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contacts are attacked. When pondering on these facts, it suddenly occurred to the writer that there is another affection of childhood which behaves in a somewhat similar manner. I refer to infestation with threadworms. Recent research has thrown much light on this condition. It is now known to be far more common than was formerly believed. Reliable statistics of its age and sex incidence in normal population groups (as opposed to selected social groups, hospital patients, &c.) are difficult to obtain, but some interesting figures are available from the Peckham Health Centre* The population concerned is a good cross-section of a middleclass London suburban community, only whole families being admitted to membership of the Centre, and medical overhauls being obligatory. In the following table (Table XI) the percentages of each age group in which worm infestation was confirmed by laboratory examination are shown alongside our figures for " suspect" illnesses in Auckland :

Table XI. —Comparison Between Incidence of Threadworm Infestation, Peckham, and "Suspect" Illnesses, Auckland

A preponderance of male children, especially after school entry, and a higher proportion of female adnlts affected than of males, are features alike of the Peckham figures and of our records of " suspect " illnesses in Auckland. It will be noted, also, that Rhodes' comments on the general incidence of poliomyelitis, quoted above, would apply equally well to the Peckham figures for worm infestation. (Females : males = 1-3:1. Females exceed males after age 20.) The resemblance between the behaviour of Enterobius vermicularis and of the virus of poliomyelitis does not stop, however, at a mere similarity of age and sex incidence. If we consider the following facts about threadworm infestation we are reminded at every point of similar features of poliomyelitis. I hasten to add that it is not suggested at this stage that there is any connection between them, but rather that the epidemiology of one may throw light on that of the other. Enterobius vermicularis appears, as a parasite, to be strictly confined to man as its host. Failure has attended all attempts to infest guinea-pigs, mice, dogs, and rhesus monkeys, j We have here, then, a bowel parasite of man alone which so far as is known has no intermediary. One would expect that its incidence could be correlated with defective sanitation, but such is not the case, and, like poliomyelitis, this is one of its most puzzling features. In America, for example, of about 4,000 persons examined, the percentages found to be infested were : 2,895 Whites .. .. .. .. 41-5 per cent, infested. 1,099 Negroes .. .. .. .. 12-9 per cent, infested. Other writersj enlarge on their failure to find infestation in negroes and mestizos in the proportion which would be expected from their low standards of cleanliness, and admit that to date no satisfactory explanation has been forthcoming.

* " The Peckham Experiment," Pearse and Crocker, London, 1943. f Eloise B. Cram (1943): Am. J. Dis. Child, 65, 46-59. j Millbb and Einhokn (1944) : Am. J. Dis. Child, 68, 376.

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Age Group. Peckham Health Centre: Worm Infestation. Auckland Urban Area —" Suspect " Illness: Percentage Affected. Population Concerned. Number with "Worms. Percentage Infested. Male. Female. Male. Female. Male. Female Male. Female. 0-5 6-10 11-15 16 and over 248 200 212 1,323 248 197 199 1,375 45 83 55 52 39 46 29 69 18-1 41-5 25-9 3-9 15-8 23-4 14-6 5-0 19-2 21-5 15-9 71 14-6 16-3 12-9 8-7