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Medical Science Publication No. 4, Volume II



The final subject on the program for this afternoon is smallpox. Thereare a number of points about this disease that make it particularly interestingto the epidemiologist. It is a dramatic, serious and, in this country,uncommon disease. There is a very satisfactory method of evaluating theimmunity status of the population that may be exposed to the disease. Thepathologic anatomy of the disease and the morbid physiology are known indetail. (There has been very little added to the original material publishedby Councilman, et al. (1), about the turn of the century.)It is practically impossible to miss a correct diagnosis in the long run.The index of suspicion is frequently not high enough when the case is firstobserved, but sooner or later the true diagnosis will become apparent,perhaps at autopsy, or in retrospect due to secondary cases occurring asa result of exposure. There are very adequate diagnostic procedures whichare available in almost all Army Area Laboratories and overseas laboratories.

Another thing that makes the disease of particular interest is thatwe have a practically perfect immunizing agent against it. (While we arerecounting the history of this disease in terms of half centuries, I wouldrecall to you that we have had this method of immunization (2) availableto us for about 150 years.)

Finally, one of the finite points pertaining to the study of this diseaseis that the method of immunization leaves, in almost all cases, a recognizablescar on the individual concerned, so that it is not necessary to referto the immunization register to determine whether the individual had been,in fact, vaccinated. When this has been done, the results recorded on themilitary immunization register frequently are erroneous.

In any discussion of communicable diseases in the Army, it is essentialthat consideration be given to the immunity status of the exposed populations.Despite the desirability of this knowledge, our firm information is scantyin many diseases. For smallpox, certain

*Presented 29 April 1954, to the Course on Recent Advances in Medicine and Surgery, Army Medical Service Graduate School, Walter Reed Army Medical Center, Washington,
D. C.


studies have been conducted. The information described in the next fewparagraphs is drawn from the work of Paul and associates (3).

In 1951, recruits at Army, Navy and Air Force reception stations werestudied to determine their immunity status for several diseases. Smallpoxwas one of these, and the response to vaccination was used as a tool. Ofapproximately 2,300 recruits studied, vaccination was followed by a primaryresponse in about 20 percent, and an accelerated response was noted inanother 50 percent. Individuals drawn from rural areas showed a slightlyhigher response than did those from urban areas. (Because there is an exceedinglylow incidence of smallpox in this country, these results reflect most probablythe potency of the vaccine used, the technic of vaccination, and the frequency.)In the description of how the study was carried out, there is a pungentfootnote which reads as follows: "It appears that while this surveywas in progress only occasionally was there an official reading of a recruit'svaccination responses in the Army" (3).

With this knowledge of the immunity status and with the belief thatthe nonimmune recruits were vaccinated successfully, we can now profitablyreview the actual incidence of smallpox in the Far East. Most of the casesthat were reported were during the winter of 1950-51, occurring generallyfrom about October through April, with one or two cases tailing into thesummer (table 1) (4). There were a total of 40 cases in United Nationspersonnel, with 14 occurring in Americans. These figures do not includecases in ROK troops. It is considered that all except one were contractedin Korea. Please note the use of the term "contracted" becausesome were actually recognized at a considerable distance from Korea. Ofthe 40 recognized cases, there were 14 deaths. It is known that duringthis winter, some 35,000 cases occurred amongst the Korean Nationals. Therewere 22 cases reported in Chinese and North Korean prisoners of war. No

Table 1. Smallpox in U. S. and U. N. Personnel (Militaryand Civilian - less ROK)


Oct. 1950


Nov. 1950


Dec. 1950




Jan. 1951


Feb. 1951


Mar. 1951


Apr. 1951


May 1951




June through Dec. 1951


Jan. through Dec. 1952


Jan. 1953


Feb. 1953


Mar. 1953


Apr. 1953


May 1953


June 1953





cases were observed in United Nations personnel between June 1951 andDecember 1952, but in the early part of 1953 scattered, isolated casesoccurred.

Certain of the American cases encountered in 1950-51 will have a familiarsound to those of you who have seen smallpox elsewhere in the Army. Thesame difficulty in diagnosis that has been repeatedly encountered was againapparent.

A frank case of smallpox in the pustular form is practically impossibleto miss; however, in the early stages of the disease, it can be and wasconfused with a great many other entities. (Various lantern slides of patientsfrom Korea and Japan were used to illustrate this portion of the presentation.)Almost any good textbook (5) has an adequate description of thedisease.

Helpful in the differential diagnosis is the fact that smallpox is usuallyushered in by signs of a severe systemic disease. Frequently there is avery marked backache. Abdominal pain is so severe in some instances thatlaparotomies have been done. The temperature is elevated and with the appearanceof the rash, the temperature usually drops. There may be a prodromal rashoccurring prior to the development of true vesicles or papules which maymimic almost any other type of cutaneous eruption or other systemic manifestationof disease. In certain cases, this prodromal rash is followed directlyby the development of purpura. These purpuric lesions occur before thetypical clinical signs of the disease become manifest, and constitute asyndrome referred to variously but usually as purpura variolosa.

The prognosis, if purpuric signs develop, is very poor. I would makeone plea here. In patients dying with purpuric manifestations and highfever, there should be obtained adequate sections of the skin. Despitethe fact that the typical vesicular lesion of smallpox is not apparentto the naked eye, it can be detected by histologic examination, and maywell be the only method available of arriving at a definite diagnosis shortof waiting to see whether additional secondary cases occur. There is anotherform of the purpuric disease which may occur after the vesicles have developed,and which may eventually spread to such an extent that practically theentire skin becomes separated into two layers as the result of hemorrhagicvesicular fluid.

Purpura variolosa is almost always fatal and constitutes the type ofdisease seen in some 10 percent of the American cases in the Far East (4).We will not stop here to go into the discussion of whether there is a differencein the virus as it occurs in that part of the world in contrast to thatelsewhere. It is sufficient to say that beginning with our troop experiencein Siberia in World War I hemorrhagic forms of the disease have been commonin that area of the world.

One of the cases depicted in the lantern slides you have just seen oc-


curred in a hospital in Japan in March 1951. Following recognition thatthis was smallpox, the normal procedure of vaccinating all members of thecommand was carried out. About 1,800 vaccinations (6) were performed,including some 800 patients. They were all Americans and they were allAmericans who presumably had been immunized prior to their departure fromthe United States. There had also been, in the preceding fall of that year,an active immunization program throughout Japan proper. The readings obtainedare to me of particular importance. Of the group vaccinated in March 1951,some 5 percent showed a primary response, and about 25 percent wereread as an accelerated response. These results are subject to onlyone interpretation-that 5 percent represents a medical failure to adequatelyuse a satisfactory immunizing procedure.

After this winter of 1950-51, smallpox did not constitute a particularproblem during the remainder of the Korean conflict insofar as Americantroops were concerned. This, as is usually the case, was probably broughtabout to a considerable extent by an active immunizing program, involvingmillions of Korean Nationals (7), so that the chance of exposurewas materially reduced.

This presentation may be summarized with the following statements:

The diagnosis of smallpox is neither simple nor certain, prior to theappearance of the eruption. Even then it may offer considerable difficultyif the number of lesions is small. In mild cases, occuring sporadically,the difficulty is increased.

During the vesicular and pustular states, differential diagnosis ordinarilyoffers no great difficulty to persons conversant with smallpox when therash is typical, but few medical officers in the Army were clinically conversantwith smallpox in atypical form . . . and there was difficulty in diagnosis.

Notwithstanding the fact that all personnel presumably had been protectedby vaccination, or re-vaccination prior to departure from the United States,a large percentage of the personnel re-vaccinated gave positive reactions.

Vaccination against smallpox . . . was highly successful as a preventivemeasure . . . . We should not be content, however, with the extraordinarilygood results obtained, but should strive to eliminate the disease altogether.Insofar as the Military Service is concerned, an approach to this idealis contingent primarily upon two factors: the development of a vaccinevirus that will retain its potency for a considerable length of time afterexposure to continuously high atmospheric temperature and perfection ofa vaccination technique that will assure a higher percentage of positiveresults.


This summary was extracted verbatim from the Medical History of WorldWar I (8) and it applies just as adequately to the Korean conflictas it does to 1917.


1. Councilman, W.T., Magrath, G. B., and Brinckerhoff,W. R.: The Pathological Anatomy and Histology of Variola. J. Med. Res.11 : 12-135, 1904.

2. Jenner, E.: An inquiry into the causes and effectsof the variolae vaccinae, a disease discovered in some of the western countiesof England, particularly Gloucestershire, and known by the name of thecow pox, 1798. Reprinted by Cassell and Company, Ltd., 1896. Availablein Pamphlet Vol. 4232, Army Med. Library, Washington, D. C.

3. Paul, J. R., and Liao, S. J.: Virus and RickettsialCommission Annual Report, April 1952, Report (No. 2) on the Immunity Surveyin Recruits in the Three Armed Services Carried out during April-June 1951.

4. Annual Report: 406th Medical General Laboratory, 1951.Pages 1-7 and 94.

5. Smadel, J. E.: In Rivers, T. M.: Smallpox and Vacciniain Viral and Rickettsial Infections of Man, 2d Ed. J. B. LippincottCo., Philadelphia, 1952.

6. Huber, Tyron E., Lieutenant Colonel, MC: Personal communication.

7. Long, Arthur P., Colonel, MC: Personal communication.

8. Siler, J. F., and Michie, H. C.: Smallpox in TheMedical Department of the United States Army in the World War, Vol. IX,pages 379, 380, 383, 384; 1928.


Colonel Long. Every case of smallpox that occurred in an Americansoldier was absolutely a direct professional failure to be laid at thedoor of some physician. Perhaps the officer does not vaccinate the troops,but the facts are that it is some medical officer's responsibility to seethat the troops are vaccinated properly and that responsibility cannotbe delegated. What do these immunization registers look like? Without fail,they show one of two things on all of these cases. You would see a dateof vaccination, and you would see the initials in the right-hand column.Now the middle column is there to show the type of reaction. It was vacantor the word "immune" was entered in 100 percent of the casesof smallpox in which we were able to get the records. In other words, thefailure was not recognized and, if it was, it was not followed up. Thereis one way to do it and that is to vaccinate as often as necessary untilyou get a successful reaction.

Will American vaccine protect against this highly virulent Orientalvirus? Of course it will. Obviously if it were not so, instead of 40 cases,it would have been 4,000 cases. Perhaps a somewhat higher level of immunityis desirable and that is one of the reasons why in Korea vaccination isdone every 6 months. The other reason is that people fail to vaccinateproperly, and by doing it every 6 months, there


is fair reason to assume that we get a good vaccination every year ortwo.

Colonel Tigertt. I suppose I have the unenviable record of havingautopsied more cases of smallpox than anyone else in the room. In about25 fatal cases, I have never been able to find any evidence of a primaryscar in the individuals who died, whether it was looked for before deathor at autopsy. I have talked with a number of other people who expressedessentially similar findings. Now, patients who have been properly vaccinatedas judged by the presence of a scar, will sometimes develop a fairly severeform of the disease, and immunization after exposure may result in theconcomitant development of both the lesion from the vaccine and the diseaseitself. In that instance, I have seen fatalities, despite the fact thatthere was a well-developed vaccine vesicle. Again, I would like to comeback to the original statement, that I have never seen death from smallpoxin an individual who was carrying a recognizable healed vaccine scar.