Prevalences of leg and chest abnormalities in four South African schoolchild populations with special reference to vitamin D status

Prevalences of bowing and knock knee, measured at a standard stance, have been obtained on Negro, Coloured, Indian and Caucasian schoolchildren aged 7, 12, and 16-17 years. These two abnormalities were unexpectedly common, affecting about one-fifth and one-third of all children respectively. Ranges of prevalences of chest abnormalities were—Harrison's sulcus, 0-5%, and pigeon chest, 0-2%. Prevalence of bowing increased with age. That of knock knee was little affected by age, but increased markedly with body mass. There was no age trend with prevalences of chest abnormalities.

Prevalences appeared unrelated to vitamin D intake. As to sunshine, the annual mean for the Transvaal is 8·4 hr daily. Results from radiological, skin pigmentation, and biochemical studies were non-contributory. Since a primary deficiency of vitamin D is evidently not the causal factor, one explanation is that a secondary deficiency is involved, arising from an impairment in metabolic availability. Further, a proportion of leg abnormalities may be physiological variants; moreover, it cannot be excluded that unknown factors may bear, or share, in responsibility.

Elucidation may be forthcoming by investigating the interrelationship between vitamin D status and frequency of leg abnormalities during and after puberty; in addition, results of serial studies of prevalences of abnormalities from birth to post-adolescence would be illuminating.

The distribution in Kenya of bluetongue virus and antibody, and the Culicoides vector

Sera from domestic cattle, sheep and goats and 11 wild bovid species taken at 41 locations throughout Kenya were screened for antibody to bluetongue virus using the indirect fluorescent antibody method. Positive sera were found at 39 locations and in all the species tested. The distribution of clinical disease was mapped and found to be more restricted than the distribution of antibody. Culicoides were collected in light traps at 55 locations throughout Kenya. The presumptive vector of bluetongue in Kenya, C. pallidipennis, was the most widespread species, found in 38 locations. Both the distribution of antibody and Culicoides have been tabulated by ecological zones to demonstrate that bluetongue virus in its natural state in cattle and wild bovids is far more widespread than clinical bluetongue disease seen in exotic sheep of restricted distribution; and that C. pallidipennis has great ecological range.

Survival rate at middle age in developing and western populations

Whereas expectation of life at birth invariably is greater in more privileged populations, the respective survival patterns at middle age can be entirely different. Comparisons have been made between South African and other populations, using, as a survival index, the number who are 70 years or more at present, as a percentage of the number who were 50 years or more 19 years earlier (data for the desired 20-year period were not available for all populations). Briefly (1) South African Negroes had the highest index; Indians both in India and South Africa the lowest; Caucasian populations in South Africa, United States, and England and Wales, were intermediate. (2) Indices for females were higher than for males; the disparity was least in Indians, but greatest for the population of England and Wales. Evidently, with progressive sophistication of diet and manner of life, the concomitant change from infections to degenerative diseases, as main causes of death at middle age and beyond, reduces rather than increases chances of survival.

Omental, mesenteric, and retroperitoneal cysts: a clinical study of 33 new cases

Images

Appendicitis, fibre intake and bowel behaviour in ethnic groups in South Africa

Information on appendicectomy-prevalence was secured on 15,317 16-20-year-old South African pupils and students—Negroes, Coloureds (Eurafricans), Indians and Caucasians. Data were also obtained on crude fibre-intake, frequency of defaecation, and transit-time of digesta.

Among students, 18-20 years, appendicectomy was very uncommon in rural Negroes (0·5%) and periurban Negroes (0·9%), slightly more common in urban Negroes (1·4%), but very common in Caucasians (16·5%); prevalences in Coloured and Indian groups were low (1·7 and 2·9%). Rural Negroes had a far larger fibre-intake, greater frequency of defaecation, and much shorter transit-time; yet, in the four ethnic groups in urban areas, despite wide differences in appendicectomy-prevalence, data on these variables were similar. Differences in other aspects of the bowel milieu intérieur must therefore be sought.

Corresponding studies were made on 1325 Caucasian pupils in Homes; their diet is less sophisticated (in respect of fibre, sugar and fat-intakes) than that of the general population. Pupils had slightly greater defaecation-frequency, lesser transit-time, and an appendicectomy-incidence only 23% of that of an appropriate control-group.

The conclusion is reached that the causes of appendicitis are wholly environmental.

Cardio-thoracic ratio in Negroes in Southern Africa

Negro groups in West, Central and Southern Africa, also in Jamaica, have mean cardio-thoracic ratios significantly greater than those in corresponding age-sex groups of Caucasians.

To throw more light on the situation, studies on young and elderly Negroes have been made in certain groups in Southern Africa, also on local Caucasian groups. Only slight differences in ratio were found between local Negro groups, and Caucasian groups in South Africa, also in Wales and Tecumseh (U.S.A.). Yet ratios in Negro males from Malawi and Mozambique, resident in South Africa, were significantly greater than values in local Negroes. High ratios are not therefore invariable for Negroes. The difference observed relates to heart, not thoracic diameter. Since the phenomenon, which concerns heart position, is apparent in the young, almost certainly it is of ethnic origin. Investigations on cardiomegaly in African populations must take this factor into reckoning. Its presence or absence locally may readily be assessed by determining ratios in relatively small numbers of young people of both sexes.

The influence of numerous pregnancies and lactations on bone dimensions in South African Bantu and Caucasian mothers

1. In groups of South African Bantu and Caucasian women aged 30–44 years, sub-divided into those having had (i) none to two or (ii) seven or more children, measurements of radiographs of the second metacarpal and of the humerus were made in respect of length, cortical thickness, cortical index, cortical area/total area, cross-sectional area index and cortical/surface area ratio.

2. In Bantu mothers of large compared with small families, there were no significant differences in the means of corresponding variables. This was also the case with the Caucasian mothers. Bantu mothers of large and small families had significantly lower mean values for most variables compared with those of Caucasian mothers of large and small families. In all four groups, ranges of measurements and indices were very wide.

3. It is questioned whether Bantu mothers accustomed to a low calcium intake and to numerous pregnancies and long lactations, suffer from calcium deficiency. The problem of whether the high recommended allowances of calcium during these periods confer a clinically detectable benefit requires re-examination.

Metacarpal bone dimensions in young and aged South African Bantu consuming a diet low in calcium

Groups of South African Bantu boys and girls of 14 years, compared with local Caucasian children, have lower cortical thickness, cortical score, and crosssection and volume scores for second metacarpal. Yet, when these parameters on groups of aged Bantu men and women, 70-79 years, are compared with published values on corresponding Caucasians, there are no significant differences. Further, aged Bantu have lower prevalences of hip fracture and severe collapse of vertebral bodies. Since a low calcium intake, and in aged Bantu women numerous pregnancies and long lactations, are compatible with satisfactory bone data, it is questioned whether the present insistence on a high calcium intake is justified.

A preliminary survey of the epidemiology of bluetongue in Kenya

A survey of the species composition and distribution of the Culicoides midge populations at a range of sites where bluetongue is enzootic isolated a group of dominant species: C. cornutus, C. grahamii, C. magnus, C. milnei, C. pallidipennis and C. 23. dagger Monthly light-trap sampling of Culicoides showed that the population densities of the dominant species greatly increased after the rain seasons and that these species concentrated around flocks of sheep and cattle. The larval habitats of C. cornutus and C. pallidipennis were found associated with stock pens. Precipitin tests on blood-fed Culicoides showed that most of the dominant species regularly feed on sheep and cattle. Bluetongue virus was isolated from C. milnei, C. pallidipennis and C. 23. Serological surveys of wild and domestic bovids from the enzootic area showed a high proportion with antibody to bluetongue virus. The colonization of C. cornutus, a potential vector, is described briefly. A causal relationship between peak rainfall in April-May, peak numbers of Culicoides in May-June and peak bluetongue incidence in June-July is postulated. The vector status of the above species and C. austeni was evaluated.