That what is carelessly tossed away on
the one hand may be as carefully collected on the other is well known,
as is also the fact that such material may subsequently be raised
once more to the dignity of a marketable commodity. Under these
circumstances, it is of hygienic interest and importance to ascertain
whether disease germs, should they have obtained access to this
tobacco refuse, are in a virulent or quiescent condition.
Some experiments to decide this question in connection with the
tubercle bacillus have been recently carried out in Padua by Dr.
Peserico, who, whilst extending our knowledge on the subject of
bacteria and tobacco, has also confirmed the earlier results obtained
by Kerez.
Portions of cigar-stumps smoked by phthisical persons in whose saliva
the tubercle bacillus was known to be abundantly present were
inoculated into guinea-pigs, with the result that fifty per cent. of
the animals thus treated succumbed to tuberculosis. Thus neither the
fumes nor juice of the tobacco had destroyed the consumption bacillus.
In these experiments the cigar ends were used directly they were
discarded, in another series of investigations they were collected and
kept in a dry place for from fifteen to twenty days before being
tested; but even storage for this length of time did not prevent the
animals inoculated with them from contracting tuberculosis. In another
series of experiments Dr. Peserico kept the infected cigar-ends in
damp surroundings, and it was satisfactory to find that under these
conditions the tubercle bacillus at the end of ten days was entirely
deprived of its virulence. Encouraged by these results, inoculations
were made with cigar-ends which had been left in the open and exposed
to normal atmospheric conditions, which included falls of rain and
snow, and in this case also no symptoms of tuberculosis followed their
introduction into the guinea-pigs. These experiments show that the
tubercle bacillus is prejudicially affected by contact with tobacco
when the latter is kept in a moist condition, but that in a dry
condition the properties in tobacco inimical to its vitality are not
liberated and the bacillus can retain its virulent properties for a
period of over twenty days.
In view of the importance of this discovery on the destruction of the
toxic character of the tubercle bacillus by contact with moist
tobacco, further experiments were made in which emulsions of tobacco
were infected with tuberculous sputum. It was found that the bacilli
steadily declined in virulence as the length of time they were kept in
the emulsion was prolonged. Thus whereas after a few hours they were
still armed with all their virulent properties, after three days, out
of the four animals inoculated with the emulsion three succumbed to
tuberculosis, after five days two out of four succumbed, whilst after
eight days only one animal out of the four was infected, and after a
period of ten days' immersion in the tobacco emulsion the tubercle
bacillus failed to kill a single animal.
Cigar- and cigarette-ends were collected from the streets and cafés of
Padua by Peserico, but in spite of consumption being stated to be very
prevalent in this city, in no single case could the presence of the
tubercle bacillus be discovered, although, as in the other
investigations, the surest method for its detection, _i.e._ animal
inoculations, was employed.
Brief reference may be made also to the experiments conducted to
ascertain if cigars and cigarettes, as sold, contain the tubercle
bacillus. The more interest attaches to this investigation because it
is well known that the operators employed in tobacco factories are, as
a rule, an unhealthy class, diseases of the respiratory organs, and
especially tuberculosis, being very prevalent amongst them. A German
official report on this subject states that the average duration of
life of such factory hands only reaches thirty-eight years. Doubtless
the lightness of the occupation encourages many to seek employment in
these factories whose state of health would debar them from obtaining
work under more trying circumstances. Some of the conditions under
which cigars and cigarettes are made, such as the workers using their
saliva to facilitate the rolling of them and fixing of the leaves, and
the testing of the "drawing" properties of a cigar by placing it in
the mouth, with the facilities offered for the dissemination of dried
tuberculous sputum as dust, contribute to make it highly probable that
tobacco as it leaves the factory may contain the germs of consumption.
Before leaving the subject of tobacco and disease germs it may be of
interest to inquire what justification in fact there is for the
practice adopted by anxious mothers, when travelling in times of
epidemics of zymotic disease, of thrusting themselves and their
children into the sanctum of the other sex--the smoking compartment of
a railway carriage. I have frequently seen this done, despite the
voluble protests of its legitimate occupants. Tassinari has made some
very interesting experiments on the effect of tobacco smoke on the
vitality of various descriptions of disease germs. He constructed an
apparatus in which he suspended pieces of linen soaked in broth
infected with the particular micro-organism to be tested. Tobacco
smoke was then admitted, and the microbes were retained in this
stifling atmosphere for half an hour. In these surroundings cholera
and typhoid germs were destroyed, and other bacteria, such as the
anthrax bacillus and the pneumonia bacillus, were so prejudicially
affected, that when subsequently transferred to their normal
surroundings it was only with extreme difficulty that they could be
revived. When, however, the tobacco smoke was made to pass through
water before reaching the bacteria, its pernicious influence was
entirely removed, and the latter suffered no detriment. Hence the
practice, so often seen in the East, of passing tobacco smoke through
rose or other perfumed water before inhaling it, whilst doubtless
rendering it less noxious to the smoker, deprives the exhaled tobacco
fumes of all their bactericidal or disinfecting properties.
To return, however, after this somewhat lengthy digression, to the
question of dust and its bacterial properties, we have learnt enough
to enable us to realise that the movement for the migration of the
working-classes from crowded streets to rural districts, in which Mr.
George Cadbury has played so practical and important a part in the
creation of his model village, with its gardens and open spaces, some
five miles from the city of Birmingham, is, if only bacterially
considered, a very real barrier against the dissemination of disease,
for the denser the population, the greater will be the crowd of
bacteria, and the greater the chance of pathogenic varieties being
present amongst them. Again, we know that sunshine is one of the most
potent germicides with which nature has provided us;[2] and it
requires no effort of the imagination to realise how, in the gloomy
back courts and crowded tenements of our great smoke-laden cities,
bacteria succeed in obtaining a firm hold on their surroundings, and,
in the shape of spores, attaining an undesirable and hoary old age, in
which they are in some cases almost indestructible. Fräulein Dr. E.
Concornotti has shown that this is no figment of fancy only, for she
has recently made a special and very elaborate study of the
distribution of pathogenic or disease bacteria in air, searching for
them in the most varied surroundings, such as prisons, schools, casual
wards, etc., with the result that, out of forty-six experiments in
which the character of the bacteria found was tested by inoculation
into animals, thirty-two yielded organisms which were pathogenic. Dr.
Concornotti concludes her valuable memoir by stating that her
investigations proved conclusively that the dirtier or more slumlike
the surroundings, the greater was the frequency with which she found
bacteria associated with disease in the air.
[2] See "Sunshine and Life."
Messrs. Valenti and Terrari-Lelli have quite recently been able fully
to endorse these statements in the results they have obtained in their
systematic study of the bacterial contents of the air in the city of
Modena. In their report they state that the narrower and more crowded
the streets, the greater was the number of bacteria present in the
air, and the more frequently did they meet with varieties associated
with septic disease.
Numerous detailed investigations have also been made of the bacterial
contents of the dust in hospitals. That cases of infection arising
within hospital precincts are of no uncommon occurrence may be
gathered from the observations made by Lutand and Hogg, who report no
fewer than 2,294 such cases having arisen in the space of six years in
certain Paris hospitals, whilst Solowjew records 1,880 cases as
occurring in the space of four and a half months in the St. Petersburg
city hospital. Solowjew made a special study of the bacterial contents
of dust collected in hospitals, and states that 41·8 per cent. of the
samples examined contained disease germs. The degree of infection
possessed by dust in such surroundings must, of course, depend upon
the degree of cleanliness which characterises the management of any
particular institution; and such investigations as the above can only
help to emphasise the immense importance of common cleanliness and the
reasonableness of taking every precaution possible in the disinfection
of utensils, etc.
Some years ago Messrs. Carnelley, Haldane, and Anderson carried out an
elaborate series of investigations on the air of dwelling-houses in
some of the poorest parts of Dundee. The samples were taken during the
night, between 12.30 a.m. and 4.30 a.m., and in their report the
authors state that the one-roomed tenements were mostly those of the
very poor; "sometimes as many as six or even eight persons occupied
the one bed," whilst in other cases there was no bed at all. As
regards the number of bacteria present in the air in these one-roomed
houses, an average of several examinations amounted to sixty per
quart; in two-roomed houses it was reduced to forty-six, and in houses
of four rooms and upwards only nine micro-organisms in the same volume
of air were discovered.
On comparing the mortality statistics with the composition of the air
of dwelling-houses of different dimensions, the authors arrive at the
following conclusions: "That, as we pass from four-roomed to three-,
two-, and one-roomed houses, not only does the air become more and
more impure, as indicated by the increase in the carbonic acid and
organic matter, and more especially of the micro-organisms, but there
is a corresponding and similar increase in the death-rate, together
with a marked lowering of the mean age at death."[3]
[3] It is, of course, obvious that other circumstances
besides overcrowding have to be reckoned with in considering
these statistics. In the one-roomed houses the wages earned
by the occupants must have been small, and the amount
available for even the bare necessaries of life very
limited, that, in fact, they were to be reckoned amongst
the class defined by Mr. Rowntree as living in "primary
poverty," whose earnings are insufficient to keep the body
in a properly nourished condition. Mr. Rowntree has shown by
statistics that the height, weight, and general condition of
the poor are very much below those of the well-to-do
labouring classes.