A DISCUSSION ON CHOLERA: ITS EPIDEMIC PROGRESSION AND CAUSATION. By Surgeon A. E. Roberts, i.m.s,, Dy. Sany. Commissioner, jV.- W. P. ? Oudh. The above was the title of a debate at a meeting of the Medical Society, reported in the last number of the British Medical Journal, which has readied me. As one who has on two occasions, not only built up the statistics of an epidemic of cholera in widely different purls of this country, but who also made it his duty to carry out n, "careful local investigation" in each instance, and who therefore may claim to have fulfilled the two-fold condition upon which so much stress was laid by a leading speaker at the debate in the course of a criticism of the method of hatching theories in India, may I, if not too late, take up my parable on some aspects of the question, very pertiLate
Fed.
ROBERTS ON CHOLERA.
1893.]
in the heading), and appreciated to judge by the obiter dicta of the critics of the Indian Government. Let us start with an assumption, perhaps a frail basis for an argument; but as this purports to be in some measure an answer or a supplement to the London speeches representing the state of opinion there, and as the British Medical Journal is, I take it, the chiet British exponent of the claim made by Koch on behalf of his " vibrio" to be the " vera causa causans " of the disease, I shall assume that claim to be established. What, then, do we know about the "vibrio" I do not intend here or so-called " comma "? to go into the details of the morphology and natural history of the parasite ; but the point I would draw attention to is that all the evidence goes to show that Koch's " vibrio" must be included among the class of facultative saprophytes, "bodies which complete their cycle of development as parasites, but which can exist under certain circumstances as saprophytes, and can pass through some portion of their developThe bearing of this mental cycle as such." most important fact in the natural history of the vibrio is that it passes its life, as it were, on a double stage ;?one outside the body as saprophyte, this probably under more or less unfavourable conditions of environment, thus accounting for the established facts of endemicity and non-endemicity, which" the purely and " do not include water-borne theorists solely in their partial statement of the case;?the other stage, as parasite, passed within the body, where the cycle of development is completed, and where the environment in " predisposed" or non-resistant subjects is highly favourable. For we have to bear in mind that in all diseases there are two interacting factors, viz., structure and environment, and it is this factor of environment as affecting the cholera "germ" both within and without the body that must be taken account of if we would dispel much of the mystery surrounding the disease?" its causation and epidemic spread." The "structure" term in the equation has been recognized on all hands by observers in Europe during the late epidemic, and various estimates are to hand of the percentage population in a community which has proved itself "immune "to the attack of the poison. But do the water-borne exponents really attack the tiue problem, when they overlook the facts of the "environment" term? I venture to say, that in discussing "cholera, its epidemic spread and causation," they are bound to take this into consideration. Perhaps it is not too much to say that no one doubts nowa-days that water is the chief vehicle for the spread of the disease, and in so far may be considered one and a chief item in the " epidemic spread;" but is the discussion to end there? The baffling phenomena of cholera incidence
nent to
the issue
too little
(as stated
?
?
i*i
37
have chiefly arisen, .and thrived in the cloud of theories each based on some single-observed fact of its natural history, which the ardent patrons thereof have raised about the subject. A theory holds good for one outbreak, and lands its votary in a dilemma at the next; it is this partial view (as well as to the mixture of fact and fancy) that could not but fail before a problem, that is the resultant of several "capital" factors ; and thus the very element ot truth un" derlying each theory that lias its day," is its chief snare. Thus the environment is all-important for our study; we see the rise, culmination and decline of epidemic and endemic disease, recurring at the same seasons, year by year, and we dare not reject the inference of a seasonal influence; but, at the same time, the very inexactness of this, the many exceptions to a definite inexorable rule, its partiality and uncertainty, drive us to the conclusion that the action of atmospheiic and climatic conditions is not direct, in the sum of its effects, but that it acts through some modifying medium. Thus while a law of association is not to be denied, yet we must hold that it is modified or broken in its manifestation by very diffe ring conditions of the medium through which it acts, whether this medium be soil?or other. We may well infer a working together of climatic and soil influences, from the fact that cholera prevails under the most opposite climatic conditions ; but nevertheless, the locality factor of the total environment term is much the more the unaltering and fixed condition. The facts which I wish to connect in all clearness, are the double life-stage of the cholera germ-causa, and the established endemieity of the disease in certain areas, and the equally established non-endemicity in plnces outside these areas, and thence we may lay it down that the course of an epidemic in an endemic area will differ radically from the course in a non-endemic area. As a pathogenic parasite and as a saprophyte, the germ lives essentially different lives, and lives them under differing conditions ; if therefore we look solely at one life-history (the half of the double existence) we only make us a mystery, because the two lives seem to be opposed in their vital requirements. Take the case of the non-endemic area : a victim arrives from, say, the endemic area where cholera is prevalent, and the disease breaks out following his arrival. ?
3
o
poison contained in his excreta may affect mediately or immediately the drinking-water and the food supply of his friends first and then of the community generally, and a common source of infection may thus be established,? the poison being, as it were, conveyed from man The
toman, more or less erratically, in so far as victims eat that contaminated food, or drink that contaminated water ; each fresh case being a new centre of infection for othera 6
38
INDIAN MEDICAL GAZETTE.
through food or water (I take it that we may conclude that the main, it' not the sole, way of entrance for the poison, is the mouth?considering the pathological facts). But this is an example of the spread of the disease by virtue of its parasitic affinities?the food and water only playing the part of vehicle.?and the organism only finds victims in proportion as "susceptible" persons eat the contaminated food or drink the The disease then disapcontaminated water. never returns unless re-introduced. and pears, Again, such a cholera victim may arrive in a non-endemic area, and may discharge an untold number of essential "germs," which, finding the cannot establish a environment unsuitable, saprophytic existence, and the food and water supplies
not
being contaminated,
or
being
con-
taminated only locally (as in a private well attached to a house) we have an example of a single case, or of two or three cases of cholera in a community?after which the disease disappears, not to return unless re-introduced. The former of these two instances may present the features of a universal epidemic, or of the
erratic
destroying-angel type, according
to
the chances of water or food contamination and But to the susceptibility of the population. " causa" finds a in the endemic area, where the satisfying environment for its saprophytic affinities, a new factor is introduced. The disease may be and generally is to a great extent carried and food supplies, by mediate infection of water " but, at the same time, the causa" is sown on the soil, so to speak, there also to multiply under the favouring conditions and to be a potent source of infection, which supplements and complicates the incidence of the disease, and maintains a more general and equal influence in propagating it ; here it defies the power to track its course by any one mode of spread, which is infinitely far less the case in the non-endemic area, even when the disease prevails in the latter so generally (as by contamination of a common water-supply) as to deceive observers " cholera is the same everyinto the belief that where." In the endemic areas the scourge never ceases out of the laud, and requires no " fresh introduction"?its prevalence is modified or abrogated by seasonal and personal influthere to stay, awaiting the conences, but it is
comitance of other external In support of this view let
favouring influences.
us take some facts of the incidence of the disease in the widely different areas of Lower Bengal aud the Punjab, as representing the endemic and non-endemic Aud first, we would lay it down as an areas. axiom that the occurrence of an isolated case of cholera in any place, is the best proof of the " resistance," "insusceptibility" of that locality Now to the development localbj of the disease. the proportion of villages attacked in districts in different parts of the country, where the number
[Feb.
1893.
villages correspond, will give an idea, of the susceptibility" or resistance of local conditions,?cceteris pavibus. Further, the number of
of
"
"
villages
or
"
separate communities reporting only
death (or say two or three deaths) will be greater in an area presenting altogether an unfavourable environment to a saprophytic organism. Now it is a fixed rule for each geographical area-unit of India, that in the purely endemic district or in that district which can be shown to be nearest in its physical characteristics to the true endemic area, the number of villages attacked in every outbreak of cholera is greatest; the proportion of villages attacked to the total falls olF, just in the ratio as the district in which they are situated presents physical conSome may say trasts to the true endemic type. that this is self-evident, and depends 011 the " infection " in the more abundant chances of we endemic areas; and grant that this is a, the not but one important one: this factor, error is guarded against in the second clause " infection " be of the rule above stated. If the sole factor, one case in a community should in the majority of cases be sufficient to spread the disease therein ; and yet we shall see that in the Punjab area one case is very frequently the sole cholera record of a large proportion of communities, living under conditions of interdependence from social habits, and under conditions so utterly insanitary, that infection or one
could demand no more favouring circumstances of environment. The Sanitary Commissioner with the Government of India reports that in 1875 cholera appeared in 39 districts of Bengal Proper ; these districts contain 154,205 villages; and of these, 17,729 were attacked by cholera, that is a ratio of 115 per mille. In the same year cholera appeared in 25 districts of the Punjab (there are only 31 districts in Punjab, so the "epidemic" was widespread enough 1) these 25 contain 28,986 villages, and of these only 797 were attacked, a ratio of 27 per mille. The lowest number of villages returning cholera deaths in any one district in Bengal Proper the Punwas 25, but no less than 7 districts in
contagion
jab returned only one village attacked (and by the way registration is much completer in the Punjab than in Bengal). These 7 Punjab districts (returning only one village affected in each, i.e., a total attacked of 7 villages in all)
Bethe aggregate 7,907 villages. more districts reported only 2 in each ; and these 3 districts contain in all 2,748 villages, hence a total aggregate of 10,655 villages only reported 13 contain in
yond this, three, villages attacked
villages attacked.
In 1876, 6 districts (Punjab) containing an aggregate of 5,595 villages, reported only one village attacked in each, and yet the epidemic
ROBERTS ON CHOLERA.
13
51
10
10
58 100
10
3-9% 22 553 0*57 ...
p-CT IBannu
59
1,416 0-62 ...
851 0'44 ...
fLudhiana
Kaiigra
1\ ?
I Eb
gw'i ?cr?i Gujrat
1,725 4-16
334 715
704 2-75
7*58
5S
|
4-1%
27
6-8%
34-8% G01
20
87
12 44
20-8%
299
85
24
50
26
76 42
46-7%
75
2?5 deaths.
5-10 deaths.
villages returning. No. of
Two deaths. One death.
Percentage
of attacked to total.
villages
attacked.
No. of of No.
in District.
villages
Ratio of deaths per 100
Districts.
Sanitary Commissioner.) the
{Report of
in
Cholera of
The Epidemic
PUNJAB.
the past 20 years, but the percentage of its attacked is not nearly so large as that of Rawal Pindi, where the death-rate is far lower. Sialkote District, with the thickest papulation, shows one of the lowest percentages of villages attacked ; it includes 2,357 villages, with a population of over one million, yet twice within the last 20 years has this district returned only one death from cholera. The fact of the relation between the death-rate and the number of villages attacked in a district, does not simply mean that the more numerous the centres of infection the more widely is the population affected. It may toell mean this in the endemic areas with its characteristically favouringenvironment, but not so in the non-endemic area {e.g., Punjab) as already demonstrated in the facts of attacks in isolated villages in the midst of others similar in every respect, and open to communication by all the ordinary channels. The characteristic feature here is for cholera to die out at its point of introduction, and not to spread from its original centre. I need scarcely point out how foreign this is to the conditions obtaining in the Lower Provinces. Taking the records of the Sanitary Commissioner for 20 years (1870?89) we find no less than 84 instances of districts (each containing hundreds if not thousands of villages) returning but one death from cholera for the }^ear of report; there being 47 instances of such districts returning but two deaths each in certain years. Still more remarkable is the state of things disclosed by the accompanying table (Sanitary Commissioner's Report), Here the mortality of two different sets of three districts in the Punjab is compared ; three districts severely affected, and these districts slightly affected by the great epidemic of 1879. This shows (1) that where the epidemic was severe, 34-8% to 46*7% of the
villages
1879.
the death-rate is highest, there the number of villages attacked is greatest in proportion, though there is of course a relation ; nor is it a question of the thickness of the population, e.g., Kohat District has a high death-rate for
f Hissar
no lack of infecting material. 1877, 9 districts containing an aggregate of 10,697 villages, returned attacks in 12 villages only, and the total number of deaths in these 12 communities was 29 only. In 1888, 7 districts with a total of 11,138 villages, returned 11 villages attacked only. Now it does not necessarily follow that where
In
147
Over 10 deaths.
throughout the Province carried off 5,736 victims
?surely
35
39
tion.
1893.]
popula-
Feb.
Tims the severity of ail epidemic in the lionendemic area depends on the number of centres of infection. Human intercourse may probably be a great factor in the introduction of the disease to new centres, but there it apparently stops in the unfavourable environment, and we see how resistant these localities prove to the multiplication of the"" causa." Cholera therefore finds no " home in the purely non-endemic areas ; it exists only and is propagated as a parasite, and has little or no saprophytic existence. The figures for Lower Bengal are classic and available to anyone, and the contrast is obvious. A similar contrast, if less defined, can be shown for the two main geographical divisions of the from the foot of the* N.-W. P. and villages were affected ; where the epidemic was hills down to and including the Gauges valley, slight, but 4% to 7% were attacked. (2) But and the southernmost and western districts, or the number of villages returning onlv one death the Jumna country. And here I would wish to was proportionally the same, viz., 38% and 41% point out, what I believe has long been overrespectively on the severely and slightly affected looked, owing probably to the absence of milidistricts ; also the number of villages in both tary statistics from the area, that the Gograsets of districts returning but two deaths was Gnndak country, between the foot of the hills and the Ganges, presents a perfect parallel in' proportionally identical, viz., 13% in both. .
Oudh,?u^.,
INDIAN MEDICAL GAZETTE.
40
all its physical features, to the Gangetic delta in Lower Bengal. It is under the influence of the full sweep of the monsoon ; the drainage from the hills rising tip from after its descent beneath the Bhabar land, and the numerous streams issuing from the hills makes soil-moisture conditions analogous ; there is a luxuriant vegetation, and a great part still stands unreclaimed in the condition of waste marsh ; conditions of atmospheric temperature and humidity alluare also analogous ; the soil is of the new vium, and is cut up in the likeness of the Gangetic delta with numerous streams. Compare rainfall, cholera deaths and ground-water level, on plotted curves in Gorakpur and Calcutta ; they are identical. The importance of these facts, when the opposing views of " contagionists " " and " localists are considered, are paramount. The view has obtainedcurrency that the M breed" ing ground of cholera is exclusively in the Gangetic delta, when the disease issues on its destroying journey ; but facts of epidemics have not seldom falsified this exclusive view, notably outbreaks " up-country," where communication with Lower Bengal may be considered to be eliminated, and when these up-country outbreaks occur prior to any outbreak in the so-called If there be, as can "home "of the disease. be demonstrated, another "home" of cholera, within the area of the N.-W". P. and Oudh, much of the mystery in tracing the origin of outbreaks disappears. Lewis and Cunningham certainly did not point to the Gogra-Gundak area as a true endemic focus, and hence their statement of the case for local influences lacked a link in the chain of evidence. Cholera occurs in this Gogra-Gundak area simultaneously and under the same conditions as in Calcutta; between these places we have the " transition area" of Upper where cholera incidence is modified in season, and tends to approximate towards the conditions exhibited in the N.-W. P. (save in the Gogra-Gundak country); the " break" in the chain here is really a link for the view of local influence, if, as can be shown, the physical conditions of locality are pretty well identical in the separated areas. It is impossible within the limits of a paper to do more than indicate these points for consideration. " causa" finds a If, as we must assume, the natural habitat in the peculiar local conditions of the endemic areas, we allow that here it has existence; where local a definite
bengal,
saprophytic approximate
conditions elsewhere
to
identity
with those of its " home," we must expect that it will grow if planted; but that as the conditions elsewhere are more or less " artificial," temporary and exceptional, all that we know of vital "germs" makes us expect that the resulting crop will depend 011 nearness to identity ; and that as the conditions of the " culture medium" change and vary from this identity, there will
[Feb.
1893.
be danger to the crop; complete annihilation in one case, and in another, where local conditions vary less from the endemic type, there may be attenuation of virus, slight at first, and then more and more, season by season until ultimate annihilation of that special tribe. Meanwhile the other, the pathogenic parasitic existence survives, affecting the individual and being ? O individual to individual, as it passed on from " raised stage." No theory of causawere, on a tion based solely upon one or other fact of the natural history of the "causa" parasite or saprophyte) constantly holds good. Another source of fallacy is the overlooking of the facts proving that the "virus" may and does "spread" in more than one way, by more than one Vehicle. It is this double-stage life history, a combination as it were of the faculties and limitations of two such diseases as small-pox and malaria, that Ave need to grasp, with all its relations to different vehicles: it is frailer as a saprophyte than the " " of malaria, and frailer as a pure paracausa site than the former disease?"germ," and hence its peculiar powers and limitations. Lewis and Cunningham suggested a certain analogy in jta natural history to malaria "poison," and in proportion as this locality link in the chain of its requirements is granted to it, its powers are For cholera at their highest and most deadly. is like the Apocalyptic "Beast," requiring both " " legs (its local soil relations) and wings?for transport (aqueous, aerial, human); take away one or other and Given its you non-plus it. alone and it would local environment specific cease to be an epidemic scourge; raging beyond its "home," and given its "wings" alone, it ceases out of the land. Finally, as to the completeness of the drinkingwater theory, the reputation of that, as being anything more than a chief factor of its epidemic diffusion (and the writer would be the first to uphold its pre-eminent claim to that distinction), may well be left to the tender mercies of Lewis and Cunningham: the argument they presented on the facts of chole ra incidence iiyfhe Calcutta / area, is irrefutable. ...
v
Fed.
ROBERTS ON CHOLERA.
1893.]
in the heading), and appreciated to judge by the obiter dicta of the critics of the Indian Government. Let us start with an assumption, perhaps a frail basis for an argument; but as this purports to be in some measure an answer or a supplement to the London speeches representing the state of opinion there, and as the British Medical Journal is, I take it, the chiet British exponent of the claim made by Koch on behalf of his " vibrio" to be the " vera causa causans " of the disease, I shall assume that claim to be established. What, then, do we know about the "vibrio" I do not intend here or so-called " comma "? to go into the details of the morphology and natural history of the parasite ; but the point I would draw attention to is that all the evidence goes to show that Koch's " vibrio" must be included among the class of facultative saprophytes, "bodies which complete their cycle of development as parasites, but which can exist under certain circumstances as saprophytes, and can pass through some portion of their developThe bearing of this mental cycle as such." most important fact in the natural history of the vibrio is that it passes its life, as it were, on a double stage ;?one outside the body as saprophyte, this probably under more or less unfavourable conditions of environment, thus accounting for the established facts of endemicity and non-endemicity, which" the purely and " do not include water-borne theorists solely in their partial statement of the case;?the other stage, as parasite, passed within the body, where the cycle of development is completed, and where the environment in " predisposed" or non-resistant subjects is highly favourable. For we have to bear in mind that in all diseases there are two interacting factors, viz., structure and environment, and it is this factor of environment as affecting the cholera "germ" both within and without the body that must be taken account of if we would dispel much of the mystery surrounding the disease?" its causation and epidemic spread." The "structure" term in the equation has been recognized on all hands by observers in Europe during the late epidemic, and various estimates are to hand of the percentage population in a community which has proved itself "immune "to the attack of the poison. But do the water-borne exponents really attack the tiue problem, when they overlook the facts of the "environment" term? I venture to say, that in discussing "cholera, its epidemic spread and causation," they are bound to take this into consideration. Perhaps it is not too much to say that no one doubts nowa-days that water is the chief vehicle for the spread of the disease, and in so far may be considered one and a chief item in the " epidemic spread;" but is the discussion to end there? The baffling phenomena of cholera incidence
nent to
the issue
too little
(as stated
?
?
i*i
37
have chiefly arisen, .and thrived in the cloud of theories each based on some single-observed fact of its natural history, which the ardent patrons thereof have raised about the subject. A theory holds good for one outbreak, and lands its votary in a dilemma at the next; it is this partial view (as well as to the mixture of fact and fancy) that could not but fail before a problem, that is the resultant of several "capital" factors ; and thus the very element ot truth un" derlying each theory that lias its day," is its chief snare. Thus the environment is all-important for our study; we see the rise, culmination and decline of epidemic and endemic disease, recurring at the same seasons, year by year, and we dare not reject the inference of a seasonal influence; but, at the same time, the very inexactness of this, the many exceptions to a definite inexorable rule, its partiality and uncertainty, drive us to the conclusion that the action of atmospheiic and climatic conditions is not direct, in the sum of its effects, but that it acts through some modifying medium. Thus while a law of association is not to be denied, yet we must hold that it is modified or broken in its manifestation by very diffe ring conditions of the medium through which it acts, whether this medium be soil?or other. We may well infer a working together of climatic and soil influences, from the fact that cholera prevails under the most opposite climatic conditions ; but nevertheless, the locality factor of the total environment term is much the more the unaltering and fixed condition. The facts which I wish to connect in all clearness, are the double life-stage of the cholera germ-causa, and the established endemieity of the disease in certain areas, and the equally established non-endemicity in plnces outside these areas, and thence we may lay it down that the course of an epidemic in an endemic area will differ radically from the course in a non-endemic area. As a pathogenic parasite and as a saprophyte, the germ lives essentially different lives, and lives them under differing conditions ; if therefore we look solely at one life-history (the half of the double existence) we only make us a mystery, because the two lives seem to be opposed in their vital requirements. Take the case of the non-endemic area : a victim arrives from, say, the endemic area where cholera is prevalent, and the disease breaks out following his arrival. ?
3
o
poison contained in his excreta may affect mediately or immediately the drinking-water and the food supply of his friends first and then of the community generally, and a common source of infection may thus be established,? the poison being, as it were, conveyed from man The
toman, more or less erratically, in so far as victims eat that contaminated food, or drink that contaminated water ; each fresh case being a new centre of infection for othera 6
38
INDIAN MEDICAL GAZETTE.
through food or water (I take it that we may conclude that the main, it' not the sole, way of entrance for the poison, is the mouth?considering the pathological facts). But this is an example of the spread of the disease by virtue of its parasitic affinities?the food and water only playing the part of vehicle.?and the organism only finds victims in proportion as "susceptible" persons eat the contaminated food or drink the The disease then disapcontaminated water. never returns unless re-introduced. and pears, Again, such a cholera victim may arrive in a non-endemic area, and may discharge an untold number of essential "germs," which, finding the cannot establish a environment unsuitable, saprophytic existence, and the food and water supplies
not
being contaminated,
or
being
con-
taminated only locally (as in a private well attached to a house) we have an example of a single case, or of two or three cases of cholera in a community?after which the disease disappears, not to return unless re-introduced. The former of these two instances may present the features of a universal epidemic, or of the
erratic
destroying-angel type, according
to
the chances of water or food contamination and But to the susceptibility of the population. " causa" finds a in the endemic area, where the satisfying environment for its saprophytic affinities, a new factor is introduced. The disease may be and generally is to a great extent carried and food supplies, by mediate infection of water " but, at the same time, the causa" is sown on the soil, so to speak, there also to multiply under the favouring conditions and to be a potent source of infection, which supplements and complicates the incidence of the disease, and maintains a more general and equal influence in propagating it ; here it defies the power to track its course by any one mode of spread, which is infinitely far less the case in the non-endemic area, even when the disease prevails in the latter so generally (as by contamination of a common water-supply) as to deceive observers " cholera is the same everyinto the belief that where." In the endemic areas the scourge never ceases out of the laud, and requires no " fresh introduction"?its prevalence is modified or abrogated by seasonal and personal influthere to stay, awaiting the conences, but it is
comitance of other external In support of this view let
favouring influences.
us take some facts of the incidence of the disease in the widely different areas of Lower Bengal aud the Punjab, as representing the endemic and non-endemic Aud first, we would lay it down as an areas. axiom that the occurrence of an isolated case of cholera in any place, is the best proof of the " resistance," "insusceptibility" of that locality Now to the development localbj of the disease. the proportion of villages attacked in districts in different parts of the country, where the number
[Feb.
1893.
villages correspond, will give an idea, of the susceptibility" or resistance of local conditions,?cceteris pavibus. Further, the number of
of
"
"
villages
or
"
separate communities reporting only
death (or say two or three deaths) will be greater in an area presenting altogether an unfavourable environment to a saprophytic organism. Now it is a fixed rule for each geographical area-unit of India, that in the purely endemic district or in that district which can be shown to be nearest in its physical characteristics to the true endemic area, the number of villages attacked in every outbreak of cholera is greatest; the proportion of villages attacked to the total falls olF, just in the ratio as the district in which they are situated presents physical conSome may say trasts to the true endemic type. that this is self-evident, and depends 011 the " infection " in the more abundant chances of we endemic areas; and grant that this is a, the not but one important one: this factor, error is guarded against in the second clause " infection " be of the rule above stated. If the sole factor, one case in a community should in the majority of cases be sufficient to spread the disease therein ; and yet we shall see that in the Punjab area one case is very frequently the sole cholera record of a large proportion of communities, living under conditions of interdependence from social habits, and under conditions so utterly insanitary, that infection or one
could demand no more favouring circumstances of environment. The Sanitary Commissioner with the Government of India reports that in 1875 cholera appeared in 39 districts of Bengal Proper ; these districts contain 154,205 villages; and of these, 17,729 were attacked by cholera, that is a ratio of 115 per mille. In the same year cholera appeared in 25 districts of the Punjab (there are only 31 districts in Punjab, so the "epidemic" was widespread enough 1) these 25 contain 28,986 villages, and of these only 797 were attacked, a ratio of 27 per mille. The lowest number of villages returning cholera deaths in any one district in Bengal Proper the Punwas 25, but no less than 7 districts in
contagion
jab returned only one village attacked (and by the way registration is much completer in the Punjab than in Bengal). These 7 Punjab districts (returning only one village affected in each, i.e., a total attacked of 7 villages in all)
Bethe aggregate 7,907 villages. more districts reported only 2 in each ; and these 3 districts contain in all 2,748 villages, hence a total aggregate of 10,655 villages only reported 13 contain in
yond this, three, villages attacked
villages attacked.
In 1876, 6 districts (Punjab) containing an aggregate of 5,595 villages, reported only one village attacked in each, and yet the epidemic
ROBERTS ON CHOLERA.
13
51
10
10
58 100
10
3-9% 22 553 0*57 ...
p-CT IBannu
59
1,416 0-62 ...
851 0'44 ...
fLudhiana
Kaiigra
1\ ?
I Eb
gw'i ?cr?i Gujrat
1,725 4-16
334 715
704 2-75
7*58
5S
|
4-1%
27
6-8%
34-8% G01
20
87
12 44
20-8%
299
85
24
50
26
76 42
46-7%
75
2?5 deaths.
5-10 deaths.
villages returning. No. of
Two deaths. One death.
Percentage
of attacked to total.
villages
attacked.
No. of of No.
in District.
villages
Ratio of deaths per 100
Districts.
Sanitary Commissioner.) the
{Report of
in
Cholera of
The Epidemic
PUNJAB.
the past 20 years, but the percentage of its attacked is not nearly so large as that of Rawal Pindi, where the death-rate is far lower. Sialkote District, with the thickest papulation, shows one of the lowest percentages of villages attacked ; it includes 2,357 villages, with a population of over one million, yet twice within the last 20 years has this district returned only one death from cholera. The fact of the relation between the death-rate and the number of villages attacked in a district, does not simply mean that the more numerous the centres of infection the more widely is the population affected. It may toell mean this in the endemic areas with its characteristically favouringenvironment, but not so in the non-endemic area {e.g., Punjab) as already demonstrated in the facts of attacks in isolated villages in the midst of others similar in every respect, and open to communication by all the ordinary channels. The characteristic feature here is for cholera to die out at its point of introduction, and not to spread from its original centre. I need scarcely point out how foreign this is to the conditions obtaining in the Lower Provinces. Taking the records of the Sanitary Commissioner for 20 years (1870?89) we find no less than 84 instances of districts (each containing hundreds if not thousands of villages) returning but one death from cholera for the }^ear of report; there being 47 instances of such districts returning but two deaths each in certain years. Still more remarkable is the state of things disclosed by the accompanying table (Sanitary Commissioner's Report), Here the mortality of two different sets of three districts in the Punjab is compared ; three districts severely affected, and these districts slightly affected by the great epidemic of 1879. This shows (1) that where the epidemic was severe, 34-8% to 46*7% of the
villages
1879.
the death-rate is highest, there the number of villages attacked is greatest in proportion, though there is of course a relation ; nor is it a question of the thickness of the population, e.g., Kohat District has a high death-rate for
f Hissar
no lack of infecting material. 1877, 9 districts containing an aggregate of 10,697 villages, returned attacks in 12 villages only, and the total number of deaths in these 12 communities was 29 only. In 1888, 7 districts with a total of 11,138 villages, returned 11 villages attacked only. Now it does not necessarily follow that where
In
147
Over 10 deaths.
throughout the Province carried off 5,736 victims
?surely
35
39
tion.
1893.]
popula-
Feb.
Tims the severity of ail epidemic in the lionendemic area depends on the number of centres of infection. Human intercourse may probably be a great factor in the introduction of the disease to new centres, but there it apparently stops in the unfavourable environment, and we see how resistant these localities prove to the multiplication of the"" causa." Cholera therefore finds no " home in the purely non-endemic areas ; it exists only and is propagated as a parasite, and has little or no saprophytic existence. The figures for Lower Bengal are classic and available to anyone, and the contrast is obvious. A similar contrast, if less defined, can be shown for the two main geographical divisions of the from the foot of the* N.-W. P. and villages were affected ; where the epidemic was hills down to and including the Gauges valley, slight, but 4% to 7% were attacked. (2) But and the southernmost and western districts, or the number of villages returning onlv one death the Jumna country. And here I would wish to was proportionally the same, viz., 38% and 41% point out, what I believe has long been overrespectively on the severely and slightly affected looked, owing probably to the absence of milidistricts ; also the number of villages in both tary statistics from the area, that the Gograsets of districts returning but two deaths was Gnndak country, between the foot of the hills and the Ganges, presents a perfect parallel in' proportionally identical, viz., 13% in both. .
Oudh,?u^.,
INDIAN MEDICAL GAZETTE.
40
all its physical features, to the Gangetic delta in Lower Bengal. It is under the influence of the full sweep of the monsoon ; the drainage from the hills rising tip from after its descent beneath the Bhabar land, and the numerous streams issuing from the hills makes soil-moisture conditions analogous ; there is a luxuriant vegetation, and a great part still stands unreclaimed in the condition of waste marsh ; conditions of atmospheric temperature and humidity alluare also analogous ; the soil is of the new vium, and is cut up in the likeness of the Gangetic delta with numerous streams. Compare rainfall, cholera deaths and ground-water level, on plotted curves in Gorakpur and Calcutta ; they are identical. The importance of these facts, when the opposing views of " contagionists " " and " localists are considered, are paramount. The view has obtainedcurrency that the M breed" ing ground of cholera is exclusively in the Gangetic delta, when the disease issues on its destroying journey ; but facts of epidemics have not seldom falsified this exclusive view, notably outbreaks " up-country," where communication with Lower Bengal may be considered to be eliminated, and when these up-country outbreaks occur prior to any outbreak in the so-called If there be, as can "home "of the disease. be demonstrated, another "home" of cholera, within the area of the N.-W". P. and Oudh, much of the mystery in tracing the origin of outbreaks disappears. Lewis and Cunningham certainly did not point to the Gogra-Gundak area as a true endemic focus, and hence their statement of the case for local influences lacked a link in the chain of evidence. Cholera occurs in this Gogra-Gundak area simultaneously and under the same conditions as in Calcutta; between these places we have the " transition area" of Upper where cholera incidence is modified in season, and tends to approximate towards the conditions exhibited in the N.-W. P. (save in the Gogra-Gundak country); the " break" in the chain here is really a link for the view of local influence, if, as can be shown, the physical conditions of locality are pretty well identical in the separated areas. It is impossible within the limits of a paper to do more than indicate these points for consideration. " causa" finds a If, as we must assume, the natural habitat in the peculiar local conditions of the endemic areas, we allow that here it has existence; where local a definite
bengal,
saprophytic approximate
conditions elsewhere
to
identity
with those of its " home," we must expect that it will grow if planted; but that as the conditions elsewhere are more or less " artificial," temporary and exceptional, all that we know of vital "germs" makes us expect that the resulting crop will depend 011 nearness to identity ; and that as the conditions of the " culture medium" change and vary from this identity, there will
[Feb.
1893.
be danger to the crop; complete annihilation in one case, and in another, where local conditions vary less from the endemic type, there may be attenuation of virus, slight at first, and then more and more, season by season until ultimate annihilation of that special tribe. Meanwhile the other, the pathogenic parasitic existence survives, affecting the individual and being ? O individual to individual, as it passed on from " raised stage." No theory of causawere, on a tion based solely upon one or other fact of the natural history of the "causa" parasite or saprophyte) constantly holds good. Another source of fallacy is the overlooking of the facts proving that the "virus" may and does "spread" in more than one way, by more than one Vehicle. It is this double-stage life history, a combination as it were of the faculties and limitations of two such diseases as small-pox and malaria, that Ave need to grasp, with all its relations to different vehicles: it is frailer as a saprophyte than the " " of malaria, and frailer as a pure paracausa site than the former disease?"germ," and hence its peculiar powers and limitations. Lewis and Cunningham suggested a certain analogy in jta natural history to malaria "poison," and in proportion as this locality link in the chain of its requirements is granted to it, its powers are For cholera at their highest and most deadly. is like the Apocalyptic "Beast," requiring both " " legs (its local soil relations) and wings?for transport (aqueous, aerial, human); take away one or other and Given its you non-plus it. alone and it would local environment specific cease to be an epidemic scourge; raging beyond its "home," and given its "wings" alone, it ceases out of the land. Finally, as to the completeness of the drinkingwater theory, the reputation of that, as being anything more than a chief factor of its epidemic diffusion (and the writer would be the first to uphold its pre-eminent claim to that distinction), may well be left to the tender mercies of Lewis and Cunningham: the argument they presented on the facts of chole ra incidence iiyfhe Calcutta / area, is irrefutable. ...
v
