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success. The position of India is especially tragic,for, despite attempts to introduce family planning,her population has increased from 370 millionin the early 1950s to 537 million in mid-1969,and the growth-rate per annum has gone up from1-3% to 2-5%-an increase now of over a milliona month. For such countries the problem seemsalmost insoluble. Responsible family limitation canbecome acceptable only when parents realise that it isin their own and their children’s interest to practiseit. And this situation can be achieved only by aconsiderable and sustained improvement in educationand living standards generally, including the establish-ment not only of family-planning centres, but also ofefficient maternity and child-welfare services.4 Butnations rich and poor have other priorities, includingexpenditure on arms, now approaching$200,000million annually. Whether enmity between nationsconstitutes a greater threat to man’s future than the

daily avalanche of babies is debatable. But what thisavalanche means and what can be done about it are

going to test man’s capacity for intelligent action andcooperative effort more searchingly than ever before.International action is clearly essential, but everynation will also have to plan its programme in thelight of its own circumstances. GIFFORD 5 has urgedthe Btitish Government to adopt publicly a popula-tion policy and to promote it through the NationalHealth Service. An interdepartmental committeeof senior Civil Servants has been set up to studythe problem of population, and the Commons selectcommittee on science and technology in the lastParliament also appointed a subcommittee on thesubject. These useful beginnings should lead to theformation of a permanent committee on populationand environment. The two subjects are intimatelylinked and should be considered together, with theaid of advice from experts in all relevant areas.

Politics and economics are important, but biology isfundamental, and failure to recognise this in time andaccord it priority could be man’s final and fatal error.

Recurrent Bacteriuria

THE first description of a disease is generallyfollowed by an intensive study of the pathologicalabnormalities to which it gives rise. The recognitionof bacteriuria, on the other hand, in an otherwisehealthy section of the population has been followedby a search for clinical significance. But, despite amass of work on this subject, we still have no clearidea of the prognosis for the bacteriuric patient.Bacteriuria is influenced by a wide range of factors-racial, constitutional, anatomical, environmental,and social. It is also fairly common, being exhibited4. Williams, C. See Lancet, July 11, 1970, p. 93.5. Gifford, P. W. W. ibid. Aug. 29, 1970, p. 463.6. Kass, E. H. Trans. Ass. Am. Physns, 1956, 69, 56.

by 4% of adult females. There may, therefore, befortuitous associations with other disorders whichare subject to these same influences. There is thusno place for case-reports or small series: only carefulinvestigations of substantial series will provideworth-while information.

One such investigation is that which KUNIN andothers have been conducting among schoolgirls incentral Virginia for the past ten years.8 Significant,persistent bacteriuria is defined as the presence ofmore than 100,000 bacteria per ml. urine culturedon three or more consecutive occasions: each timethe same species has to be obtained or, for Escherichiacoli, the same serotype. Such bacteriuria is foundin only 0-03% of boys,9 while 5% of schoolgirlswill exhibit it at some time.The latest report 10 is concerned with the recurrence

of bacteriuria after a fortnight’s course of anti-microbial treatment. 80% of recurrences seemedto be due to reinfection rather than relapse, in thata different organism or serotype was cultured on thesecond occasion. It might have been anticipatedthat anatomical abnormalities such as vesicouretericreflux would predispose to such recurrence. Butthis was not so, confirming a previous finding thatabnormal pyelograms and cystograms do not denotepredisposition to reinfection. Even if they do notmake the genitourinary tract more accessible to

bacteria, however, such abnormalities may wellmake pyelonephritis more likely once the bacteriahave entered. Likewise, KUNIN found no evidencethat social class influenced the recurrence-rate,although the incidence of bacteriuria is related tosocial class Indeed, only two factors did influencerecurrence-age and race. Recurrence was lesscommon in the older age-groups and in Negro girls.The most surprising finding, however, is that the

likelihood of recurrence diminished with the passageof time after infection. Thus, each infection seemsto predispose to the next, and the longer the patientis free of infection, the less likely she is to becomeinfected again. Each treatment produced a long-term remission in 20-25% of White girls, inde-

pendently of the number of previous infections,which might number as many as fourteen. The

result, therefore, was that, towards the end of thestudy, few bacteriuric girls remained.

It is difficult to explain such findings in terms ofa constitutional abnormality which rendered thesegirls liable to bacteriuria. Nevertheless, the girlswere exceptionally susceptible to infection later in

life, when recurrence of bacteriuria, frequently with7. Kass, E. H. in Progress in Pyelonephritis (edited by E. H. Kass)

Philadelphia, 1965.8. Kunin, C. M., Southall, I, Paquin, A. J. New Engl. J. Med. 1960,

263, 817.9. Kunin, C. M., Paquin, A. J. in Progress in Pyelonephritis (edited by

E. H. Kass), p. 33. Philadelphia, 1965.10. Kunin, C. M. New Engl. J. Med. 1970, 282, 1443.11. Turck, M., Goffe, B. S., Petersdorf, R. G. ibid. 1962, 266, 857.

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symptomatic infections, occurred in association withsexual intercourse and pregnancy. It seems, there-

fore, that certain people are more likely to havebacteriuria than others, but that the most importantfactor is an episode within the previous year or two.Can we gather any therapeutic message from the

literature which has accumulated around the subjectof bacteriuria ? Firstly, there is no doubt thatbacteriuria is associated with a tendency to sympto-matic renal disease. This is clear not only fromKuNIN’s study, but from the study of bacteriuricwomen who become pregnant.12 Especially strikingare BRUMFITT’s data 13: no fewer than 25% of

pregnant bacteriuric women developed pyelone-phritis, but when the organism was eliminated bytreatment, the frequency fell to 2-8%. Patientswho have recently suffered a renal infection and

pregnant women, therefore, constitute an especiallyvulnerable group in whom bacteriuria unquestion-ably demands eradication. To these, we must addpatients who are about to undergo genitourinaryprocedures requiring instrumentation.’ 7

The dangers of bacteriuria are not confined tothe risk of acute pyelonephritis. There is no generalagreement about how dangerous a condition asymp-tomatic bacteriuria is, but certain observations

support the view that it merits treatment in its own

right. There is evidence of renal damage in theform of an impairment of urinary concentration,14which can be reversed by antibiotic treatment. ISThe renal medulla provides an excellent environ-ment for bacterial multiplication, so it is not

surprising that it suffers first. There is a second

important abnormality associated with bacteriuriawhich has a more clearcut prognostic import.MIALL et al.16 found significantly higher systolicand diastolic blood-pressures in individuals withbacteriuria among the populations of Jamaica andWales. Cause and effect are difficult to sort out

here, for essential hypertension is associated withan increased incidence of renal infection.17 On theother hand, bacteriuria does not show a familial

tendency, while essential hypertension does,7 sug-gesting that the primary disturbance is the bacteriuriaand not the hypertension. It is, however, difficultto understand how hypertension could be producedwhen the only evidence of functional disturbanceis a mild disorder of medullary function.16

Specific antibodies can often be demonstrated

against the infecting organism, and, under such

circumstances, bacteriuria is more difficult to elim-12. Norden, C. W., Kass, E. H. A. Rev. Med. 1968, 19, 431.13. Brumfitt, W. in Fourth Symposium on Advanced Medicine

(edited by O. M. Wrong); p. 51. London, 1968.14. Kaitz, A. L. J. clin. Invest. 1961, 40, 331.15. Norden, C. W., Tuttle, E. P. in Progress in Pyelonephritis (edited by

E. H. Kass); p. 73. Philadelphia, 1965.16. Miall, W. E., Kass, E. H., Ling, J., Stuart, K. L. Br. med. J. 1962,

ii, 497.17. Shapiro, A. P., Moutsos, S. E. Krifcher, E., Sapira, J. D. Am. J.

Cardiol. 1966, 17, 638.

inate, demanding intensive, high-dosage therapy.13When such therapy is given, the antibody titre falls.This, again, suggests that bacteriuria represents anactive infection.

Even symptomatic renal infection is a compara-tively small inconvenience compared with the

possible dangers of persistent bacteriuria. Of thesedangers two have claimed considerable attention-obstetric complications and chronic pyelonephritis.Bacteriuria may influence the outcome of pregnancy,and eradication of bacteriuria may improve theobstetric prognosis.l8 But follow-up is difficult inview of the low incidence of complications, and thedifficulty of obtaining a control group matched forsocial class, which is important in relation to theincidence (as opposed to the recurrence-rate) ofbacteriuria. 11

The major problem, however, remains unsolved.How many patients with recurrent bacteriuria willget chronic pyelonephritis with renal failure ? Ifthe proportion is a significant one, some of theeconomic burden presented by the management ofadvanced renal failure might be avoided by thelesser expense of antibiotic prophylaxis. It is not

always possible to demonstrate renal infection in

patients with histologically proven " chronic pyelone-phritis ", even when such patients are deterioratingclinically,19 and not all such cases may be due to

persistent infection. 20 However, SMELLIE 21 hasshown that children with uncontrolled infection dosometimes proceed to progressive scar formationand renal contraction. Individual case-histories

suggest the same conclusion.13 Long-term follow-upof patients with the bacteriuria of pregnancy demon-strates the frequent occurrence of radiographicabnormalities suggesting chronic pyelonephritis.22It is probable, although not proven, that such

changes are the result, rather than the cause, of thebacteriuria. AOKI et a1. 23 adopted a different approachto this problem. They investigated seven patientswith histologically confirmed " chronic pyelone-phritis

" but no bacteriological evidence of infection.In six of these patients, bacterial antigen could bedemonstrated in renal tissue by immunofluorescence :controls with other types of renal disease did notshow such a phenomenon. It is possible that

asymptomatic bacteriuria sets up a chain reactionwhich leads to progressive pyelonephritis, withoutsubsequent evidence of infection.The evidence, therefore, strongly suggests that

we should eliminate bacteriuria where we find it,whether the patient has a clinical infection or not.18. Savage, W. E., Hajj, S. N., Kass, E. H. Medicine, Baltimore, 1967,

46, 385.19. Angell, M. A., Relman, A. S., Robbins, S. L. New Engl. J. Med.

1968, 278, 1303.20. Lancet, 1968, ii, 1125.21. Smellie, J. M. Jl R. Coll. Physns, 1967, 1, 189.22. Leigh, D. A., Gruneberg, R. N., Brumfitt, W. Lancet, 1968, i, 603.23. Aoki, S., Imamura, S., Aoki, M., McCabe, W. R. New Engl. J. Med.

1969, 281, 1375.

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KuNIN’s observations indicate that, if we can preventa recurrence for a year or two, the prospect of long-term success is good. Thereby, the unpleasantsymptoms and sequelse of acute urinary infectionsmay be avoided. More speculatively, the incidenceof chronic pyelonephritis and renal failure may alsobe reduced.

AT WHAT TEMPERATURE SHOULD YOU KEEPA BABY?

THE human baby, even if he is born before term, hasconsiderable ability to regulate his temperature. 1, 2When exposed to an environment below that ofthermal neutrality, he increases his metabolic rate,consuming more oxygen and metabolic fuel, and heshows a tendency to metabolic acidosis 3 and lowarterial oxygen tension.4 Thus, there are good reasonsfor expecting that a cool environment might jeopardisehis life, and clinical observations and experience con-firm this.5,6 His range of neutral thermal environmentis less wide than that of an adult, because a baby hasthe disadvantages of a relatively large surface area fromwhich to exchange heat and a small mass to act as aheat sink.The neutral thermal environment appropriate for

the naked baby has been widely studied in the past tenyears.1,2,7,8 Most investigations have been conductedin specially constructed incubators where air tempera-ture and incubator-wall temperature are within a

degree of each other, so that the air temperature is a notunreasonable statement of thermal environment. The

temptation to extrapolate the findings to babies nursedin clinical incubators has dangers, for here air tempera-tures and the temperature of the inside skin of the

transparent canopy are usually very different. This

disparity was emphasised by Hey and Mount 9 whocalculated that a baby may lose half his heat dissipationto the skin of the canopy by radiant heat loss. Theydescribe a simple device, a ’ Perspex ’ heat-shield,which helps control this channel of heat-loss; when itis in place, the air temperature becomes a reasonablemeasure of thermal environment.

In temperate climates air temperatures rarely exceeda baby’s body temperature, so that the commonthermal stress a baby experiences is that of cold. Moststudies therefore have been concerned with the lower

margin of the neutral temperature zone, the so-calledcritical temperature.10 In thermal surroundings whichare close to or warmer than body temperature, heatdissipation must take place by evaporation of waterfrom the respiratory tract or from the skin. From aknowledge of the factors affecting thermal balance,1. Bruck, K. Biol. Neonat., Basle, 1961, 3, 65.2. Scopes, J. W. Scientific Basis of Medicine: Annual Reviews 1970.

London, 1970.3. Gandy, G. M., Adamsons, K., Jr., Cunningham, N., et al. J. clin.

Invest. 1964, 43, 751.4. Stephenson, J. M., Du, J. N., Oliver, T. K. J. Pediat. 1970, 76, 848.5. Mann, T. P., Elliot, R. I. K. Lancet, 1957, i, 229.6. Silverman, W. A., Fertig, J. W., Berger, A. P. Pediatrics, Springfield,

1958, 22, 876.7. Hill, J. R., Radimtulla, K. A. J. Physiol. 1965, 180, 239.8. Hey, E. N., Katz, G. Archs Dis. Childh. 1970, 45, 328.9. Hey, E. N., Mount, L. E. ibid. 1967, 42, 75.

10. Scopes, J. W., Ahmed, I. ibid. 1966, 41, 407.

including measurement of a baby’s capacity to

increase evaporative water loss, Hey and Katz 8

calculated temperatures which are too hot, and thusdefine both the upper and the lower margins of theneutral range. Within such a range, body temperatureremains normal while oxygen consumption and

evaporative heat loss are both at a minimum. Their

findings emphasise that there is no single temperaturethat is appropriate for all sizes of baby. A temperatureappropriate for a term baby may be far too cold for a1500 g. baby, and a temperature which is right for the1500 g. baby could be dangerously warm for a 2500 g.child. (Needless to say, all temperatures suitable fornaked newborn babies are unpleasantly warm for theadult.) It is possible to make an informed guess of theproper temperature for a particular naked baby in anincubator (with a heat-shield in place). Since there issome biological variation this guess may always be wrong,so it is still essential to monitor the baby’s owntempera-ture to ensure that he does not overheat or become toocold. This procedure is, of course, a form of servo-control, and a logical extension is to use the incubatoritself a a monitoring device as in ihe servo-controlincubatorAs soon as a baby is clothed 01 b waddled, most of the

channels of heat-loss are partially occluded. The airtemperature within the clothing of a baby in an

ordinary room is in the order of 35°C.11 Hey andO’Connell 12 examined the neutral zone and responseto cold in clothed babies. They found, of course, lowercritical temperatures than in naked babies, and theyconclude that a draught-free environment of 24°C

(75 °F) is necessary to provide neutral thermal condi-tions for most cot-nursed babies in the first month oflife. Here, at last, is a scientifically based recoinmenda-tion for room temperatures which apply in the usualclinical situation. In a temperature below the criticalone the metabolic cost to a clothed baby is less than toa naked baby, and in hot conditions a cot-nursed baby,whose face is inevitably exposed, can dissipate heatfrom this area. Thus, the clothed baby in a cot is saferthermally than the naked baby in an incubator in thesense that his attendants need not control the environ-ment so precisely. Clearly, control is still needed,since extremes are dangerous, but the latitude is

greater. Added advantages are that coolness on theface is a stimulus to respiration and the face and headare important sweating areas for heat dissipation whenthat is necessary. It is notable that adults prefer theface to be cooler than the rest of the body.

ADDING DRUGS TO INTRAVENOUSINFUSIONS

IT is commonplace for patients to take severaldifferent drugs concurrently. Thoughtful recipientssometimes wonder " what is going on inside" or

suspect that one preparation may react with or

neutralise another. The wise doctor should also givethought to this matter; and, in general, care is takento ensure that drugs swallowed by or injected into

11. Scopes, J. W. Br. med. Bull. 1966, 22, 88.12. Hey, E. N., O’Connell, B. Archs Dis. Childh. 1970, 45, 335.