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Chapter 7, Part 4

Medical Science Publication No. 4, Volume II



The final subject on the program for this afternoon is smallpox. There are a number of points about this disease that make it particularly interesting to the epidemiologist. It is a dramatic, serious and, in this country, uncommon disease. There is a very satisfactory method of evaluating the immunity status of the population that may be exposed to the disease. The pathologic anatomy of the disease and the morbid physiology are known in detail. (There has been very little added to the original material published by 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 first observed, but sooner or later the true diagnosis will become apparent, perhaps at autopsy, or in retrospect due to secondary cases occurring as a result of exposure. There are very adequate diagnostic procedures which are available in almost all Army Area Laboratories and overseas laboratories.

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

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

In any discussion of communicable diseases in the Army, it is essential that consideration be given to the immunity status of the exposed populations. Despite the desirability of this knowledge, our firm information is scanty in 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 few paragraphs is drawn from the work of Paul and associates (3).

In 1951, recruits at Army, Navy and Air Force reception stations were studied to determine their immunity status for several diseases. Smallpox was one of these, and the response to vaccination was used as a tool. Of approximately 2,300 recruits studied, vaccination was followed by a primary response in about 20 percent, and an accelerated response was noted in another 50 percent. Individuals drawn from rural areas showed a slightly higher response than did those from urban areas. (Because there is an exceedingly low incidence of smallpox in this country, these results reflect most probably the 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 pungent footnote which reads as follows: "It appears that while this survey was in progress only occasionally was there an official reading of a recruit's vaccination responses in the Army" (3).

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

Table 1. Smallpox in U. S. and U. N. Personnel (Military and 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 and December 1952, but in the early part of 1953 scattered, isolated cases occurred.

Certain of the American cases encountered in 1950-51 will have a familiar sound to those of you who have seen smallpox elsewhere in the Army. The same difficulty in diagnosis that has been repeatedly encountered was again apparent.

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

Helpful in the differential diagnosis is the fact that smallpox is usually ushered in by signs of a severe systemic disease. Frequently there is a very marked backache. Abdominal pain is so severe in some instances that laparotomies have been done. The temperature is elevated and with the appearance of the rash, the temperature usually drops. There may be a prodromal rash occurring prior to the development of true vesicles or papules which may mimic almost any other type of cutaneous eruption or other systemic manifestation of disease. In certain cases, this prodromal rash is followed directly by the development of purpura. These purpuric lesions occur before the typical clinical signs of the disease become manifest, and constitute a syndrome referred to variously but usually as purpura variolosa.

The prognosis, if purpuric signs develop, is very poor. I would make one plea here. In patients dying with purpuric manifestations and high fever, there should be obtained adequate sections of the skin. Despite the fact that the typical vesicular lesion of smallpox is not apparent to the naked eye, it can be detected by histologic examination, and may well be the only method available of arriving at a definite diagnosis short of waiting to see whether additional secondary cases occur. There is another form of the purpuric disease which may occur after the vesicles have developed, and which may eventually spread to such an extent that practically the entire skin becomes separated into two layers as the result of hemorrhagic vesicular fluid.

Purpura variolosa is almost always fatal and constitutes the type of disease 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 difference in the virus as it occurs in that part of the world in contrast to that elsewhere. It is sufficient to say that beginning with our troop experience in Siberia in World War I hemorrhagic forms of the disease have been common in 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 that this was smallpox, the normal procedure of vaccinating all members of the command was carried out. About 1,800 vaccinations (6) were performed, including some 800 patients. They were all Americans and they were all Americans who presumably had been immunized prior to their departure from the United States. There had also been, in the preceding fall of that year, an active immunization program throughout Japan proper. The readings obtained are to me of particular importance. Of the group vaccinated in March 1951, some 5 percent showed a primary response, and about 25 percent were read as an accelerated response. These results are subject to only one interpretation-that 5 percent represents a medical failure to adequately use a satisfactory immunizing procedure.

After this winter of 1950-51, smallpox did not constitute a particular problem during the remainder of the Korean conflict insofar as American troops were concerned. This, as is usually the case, was probably brought about to a considerable extent by an active immunizing program, involving millions of Korean Nationals (7), so that the chance of exposure was materially reduced.

This presentation may be summarized with the following statements:

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

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

Notwithstanding the fact that all personnel presumably had been protected by 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 preventive measure . . . . We should not be content, however, with the extraordinarily good results obtained, but should strive to eliminate the disease altogether. Insofar as the Military Service is concerned, an approach to this ideal is contingent primarily upon two factors: the development of a vaccine virus that will retain its potency for a considerable length of time after exposure to continuously high atmospheric temperature and perfection of a vaccination technique that will assure a higher percentage of positive results.


This summary was extracted verbatim from the Medical History of World War I (8) and it applies just as adequately to the Korean conflict as 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 effects of the variolae vaccinae, a disease discovered in some of the western counties of England, particularly Gloucestershire, and known by the name of the cow pox, 1798. Reprinted by Cassell and Company, Ltd., 1896. Available in Pamphlet Vol. 4232, Army Med. Library, Washington, D. C.

3. Paul, J. R., and Liao, S. J.: Virus and Rickettsial Commission Annual Report, April 1952, Report (No. 2) on the Immunity Survey in 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 Vaccinia in Viral and Rickettsial Infections of Man, 2d Ed. J. B. Lippincott Co., 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 The Medical 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 American soldier was absolutely a direct professional failure to be laid at the door of some physician. Perhaps the officer does not vaccinate the troops, but the facts are that it is some medical officer's responsibility to see that the troops are vaccinated properly and that responsibility cannot be 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 date of 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 vacant or the word "immune" was entered in 100 percent of the cases of smallpox in which we were able to get the records. In other words, the failure was not recognized and, if it was, it was not followed up. There is one way to do it and that is to vaccinate as often as necessary until you get a successful reaction.

Will American vaccine protect against this highly virulent Oriental virus? 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 immunity is desirable and that is one of the reasons why in Korea vaccination is done every 6 months. The other reason is that people fail to vaccinate properly, and by doing it every 6 months, there


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

Colonel Tigertt. I suppose I have the unenviable record of having autopsied more cases of smallpox than anyone else in the room. In about 25 fatal cases, I have never been able to find any evidence of a primary scar in the individuals who died, whether it was looked for before death or at autopsy. I have talked with a number of other people who expressed essentially similar findings. Now, patients who have been properly vaccinated as judged by the presence of a scar, will sometimes develop a fairly severe form of the disease, and immunization after exposure may result in the concomitant development of both the lesion from the vaccine and the disease itself. In that instance, I have seen fatalities, despite the fact that there was a well-developed vaccine vesicle. Again, I would like to come back to the original statement, that I have never seen death from smallpox in an individual who was carrying a recognizable healed vaccine scar.