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parts of Africa would not consider letting their children beadmitted at all unless they could accompany them. The

suggested " emphasis ... on much improved outpatientservices " is unrealistic unless the home conditions are favour-able and the mother is capable of carrying out the necessarynursing procedures.

J. TWOMEY.Halesowen,

Worcestershire.

DELAYED HYPERSENSITIVITY IN LEPROSY

SIR,-The article by Dr. Waldorf and his associates (Oct. 8;p. 773) provides partial confirmation of the previous observa-tion 1 of the U.S. Naval Medical Research Unit no. 2, Taipei,Taiwan, that the capacity to manifest contact allergy to a hap-tenic substance is impaired in persons with leprosy. Unfortu-nately, they are not correct in asserting that our study failed toestablish the incidence of sensitivity to hapten (picryl chloride)and other antigens " in a comparable control population ". Asspecifically stated in the abstract, a non-leprous control groupof 30 volunteers was tested with all antigens used in a group of107 leprosy patients. That the incidence of sensitivity to theseantigens must have been determined in the normal controlgroup was implicit in the use of tests of statistical significancefor validation of group comparisons.Dr. Waldorf and his associates emphasise an apparent

difference in reactivity to 2,4-dinitrochlorobenzene (D.N.C.B.)detected between 17 lepromatous patients without erythemanodosum leprosum (E.N.L.) and 7 with E.N.L. In our study of54 lepromatous patients, 36 were without E.N.L. and 13 ofthese developed sensitivity to picryl chloride; 10 of 18 patientswith E.N.L. became sensitised. Differences between the two

groups in the proportion of individuals sensitised were notsignificant on X2 analysis. Both groups differed significantly(P<0-01) from the normal control group wherein 28 of 30individuals became sensitised. In view of these findings furtherstudies will be necessary before the capacity to manifest

contact-type allergy can be assessed as a possible immunologicalmarker for those with E.N.L. Although many consider E.N.L. tobe a form of hypersensitivity reaction, there is, as yet, no solidevidence to support the concept that immunological respon-siveness is fundamentally different between those who do ordo not happen to have E.N.L.Lacking tuberculoid patients for study, Dr. Waldorf and his

associates have overextended their data in order to make the

assumption that patients with pure tuberculoid leprosy wouldalso react normally to contact allergens. The finding of positiveskin tests to D.N.C.B. in 4 patients with dimorphous leprosy saidonly to be

" clinically closer " to tuberculoid leprosy provideslittle support for such a supposition. Again, in work withpicryl chloride, I noted the incidence of reactivity to this

hapten to be significantly less in 53 tuberculoid patients thanin normal controls. Other studies of delayed hypersensitivityto purified protein derivative of tuberculin and antigens ofCandida albicans 2 3 also provide evidence for a relative impair-ment of the delayed hypersensitivity response in tuberculoidleprosy.

WARD E. BULLOCK, Jr.

University of RochesterSchool of Medicine and Dentistry,

260 Crittenden Boulevard,New York 14620.

*** This letter has been shown to Dr. Waldorf and hisco-authors, whose reply follows.-ED. L.

SIR, We wish to thank Dr. Bullock for his comments on ourpaper and also for providing details of his work not reported inhis original abstract. Our statement, made in reference to thisabstract, that " the incidence of sensitivity ... in a comparablecontrol population was not determined ..." is incorrect, for, as

1. Bullock, W. E., Jr. Clin. Res. 1966, 14, 337.2. Guinto, R. S., Mabalay, M. C. Int. J. Lep. 1962, 30, 278.3. Buck, A. A., Hasenclever, H. F. Am. J. Hyg. 1963, 77, 305.

Dr. Bullock states in his letter, 30 volunteers were studied as a" non-leprous control group".Although our findings are generally in agreement with those

of Dr. Bullock, there are some areas where our results differ,perhaps owing to use of different antigens, testing techniques,patient-population, or kind of patient-classification. Wewish to compliment Dr. Bullock on his extensive investigationsand we are confident he would agree that more intensiveexploration in this area is necessary.

DONALD S. WALDORF.

Department of Dermatology,New York University School of Medicine,

New York.

JOHN N. SHEAGREN.National Institute of Allergy and

Infectious Diseases, Bethesda, Maryland.

JOHN R. TRAUTMAN.United States Public Health Service Hospital,

San Francisco, California.

JEROME B. BLOCK.United States Public Health Service Hospital,

Baltimore, Maryland.

VITAMIN-B12 DEFICIENCY IN PSYCHIATRY

SIR,-We were interested in the article by Dr. Hendersonand his colleagues (Oct. 15, p. 809), and in the ensuing lettersfrom Mr. Hansen and his co-authors (Oct. 19, p. 965) and Dr.Reynolds and Dr. Matthews (Nov. 5, p. 1024). The objectionraised by Dr. Reynolds and Dr. Matthews, that the antigastric-antibody (A.G.A.) test is an inadequate screening test of all causesof vitamin-B12 deficiency, is extremely pertinent. They men-tion anticonvulsant-drug-induced disturbances of folate andvitamin-B12 metabolism. A further cause is vitamin-B,2 defici-ency occurring as a long-term complication of partial gastrecto-my.l 2 This may result in neurological sequelae such as subacutecombined degeneration of the cord 3 4 and confusional states. 5

It might be expected therefore that some of these post-partial-gastrectomy patients are now being referred to psychiat-ric hospitals. In a survey over the past year of patients admittedto St. Patrick’s Psychiatric Hospital, Dublin, with confusionaland depressive symptoms, one of us (M. G. T. W.) has foundserum-vitamin-B12 deficiency in 13 out of 50 patients assessed.We have investigated these 13 patients by determining the acidand intrinsic-factor secretion during the augmented histaminetest and by estimation ofvitamin-B12 absorption by the Schillingmethod. 8 of these patients had malabsorption of vitamin B12associated with achlorhydria and intrinsic-factor secretion ofless than 200 ng. vitamin-Bl2 units. 2 of these patients hadhad a partial gastrectomy eight and ten years previously; inneither of these patients would the A.G.A. screening-test havebeen positive.We consider that any patient admitted to a psychiatric hos-

pital who has previously had a partial gastrectomy should havethe serum-vitamin-B12 level estimated.

D. G. WEIR.Department of Clinical Medicine,

Trinity College, Dublin.

M. G. T. WEBB.St. Patrick’s Hospital,

Dublin.

MEASUREMENT OF GASTRIC ACIDITY

SIR,-Professor Lubran (Nov. 12, p. 1070) recommendstitrating aspirated gastric juice to pH 3-5 in order to measure"

strong acid ". As far as I know, the measurement of " strongacid " is notionally impossible and in any case presupposes arelation to parietal-cell function which is certainly not proven.When we titrate gastric juice to an end-point of pH 7 or 7-4,we assume that all the excess hydrogen ions are derived fromthe parietal cells. While this may not be true, and while acidssuch as the bound aminoacids and sialic acid may be secreted

1. Deller, D. J., Witts, L. J. Q. Jl Med. 1962, 31, 71.2. Weir, D. G., Temperley, I. J., Gatenby, P. B. B. Ir. J. med. Sci. 1966,

p. 97.3. Weir, D. G., Gatenby, P. B. B. Br. med. J. 1963, ii, 1175.4. Williams, J. A. The Small Intestine; p. 42. Oxford, 1965.5. Olivarius, B. de F., Roos, D. Lancet, 1965, ii, 1298.6. Webb, M. G. T., Weir, D. G. Unpublished.