[ T l u ~ grevious uumber of these Transactio~ts, Kol. 43, No. 2.
zva¢ published on 27th September, 1949.]
TRANSACTIONS
OF T I l E
ROYAL SOCIETY OF TROPICAL MEDICINE
AND HYGIENE
VoL. 43.
No. 3.
.NOVEMBER, 1949.
OPENING MEETING OF THE FORTY-THIRD SESSION
of the Society held at
Manson House, 26, Portland Place, London, W.1,
on
Thursday, 20th October, 1949, at 7.30 p.m.
"I'ItE PRESIDENT,
Professor H. E. SHORTT, CJ.r., M.D., D.SC., D.T.M. & tL, Colonel l.?&s. (retd.),
in the Chair.
PRESIDENTIAl,
ADDRESS.
In considering what might be a suitable subject for m y Presidential
Address, I felt a little timorous when I recalled the addresses delivered by
my predecessors in this Chair, men to whom I have looked up with reverence
as my teachers, men I am proud to succeed as a humble follower.
One thing, however, gave me heart of grace: I r e m e m b e r e d that there
is no discussion on the Presidential Address, and one is therefore in the strong
position of the broadcaster who can make you furious but to whom, at the
moment, you cannot r e p l y ! Having thus regained courage, I decided that
courage was a good thing and that 1 must advocate its cultivation.
Now, the older generation among us has been through two world wars,
and we feel that the world is in a sorry mess. I have decided, therefore, to
address m y remarks chiefly to the younger generation, to those of you who
are starting your careers in the midst of this mess. It is for you, and it should
be your privilege as well as your burden, to take your courage in both hands
240
PRESIDENTIAL ADDRESS
and proceed to clear up the mess ; and it will need courage and resource, but
the recompense will be great. The rewards will probably not be wealth or
advancement, although these may follow, but there will be the satisfaction of
achievement for its own sake and for the benefits it will shower on others.
Now you may ask what all this has to do with tropical medicine. T h a t
is a fair question, and my address tonight is largely my attempt to answer it.
As my text, I take the title of my address " Tropical Medicine as a Career."
From what I have already said you will understand why I address myself
tonight chiefly to the younger man starting his career and why I urge any of
you in that position who are attracted by the study of tropical medicine
seriously to consider making it your life study. Such a decision will demand
much of you ; you will have to devote all your talents, all your energy and all
your enthusiasm to the task; nothing less will do and you can do nothing
more. Your choice of career is wide open. Are you interested in clinical
medicine ? There are vast unexplored r i d & to traverse. Are you interested
in parasitology or entomology ? Although the days when you could describe
a new species of parasite from every animal caught in nature are past, the
amount still to discover knows no end. Are you interested in sanitation ?
There is a veritable jungle of dirt, disease and destitution to be cleared. Are
you interested in nutrition and nutritional deficiencies ? You have here one
of the widest spaces of all to explore.
On the other hand, have you some restless fire in your blood which irks
you under the restrictions and conventions of modern civilized life in grcat
centres of population like most European countries ? T h e n think of work in
the tropics, where open air is cheap and in plentiful supply, where you will
often be far enough away from headquarters to feel your own master, to take
responsibility for your own actions, to make your own mistakes and to rectify
them because you have no one else to lay the blame upon. This makes for
humbleness while you are building up self-reliance.
I have said enough, I think, to make it clear that in deciding to take up
the study of tropical medicine you are not entering a one-way street leading
only at the end of life to a tanned wizened skin, an enlarged liver, and
retirement to a cottage on a small pension. You are entering a labyrinth of
highways and byways each opening out interesting and even enchanting vistas
of achievement, and the treading of these roads will leave you with a store of
interesting and exciting memories for later digestion in the cottage I have
mentioned.
Now I come to a very important aspect of our subject. What are the
mental and physical disciplines we must undergo to attain our object of a
successful career in tropical medicine ? T h e y are the same, whatever may be
the line of work chosen among those I have enumerated. Tropical medicine
is, of course, an extension of general medicine into new territory and, as such,
PRESIDENTIAL ADDRESS
24 1
is almost a new subject. Being practised in new territory much is unknown,
and it is, therefore, essential rather than incidental that anv approach to it
should be made in a scientific spirit of enquiry, whether the student is a
clinician, a laboratory worker or a sanitarian. What, then, is this state of mind
in which we should approach the problems of tropical medicine ? It is, of
course, not peculiar to these problems but should become a habit in any
scientific enquiry and is called the " scientific m e t h o d . " Let me take, one
by one, some of the components which go to make up the scientific approach
to any problem. As I enumerate and explain these, you will notice that some
of them are closely related, one to another, and that when taken together as
a directive they amount to instructions to observe accurately, t o criticize
sternly and to allow no personal bias to affect logical conclusions.
In the first place, one nmst be open-minded, casting aside bias and
prejudice of every kind. A problem should be approached objectivcly. T h e r e
should be an eagerness to consider and weigh all evidence even when it appears
to traverse opinions thought to be already established. Failure to do so puts
one at a disadvantage compared with one receptive to new ideas and prepared
to investigate before discarding them. Thousands of times bacteriologists have
found moulds growing on their cultures and thrown them away as contaminated.
FLEMING went f a r t h e r ; he looked at his mould and found it was producing
something which destroyed the bacteria around it. It appeared an insignificant
effect, but it was the germ of a new idea which was not jus: cast aside, i{e
was open-minded and prepared to accept a possible significance in the
phenomenon and the result was penicillin and a whole range of useful
antibiotics.
T h e n one should cultivate what I may ca!l an allergy to problems. This
characteristic really differs little from the open-mindedness I have just described.
T h a t is to say, one should be quick to see a p h e n o m e n o n and then to wonder
why it occurs. F r o m this naturally follows an attempt to investigate the
underlying causes. Millions of people had seen applcs fall from trees but thev
were not allergic to what, after all, was a very remarkable occurrence, viz.,
the transference of a solid object across space without apparent force applied.
Of all the millions who had seen this take place, only NEWTON was allergic
enough to sense a problem and to carry the matter farther.
T h e third essential to the scientific method is a passion for facts as opposed
to mere impressions. This is another way of defining the search for accuracy ;
accuracy in observation and in recording these observations. This striving for
accuracy is exemplified by the use of many scientific instruments meant to
extend and make more accurate the information given by our senses. A simple
example is an instrument such as a ruler, which enables us to say that an object
is not merely as long as one's finger but that it is a given n u m b e r of inches long.
Anyone with a ruler can then make comparable observations, and so the
242
PRESIDENTIAL ADDRESS
statement becomes strictly accurate and verifiable by others. In the same way
the microscope extends and makes more accurate the vision of the eye and
the stethoscope the accuracy and range of the ear.
The fourth essential to cultivate is a passionless logic and honesty which
compels one to give an equal value to all facts, both those proving and those
against a favourite hypothesis. It must admit the necessity to retrace steps
which have been found to lead along the wrong road, and this admission of
wrong should be welcomed as keeping one on the right track and in the right
faith.
The fifth essential is what I would call controlled enthusiasm which should
make your outlook not static but dynamic. This habit of mind will cause us
to reach out intellectually and ardently in all directions but also to weigh
carefully all the information gained in our search for causes. It will enable
us to sift the likely from the unlikely and so ever edge us towards the truth
until that is finally attained.
"['he sixth habit to cultivate is the critical mind. This enables us to consider
our findings, both negative and positive, from all points of view. All unproved
hypotheses, even those generally accepted, must be considered at least suspect
until finally proved or disproved, and this applies with special force to one's
own hypotheses because we know that we are biased in their favour.
The seventh attitude to cultivate is to
problem until you have sufficient proof to
A supreme example of this principle was
for over 20 years before he enunciated his
delay your pronouncements on any
make no other conclusion possible.
the collection of data by DAr~WIN
theo W of organic ew~lution.
The last of your disciplines I would recommend is to work doggedly at
your problem along the lines you believe to be correct and not to be discouraged
or turned aside when everything seems against you. T r y to make your philosophy
such that you acknowledge no such thing as failure or defeat; that these are
only obstacles to make new endeavours necessary. Time and again I have
found that when things look their worst, when you are discouraged and no
gleam ~:ppears in the darkness, thi:~ is the time to feel hopeful and to look for
some relieving light of success. It is often when you are most exhausted and
your cause seems hopeless that you exact the greatest forfeit from Nature, who
is loath to give up her secrets but, when she relents, rewards abundantly. All
your work which has gone before is like the sun and the rain on corn. You
have, without knowing it, been approac!-ing the time of harvest and, one day,
you find the corn ripe for the garnering.
To illustrate this, let me give you a personal experience. [ had worked
intensively at the problem of the transmission of kala-azar for about 10 years,
the last 6 of them in attempts to transmit geishmania donovani to animals
and man by the bite of the sandfly, Phlebotornzls argentipes, but all in vain. The
epidemic of kala-azar which had been in progress was dying down and, in
PRESIDENTIAL ADDRESS
243
consequence, research material was becoming difficult to obtain. I could see
no new methods of approach to the problem, no new principles to explore
and, in some depression, I r e c o m m e n d e d the closing down of the Kala-azar
Commission until the next epidemic should arise. Next morning the whole
laboratory was in a turmoil of excitement. T h e very last animal to be examined
before the closure of the w o r k - - a Chinese hamster bitten by infected sandttk.~
over a year b e f o r e - - p r o v e d to be infected. In a day the clouds had rolled
away, proof that transmission by the bite of the sandtty was possible had he~-~
obtained, and the way was open to extend the work until final proof (~f
transmission to man by the bite t~f the sandfly was accomplished.
Now all 1 have said so far has been almost in the nature of a sermon, and
so I close this section of nay address---in all reverence---in the words of ~ sermon
known to you all in the fidl assurance that, if the precepts I have been advocating
are faithfully fcllowed, success will be assured. T h e words to whict- I al'udv
are, " Ask and it shall be given y o n : seek and ye shall find; knock .'.and it
shall be opened unto you."
I)o you think from what I have said so far that ~he purst:it of "r(q)ieal
medicine as a career is all serious endeavour without lig??ter moments (~f
relaxation ? Far frorn it : get it into your heads that it is a fascinating game.
In following the main roads there are m a n y side tracks up which we can wander,
in relaxation, to our great advantage and entertainment. Even in one's everyday
work there is h u m o u r and cause for laughter, often perceive(! and best appreciated
after the event rather than at the time.
Nowadays, one hardly dares send a worker into lhe lield ~lnless b,c i~
provided with living conditions--houses, lights, fans and frigidaires---~}~ic}~
we in the past considered to be the luxuries only of large centres of habitatbm.
This is all to the good when i: can be done, but the enthusiast wilt not bc
dissuaded when these are nor forthcoming. In nay own experience of fieht
work in India we built our own mud and bamboo huts where the work happened
to be. These served both for temporaQ" homes and for laboratories, in fact
the latter took precedence, i r e m e m b e r at one time in Ass:.,m, when working
on kala-azar, the Governor of Assatil visited my field station.
At the time
m y wife and two small chitdren were living there with me, and IIis Excc!lencv
was astonished to see ,Is all domiciled in a mud and lath hut in the comp~mnd
of a good government bungalow while the whole of the latter was used a'; :~
laboratory,
t t e was reported to have said on regaining the t~roviz~cial
headquarters, " T h e r e were the Shortts living in mud huts in the c~nnpo~md
of a perfectly good Government bungalow and the little Sb,ortts rtlnr~i_n!~ ::b()t~l
among the bugs."
W h e n the monsoon broke m y family went up to the hills and I was 1eft
among the bugs in the mud hut. M y wife, in pity, left me a nice Persian rug
beside m y camp bed for me to step on to in the morning when I got up. l ' h e
244
PRESIDENTIAl'. A D D R E S S
floor was mud, covered with bamboo matting, and on the latter---the rug.
One day, after a week of continuous rain, when I got up in the morning I saw
to m y horror grass growing through the rug ! I lifted it by two corners and
at the door shook it vigorously. T h e damp had rotted it and the rug flew
through the air across the compound while the corners remained in my hands !
I do not mean to infer from all this that roughing it is necessary when it
can be avoided, but it is certainly a good training in teaching one to " make
do " when all we need is not available.
I often laugh at my initiation into medical research of a young Indian
medical man who afterwards became a well-known Indian malariologist. I
was trying to reach a certain tea garden in the monsoon by car along a so-called
ro~d across the rice fields. I was accompanied by three Indian workers: a
Mr. JAMES JO~IN, the late Mr. C. S. SWAMINATH,my collaborator in many
papers, and t}:is young recnlit whom we may call Dr. X. Every few yards
we had to get out and push the car out of the mud or tie ropes round the wheels
t(, act as chains and renew these as they got cut on harder parts of the track.
Picture to yourself our condition by the afternoon It was monsom~, it was
raining a tepid flood and steamy ho~. On each side of the track stretched
flooded rice fields. We were all exhausted and had drunk all the liquid we had.
Pr,csently, Mr. JA~.rES JOHN came and asked me for my handkerchief--already
soaked with sweat and rain. He looked at it somewhat ruefully, then laid it out
flat on the water of the rice field and drank through it in the hope it would
act: as a filter ! t i e handed it back to me with a shudder and the words, " Sir,
1 Imve never had to do that before." As the afternoon wore on, and it looked
as if we would be benighted, it became too much for the new recruit, who
conjured up atl sorts of horrors at the thought of a night in the jungle, and he
began to weep. Ife was sternly rebuked by Mr. SWAMINATH, who said to
h i m : " Now, now, Dr. X., you needn't w e e p ; this is nothing to what you
will endure in the f u t u r e ; this is research work under the Indian Research
F u n d Association." His words were true and, as I have said, I)r. X. made
good.
If any of you are keen on languages, there is infinite scope for you, and
there is no doubt whatever that, at least a working knowledge of the language
of the people among whom one is working is an immense help, as those of you
who have had to work through interpreters, as I have at times, will agree.
Besides, a knowledge of the language may be useful in other ways as what I
am now going to tell you will forciblv illustrate.
Sir RmKAnD CHnISTOPHERS and I were swimming in a creek off the river
Shatt el Arab, in Iraq. We noticed some Arab children, boys and girls, squatting
on the bank opposite to us, and these were continually being reinforced in
numbers. We soon realized that we were not being merely admired, either for
our swimming or our figures, and that there was an expectant look on some
PRESIDENTIAL ADDRESS
245
of the faces. At last, partly in exasperation and partly in curiosity, I shouted
to them in Arabic, asking them what they were waiting for. One of them,
with almost an eager look in his eyes, said, " We're waiting to see the sharks
get y o u ! "
Now, we had not expected sharks in fresh water, but shortly
after~vards [ realized that the danger was not so remote when, having been
admitted to hospital for malaria, I had as a fellow-patient in a nearby bed
a man whose leg had been badly torn by a shark at a place not far from where
we had been bathing. Only the presence of companions who pulled him into
a boat saved his life.
In speaking a little earlier, 1 mentioned the need for improvizing, whether
it be laboratories or houses, where this is necessary and the principle applies
also to many of the procedures used in the practice of medicine in places where
all modern facilities are not available. One quickly learns to do this, and it is
surprising what results we sometimes get with what can only be described as
Heath Robinson apparatus. Again, I illustrate this from my own experience.
A great friend of mine, a tea garden doctor in Assam, was lying dangerously
ill. ttc had been diagnosed malaria but he himself thought he had kala-azar.
I was then working some 150 miles away, and one day got a telegram from his
wife asking me in urgent terms to come and see him. On arrival, I found him
desperately ill and delirious, and for this reason the local medical officer, also
a friend of ,nine, was living in the house. After consultation together, we
decided that the most probable diagnosis was enteric. However, we had no
culture media, no diagnostic sera and not even a test tube. How could we
confirm the diagnosis ? I repaired, some miles away, to the local Indian
butcher and persuaded him to kill a calf. From this, with a syringe, I extracted
bile from the gall bladder into a bottle. On arrival back at the patient's
bungalow I found the doctor had unearthed a small tube which would serve
as a test tube. Into this we put some of the bile. We then extracted the inner
tube from a tyre of the patient's bicycle and, cutting off a piece of rubber, tied
it tightly over the mouth of the tube. A hypodermic needle was now thrust
through the rubber and left in position. The tube of bile was now boiled for
some time in a pan, steam from the boiling tube escaping through the hypodermic
needle. When the tube had cooled down, we inoculated the bile with the
patient's blood and sent it off to the headquarters laboratory, together with some
blood for a Widal test.
Strange to relate, considering the chances of
contamination, the bile grew a pure culture of Bacilhls tvphosus, and the blood
gave a positive Widal reaction, for the patient had been ill for 3 weeks.
Fortunately, although at one stage it looked as if he could not recover, wonderfl,.1
nursing by his wife pulled him through.
You may by now" be saying it is all very well to advocate a life given to
tropical medicine with its deprivations, its sometimes inevitable separations,
and its comparative lack of the amenities of modern life, although many of
these now reach the most remote places, but this is not a strictly true picture.
246
PRESIDENTIAL ADDRESS
To come away for a moment from the business side of our subject, let us
consider, but very shortly, some of the amenities. We do not work all the
t i m e ; we also play. Not only do we thus amuse ourselves but we actually
have a wider choice of amusements, a t least athletic amusements, than in the
centre of civilization. M a n y things become possible, and even easy, which
elsewhere can only be done by the very rich---now, of course, an extinct class
in Great Britain. I refer to such things as polo, big game shooting, and even
such apparently unlikely activities as skiing on the equator.
As residents in the country where they exist you can shoot elephants,
lions, tigers, leopards, bear, bison, buffalo and what you will at moderat:2 cost
or, if you have no desire to kill for tangible trophies, you ca~ photograph these
same things and still have something to jog your memory in later years and
attest to your veracity.
But what is the other side of the picture ? What are the positive gains
to ourselves and to our fellow men which may accrue ? '['his question can
only be answered by considering the many problems awaiting solution by you
younger men, problems some of which have been only half solved by workers
of previous generations and require completion, some of which have been little
more than formulated and some which as yet we are not even aware of. "l'i,is
is equivalent to saying that there is no end to the asking of questions, and however
much one generation may elucidate it is only a very small part of the structure
of knowledge it is our privilege to explore and from which we must try to wrest
the secrets which nature always so jealously guards, whil,.~ we need not fear that
in this great quest there will ever be any finality when nothing more remains to
discover. Even when we have discovered the immediate causes of disease,
the ultimate causes will still be eluding us. As Walt Whitman has said, from
every fruition (~f success, however full, comes forth something to make a ~reater
struggle necessary.
In mentioning even a few only of the endless problems awaiting :soh~tion,
you will realize how widely the net may be cast and that in it are treasures to
satisfy every bent. Nor is it necessary to plough a lonely furrow, for many
problems require the co-ordination of different lines of attack convergkn~ on
a given objective. Take, for instance, a syndrome such as sprue. It i:~ still a
very mysterious condition. Its curious distribution, its pathology, its physiology,
its bacteriology and its bio-chemistry, open a field for combined attack from
many angles. Think of the joy of directing a successful attack on its hitherto
inscrutable obscurity, of lighting up its dark places and so bringing its treatment
within the realm of scientifically applied measures based on an adequate
knowledge of its aetiologyI
Here is an opportunity for pathologists,
physiologists, bacteriologists, bio-chemists and chemotherapists to play t,~ether
as a team. It could be done--therefore why not do it ?
What of that greatest of all killers of the human race---malaria ?
Great
PRESIDENTIAL ADDRESS
247
strides have been made in our knowledge of malaria and how to cure and
prevent it. But do you think that D D T residual spraying, the various repellents
and the new antimalarial drugs in our armamentarium have fired the last shot
and given its quietus to malaria ? That result may come some day, but the day
is not yet. We are still a long way from lhe ideal specific drug or drugs, and
if such a drug were found tomorrow we are still a long way from ensuring its
universal distribution and use. W h y is it that so much research is going on
in connection with the prevention of malaria from m a n y angles ? It is
because much has still to be learned and only those actively and practically
engaged on the work realize how much this is. We still do not know how much
harm, as well as good, we may be doing by the widespread use of D D T . It
must not be forgotten that many forms of in'.~ect life destroved by D D T play
their part in the ecology of nature in any given area and tt, at the state of ecological
equilibrium has been built up over periods geological in their duration. If
we suddenly upset this equilibrium only time wilt reveal the result, but it is
a fruitful field for study. The very malaria parasite which it is the object of
malariologists to abolish has its place in th,c ecological picture and who knows
whether, if they succeed in driving out this de-vil ,. ,~::npletely, seven other devils
may not take its place !
But even if we do not whcqly exterminate the malaria parasite there are
many of the intimacies of its private life we may still pry into to satisfy our
morbid curiosity. The adjective " morbid " is probably correct when it refers
to the curious prying of the so-called highest form of life into the inmost
privacies of one of the lowest forms of life. W h y does the malaria parasite
find one kind of mosquito a congenial host and another kind wholly inimical ?
W h y have we not vet discovered the answer to this problem which is common
ground to entomologist and protozoologi,-',t ? Why d'.,cs the erythrocyte, which
is host to the benign tertian malarial parasite, dexelop freckles, more usually
known in this connection as Schiiffner's dots ? Is there s~,ch a thing as malarial
toxin, as some of the findings in the pathology of malaria would appear to
indicate ? If so, why have the biochemists not isolated or even found it ? I
blush to delve further, but those with less fastidious!; minds could think (;f many
other intimate and hitherto unrevealed details of its private life, knowledge
of which the malaria parasite will no doubt do its utmost to maintain inviolate.
And what of blackwater fever ? Almost tile only established fact about
this is that the syndrome is connected with malarial infections. W h y does
the malarial subject suddenly, and often without warning, suffer the loss of
a large proportion of his erythrocytes and arrive, in a matter of hours, at death's
door ? What has made his red cells so dangerously wdnerable that some trigger
action releases, in a moment, the destroying force. Could the catastrophe
have been prevented ? Once it has happened is there any effective means of
retrieving the position ? None of these questions can yet be adequately
answered, and they are a challenge to you all but, perhaps, especially to the
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P R E S I D E N T I A L ADDRESS
physiologists. When they are answered we may arrive at a knowledge of rational
methods of prevention and, if these are neglected by the ignorant or ignored
by the careless, of cure.
Now let us consider the problem of African trypanosomiasis. Or do you
think it is no longer a problem ? Do you think that, here again, the modern
insecticides used to attack the vector tsetse flies will supply the complete answer
to prevention at least ? Well, it may be so, but the cautious will defer judgement
in line with the principles I enunciated at the commencement of this address.
The fact remains that numerous instances could be quoted showing that
outbreaks of trypanosomiasis due to Trypanosoma viz, a.v and T. congale~zse
have occurred in the apparent absence of tsetse flies. In these cases transmission,
normally achieved by t!-e agency of tsetse flies, was probably effected by
interrupted feeding of various bi'.ing flies such as tabanids and stomoxys, known
to be present in very large numbers. But, apart from the disease and its
transmission, there is still a great deal to be learned about the trypanosome
itself. I believe we still have a very imperfect knowledge of its life history
in the vertebrate host, and this i~ a problem requiring immediate solution.
Some are working upon it, but if more were to do so the answer might come
sooner. This is only one aspect. The classification of trypanosomes is still
in a state almost chaotic, especially when we consider the wide phylogenetic
range occupied by the genus in the vertebrate kingdom--mammals, birds,
reptiles, amphibia and fishes--and this chaos will not be changed to order
until we know enough of the full life histories of a su~cient number of species
to give us data for a rational classification.
Then, again, there has recently been described a new trypanosome of man
in S. America- :Y. ratE,eli. Is this a cause of disease or is it an accidental and
evanescent visitor in man ?
Let us turn for a moment to a closely related genus of parasite which
occurs as an agent of disease in man and animals in every continent except,
possibly, Australia. I refer to the genus Leishmania, the cause of kala-azar,
oriental sore and espundia. We know the vector in the case of Indian kala-azar,
but in the case of the visceral disease elsewhere in the world the alleged vectors
have been incriminated, if at all, only on epidemiological grounds and
unequivocal scientific delimitation of vectors has still to be achieved. The
same remarks would apply to the vectors of the various dermal lesions produced
by Leishmania in different parts of the world, although verification of the
vectors of oriental sore in the Mediterranean area now require only the dotting
of the " i's " completely to satisfy the requirements of scientific proof.
A good deal of attention has lately been fixed upon toxoplasmosis. Now
we know the organism responsible for this condition, the Toxoplasma, but
we have no idea as to the method of infection, although the parasite is found
in mammals, birds and reptiles. The human disease is most often manifested
PRESIDENTIAL ADDRESS
249
in very young children who show encephalitic symptoms shortly after birth
and who are already infected in utero. In many or most cases the mother does
not and never has shown any symptoms of infection yet, when her blood is
tested, it can be shown to contain antibodies to Toxoplasma. Here is an
interesting field for research--although not strictly speaking in tropical medicine
-becau.~e we do not as yet know even the taxonomic status of Toxoplasma;
we do not know whether to call it an animal or a vegetable and we know nothing
of its life cycle or whether it has any free-living existence.
I ct us leave animals for tile time and consider the plants. Tropical mycology"
• x~hat an unexplored and labyrinthine jungle it conjures up to those of us who
have lived for any time in the tropics and seen the varied manifestations of
mycotic diseases in man and animals. This is probably one of the least explored
branch,:" of tropical medicine and therefore a fruitful field for endeavour. T h e
majorhy of the diseases caused by the mycetozoa do not kill and therefore are
less s D c t a c u l a r than the killing diseases such as cholera and plague, to mention
only two>. but the suffering and disfigurement they cause, their ubiquity in the
tropics. ~htir relative refractoriness to treatment and the lack of precise
knov~Ied~e about them make them one of the major medical problems of the
t:opics. !tern is a field where new knowledge is to be acquired as soon as the
study is taken up because at present the ground is almost untrodden.
Now let us consider an example of hehninthic diseases--onchocerciasis.
This is caused by a filarial worm of the genus Onchocerca. T h e condition is
found in man in Africa and Central America. It is responsible for nodules
in the s~b-cutaneous tissues and for eye lesions which may even lead to
blindness.
T r e a t m e n t with the newer anti-filarial drugs is not wholly
satisfac:ory. T h e disease is spread by flies of the genus Simzdium. In Kenya,
where ti~e local vector is £'. Jtea*:ei, no one has vet been able to find the breeding
place of this insect.
[ p to this point I have not touched upon the virus diseases, and we may
now consider these. Yellow fever is a virus disease in connection with which
research work in recent years has revolutionized our ideas of its distribution.
-its vectors, its animal reservoirs and its epidemiology and endemiology in
genera!. Work of vital and fascinating interest is even now in progress and in
this you can take a part for there is still a multitude of lines of enquiry awaiting
workers with imagination and application. It offers a wonderful tangle to be
up, ravelled from the intimate association of virus, mosquito, man, monkey and,
possibly, other animals.
What of dengue fever ? This occurs sporadically as well as in severe epidemic
form, the latter often in ports, such as the epidemics which have occurred in
Athens and in Calcutta among other places. What happens to the virus in the
inter~'als between epidemics ? Are there human carriers or is there some animal
reservoir ? If the latter, why does the virus suddenly concentrate on the
human host ?
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While on the subject of virus diseases, I should draw attention to a field
which is still comparatively virgin ground and where every step taken should
carry the thrill felt by an explorer entering territory never before traversed.
I refer, here, to the viral encephalitides, the series of virus diseases--probably
mostly insect-borne---causing encephalitis in man and animals in different
parts of the world. Among these, to name some which have been partially
studied, are St. Louis encephalitis, Japanese B encephalitis, Australian X
disease, Western equine encephalitis, Eastern equine encephalitis, Venezuelan
equine encephalitis and Russian far east encephalitis. 'Fo come to infecti,ms
in the tropics or subtropics, we have West Nile , i r u s ; Bwamba fever in
Uganda; Semliki forest virus and Bunyamwera virus both in Uganda, and
several others I have not mentioned. Not all of these occur in tropical countries,
but some do as the names obviously imply and there are here, among these
various conditions, great lacunae in our knowledge waiting to be filled. The
general pathological findings in the viral encephalitides are dependent on the
fact that viruses are obligate dwellers in intra-cellular habitats and they produce
their first effects on the cells they inhabit, in the cases I am considering usually
the cells of the central nervous system. The symptoms will necessarily be
related to the parts of the central nervous system involved, but this will often
not be enough to delimit a virus and laboratory investigation will be necessary.
A variety of arthropods are suspect as vectors and various animals as reservoirs
of these viruses. This means a cycle c,f reservoir-arthropod-man, but the proof
of these assumptions by scientifically controlled experiments has still to be
demonstrated. The virologist, the entomologist and the epidemiologist, are
the workers who should wield the spades to fill in the gaps.
So far, I have not mentioned one of the most important tropical diseases
-amoebic dysentery and its complications such as liver abscess. Wha~ are
the factors influencing the onset of amoebic hepatitis and its more ~dvanced
stage of liver abscess ? Why is it that while people in temperate climes such
as Great Britain may harbour the parasite, Entamoeba histolytica, vet true
amoebic dysentery is extremely rare and liver abscess ahnost unknown ." Are
nutritional factors involved, or are there pathogenic and non-pathogenic strains
or even distinct species of amoebae ? ttere is a truly intricate subject for
research which might well employ an ad hoc team of clinicians, nutrition
experts and protozoologists, who would have to work in the cl~>sesl association.
Earlier in my address I mentioned the importance of nutritional research
in the tropics. This subject is assuming an ever-increasing prominence and
none can deny its paramount importance in considering any schemes of
development not only in our colonial empire, to mention the aspect which
most closely concerns our own domestic outlook, but in all countries <;f the
tropical world. It seems paradoxical that in many cases the peoples who live
on a soil and in a climate which produce potential sources of food, animal and
vegetable, with a luxuriance not seen in temperate climes and where the
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minimum of effort over a part only of the year will yield enough food to live
upon for the rest of the year, should sulfer from deficiencies of diet, but so
it is in many places. Many of these deficiencies are known to have been
extensively studied, but only those engaged on such work know how small
our store of established knowledge still is in comparison with that it is essential
to acquire before remedial measures can first be formulated on established
facts and then be applied in a manner acceptable to the people concerned.
The latter part of the problem is not the least important as it may have to take
into consideration religious, social and racial prejudices which only education,
time and successful demonstration of the benefits elsewhere will remove. In
some cases these deficiencies may be the actual cause of the abnormal conditions
they precipitate, while in other cases cause and effect may be less clearly cut
and the deficiencies may aggravate diseases due to other causes. In still other
cases, the converse may hold and the abnormal states may be the result, not
of deficiencies, but of nocuous substances present in food or water. This
condition is seen in the case of endemic fluorosis in Madras province where,
in certain districts, a large percentage of the population, and also of the cattle,
are affected with bony growths on the long bones and ribs, and complete
rigidity of the spine due to intervertebral ossification leading to great incapacity
and, in extreme cases, to death from intercurrent disease, all due to excessive
amounts of fluorine in the natural sources of drinking water. No practical
solution has yet been found t\)r this problem, although such a solution would
be to the incalculable benefit of the whole population of the district.
In denoting the various problems requiring solution, I have dealt chiefly
with those conditions resulting from the action of agents of disease, but there
is one very important line of investigation in which knowledge is required most
urgently although no disease process is involved. I refer to the special
physiological functioning of the body in tropical climates. This is a very large
subject on which much has been done but more remains to be done. It should
open up a highly interesting field for study to the worker interested in
physiology, and the knowledge gained will have important and immediatv'
applications in many directions. As the tropics are opened out for habitation
by non-indigenous peoples, and remember there are at present vast uninhabited
or extremely sparsely-inhabitated areas, a knowledge of physiological variations
in hot and humid and hot and dry climates will be of great importance in
making life not only supportable but pleasant for such newcomers.
Such a process of opening out a country will necessarily involve large-scale
employment of labour, either in industry or agriculture or both, and physiological
problems will be involved in the general care, housing, feeding and conditions
of work and play of these people. A fore-knowledge of what to do will be repaid
a hundredfold in the health and happiness of the newly-opened territories.
One aspect of careers in tropical medicine I have not yet touched upon
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is the possibility, when a reputation has been established, of becoming a teacher
of the subject. There are openings, both in temperate climes and in the tropics
themselves, for such activities and for those with a bent in this direction there
could be no better outlet than to pass on the knowledge they have acquired
to the coming generation of workers. Teaching can be a very hv.mdr~m~
business, both for teacher and student, and the really inspired teacher c,_m~es
seldom--for the fire must be t h e r e - - b u t , when found, is a gift to be cheris[:ed,
for he can pass on his inspiration, which may be even greater than his knowledge,
to generations of students.
S:) far, I have been trying to draw for you a picture of what to expect, if
you take up a career in tropical medicine, of its fascination as a very yoking
sister of medicine in general, of the possible hardships and deprivations, but
also of the abundant and satisfying rewards. In speaking of these rewards,
here, at least, is a work with some incentive, that rare commoditx" in thesc clays
of levelling, when all men are proved equal by mere reiterated assertion, where
man-made laws attempt to frustrate the immutable laws of nature and the
rewards of labour are no longer ours to enjoy. Thank heavens, the rewards
i refer to are intangible and beyond the reach of the levellers, the pl'mners
and the income tax collectors. The worker who has succeeded in laying bare
some of the secrets of nature and thereby possibly benefited his fcll,~w me-n,
has his own personal reward in the shape of achievement, and who shall say
that he has not proved the fallacies of the levellers by the mere fact of rising
above mediocrity.
But, having drawn the picture, you will want to know how to achievt: the
aim of a career in tropical medicine and, as I wish to keep my address on a
practical not% it is only fair that I should give you some guidance. On account
of the speed of modern transport, the world i.:; now a small place, and this alone
has enhanced the importance of tropical medicine. As an empire, and I am
not afraid to use the word which we, as a people, have made honourable, and
as a member of a world-wide commonwealth of nations, our commitments are
also world-wide and so our armed services penetrate to every quarter of the
globe. This necessitates a similar penetration by their medical services, so
this is a first suggestion as to a means of entry to the practice of tropical medicine.
How fruitful a method this is could readily be exemplified by names sucl:l as
Ross, GORClAS, LEISttMAN, JAMES, CHRISTOPHERS, SINTON, and many others l
could mention. If any of you should decide on this method, do nv~t be
discouraged if you are not immediately asked to undertake some difficult
research problem in the tropics. You will only become worthy after enduring
many disciplines which may seem futile at the time but which are inescapable
in any service and the worth of which is often only recognized in later life.
Discipline, in any of its connotations, is a very valuable thing and indispensable
in truly civilized communities. For those of you who are not fired with martial
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ardour, love of the sea, or going to strange places by air, there is the colonial
service. The widespread nature of the Empire gives you ample scope here
and, to a large extent, you can choose your sphere of work not only as regards
territory but as regards the branch of tropical medicine you wish to take up
---again provided you are prepared to undergo the preliminary disciplines of
the early stages of your career. There are ample opportunities for work on
the clinical, laboratory and public health aspects and ability and initiative will
reap their reward.
In the case of those entering tile colonial service, it used to be customa W
to take the Diploma in Tropical Medicine and Ity~iene before going out to
the tropics. When there arose an acute shortage of recruits for the service
this was no longer possible and those entering the .,'ervice were sent out without
preliminary training and had to learn what they could in the actual practice
of the profession. Such men could later come back and take the Diploma
in this country, having already gained some experience in the tropics. It is
at least open to consideration which method is the better, but my own
inclination would be to give the m-m instruction in tropical medicine and let
him take his Diploma before going to tile tropics, tie would thus gain his
experience with at least some theoretical background of knowledge and could,
when he returned, and if he was specially interested in some particular aspect
of tropical medicine, concentrate on advanced studies on that aspect. Itowever,
I am open minded on the subject, and perhaps this question could best be
left to the Colonial Office, with its special knowledge of the conditions of
service.
Some of you may wish to work completely untramelled by the rules and
regulations of services, whether armed or civil, and for you there are other
openings to consider. Many of our major industrial undertakings, still outside
the reach of the planners' grasp, such as the oil industry, the tea and coffee
industries, the rubber industry and others less well known, have large interests
in tropical countries and maintain large staff's there. Most of these undertakings
now maintain their staff under very favourable conditions as regards pay and
general amenities, and among the latter are excellent medical services, tile
hospitals of which are quite often bettcr equipped than those of official
Govermnent organizations.
This does not exhaust the variety of openings for work in tropical medicine,
but I have said enough to indicate that for those who uill, the opportunity is
there and the work is worth while.
One thing, at least, you can look forward to and that is that you need never
fear a stale humdrumness in life, where day in day out and year in year out
you follow a few stereotyped activities repetitively performed for ever and
ever. In the life I am advocating you may, in your time, be many things.
You may on Monday have to start building a bridge; on Tuesday you may
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be performing an abdominal operation by candlelight; on Wednesday you
may spend half the day burning an anthrax carcase ; on Thursday you may
be settling a quarrel between two sets of villagers; on Friday you may be
taking over, as a temporary measure, the duties of Governor of a province;
on Saturday you may actually be doing something connected with tropical
medicine; and on Sunday you may be taking a church service. All but two
of these duties have fallen to my own lot at different times.
Well, ladies and gentlemen, I have occupied your time long enough, and
I only wish that someone more eloquent and more persuasive than I could
have delivered my address and made the plea which I have made for the study
of tropical medicine as a worth-while career. In the earlier part of my address
I advocated courage, and I now close on the same note. We live in great and
stirring times. The days of Elizabethan England, the period of the Napoleonic
wars and the time of British Empire building, to mention only three recent
phases in our island history, pale into insignificance in the dazzling glare which
lights events in our own time. As with the times, so with the men. As current
events are on an altogether mightier scale than those of past times, so the actors
in them, both malevolent and beneficent, are giants by comparison, and you
yourselves can easily give them names. Likewise, the responsibilities shouldered
by us all are greater in proportion to the increasing numbers of people affected
by events in a world rapidly contracting in virtue of modern speed of
transportation, and this calls for the highest qualities of faithfulness, confidence,
clear vision, far-sightedness and ruthless resolution if world problems are to
be settled in a way to allow man to pursue his destiny in peace and happiness.
I do not wish to enlarge on this and have only made these comments to
emphasize that if we live in difficult times, they are great and glorious times,
giving the opportunity to do greater things to remedy greater evils, and it is
well we should realize our good fortune and be Worthy of it.
Now is the time for British youth to be adventurous, to be prepared to
welcome and challenge present world problems, and one of the most important
of these for our country, is to fill the unoccupied spaces in the Empire, if possible
with people of our own blood and with people from our Commonwealth of
Nations, the daughter countries which are now vying with the mother country
in their influence on world affairs. Even if there were no worthier motives
for peopling the waste spaces of the earth, surely the recent world war supplied
evidence enough of the danger to their peoples of thinly inhabited countries.
The quickest way to achieve this result is to get rid of the causes which make
these places waste lands for man, the agents of disease in man and his domestic
animals, and so to create the conditions which will make them suitable and
fit to produce food and breed men. Be up and doing ; be prepared to venture
when opportunity beckons. We still have the brains, let us show that we also
have the guts !