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severe winter without any large increase in their risk ofheart-attack. The same seems not to be true of the lesssevere British winter. This indicates that at least one ofthe previously suspect factors-namely, the breathingof cold air-is unlikely to be important in explainingthe British experience.

It remains possible that in this country either ourhabits change differently in response to cold, or else wesuffer greater body cooling. Those who have travelledboth here and in North America will probably agreethat they tend to feel a lot colder on this side of theAtlantic, whatever the thermometer may say. Similarly,it appears that chilblains are a British phenomenon:doctors from Northern Scandinavia or Canada are

generally quite unfamiliar with the condition.To an epidemiologist the discovery of a difference in

the disease experience of two populations is the

starting-point of research to uncover an explanation.It is to be hoped that this report from Ontario willstimulate such an inquiry. If successful, it might helpus to avoid the winter toll of fatal heart-attacks inBritain.

ATTACK ON SMALLPOX

NoBODY who has studied the statistical material putout by the World Health Organisation is likely to

accept it as an exact image of the world as it is. Never-theless, these figures are welcome, for there are nocomparable sources of information, and they can beboth interesting and encouraging. In a report 1 on theincidence of smallpox, Brazil is the only country inSouth America which admits to the disease. This maybe true, but Brazil shares its frontiers with nine otherStates and viruses require no visas. No-one ought tobe too self-satisfied about the detection and reportingof smallpox: within the past twenty years alastrim hascertainly escaped detection in this country. It is amatter for congratulation that so many impoverishedStates deliver credible reports to W.H.O.Three years ago it was decided to make an attempt

to eradicate smallpox throughout the world. This

campaign was to begin with mass vaccination in all theinfected countries, followed by the detection and isola-tion of the individual victim. It was soon seen, how-ever, that, while smallpox was not reported as com-pletely as it might be, the estimated incidence was lowerthan had been expected. In 1968 the countries wherethe incidence of smallpox exceeded 5 cases per 100,000were limited to India, Indonesia, and a few countriesin west and central Africa; in only three of them wasthe incidence as high as 20 per 100,000. Vaccinationscars were unexpectedly common. Another finding(which reference to the older literature might havedisclosed) was that smallpox is seldom a pandemic butis usually concentrated in a few neighbouring villages.There were grounds for thinking that infection is

usually acquired in the home or at school rather than inthe world at large.These findings suggested that, while systematic

vaccination must be given every encouragement, muchmight be done to control the disease by the detectionand isolation of the individual cases. The diagnosis of

1. W.H.O. Chron. 1969, 23, 465.

the isolated case is not always easy, even for the doctorwho sees the disease often. As the incidence of thedisease falls, the number of such doctors falls at least asfast. Certain diagnosis depends on the laboratory, andit has been an important part of this W.H.O. projectto establish diagnostic laboratories in every countryand to train the staff. As a part of this plan W.H.O. haspublished an admirable booklet of practical advice.2Until a few years ago much of the vaccine in use wasof low quality. A freeze-dried vaccine of high potencyis now produced in several of the worst affectedcountries and is also supplied by some of the wealthiernations. Vaccination methods too have been improvedso that 400-500 vaccinations by one operator each dayare not unusual.

It is too early to say whether these new (or revived)methods of smallpox control will eradicate the diseaseeverywhere. The figures since 1967 show that in al-most every country reported cases have been well belowthose for 1962-66. Provisional estimates for 1969 indi-cate that more than 5 cases per 100,000 will be seenonly in Indonesia and the Congolese Republic. Thenatural fluctuations of infectious disease must still

any unquestioning optimism. Nevertheless, we mustexpect systematic vaccination to depress the level ofsusceptibles to a point where the virus will find it hardto discover a host. This campaign may well be a mile-stone in public health comparable to the introductionof diphtheria immunisation or dicophane (D.D.T.). Dr.Jenner would have been pleased, and the countriestaking part might do worse than to erect a modestmemorial in Berkeley, Glos., when the world’s last

epidemic is concluded.

OUTCOME OF ACUTE OTITIS MEDIA

AT least a quarter of all children in the UnitedKingdom have acute otitis media at some time orother. The serious complications of mastoiditis andintracranial suppuration have become rare, but hearingdoes not always return to normal. Although theresidual deafness tends to disappear over the years,it often persists long enough to cause difficulty in thechild’s social and educational development. Fry andhis colleagues 3 studied 403 children who had been seenwith acute otitis media in a London middle-class generalpractice five to ten years earlier. The hearing wasassessed by audiometry and the patients were examinedby a specialist. The peak incidence of acute otitismedia was in the pre-school and early school years,and discharge from the ear was a feature in 20% ofattacks. Antibiotics were prescribed in 54% of

patients and in 20% of attacks. In the follow-upperiod, 17% had a significant hearing loss, comparedwith 4-5% of matched controls. Deafness was com-moner in girls than in boys; in those children withsiblings than in only children; in those who had hada discharge in any attack; and in those with a familyhistory of ear disease. There was no correlation be-tween deafness and age at first attack, age at last attack,total number of attacks, or history of associated allergies.2. Guide to the Laboratory Diagnosis of Smallpox. W.H.O., Geneva,

1969. See Lancet, 1969, i, 613.3. Fry, J., Dillane, J. B., Jones, R. F. McN., Kalton, G., Andrew, E.

Br. J. prev. soc. Med. 1969, 23, 205.