Chapter XLIII

DIAGNOSTIC PROBLEMS AND PROCEDURES TOGETHER WITH COSMOPOLITAN DISEASES IN THE TROPICS

In temperate climates we always keep in mind syphilis, tuberculosis and the pyogenic infections when a diagnosis is in question. In the tropics these conditions are just as common, if not more so, and added to them we have many other diseases with protean manifestations such as malaria, beriberi, leprosy, ancylostomiasis and other helminthic infections, pellagra and amoebiasis.

The common mistake made by the physician when he first arrives
in a tropical country is to expect to deal chiefly with diseases
designated tropical. Before going to any tropical country the most
important preparation is the study of the statistical reports
from that section, covering a number of years. Everyone taking up
the study of tropical disease should first study the geographical
distribution of such diseases and those practising in temperate
climates should remember that the first question to be asked a man
suspected of having a tropical disease is “Where have you been
during the past months and years?” Then too the same question
should be applied as to intimate associates of the patient.

We all know how rare it is in temperate climates to find definite pathological conditions in people who are apparently well. In such people a definite finding of a cause sufficient to account for an illness is usually the key to the diagnosis. With those from the tropics, however, it is different. A single individual may be found upon examination to have amoebiasis, malaria, filariasis and syphilis, yet none of these infections prevent him from following his usual occupation. When such a patient comes to a ward it requires a correlating mind to eliminate four or five definite diagnoses, and fix upon some disease which is common to both tropics and temperate climates, as for example, typhoid fever.

In diagnosis in the tropics it is necessary to have at one’s
fingers’ ends the various physical signs and subjective symptoms
more or less characteristic of every disease of man as well as the
laboratory findings. It is only when one has at hand all obtainable
information that the solution of the medical problem becomes
possible.

Furthermore, it is necessary to be familiar with the fact that
certain infections, which at times give rise to marked alterations
in the health of a patient, may at other times, and in particular
when different races of man are concerned, give rise to no
recognizable interference with health. This is particularly true
of certain helminthological diseases, as for instance the slight
effects often noted in hookworm infection in the African races as
against the marked damage to those of the white race harboring such
parasites.

While the medical man is apt to have superabundant energy during the first few months of his tropical service this later gives way to the opposite state and in particular to a lack of initiative. It is possible to do that which is absolutely demanded in the daily work, but this is along the lines of routine requirements and to the exclusion of new and difficult methods of diagnosis.

Consequently, while in possession of full energy and zeal one should cultivate thorough and modern methods of study of his cases and make these matters of routine, to use in the listless period to follow.

We do not usually fully appreciate the assistance the history of
the present illness as well as personal and family history of a
patient gives us, although it is generally recognized as the first
line of approach in diagnosis. In the tropics, when dealing with
natives, we have the difficulty of language to contend with as
well as with native superstition and popular ideas as to nature
and causation of disease. When employing a native interpreter
it is always well to keep in mind the fact that such assistants
will rarely admit of ignorance of the language of the medical man
and, furthermore, they try to twist the answers of the patients
to make them agree with what they may think is in accordance with
the desire of the examiner. Again in carrying out the physical
examination it is difficult to be certain that the findings as to
location or degree of pain, sensations, or time of appearance of
lesions, as well as data as to pulmonary, renal and alimentary
tract disorders, are correct.

For these reasons it would seem advisable to reverse the ordinary methods of diagnosis when employed in the tropics. Instead of making a tentative diagnosis following the physical examination, and then confirming or adding to evidence with laboratory data, it is better to first secure the findings as to blood, faeces, urine, sputum, etc., and then check up such indications as to the diagnosis by a final and thorough physical examination.

This method of procedure has been criticised by some of my
friends and in fact is a source of criticism on my part when,
as a laboratory worker, I have been asked by a purely clinical
colleague to make a routine laboratory examination of one of his
patients without any previous study of the case on his part. Every
laboratory man recognizes the assistance a tentative diagnosis
on the part of the clinician gives him in that it suggests the
examinations which should be gone into with particular care.

The present trend, even in temperate climate practice and always
with the tropical internist, is to have familiarity with laboratory
technique and interpretation as well as with the methods of
physical diagnosis; consequently the tropical practitioner makes no
dividing line between the diagnostic information obtained in the
laboratory and that gotten at the bedside.

It is not difficult to train a native helper to make and stain
good blood smears as well as to examine such preparations, and the
same holds for the urine and faeces preparations. The skill in
making preparations, the familiarity with pathological findings
and the patience in studying a preparation on the part of these
assistants is at times a matter of surprise. Thus in a few minutes
the physician can check up these findings or the lack of findings
and have them at hand to assist him in his study of his case.

=Laboratory Examination.=—In the laboratory the routine examination should embrace, first, a study of a _stained blood smear_. It is essential that the smear be well made and the Romanowsky stain used a good one.

While more difficult to make than a smear on a slide the
cover-glass smear method of Ehrlich has the advantage that the
white cells are more evenly distributed and consequently the
differential count more reliable. Furthermore, after a little
practice, one can approximate the white count of a patient by
examining the stained smear with a low power objective (16 mm).
In my experience I get a better general impression of a large
mononuclear increase with the low power than I do with the
oil-immersion. As a matter of fact one can make his differential
count with a low power objective after some practice. Next, using a
high dry or immersion objective, we search for malarial parasites.
It must be remembered that even when there is nothing diagnostic
in a stained blood smear there is much information to be obtained
in the way of diagnostic exclusion. Furthermore, while looking
over the preparation some diagnosis may suggest itself and there
is nothing more important in diagnosis than to have possibilities
of diagnosis in mind. It is often stated in connection with the
diagnosis of liver abscess that one should always suspect liver
abscess in a tropical patient and this will hold for other diseases
and thus the careful examination of a blood smear may be suggestive
if not diagnostic.

Next the _faeces_ should be examined both in an ordinary preparation and in one mounted in Gram’s iodine solution.

In the preparation made from a particle of faeces, emulsified
in salt solution, we can note any excess of fatty acids or soap
crystals and lack of normal digestion of meat fibres as well as
presence of ova of intestinal parasites. Again such a preparation
is necessary for noting amoeboid activity of amoebae as well as for
the motility of flagellates and _Strongyloides_ embryos. In the
preparation mounted in Gram’s iodine solution we have distinctly
brought out the nuclear division of encysted amoebae, our most
practical means of differentiating between the pathogenic and
nonpathogenic amoebae. This method also brings out flagellate
characteristics. Again, any undigested starch grains show up
distinctly by reason of their blue color. Blood cells and yeast
cells stain a golden yellow.

In the examination of the _urine_ it is well to take up with a pipette the entire sediment from a centrifuged tube of urine and deposit it on a slide.

Examination with diminished illumination and using the two-thirds
objective quickly enables us to ascertain presence and character
of casts. This same sediment is then treated with Gram’s iodine
solution and a cover-glass applied. Such a preparation, using the
one-sixth objective, brings out distinctly the differentiation
of pus cells from renal epithelium as well as showing clearly
golden-yellow red blood cells. While centrifuging one can test for
albumin. A qualitative test for sugar takes only a few moments to
make.

These simple quick tests of blood, faeces and urine suffice for the preliminary laboratory work in a case. Following the physical examination we can carry out more elaborate laboratory tests as indicated by the tentative diagnosis obtained from the physical examination and preliminary laboratory investigations.

=Physical Examination.=—As regards the physical examination it must be remembered that in the tropics glandular enlargements and skin eruptions are so essential in diagnosis that the rule generally adopted in skin clinics should be adhered to, that is an inspection of the entire body surface, either by stripping the patient or removing clothing from one part at a time.

The sphygmomanometer is of value in the diagnosis of tropical
affections as well as those of temperate regions. Similarly,
functional tests of the heart and kidneys, basal metabolism
determinations, chemical examination of the blood, and tests for
acid-base equilibrium may give definite information—in one climate
as in another.

Palpation is peculiarly important in the diagnosis of the enlarged
spleen, liver and glands of many tropical affections as well as for
mapping out intestinal thickenings. Again in going over the patient
for outlining heart, liver, etc., palpatory percussion is more
satisfactory than the usual mediate percussion.

I find the use of the entire palmar surface of the middle finger,
gently tapped over the surface, to give better results than any
other method. In this way the percussion note is well elicited
and the sense of resistance most satisfactorily obtained. The use
of the tips of the index, middle and ring fingers, with a piano
playing stroke, also should be employed.

One should always determine the character of the reflexes. Of these
the most important are the patellar and biceps ones. This latter
reflex is normally rarely obtained.

The pupillary reactions also require little time for eliciting and
are of much value in differentiating a peripheral neuritis from a
cord lesion.

COSMOPOLITAN DISEASES IN THE TROPICS

In considering the matter of the general prevalence of disease in the tropics it has seemed advisable to present statistics from the standpoint of deaths rather than admissions for disease, the probability of accuracy in diagnosis being greater where there may be the assistance of an autopsy.

In the following table I have selected three tropical places under
American sanitary control, the city of Manila, the city of Panama
and the Island of St. Thomas, Virgin Islands. The statistics
embrace the calendar years of 1918, 1919 and 1920 The statistics of
Manila relate solely to the Filipino population resident in Manila,
it does not include Americans or other nationalities. The Filipino
population of Manila in 1920 was 263,386. The three years covered
had respectively a death rate of 49.97, 28.66 and 27.48 per 1000.

-----------------+------------------+-----------------+-----------------
| City of Manila | | St. Thomas, Vir-
Place | (Filipinos only) | City of Panama | gin Islands of
| | | United States
-----------------+------------------+-----------------+-----------------
Population | | 263,386| | 60,500| | 10,191
No. of deaths |11,840|7,378|7,238|1,314|1,211|1,297| 248| 176| 185
Rate per 1000 | 49.97|28.66|27.48|21.41|19.73|21.44|24.33|17.27|18.15
Calendar year | 1918| 1919| 1920| 1918| 1919| 1920| 1918| 1919| 1920
-----------------+------+-----+-----+-----+-----+-----+-----+-----+-----
Typhoid fever | 180| 171| 226| 0| 3| 2| 4| 0| 0
Malaria | 64| 46| 75| 14| 10| 4| 1| 1| 0
Smallpox | 837| 31| 1| 0| 0| 0| 0| 0| 0
Measles | 16| 3| 12| 2| 0| 1| 0| 0| 0
Whooping-cough | 7| 0| 5| 1| 7| 2| 0| 1| 1
Diphtheria | 14| 16| 9| 4| 10| 5| 0| 0| 0
Influenza | 424| 42| 31| 7| 1| 29| 8| 1| 0
Asiatic cholera | 108| 328| 2| 0| 0| 0| 0| 0| 0
Dysentery | 678| 390| 253| 3| 9| 5| 2| 1| 0
Leprosy | 2| 2| 3| 3| 1| 2| 0| 0| 0
Purulent | | | | | | | | |
infection and | | | | | | | | |
septicaemia | 26| 23| 28| 9| 9| 7| 0| 1| 0
Tetanus | 82| 83| 84| 3| 2| 1| 1| 1| 0
Pellagra | 0| 0| 0| 6| 5| 5| 15| 4| 0
Beriberi | 551| 324| 548| 1| 2| 1| 0| 0| 0
Tuberculosis of | | | | | | | | |
the lungs | 1,605|1,334|1,340| 223| 206| 169| 20| 20| 27
Cancer and other | | | | | | | | |
malignant tumors| 80| 73| 65| 26| 34| 44| 6| 11| 6
Alcoholism | 3| 3| 2| 2| 1| 2| 0| 1| 0
Diabetes | 6| 6| 11| 3| 3| 0| 0| 0| 0
Simple meningitis| 448| 292| 300| 12| 11| 14| 1| 2| 0
Cerebral | | | | | | | | |
hemorrhage | 109| 99| 93| 27| 39| 40| 10| 9| 4
Convulsions | | | | | | | | |
(infants) | 224| 148| 91| 3| 4| 5| 4| 1| 1
Acute | | | | | | | | |
endocarditis | 46| 29| 28| 17| 14| 7| 0| 1| 2
Organic diseases | | | | | | | | |
of the heart | 118| 95| 93| 63| 37| 45| 9| 17| 27
Diseases of the | | | | | | | | |
arteries | 18| 23| 15| 15| 27| 34| 9| 7| 9
Acute bronchitis | 975| 335| 630| 34| 14| 17| 0| 0| 0
Chronic | | | | | | | | |
bronchitis | 286| 331| 235| 4| 1| 3| 0| 0| 0
Broncho-pneumonia| 872| 293| 372| 86| 109| 108| 15| 10| 6
Pneumonia | 220| 86| 101| 60| 62| 59| 5| 8| 8
Diarrhoea and | | | | | | | | |
enteritis (under| | | | | | | | |
two years) | 642| 365| 365| 156| 136| 162| 13| 4| 11
Diarrhoea and | | | | | | | | |
enteritis (over | | | | | | | | |
two years) | 429| 253| 164| 9| 16| 13| 9| 4| 5
Acute nephritis | 159| 88| 102| 18| 21| 14| 0| 1| 1
Chronic nephritis| 265| 248| 156| 72| 63| 63| 15| 16| 21
Intestinal | | | | | | | | |
parasites | 16| 12| 5| 0| 2| 0| 1| 0| 0
Congenital | | | | | | | | |
debility | 614| 460| 611| 32| 13| 21| 13| 14| 6
Senility | 531| 451| 357| 17| 7| 9| 13| 0| 1
+------+-----+-----+-----+-----+-----+-----+-----+-----
|10,655|6,483|6,413| 932| 879| 893| 174| 136| 136
-----------------+------+-----+-----+-----+-----+-----+-----+-----+-----

The population of the city of Panama during the year 1920 was
60,500. The death rate during the years covered was 21.41, 19.73,
and 21.44 per 1000, respectively.

It may be stated that the average population of the Canal Zone
during 1920 was 27,459, with 242 deaths, giving a death rate of
8.81 per 1000.

The population of St. Thomas during 1920 is estimated at 10,191.
The death rate during 1918 was 24.33, during 1919, 17.27 and during
1920, 18.15 per 1000.

The diseases in the table of deaths do not account for all the
deaths, the others having been from other diseases, accidents, etc.

In studying the Manila statistical reports more in detail we note
that during 1920 there were reported 64 cases of diphtheria, 387 of
measles and 577 of typhoid fever. The reasons for the high death
rate in 1918 are clearly seen, namely, the epidemics of influenza
and smallpox. As is the case in nearly every epidemic of influenza,
the increase in deaths from this disease was accompanied with a
large increase in deaths from acute bronchitis and the various
pneumonias, conditions that in many cases should have been ascribed
to influenza. The smallpox epidemic during 1918 was brought under
control by a very extensive vaccination campaign. Only one death
from this disease occurred in 1920.

During 1920, there were reported in Panama 95 cases of diphtheria,
313 of influenza, 154 of measles, 9 of typhoid fever, 4 of scarlet
fever, 14 of smallpox and 311 of tuberculosis.

During the same period there were reported in St. Thomas 6 cases
of chickenpox and 40 cases of tuberculosis. No cases of influenza,
smallpox, measles or typhoid fever occurred. From reports for the
year of 1921, it is noted that an extensive although not severe
epidemic of measles has been present in the Virgin Islands during
said year.

From the above tables we note that as far as actual causes of
deaths are concerned the cosmopolitan diseases play a more
important rôle than those we designate tropical diseases.
Tuberculosis ranks first, other respiratory infections come a
close second. Organic diseases of the heart and other degenerative
diseases, such as chronic nephritis, are also noted for their
frequency. The gastro-intestinal infections, typhoid fever,
dysentery, diarrhoea, probably serve as a barometer of the sanitary
conditions of a city.

But there are many other diseases whose importance from an economic
standpoint may not be fully appreciated from mortality tables.
Notable among these are venereal diseases, malaria, filariasis,
yaws and hookworm diseases. Further it may be noted that many
diseases without being the direct cause of death have a distinct
bearing on the mortality. Amongst these we note particularly the
various worm-infestations. The experience in Bilibid prison is an
illustrating example. The mortality amongst the prisoners dropped
markedly after the inmates had been cured of their various worm
conditions.

=Rheumatic Fever and Scarlet Fever.=—From a study of the statistical reports and from the writings of various authorities there would seem to be two cosmopolitan diseases, which are of extreme rarity in the tropics, rheumatic fever and scarlet fever.

It is true that in the Gold Coast report for 1911 there are noted
614 cases of rheumatic fever with one death.

There does not, however, appear to be any striking increase in
admissions for valvular disease of the heart as would naturally be
expected.

In Calcutta, in 1911, there were 74 deaths from rheumatic fever.

As regards scarlet fever, statistical reports from various parts of the tropical world fail to show cases.

In a report from Shanghai, which can hardly be considered as a
tropical city, there is a statement that this disease first made
its appearance in 1900, since which time it has spread among the
Chinese, exhibiting marked virulence. Again in a Basutoland report
there were quite a number of cases reported (67), but as this
colony is in the extreme south of Africa it could hardly be called
tropical.

=Typhoid Fever.=—When reliance for diagnosis rested almost solely on clinical manifestations, it was held that typhoid fever was rare or unknown in the tropics.

Since the advent of laboratory methods of diagnosis it has become
known that typhoid and the paratyphoid fevers are quite common. The
paratyphoid infections are more common in the tropics than in the
temperate regions. The fever course and clinical picture of typhoid
in the tropics are distinctly atypical. It was formerly common to
consider cases of typhoid as malaria and in the southern states of
the United States it was a common thing to diagnose typho-malarial
fever.

Of course, latent malaria is apt to flare up in a person sick with
typhoid, but the idea that there was a symptom-complex partaking
of the characteristics of typhoid fever and malaria is now classed
with historical data.

It is a remarkable fact that in many of the cities of the Orient
conditions favoring infection with typhoid fever, such as neglect
of the most elementary measures of disposal of faeces and lack of
safeguarding of water supplies, exist and yet the natives seem to
have an immunity to organisms causing alimentary tract diseases. It
must be that such immunity is acquired by attacks of the disease
in childhood. Certainly, Europeans in such communities have no
protection unless they are vaccinated. It must be remembered that
the protection from vaccination against the enteric group of
bacteria can be relied on for not longer than a period of two years.

It would seem that typhoid fever in tropical countries is more
serious than in temperate climates—thus the death rate in India is
about twice as great.

In the absence of laboratory tests the chief reliance in the
clinical diagnosis of typhoid should rest in the rather gradual
onset of a continued fever, with a rather apathetic toxaemia. Of
course atypical cases may have a fairly abrupt onset. An important
point in the diagnosis is the rather slow pulse rate for the
temperature elevation.

_Marris Atropine Test._—Manson-Bahr regards the Marris atropine
test as of the utmost value in the diagnosis of the enteric
group of fevers. In this test one gives a hypodermic injection
of grain 1/50 of atropine sulphate. Should the case be typhoid
or paratyphoid the pulse rate is practically uninfluenced during
the period from 25 to 50 minutes after the injection. In other
infections or in normal individuals, the pulse rate drops at first
but after 10 or 15 minutes rises to exceed the pulse rate before
the injection by 30 or 40 beats during the period of 25 to 50
minutes following the injection.

In the laboratory tests the prime reliance must be placed in blood
culture, which of course should be made during the first ten
days of the illness. Blood cultures give positive results in the
inoculated as well as in those not protected by vaccination.

Agglutination tests are the ones of choice after such a period, but
one must discount agglutination in those who have been vaccinated
previously. Of course the rising agglutination titre during the
course of the disease gives valuable information, and the Dreyer
technique, where simultaneous tests are made on emulsions of
typhoid, paratyphoid A and paratyphoid B at intervals of 4 days,
noting a distinct rise for one of these organisms, is based on this
factor. At the same time this technique is exacting and does not
seem to have given the results that were at first expected.

Culturing the urine is of more value in diagnosis than that of the
faeces. Bacilluria may be expected in about one-fifth of cases
after the second week. Faeces culturing gives positive results in a
smaller proportion of cases and is attended with much difficulty.

_The Paratyphoid Fevers._—The paratyphoids would seem to be
more prevalent, in proportion to typhoid, in the tropics than
in temperate climates, thus in India, of 1886 British soldiers,
convalescent from enteric fevers, 791 were diagnosed as typhoid,
633 as paratyphoid A, 136 as paratyphoid B and 326 as enteric cases
of uncertain etiology. Paratyphoid B cases seem more frequent in
temperate climates than paratyphoid A ones, as noted during the
war in France. Cruickshank, and Lafrenais, in a study of carriers,
among the 1886 cases noted above observed that 49 became carriers
and of these 34 were from paratyphoid A cases, 9 from typhoid
convalescents and 6 from paratyphoid B convalescents. Of 13 chronic
carriers (those carriers excreting organisms after a period of six
months) 8 were carriers of paratyphoid A, 4 of typhoid and 1 of
paratyphoid B.

This evidence would indicate that paratyphoid A, once introduced,
would spread more widely than the other enteric affections.

Clinically, paratyphoid A cases resemble typhoid ones rather
closely, although as a rule less severe in course. With paratyphoid
B the course is less severe than with the other enteric organisms
but it often shows an abrupt onset and is frequently similar to
cases of meat poisoning. This organism and the Gärtner bacillus
are common excitants of the so-called ptomaine poisoning cases.
Paratyphoid B cases show a tendency to localize in the pelvis of
the kidney or elsewhere and may cause a broncho-pneumonia.

_Colon Infections._—Such infections seem to be rare in temperate
climates other than as localized conditions especially of the
urinary bladder. Cholecystitis is not infrequently due to a colon
bacillus infection. In the tropics, however, especially following
bacillary dysentery, we may have a generalized infection which may
result in a fatal septicaemia. In such cases abscess formation in
the kidneys is usually found.

Cases diagnosed as mild typhoid fever have as a result of blood
cultures been found to occasionally be due to a colon bacteriaemia.

In temperate climates as well as in the tropics pyelitis is often
due to a colon infection and probably 10% of cases of appendicitis
are caused by the colon bacillus alone, although it is extremely
frequent in association with streptococci or staphylococci.

_Bacillus alkaligines faecalis_ infections. Cases similar to
typhoid fever have been found to be due to infections with this
member of the typhoid-colon group of organisms.

=Tuberculosis.=—The negro race seems to possess a greater susceptibility to tuberculosis than the white one, a fact well recognized in the United States, where the colored population suffers far more severely than their white neighbors. The yellow races also show marked susceptibility to the scourge and in the Philippines it is easily the greatest cause of death.

In tropical regions the natives of the sea-level regions suffer
more than those of the mountain plateaus and where the humidity is
high rather than in arid sections. Thus tuberculosis is very rare
or almost unknown in the dry desert-like regions of upper Egypt and
the Sahara desert.

The disease gains headway in the rainy season and diminishes in
prevalence during the dry season.

One factor in the great spread of the disease is the intimate
contact of natives living together in a small room.

It is generally recognized that susceptibility is greater in childhood and that infection by way of the alimentary tract is common in children.

When one notes the habit of expectorating anywhere and everywhere
on the part of people untrained in hygienic rules, it is easy
to recognize the opportunity babies and young children have of
ingesting tuberculous material taken up on their hands while they
are crawling about.

During the war there was a great deal of tuberculosis among the
native African troops serving in France, and a study of the disease
in these men has furnished us information as to the existence
of two clinical types among them. In the soldiers from Morocco
and Algiers, the type observed was similar to that occurring in
Europeans, and this was explained on the basis of the opportunity
that had been given the people of the areas from which the troops
came to acquire tuberculosis from contact with white colonists and
during a period of many years to have acquired a certain degree of
resistance to the invasion of the tubercle bacillus.

In connection with the Senegalese troops and some others coming
from sections of Africa where tuberculosis was rare or nonexistent
another type was observed which corresponded with the tuberculosis
one sees in a young child or a guinea pig.

In these cases the disease starts with enlargement of the glands
at the roots of the lungs. This finding of course would require
an X-ray plate but it was found that the enlargement of the
supraclavicular glands at a point near the insertion of the
sternocleidomastoid was one of the best early signs. The glandular
stage lasted about five to ten weeks during which time the general
health did not seem to be materially impaired. Following this stage
and lasting only about two weeks or up to two months a stage of
generalized tuberculosis sets in with fever, emaciation, caseous
pneumonia or manifestations of miliary tuberculosis. There was
no tendency to fibrosis or cure of the process, death almost
invariably occurring. Borrel, who studied the disease in these
natives, states that if put at rest and placed on a generous diet,
while the case is in the glandular stage, one-half of them may
recover. It was noted that sputum examinations of these cases were
almost invariably negative.

=Smallpox.=—This disease may justly be considered the greatest scourge of the natives of tropical countries. It is responsible for much of the blindness noted in natives of sections where vaccination has not been employed.

In some of the countries of the Orient smallpox kills more people
than cholera, plague and dysentery together. Many reports have
shown that as many as 80 to 90% of a native population may be
attacked in an outbreak and of these practically one-half die. In
such communities the disease is more one of young children, the
adults possessing a certain degree of immunity from attacks in
childhood during previous epidemics. It has frequently been noted
that the native colored races do not seem to acquire as marked an
immunity as is observed among the white races of temperate climates
following an attack of the disease. Again it has been insisted
that the immunity following vaccination is not as marked as that
obtaining in European countries. This point would seem not well
founded because efficient and universal vaccination has apparently
caused smallpox in the Philippines to be of no more importance
than it is among any other well vaccinated people. It is striking
to note the great number of pitted faces among adult Filipinos,
whereas this condition is practically absent in the generation
following the general vaccination introduced by the Americans.

In tropical natives the most severe forms of smallpox are observed—confluent and haemorrhagic.

Opportunities for the spread of the disease are most favorable in
many parts of the tropical world by reason of intimate association,
religious festivals and pilgrimages.

Under the name _alastrim_ or Kaffir milk-pox, a disease similar
to a mild form of smallpox has been reported from Africa and the
West Indies. Various points were raised to differentiate it from
smallpox, but in a recent epidemic in Jamaica and Haiti proof was
adduced to demonstrate its identity with smallpox. In Haiti the
epidemic was controlled by vaccination with smallpox vaccine, and
those individuals exposed to the infection but properly vaccinated,
uniformly escaped. Among the soldiers of the Marine Corps in Haiti
there were only two cases and these occurred in men who gave no
evidences, of successful vaccination.

=Varicella.=—This disease is of common occurrence in the tropics and does not seem to give rise to greater mortality than it does in temperate climates.

In the Philippines I have been struck by the resemblance it bears
to cases of varioloid, inasmuch as we frequently note as numerous
lesions on the face as on the body. In fact I have been sure that
the pustular lesions of the face of such cases were those of
smallpox, until I noted typical varicella lesions on the body.

=Mumps.=—This disease is found in many parts of the tropics and presents similar features to the epidemic parotitis of temperate climates.

In the Philippines there seem to be cases similar to mumps but
without the contagious feature so characteristic of the disease in
Europe.

=Glanders.=—This rare disease of Europe and the United States seems to be much more common in many tropical countries. In the Philippines it generally shows itself in the acute form and is much dreaded by reason of its great infectiousness.

=Diphtheria.=—Formerly there was an idea that diphtheria, like scarlet fever, was extremely rare or unknown in the tropics.

The assistance of the laboratory has shown that this old idea is
incorrect and that the disease is fairly prevalent in many tropical
regions.

=Vincent’s Angina.=—While not rare in temperate climates, various affections of the oral mucous membrane due to the fusiform bacillus in symbiosis with various species of spirilla are fairly common in the tropics. The best known condition is one in which the tonsils show somewhat the appearance of a follicular tonsillitis but ulceration is more common and severe, with however, less evidence of toxaemia.

The temperature in a case of pure Vincent’s Angina rarely exceeds
101°F. but if there is a mixed infection with other pyogenic
organisms the temperature and other signs of a severe infection
may be more marked. There is usually more or less swelling of
tributary glands. Associated with the angina or alone we may
have a gingivitis in which the spongy gums more or less resemble
those of scurvy or of pyorrheoa alveolaris. In fact these Vincent
organisms have been considered as factors in the development of
pyorrhoea alveolaris. In the tropics there have been many reports
of organisms of the type of those described by Vincent occurring in
skin ulceration or affection of the mucous membranes other than the
oral ones, more particularly the pudendal mucous membranes.

The infections are readily and easily diagnosed by a smear stained
with any simple aniline dye. Care must be taken not to accept such
a finding as the sole cause, as an underlying diphtheria, syphilis
or other dyscrasia may be more important.

=Malignant Tumors.=—It is usually stated that malignant tumors are very rare among tropical natives. The proper solution of this question, however, is complicated by the frequent lack of careful autopsies.

=Pneumonia.=—Just as with the tubercle bacillus so does the black race seem to have less resistance to the _Pneumococcus_ than does the white one.

Great engineering works employing tropical natives are frequently
associated with very fatal epidemics of pneumonia, especially
broncho-pneumonia. Again in the black races the infection tends to
become generalized rather than localized in the lungs. It is more
toxic and insidious in its course than is true of the infection in
the white man; it has the fatal trend of pneumonia of the aged.
Another tendency is to invasion of the meninges.

=Influenza.=—In temperate climates we associate this disease with bronchial and coryzal manifestations. In the tropics types almost unrecognized in Europe are noted, especially the gastro-intestinal and nervous ones. The similarity in the clinical picture of dengue with slight eruption and tropical influenza is striking.

During the recent pandemic of influenza there was a frequent
complication of influenza pneumonia; many of these influenza
bronchopneumonias resembled plague pneumonia.

=Tetanus.=—This infection is far more prevalent in tropical than in temperate climates. It is particularly fatal to infants, the infection occurring from errors in the dressing of the cord at the time of childbirth.

=Syphilis and Other Venereal Diseases.=—Syphilis is rampant in many parts of the tropical world. Jeanselme has noted that syphilis among tropical natives often starts with an extra-genital lesion which tends to become phagedenic and that the secondaries are but slightly marked. It is in the tertiary stage that the disease shows itself in its malignancy.

All tropical workers have noted the absence of tabetic and paretic
manifestations in the native syphilitics. LeDantec notes that he
has not observed parasyphilis in any European who had contracted
syphilis from a native woman and brings up the question of a
difference in strains of syphilis.

The American Naval Surgeons at Guam and Samoa have been struck
with the absence of primary lesions of syphilis among the natives
of these islands and Butler has suggested that this is due to an
immunity received as result of contracting yaws in childhood. There
certainly are many reasons for considering syphilis and yaws as
closely related.

_Soft chancre_ is common in many tropical seaports and shows itself in a rather virulent form. In particular it is apt to be complicated by suppurating buboes.

In _tropical gonorrhoea_ it would seem that involvement of the testicles is more common than in temperate climates.

=Endocrine Disturbances.=—Internists in all parts of the world are beginning to appreciate that many of the puzzling complaints of ill-health are connected with abnormal functioning of the ductless glands. The conditions resulting from excessive or diminished functioning of the thyroid gland are well understood and the determination of the basal metabolism rate is now a standard laboratory procedure. There are many types of apparatus on the market and the determination is within the reach of any hospital staff.

Hyperthyroidism is now rarely unrecognized as is also true of myxoedema but sub-states of thyroid functioning are less frequently recognized.

McCarrison has stressed the importance of endocrine disturbances
in dietetic deficiencies and notes atrophy of all the glands
of internal secretion in such conditions with the exception of
the adrenal which tends to hypertrophy. There is possibly some
hypertrophy of the pituitary in males. The oedema which accompanies
most of the food deficiency diseases he associates with the adrenal
enlargement and hyperactivity of function, although oedema does
not invariably result from such hypertrophy. In pellagra there is
a low blood pressure, possibly due to adrenal hypofunction. Goitre
is found in many parts of the tropical world and Castellani states
that this disease is met with frequently in Ceylon and various
regions of Africa. Disturbances of the internal secretion of the
pancreas, resulting in diabetes, are common in parts of Asia.

_Determination of Basal Metabolism_.—In the study of cases where abnormal thyroid functioning is suspected the most accurate method of such determination is by estimating the percentage of the patient’s metabolism as above or below the normal average.

Basal metabolism is that caloric value which an individual produces
while resting in bed and prior to taking breakfast—in other words
when the effects of food and exercise on caloric output are least
operative. Basal metabolism is expressed in terms of calories per
hour per square meter of body surface. It varies with different
ages. It is proportionate to body surface which is calculated
from the height and weight of the individual. Normally this
metabolism should not vary more than 15% above or below accepted
normal figures. The use of the respiration calorimeter is the most
accurate method for determination of heat production but it has
now been found that the oxygen consumption during short periods
gives data for calculation of such heat production (indirect
calorimetry). In the Benedict portable respiration apparatus
the patient breathes into and out of a confined volume of air
circulating through a series of purifiers which remove the carbon
dioxide. A determination of the volume of oxygen consumed is made
from the decrease in the total air volume. The heat production
resulting from the absorption of one litre of oxygen is relatively
constant whether used to burn fat or carbohydrate and gives an
accurate index of total heat production. The Benedict apparatus
can also be employed for determining carbon dioxide excretion and
thereby giving data for the respiratory quotient. The determination
of the heat produced in the excretion of carbon dioxide is less
accurate although easier of determination. In marked cases of
hyperthyroidism the basal metabolism ranges 75% above the normal
figures, between 50 and 75% for severe cases and less than 50% for
mild cases. In hypothyroidism the figures are usually 20 to 40%
below the normal averages. The average respiratory quotient is
taken as O.82 and the calorific value of oxygen at this respiratory
quotient is 4.825 per litre. We multiply the litres of oxygen
by 4.825 to compute the heat output. It must be remembered that
patients with high fever give 30 to 40% heat production over normal
figures. Severe cardiac and renal conditions as well as leukaemias
also give high values. The average calorie output per square meter
of body surface per hour based on the Du Bois “height-weight”
formula, is 39.7 for man and 36.9 for women between the ages of 20
and 40, being greater in youth and less beyond forty.

=Focal Infections.=—In recent years our attention has been directed to the importance of certain localized bacterial foci which may extend through blood or lymph channels and give rise to various systemic or localized diseases. Most important of these diseases are various types of arthritis together with endocarditis, myocarditis and pericarditis. Next in importance are renal infections, chiefly of the glomerulonephritis type.

Cholecystitis, appendicitis, pancreatitis and various skin lesions
may also have origin in a focal infection. The primary foci may be
localized in any part of the body but those seated in the tonsilar,
peridental membrane, nasal and accessory sinus tissues are the
most common and important. Focal infections of the genito-urinary
tract may also give rise to generalized conditions as is also
true of such foci in the alimentary tract. In the tonsils we
should particularly examine the material of crypts for various
streptococci and likewise the bacterial flora of tooth abscesses or
pyorrhoea alveolaris.

TABLE SHOWING NUMBER OF TIMES EACH FOCUS WAS CONSIDERED A PROBABLE SOURCE OF INFECTION IN A SERIES STUDIED BY BILLINGS AND ASSOCIATES

No.
Tonsil 336
Teeth 136
Sinus 12
Bronchi 5
Uterus and tubes 12
Prostate and genito-urinary tract 24
Gallbladder 3
Enterocolitis 2
Appendix 1
Middle ear 1