The aetiology of desert sore

909

~'['ftANSACTIONSOF THE .~[OYALSOCIETY OF TROPICAL MEDICINE A N D HYGEINE. Vo[. 40. No. 6. July, 1947.

CORRESPONDENCE. YAWS

AND

SYPHILIS.

~Ib the Edito'f, TRANSaCTtONS of the Royal Society of Tropical Medicine and Hygiene. SIR, W i t h r e f e r e n c e to t h e d i s c u s s i o n o n Yaws a n d S y p h i l i s in t h e TRANSACTIONS (1946) 4 0 , 206, t h e f o l l o w i n g e x t r a c t f r o m ItAC,C~ARD'S Devils, Drugs and Doctors* m a y b e o f i n t e r e s t :--" One of the earliest records of tropical medicine was made by Gonsala Fernandez de Oviedo. He was raised among the pages in the palace of King Ferdinand and Quee~l Isabella [of Spain], and was at Barcelona in 1493 when Columbus returned from the island of Haiti. H e was intimately acquainted with most of the men who had made the voyage and many of them he knew were ill of a disease which they had contracted in America Twenty years after Columbus's voyage, Ferdinand sent Oviedo to America as superintendent over the gold and silver mines. After a residence of twelve years, Oviedo wrote a natural history of the Spanish possessions and dedicated it to Emperor Charles V. He describes a disease known as bubas, or yaws, which he says is a very ancient disease in those localities. Oviedo identifies bubas with syphilis, for, he says, bubas is ' n o other than the pocks (syphilis) which rageth and hath power over all Europe, especially among the Frenchmen . . . I can assure your Imperial Majesty that this disease which is new in Europe, is well known in the Antille islands lately discovered, and so very common there that almost everyone of the Spaniards who lay with the Indian women contracted it from them.' T h u s it was imported from thence into Spain by those who returned with Columbus after his first or second voyage." ~[ am~ etc.,

J. WALKER TOMB, Sydney, New South Wales * H^GC,AaV,

H.

W

pp. 236, 237.

THE

(t929)

Devils, O~-ug~ and Doc~t~.,'s New Yock ~[a~:~e~

AETiOLOGY

OF

DESERT

SORE.

SIR, As a f e l l o w amateu~ w i t h o n i y a v e r y b r u i t e d a c q u a i n t a n c e ¢¢ith statist~cai m e t h o d s , o n e f e l t s o m e h e s i t a t i o n in c r i t i c i z i n g L i e u t . - C o l . S, T . ANN~NO"S r e c e n t p a p e r in y o u r j o u r n a l (Trans. R. Soc. trop. Med. Hyg., ~A), 313). [qo,~ever, in t h e a b s e n c e o f m o r e e x p e r t i n t e r v e n t i o n , it is felt t h a t t h e statisticai t r e a t m e n t o f his m a t e r i a l c a n n o t b e a l l o w e d to pass w i t h o u t c o m m e n t I n t h e first place, his i n t r o d u c t i o n o f t h e i d e a o f p r o p o r t i o n s is h a ; d l ? a p p r o p r i a t e to t h e p a r t i c u l a r t y p e of e x p e r i m e n t , i t m u s t in a n y c a s e b e p o i n t e r

910

cOFtlt ES PONDE.N CE

out that, whereas Col. ANNING rightly states on p. 325 that p and q in his fimnula represent proportions, in his calculation he incorrectly substitutes absolute numbers of cases. In this particular instance the result arrived at is the same ; but it would be unfortunate if others copied his temptingly simple arithmetic, which might not always lead to a result so close to the correct answer. However, the question at issue being whether or not cases receiving vitamin supplements heal on an average more rapidly than those without, the significance of the observed difference should surely have been tested by the formula :--~ Standard error of difference of Means =

/ -_ -j..... ,V /

nI

n2

where cr is the standard deviation of all observations in the two samples combined, and na and n2 are the respective numbers in the two samples (BRADFORD HILL'S Medical Statistics, p. 75). The published data do not, unfortunately, permit the application of this test, since Colonel ANNINC has not thought it necessary to include a table of individual data, as recommended by BRADFORDHILL (Ibid., p. 21) ; and the standard deviation cannot therefore be calculated. A further point that calls for criticism is the inclusion, in one group, of cases treated by several different therapeutic measures (viz. C alone, A alone, and A and C combined). Finally, one's experience of ulcers in general would lead one to expect the time required to produce complete healing, in a group of otherwise healthy young adults, to depend on a number of factors, including at least : - (i) The virulence of any organisms present and their sensitivity to variation in biological conditions, including contact with therapeutic substances. (ii) The duration of the ulcer before commencement of the test, as affecting its depth and the degree of cellular reaction produced. (iii) The area of the ulcer at the commencement of the test, this being not entirely accounted for by (ii). (iv) The nature of the treatment employed. Only after satisfying oneself that factors (i) to (iii) are equally represented in all groups can one reasonably proceed to test statistically the effects of (iv). The present paper presents no evidence that steps were taken to provide for such equal distribution ; and in view of the small samples employed it is highly unlikely that this would have established itself by chance. One is accordingly :forced to the conclusion that the material in question, though interesting and suggestive, is quite unsuitable fi~r applying statistical tests to the author's hypothesis. am, etc.,

J. i. L~srq Colonial MedicM Se'mice, N.ige~'m.