Hypertension in adult Africans in Uganda

89 TRANSACTIONS OF THE ROYAL SOCIETY OF TROPICAL MEDICINE AND HYGIENE.

Vol. 55. No. 1. January,

1961.

H Y P E R T E N S I O N IN A D U L T A F R I C A N S IN U G A N D A

BY H. M. LEATHER, M.D., M.R.C.P.*

(From the Departments of Medicine, Makerere College, Kampala, Uganda, and University of Bristol.) Systemic hypertension is common in the North American negro (SHULZEand SCHWAB, 1932, 1936), occurring more frequently than in North American whites (KESILMAN,1941 ; ORENSTEIN,1943). Most authors regard this hypertension as being " essential " in type. Complications including myocardial insufficiency and cerebral-vascular accidents occur commonly (WEISS and PRUSMACK, 1938). By contrast, little is known of hypertensive disease in the African in his home environment. Field surveys of the incidence of hypertension in East and Southern Africa have yielded conflicting results. DONNISON (1929), in Kenya, and WILLIAMS (1941, 1957, pers. commun.) in Uganda, found that blood pressure levels in the native population, up to the age of 40 years, correlated well with European figures, but neither investigator was able to dcmonstrate a rise in arterial pressure with advancing years. SANKALE,RIVOALEN and MILHADE (1958) from Bamako, also state that arterial blood pressure in African natives over the age of 50 years is the same as in younger subjects. However, studies in South Africa (ORDMAN,1948) on 1,522 apparently healthy urban and rural Bantu subjects, revealed not only that hypertension was common, but that the incidence rose with advancing age. The peak incidence was at the 6th decade when hypertension was recorded in over 40 per cent. of both sexes. As opposed to the East African workers, Ordman made no attempt to obtain basal readings and much of the difference in the results may be attributed to this factor. It should be emphasized that in all these studies the age of the patients was not accurately known. Though various necropsy studies have been made of the pathology of renal disease in the Bantu (DAVIES, 1949 ; UYS, 1954, 1956) and of hypertensive heart disease (BECKER, 1946), the only clinical work reported has been that of WILLIAMS(1944) in which hypertensive heart disease was included in a study of heart disease in general in the native population of Uganda. The present study was therefore made with the object of learning more of the natural history of hypertension in the Bantu. * I wish to acknowledge the constant help and encouragement I received from Professor A. W. Williams of Makerere College in whose department this study was made. My thanks are also due to Professor J. N. P. Davies of Makerere College, and Professor T. F. Hewer of Bristol University for assistance in the interpretation of histological specimens, and to Professor C. Bruce Perry of Bristol University for advice in the preparation of the paper. J. Kyobe of Makerere College acted as interpreter throughout the study and gave much technical assistance, and Miss J. Summerscales of the Uganda Medical Service carried out the electrophoretic studies~

90

HYPERTENSION IN ADULT AFRICANS IN UGANDA MATERIAL AND METHODS

All patients with hypertension admitted to the wards of one of the medical units at Mulago Hospital between January, 1956, and February, 1957, were studied. A history of the patient's illness, including past medical and dietary history was taken on admission to hospital. T h e family history was of course, rarely known. Clinical examination included a review of all systems. T h e blood pressure was measured with the patient lying supine. Several readings were taken from each patient, and first readings, if unduly raised, were discarded. T h e systolic pressure was taken as the point at which sounds were first heard on auscultation, the diastolic pressure as the point at which the sounds became muffled. Hypertension was considered to be present when the diastolic pressure was persistently at, or above, a level of 100 ram. Hg. throughout the period of observation. I n all but a few of these patients the systolic pressure exceeded 160 mm. Hg. ; when it was below this level, heart failure was usually present. The fundi were examined, following the instillation of a mydriatic. In male patients the bladder, urethra and prostate were palpated, the urine stream was examined, a soft rubber catheter passed and residual urine, if any, measured. (A symptomless stricture was sometimes only detectable by these methods). " Midstream " specimens of urine from males, and catheter specimens from females, were examined for albuminuria and glycosuria and the centrifuged deposit searched for any abnormality. A count of the formed elements in the urine was also made from uncentrifuged urine. For this purpose a sample of freshly voided urine was taken from the middle of the specimen jar which had been inverted to ensure mixing, and a count made of one c. ram. in a counting chamber. Three c. ram. from each specimen were examined in this way and the average of the three recorded. A specimen of urine was cultured. T h e degree of proteinuria was estimated with Esbach's reagent. Routine clinical examinations including frequent measurements of blood pressure and urinalysis were made throughout the patient's stay in hospital and at follow-up examination.

Investigations. A full blood count was taken and blood films (thick and thin) searched for malaria parasites. T h e presence or absence of sickling was noted. The blood urea and blood cholesterol were measured and serum protein levels estimated, including albumin and globulin fractions. In all but the earliest cases in the series, the electrophoretic pattern of the serum proteins was studied (FLYNN and DE MAYO, 1951). Renal function was assessed from urine concentration and dilution and maximum urea concentration and urea clearance. Intravenous pyelography was carried out in some cases. A renal biopsy was taken in all cases except from subjects who were gravely ill, or from those in whom the blood urea was over 100 rag. per cent. T h e technique employed was a modification of the methods of IVERSEN and BRUN (1951), and KARK and MUEHRCKE(1954). A routine chest radiograph and electrocardiogram were taken on all patients and the heart and lungs examined by fluoroscopy. Diagnosis was made from an assessment of the clinical findings, investigations, and histological evidence. No diagnosis was made contrary to histological findings. Occasionally, however, when histological findings were equivocal, a diagnosis was made in accordance with the clinical findings, if these were strongly suggestive of a particular disease process. Three cases in which biopsy of the kidney failed, and two others in which it was not attempted, were unclassified, though a firm diagnosis in some of these was possible from clinical and other evidence. FINDINGS There were 46 patients of whom 34 were male and 12 were female. Age and sex distribution are shown in Figure I. There were three times as many males as females (the approximate proportion of males to females for all medical admissions). Relatively few patients were over S0 years of age, owing partly to the young age structure of the population of Uganda, and partly to the reluctance of the elderly African to seek European medical aid. In Figure 2 the relationship of diastolic pressure to abnormality in the optic fundus is shown. It is seen that the degree of change bore some relation to height of the diastolic pressure. In the majority of patients with diastolic pressures above 110 mm. Hg. retinopathy was present, with or without papilloedema. In the six cases of malignant hypertension (severe hypertension with papilloedema) the diastolic pressure was above 140 ram. Hg.

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Primary and secondary hypertension Fourteen of the 46 patients were found to have primary or " essential " hypertension, while in 27 the hypertension was secondary to renal disease. Five cases were not classified. The height of the diastolic blood pressure in primary and secondary hypertension is shown in Table I. Secondary hypertension existed at all levels of blood pressure, but the diastolic pressure in patients with primary hypertension in this small series, was always below 140 mm. Hg. The reason for this was not apparent.

92

HYPERTENSION

IN ADULT AFRICANS IN UGANDA

TABLE I. Height of diastolic pressure in hypertension of various types.

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Unknown

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120 -129

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The incidence of primary and secondary hypertension in relation to age is seen in Figure 3. Primary hypertension did not occur below the age of 38 years and increased in incidence from 40 years onwards; of the 16 patients over 40 years old, primary hypertension was present in 11. Conversely, of the 25 cases between the ages of 17 and 40 years, hypertension was secondary in 22 and primary in only three. The proportion of patients with primary and secondary hypertension reflects the high proportion of young subjects in the study. Had the average age been higher, the proportion of patients with essential hypertension would also probably have been higher.

Aetiology of secondary hypertension Glomerulo-nephritis. In 16 cases a diagnosis of glomerulo-nephritis was established. Ages of the subjects ranged from 17 to 41 years but only three were over 30 years of age (Fig. 4). The disease was seen in all its stages and clinical details are recorded elsewhere (LEATHER, 1960). Six of the 16 cases were fatal during the period of observation. Pyelonephritis. Nine patients (seven male and two female), were found to be suffering from pyelonephritis. Ages ranged from 26-60 years, four patients being over 40 (Fig. 5). In one case acute pyelonephritis was superimposed on bilateral hydronephrosis secondary to a urethral stricture, while in another, terminal acute pyelonephritis had developed in a patient with chronic pyelonephritis. In the remainder chronic pyelonephritis only was present. Abnormality of the lower urinary tract was a common finding. Three had urethral strictures, a fourth gave a history of repeated instrumentation for stricture though none was found clinically or at necropsy, a fifth had a bladder stone with chronic urinary infection, while in a sixth, a woman, marked tortuosity of the urethra was present. Apart from such evidence of lower urinary tract disorder there was lktle to suggest the possibility of pyelonephritis from clinical investigation. A history of acute pyelonephritis was lacking in all cases, and a history of gonorrhoea, though common, was no more frequent than was usual in African patients. Active urinary infection was usually absent at the time of examination and the diagnosis was established only from histological evidence from renal biopsy or necropsy.

H.

M.

LEATHER

93

The prognosis was bad; four patients died while under observation and three others were deteriorating.

Amyloidosis. Primary renal amyloidosis was present in two cases. described elsewhere (LEATHER,1959).

These have been

Findings in secondary hypertension Fourteen patients presented with congestive heart failure, 10 with generalized oedema (glomerulo-nephritis in eight and primary amyloidosis in two cases), one with severe headache and failing vision due to papilloedema, and one with anuria. The remaining patient complained only of palpitations. Changes in the optic fundi were common ; 14 patients had hypertensive retinopathy with haemorrhages and exudates, including three with papilloedema. Cardiac enlargement was constant in the presence of heart failure and gallop rhythm was frequently present. Electrocardiographic evidence of left ventricular strain was usual. With the exception of one patient, albuminuria was constant and microscopic haematuria and casts usually present. Urine culture rarely yielded pathogenic organisms. Renal function tests revealed impairment of kidney function with a rise in blood urea level in 22 cases of admission. In 10 the blood urea was over 100 mg. per cent. The prognosis was bad ; 11 patients died while under observation and in 13 others a rising blood urea, or repeated attacks of left ventricular failure, presaged a fatal outcome. This prognosis was often indicated from the extent of renal damage as seen in renal biopsy specimens in which irreversible and extensive histological changes were often present.

Findings in essential hypertension Essential hypertension was present in 14 patients (eight males and six females). Ages of males ranged from 38 to 75 years with an average of 55 ; females from 38 to 60 years with an average of 47. A diagnosis of essential hypertension was made when no other clinical cause for hypertension existed and where renal biopsy revealed no evidence of primary renal disease. In some the histological appearance of the kidney was normal ; in others, varying degrees of renal damage secondary to vascular change, were present. Patients with essential hypertension presented in three w a y s - with heart failure; as a result of cerebral vascular accidents ; or with headache and palpitations. Six were admitted in congestive heart failure, including the four youngest patients with essential hypertension. In four of these the heart was large ; in the other two, both with a relatively low blood pressure, enlargement was slight. The response to treatment was satisfactory and in sharp contrast to patients with heart failure from secondary hypertension, in whom death usually occurred within a fairly short time. This difference was thought to be partly due to the high incidence of renal failure in patients with secondary hypertension, and partly to the higher blood pressure in secondary hypertension. In three male patients, aged 45, 56 and 65 years, a hemiplegia occurred, attributed clinically to a cerebral thrombosis. In one there was evidence of wide-spread arterial disease elsewhere, including thickening and tortuosity of the radial artery, marked arteriolar changes in the fundi, electrocardiographic evidence of an old anterior myocardial infarcation and thickening of the renal vessels on renal biopsy. The blood pressure was 160/110.

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HYPERTENSION

I N A D U L T AFRICANS I N U G A N D A

Five patients, including four women, complained of headache and palpitations. One of them, a female of 60, also suffered from cardiac effort pain, the only patient in the whole study so to do. In the main, however, the symptoms in these patients were bizarre and TABLE II.

Serum protein levels in patients with essential hypertension. Total g. o/ /o

Alb. g %

Glob. g. O//o

Nine patients with heart failure or hemiplegia

6.1

2.3

3.8

Six patients with headache and palpitations

6.9

3.4

3.5

exaggerated, and the impression was formed that they did not arise from organic disease. The blood pressures were high and in three of the five cases the diastolic pressure was over 130 mm. Hg. Cardiac enlargement, however, was usually absent or slight. Urinalysis in heart failure and essential hypertension usually revealed moderate albuminuria ; in other cases albuminuria was absent or very slight. Microscopic haematuria was uncommon and casts rarely seen. Urine culture was sterile. The fundi were normal in eight cases, arteriolar changes were present in three. In the remaining three subjects aged 45 to 60 years, a minor degree of arteriosclerotic retinopathy was present. Three of the patients had urethral strictures. Haemoglobin, blood urea and blood cholesterol levels were all within normal limits in patients with essential hypertension. The mean serum protein level was 6.4 g. per cent. with albumin 2.7 g. per cent. and globulin 3.7 g. per cent. and are in accordance with findings among Africans in general in Uganda (HoLMeS et al., 1951) ; the characteristic electrophoretic pattern is shown in Figure 6. In Table II serum protein levels in nine patients with heart failure or hemiplegia have been contrasted with those in patients complaining only of headache and palpitations. It is seen that in patients with headache and palpitations the serum albumin was higher than in the other group. This finding, though the numbers are small, may lend support to the clinical impression that patients with essential hypertension, whose symptoms were probably not attributable to organic disease, tended to come from the wealthier African classes. Possibly the higher serum albumin levels reflected a better diet than was normal among Africans in Uganda.

Malignant hypertension In six cases papilloedema was associated with hypertension. Five were in males and one in a female. Three of the patients were suffering from chronic glomerulo-nephritis and one from acute on chronic pyelonephritis. In the remaining two cases the hypertension was unclassified. Four of the six patients died, and the remaining two were deteriorating when last seen.

Urethral stricture In the present study a urethral stricture was present in seven out of 34 males. Three were suffering from pyelonephritis, three had essential hypertension, while one was unclassified. In the three patients with pyelonephritis, the stricture was impassable and back

H. M. LEATHER

95

pressure had occurred with hydronephrosis in two, and gross bladder wall hypertrophy in the third. Terminal acute pyelonephritis was present in two of these cases. In the three patients with urethral stricture and essential hypertension the stricture was, in all cases, symptomless and was only detected by routine examination of the urine stream. In none was there any evidence of back pressure and though in one case slight microscopic pyuria was present on one occasion, urine culture was sterile, the blood urea was normal and intravenous pyelography revealed a normal and symmetrical calyceal pattern, with good excretion from both kidneys. Renal biopsy, as in the other cases, revealed no evidence of primary renal disease, arteriolar thickening being the only abnormality present. DISCUSSION

Essential hypertension appears to be a fairly common condition among the Bantu in South Africa. BECKER(1945) found that in 8.2 per cent. of 3,000 necropsies, hypertensive heart disease was the cause of death and in over 60 per cent. of these, the hypertension was " essential " in type. Though the incidence of hypertension may not be as high as ORDMAN (1948) suggested, for some observers would disagree with the method by which he assessed the presence of hypertension, there is no doubt that it is frequently seen. By contrast, essential hypertension is alleged to be uncommon in Uganda, and WILLIAMS (1944) found only 16 such cases over a period of 2 years of study. In the present series, 14 patients were found to have essential hypertension. Obviously no conclusions regarding incidence can be drawn from this beyond the fact that the condition undoubtedly exists in Uganda, at any rate in hospital practice. It has been noted that a certain proportion of patients with essential hypertension complained only of headache and palpitations. It must be emphasized that of the many patients attending as out-patients with symptoms (including headache) for which no organic cause can be found, only a few have a raised blood pressure. It is interesting, nevertheless, to find that this type of patient exists among central African natives as it does among Europeans, and also that these subjects tended to be drawn from the upper social classes, were better nourished, and had serum albumin levels that were, on average, higher than those of the remainder of the group. (In fact, their serum albumin level and serum protein electrophoretic patterns approximated to those of healthy African college students). In European subjects hypertension in young people is usually secondary in type. PLATT (1948) found that only 16 of 64 hypertensive subjects under the age of 40 years had essential hypertension. An even lower proportion was observed in the present study, (three out of 25 cases in this same age range). On the other hand, over the age of 40 years the proportion of patients with essential hypertension was high (11 of 16 cases). Glomerulo-nephritis was found to be the most frequent cause of secondary hypertension (16 cases), and pyelonephritis the next most common (nine cases). This is similar to the findings of UYs (1954) who found glomerulo-nephritis responsible for 59.2 per cent, and pyelonephritis for 25.3 per cent., of 71 cases of secondary hypertension found at necropsy in Bantu subjects in Johannesburg. HENNESSEY (1939) stated that " cardiac hypertrophy and sclerotic changes in peripheral arteries were seldom encountered clinically or at post mortem " (in Africans in Uganda). This was not found to be the case in the present study. In elderly patients with hypertension, thickening and tortuosity of the radial artery wall was by no means unusual and cardiac hypertrophy common. Likewise, changes in the optic flmdus were common with

96

HYPERTENSION IN ADULT AFRICANS IN UGANDA

secondary hypertension, and retinopathy, with or without papilloedema, was present in nearly all severe cases. Gonorrhoea is a common disease in many Bantu tribes and urethral stricture also common. The actual frequency of this complication is not known. In DAVIES' (1949) series of 2,994 necropsies, a urethral stricture had led to death in only 59 cases, but Davies had no doubt that numerous minor degrees of stricture had been overlooked and felt that the autopsy incidence failed to express the clinical importance of the condition. In 43 patients with renal hypertension "nearly all of whom were men," WILLIAMS (1944) found eight cases of urethral obstruction due to stricture. In the present study seven out of 34 males had urethral strictures. In three of these essential hypertension was present. At first sight a diagnosis of essential hypertension made in the presence of a urethral stricture would appear questionable. However, in view of the local prevalence of gonorrhoea and the unknown incidence of urethral stricture there seems little reason to attribute hypertension, especially in an old man, to the effects of gonorrhoeal stricture when thorough investigation has disclosed no evidence of a causal relationship between the two conditions. The remote possibility of localized undetected pyelonephritis could never be excluded with certainty as, of course, it could not be excluded for certain in other patients with essential hypertension in whom no stricture was present.

Cardiac pain A history of cardiac pain was given by only one patient. In one other case electrocardiographic evidence of myocardial infarction was present though there was no history of the episode. There were no other cases in which there was clinical or electrocardiographic evidence of myocardial ischaemia. This is, perhaps, surprising as hypertension was sometimes severe, congestive failure common, and anaemia, (associated with uraemia) often present. However, myocardial ischaemia is known to be uncommon among Bantu peoples. BECKER (1946) found only one case of coronary thrombosis in 3,000 autopsies on African natives in Johannesburg hospitals, while GELFAND (1957) from Southern Rhodesia encountered it only very rarely. Though Decker found coronary thrombosis to be so rare, and though atheroma was held to be the direct cause of death in only 0.4 per cent. of the 3,000 persons examined postmortem, symptomless atheroma was nevertheless a common finding, and Decker considered that its incidence in the ascending period of life was not very different from that in other races. In Uganda, DAVIES (1948) confirmed this observation and also stated that a very high proportion of Africans coming to autopsy over the age of 50 showed marked atheromatous lesions. Again, EDINGTON (1954) from Ghana, commented on the low incidence of coronary thrombosis and myocardial infarction despite the fact that atheroma, hypertension with arterial degeneration, obesity and diabetes were not uncommon. The low incidence of myocardial ischaemia in clinical, electrocardiographic and necropsy studies is therefore difficult to explain. It is partly attributable to the low average age of the subjects in most of these reports - - in the present study only 16 patients were over 40 years of age, of whom only eight were over 50 years. Other factors may include a diet low in animal fats, the effect of exercise, and possibly anastomosis within the coronary circulation itself (LAURIEand WOODS, 1958 ; PEPLER,1958). Cerebral vascular disease The frequency of cerebral vascular disease in the African native has been the subject of conflicting reports. BECKER(1946) found only one cerebral catastrophe in 3,000 necrop-

H. M. LEATHER

97

sies on Bantu subjects in Johannesburg. EDINGTON (1954), however, found 53 cases of cerebral haemorrhage in 3,645 necropsies from Ghana, and in LAURIE and WooDs' (1958) series, cerebral haemorrhage or thrombosis had led to death in 31 of 2,000 necropsies from which diabetes mellitus and syphilis had been excluded. SANKALE,RIVOALENand MILHADE (1958) state that cerebral vascular accidents are common over 45 years of age in African natives suffering from hypertension. This may well be true of Uganda where in three of the 16 subjects in the present study who were over the age of 40 years, a hemiplegia had developed, apparently from a cerebral thrombosis. SUMMARY

1) Forty-six African patients in Uganda who were suffering from hypertension have been studied. There were 34 males and 12 females aged from 17 to 75 years. Only 16 were over the age of 40. 2) Hypertension was secondary to renal disease in 27 cases, and was primary or " essential " in 14. Five cases were unclassified. Secondary hypertension was present in nearly all subjects below 40 years of age and was secondary to glomerulo-nephritis (16 cases) pyelonephritis (nine cases) or primary renal amyloidosis (two cases). The prognosis was bad, and 11 of the subjects died, usually from cardio-renal failure. 3) Essential hypertension was present in 14 cases and was the commonest cause of hypertension at over 40 years of age. Some of these patients complained only of headache and palpitation and in these the prognosis may have been fairly good. Others presented in heart failure or as a result of a cerebral vascular accident. REFERENCES

BECKER,B. J. P. (1946). S. Aft. J. reed. Sci., 11, 107. DAVIES, J. N. P. (1948). E. Afr. med. J., 25, 454. - (1949)• Ibid., 26, 76. DONNISON, C. P. (1929). Lancet, 1, 6. EDINGTON, G. M. (1954). Trans. R. Soc. trop. Med. Hyg., 48, 419. GELFAND,M. (1957)• The Sick African. Cape Town : Jura and Co. Ltd., p. 515. HENNESSEY, R. S. F. (1939)• E. Afr. med. J., 15, 329. HOLMES, E• G., STANIER, M• W., SEMAMBO,Y. B., & JONES, E. R. (1951). Trans. R• Soc. trop. Med. • Hyg., 45, 371. IVERSEN,P. & BRUN,C. (1951). Amer. J. Med., U, 324. KARK, R. M. & MUEHRCKE,C. M. (1954). Lancet, 1, 1047. KESILMAN, M. (1941). Med. Rec., 154, 16. LAURIE,W. & WOODS, J. D. (1958). Lancet, 1, 231. - & (1958). Ibid., 2, 812. LEATHER,H. M. (1959). E. Afr. med. J., 36, 305. - (1960). Brit. reed. J., 1, 1930. ORDMAN, B. (1958)• Clin. Proc., 7, 183. ORENSTEIN, L. L. (1943). War Med., 4, 422. PEPLER, W. J. (1958)• Lancet, 2, 1178. PLATT, R. (1948). Quart. J. Med., 17, 83. SANKALE, M•, RIVOALEN,A., MILHADE,J. (1958). Pr. todd., 66, 439. SCHULZE,V. E., & SCHWAB,C. H. (1932). Amer. HeartJ., 7, 710. - &- (1936). Ibid., 11, 66• UYs, C. J. (1954). S. Aft. J. clin. Sci., 5, 206. - (1956). S. Afr. J. Lab. clin. Med., 2, 232. WEISS, W. M. & PRUSMACK,J. J. (1938). Amer. J. reed. Sci., 195, 510. WILLIAMS,A. W. (1941). E. Afr. reed. J., 18, 109. - (1944). Ibid., 21,328,368.