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

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