VIEWS ON POLIOMYELITIS

VIEWS ON POLIOMYELITIS

1121 . Another and perhaps less weU.1mown;danger in sewers is simple oxygen lack. There have been reports oftwo accidents in the United States in wh...

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1121

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Another and perhaps less weU.1mown;danger in sewers is simple oxygen lack. There have been reports oftwo accidents in the United States in which 3 men lost their lives from - asphyxia’immediately after descendinginto manholes. In the earlier report1 the accident occurred in a sewer manhole which was wet and situated in- silty loam soil. In the more recent incident, in Minneapolis, the manhole, 9 feet deep, was-dry, was lined with concrete and mortar, and contained nothing more sinister than Michaelsenand Park, who a water-main junction. investigated this accident, found that mice lowered into the manhole sometimes died in about 20 seconds, and that the oxygen content was on some occasions as low as 32% at 5 feet and nil at 9 feet. The carbon-dioxide concentration was higher than normal. Since it is known that symptoms of anoxia appear at oxygen concentrationss below 16% and that life cannot be sustained at concentrations below 6%, the deaths were clearly due to oxygen depletion. But the manhole had been entered twice daily without mishap for some time before the accident and there was no obvious explanation for the rapid loss of oxygen. The investigations that followed included continuous analysis of air-samples from the manhole under ordinary conditions, after blowing out with fresh air and after replacement by nitrogen. It was found that the local soil, sampled from the floorof the manhole, had a very high oxygen demand, and that the rate of gaseous diffusion and oxygen depletion could be remarkablv rapid. Changes in barometric pressure had some, minor, influence on the rate of absorption. From extended observations ’on other manholes in Minneapolis it became evident that the dangerous sites were in low or swampy areas where the subsoil contained a large amount of organic matter. Most of the 19 manholes in such areas had a deficiency of oxygen at the time of sampling, 4 containing less than 16% and 2 less than 6%. None of the 25 on higher ground, mainly in sandy subsoil, had less than 17-3% of oxygen. These accidents draw attention to a hazard associated with closed manholes, wells, or silos not naturally aerated. Such places should not be regarded as safe until they have been blown out with fresh air or tested for the presence of sufficient oxygen-for example, by lowering a safety lamp into them.

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The most suitable dosages were found to be 4 g. of sulphadimidine (or its equivalent) for adults, 2-5 g. for children aged 5-15 years, and 1-5 g. for children under 5 years of age ; or, alternatively, 150,000 (or preferably ,more) units of procaine penicillin G in oil with 2% aluininium monostearate (P.A.M.) for adults, and 75,000 units for children under 5. There was no indication that either of these drugs in such doses was preferable to the other, but p.A.M. was more popular with the villagers and slightly less costly. The tabulated figures strongly indicate that the results were not due to chance, and Machiavello et al. advocate the extension of the method in the Sudan. In these trials of simultaneous but subtotal mass it is not clear why the treated groups were not subsequently reinfected, since they remained in close contact with the highly infected untreated groups. (Likewise in earlier trials it was found that the carrierrate after administration of sulphonamide remained low for at least three to six weeks, although the direct effect of the drug could not have lasted much more than fortyeight hours.) Possible explanations offered by the Sudan workers are : (1) that the chance of reinfection was reduced in the villages with low percentages of untreated population ; (2) that low-grade immunity developed in the previous carriers who received the chemoprophylaxis ; or (3) that infectivity decreased pari passu with the natural waning of the epidemic.

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MASS CHEMOPROPHYLAXIS OF MENINGOCOCCAL DISEASE the second world war 1 simultaneous mass prophylaxis

by sulphonamide drugs was used with considerable success to check epidemics of meningococcal meningitis in relatively closed communities, such as residential schools and large Army camps. Evidence was finally obtained that sulphadiazine in a single dose 2-5 g. by mouth, given simultaneously to the whole of the group or population concerned, greatly reduced the carrier-rate for at least three weeks and substantially reduced or even put an end to clinical cases within the group.34 This method is not applicable to a large civilian population, in which the administration of the drug to everyone on one particular day is impracticable. But Machiavello and his colleagues5 have successfully applied it to parts of four isolated village communities in the Sudan, apparently protecting to a significant extent the groups (varying from 30 to 90% of the village populations) which received the drugs, though not checking the development of the epidemic in each village. These workers ’have also shown that a single injection of depot penicillin gives results equal to those derived from a single dose of sulphonamide. 1. Raschka, G. L., Uber, W. J. Sewage induatr. Wastes, 1952, 23, 802. 2. Michaelsen, G. S., Park, W. E. Publ. Hlth Rep., Wash. 1954, 69, 29. 3. Painton, J. F. Milit. Surg. 1943, 95, 267. 4. Phair, J. J. et al. Amer. J. publ. Hlth, 1944, 34, 148. 5. Machiavello, A., Omar, W., El Sayed, M. A., Rahman, K. A. Bull. World Hlth Org. 1954, 10, 1.

VIEWS ON POLIOMYELITIS THE first

report of the W.H.O. Expert Committee Poliomyelitis1 covers many aspects of the subject. The all-important symptomless infections and minor illnesses are discussed under three headings : silent or inapparent infections, which are probably the commonest form ; abortive poliomyelitis, a minor illness which usually lasts only 24-48 hours ; and non-paralytic poliomyelitis, a more severe illness with definite signs of meningeal involvement but not progressing to paralysis. Spinal and bulbar paralyses and encephalitic manifestations are taken to be infrequent complications of a rather common infection. The host factors which might influence the development of paralysis include genetic constitution, pregnancy, associated infections, injuries, over-exertion, intramuscular injections, dental extractions, and tonsillectomy. The virus enters the body via the mouth, and a primary site of infection is established in the pharynx and in the lower alimentary tract. During the first 10-14 days after onset almost every patient excretes on

virus in the faeces, and, in some, excretion may continue for

long as 12 weeks. Virus multiplies actively in the alimentary tissues, and in a small proportion invasion of the nervous system folloiv s ; but whether spread to the nervous system takes place along nerve-fibres as

via the blood-stream cannot yet be decided. Immunity after infection is best studied by antibody determinations in various age-groups of the population. In areas where infection is highly prevalent paralytic cases are usually limited to the lower age-groups, and serum antibodies and effective immunity are acquired early in life. In countries with more advanced hygienic coxxditions, serum antibodies and effective immunity are acquired later in life, and paralytic infections are increasingly common in older children and young adults. The virus is spread by the transfer of intestinal and pharyngeal secretions of infected people, and intimate association with an infected person is probably necessary for the spread of infection. In communities such as ours, spread within the family may form foci with a high density of infection, which then tends to follow lines of movement of human beings from infected or

1. Expert Committee on Poliomyelitis : First Report. Wld Hlth Org. 1954, no. 81. H.M. Stationery Office.

Tech Rep. 3s. 6d.

1122 households and institutions. There are usually 10-100 infections to each clinical infection, and in

inapparent

circumstances the

proportion may be even higher. outbreaks were not reported epidemic Although until about a century ago the disease is worldwide in its distribution today. In many tropical countries there is a low reported incidence, of paralytic cases but a widespread incidence of subcliníòal infections. In areas

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TEACHING MEDICINE THE best way of turning out good doctors has doubtless been a subject of debate among teachers of medicine It can never be ever since the days of Hippocrates. finally settled ; for the river of medicine is always changing its banks, and those swimming in the tide are not in the best position for judging the set of the currents. Most will agree with Dr. R. D. Lawrence1 that it is better to teach the student how to think in an orderly manner than to cram him with miscellaneous facts. But how to do it ? Lawrence has some practical suggestions to make. The student arriving at hospital knows hardly anything about diseases, and most of our teaching hospitals now start him off on an introductory course, whose function is to teach not the details of diseases but the methods on which diagnosis depends-namely, the collection of accurate data and their interpretation and synthesis into syndromes. Techniques for collecting data must, of course, be taught and practised-a straightforward programme for both teacher and student. To teach how to interpret findings, however, is much more difficult ; and Lawrence recommends to the student three honest serving-men of his own, Where, What, and

such as the Eastern Mediterranean and North Africa where the local population is largely spared from .paralytic attacks the disease may nevertheless be a serious hazard for recently arrived immigrants, such as troops from Europe and North America. Situations like this raise the difficult of control measures. Theoretically one might expect that the standard publichealth measures of isolation and quarantine might reduce the spread of infection ; but, with the present inadequate facilities for laboratory diagnosis of inapparent infections, it is not surprising that little benefit has hitherto come from these methods. (If it were ill’deed possible with vastly improved diagnostic resources to recognise and isolate effectively every infected individual in this country for example, our population might eventually be highly susceptible to poliomyelitis infection and Why." liable to severe epidemics as a result of the introduction of " Why," of course, covers the whole of aetiology, virus from an endemic area.) These considerations underwhich he classifies under the headings physical, chemical, line the need for developing effective vaccines which may and biological. Under physical causes of disease he puts help us to make our peace with the virus by learning trauma, environment (covering temperature, altitude, to live with it. Nevertheless during an epidemic certain occupation, poverty, housing), old age, mechanical disprecautions in regard to isolating patients and imposing orders (such as obstruction by calculi), and congenital limited quarantine precautions are advisable. Patients abnormalities. Under chemical causes come inorganic should be nursed with the routine applied to other and organic poisons, drugs, mineral imbalance, and enteric infections ; family and intimate contacts should antigens. Biological causes cover viruses and bacteria, be considered as probably infected ; and children who larger organisms such as spirochaetes and niarise, cysts have been in intimate contact with a case should be and parasites, benign and malignant new growths, confined to their homes and avoid over-exertion. If and degenerations or sequelae resulting from any of a case occurs in a day-nursery or nursery-school the these. school should be closed. Unchlorinated swimmingW’here " and " What " he groups together under the pools should be closed ; adequately chlorinated pools title of " systems and syndromes," and classifies these need not be closed but should not be overcrowded. under seven heads : (1) cardiovascular and blood diseases ; Many simple precautions, such as avoiding over- (2) respiratory; (3) alimentary ; (4) urogenital; (5) exertion, tonsillectomies, and irritating intramuscular nerve or functional; diseases, organic, and injections, and careful treatment of all minor infections (6) nutrition and metabolism, including deficiencies, lack arising in an epidemic period, are included in the of vitamins, endocrine disorders, and allergies ; and (7) committee’s recommendations. the locomotor system, skin, and special senses. The administration of gamma-globulin is discussed The student who gets the habit of thinking his way in some detail. In a recent evaluation2 of its use in the these two classifications when he examines a prophylaxis of poliomyelitis in 1953 it was concluded through case will be safeguarded against many errors of omission. that gamma-globulin did not protect family contacts But nothing but hard work, and hard reading round his of patients with poliomyelitis; so further trials are can supply him with the facts on which to make required before firm recommendations can be made. cases, his Lawrence counsels against the swallowing judgments. It is hoped that vaccination against poliomyelitis may of textbooks the descriptions of diseases should whole become feasible in the not too distant future, but such be read not in a vacuum but when a patient suffering vaccination is still in the experimental stage. from the disease is clearly in the student’s mind. As The European Association against Poliomyelitis, when for the teacher’s part, Lawrence thinks there is a good it met in Paris on April 8-10, considered poliomyelitis deal to be said for teaching teachers how to teach ; and from the aspect of hospital care of patients in the acute he some rather agreeable weekend conferences stage. It recommended that such patients should be in proposes pleasant surroundings at which this might be done. treated in special units, each associated with a central Here the " students " would be registrars and junior urban hospital. These centres should hold a reserve of consultants, who would be invited to deliver short papers material and should have trained medical and nursing to seniors chosen as censors or preceptors. The manner, staff. The later stages of treatment should be carried out of the lecturers would then be criticised elsewhere ; but patients in whom the diagnosis is con- not the matter, attention to diction, delivery, and arrangewith publicly, firmed, whether the disease is paralytic or non-paralytic, ment of material. The best of such a conference-as of all will need to stay in the special centre for at least three conferences-would be informal discussions between weeks ; and the centre should have resources for starting members in the intervals of the arranged programme. the treatment of muscular disabilities. " There is cause," " What a glorious prospect," he comments enthusiastithe association concluded, " to regard poliomyelitis as cally : " It must happen." an infectious disease, the patient constituting a potential source of infection, although cross-infection among the WE have to record the death on May 26 of Sir JAMES attendants on acute poliomyelitis is unusual. The usual SPENCE, professor of child health at Newcastle upon measures for individual and collective protection in

question

"

"

psychosomatic

hospital

must be

Tyne.

applied."

2. Report of Committee for Evaluation J. Amer. med. Ass. 1954, 154, 1086.

of

Gamma

Globulin.

1. Clinical Medicine. Some Principles of Thinking, Learning, and Teaching. London: H. K. Lewis. 1954. Pp. 64. 7s. 6d.