The local effect of hypersensitive or inflammatory reactions to nymphal Amblyomma variegatum on simultaneous infections with Dermatophilus congolensis

Amblyomma variegatum nymphs were applied to sites infected with Dermatophilus congolensis on eight rabbits. Four rabbits were previously sensitized to the feeding of nymphal A. variegatum to produce hypersensitive reactions to the tick feeding; the remaining four rabbits had no previous exposure to nymphal A. variegatum and produced inflammatory reactions to the tick feeding. The resulting dermatophilosis infections were assessed for three weeks and there was a correlation between the position of the inflammatory tick attachment sites and the foci of infection. There was a significant increase in the lesions at sites with inflammatory reactions to the ticks, compared with sites not exposed to tick feeding; these differences appeared to be due to individual variation in the host response and were not sustained throughout the assessment.

Changes in total death rate and in ischaemic heart disease death rate in interethnic South African populations, 1978-1989

Ischaemic heart disease (IHD) in prosperous Western populations rose markedly in the 1940s, peaked between 1970 and 1975 and then fell variably--by about 50% in the USA and Australia. Undoubtedly, decreases in serum cholesterol levels, in the incidence of hypertension and in smoking frequencies are largely responsible. In South Africa, in all population groups other than blacks, IHD rates rose analogously, with Asians and whites attaining very high rates. However, from 1978 to 1989, the total death rate among white males (per 100,000 world population) fell from 1,002 to 631 (37%), and the IHD mortality rate from 312 to 139 (56%). Rates for Asians were 1,306-1,130 (14%) and 355-226 (36%), respectively, and for coloureds 1,691 to 1,392 (18%) and 171 to 110 (36%). For blacks, the total mortality rate remained unchanged; IHD rates were low, but these data are unreliable. Percentage falls in the IHD rate exceed those in the total death rate, especially among whites, indicating true decreases in IHD rate. Understandably, the accuracy of the data, as with such data overseas, is questionable. Local falls are none the less in line with those noted in Western countries. Rates for whites remain very high, and are even higher for Asians. While knowledge of the reasons for the rises and falls in IHD rates remains incomplete, whites have none the less taken some preventive action, although Asians and coloureds apparently little.

Cancer patterns in three African populations compared with the United States black population

Cancer incidence rates and patterns in three African populations in the Gambia, Mali and South Africa, have been compared with corresponding data on the Black population in Connecticut, USA. In the African populations, total rates for cancer are much lower than that of US Blacks, even allowing for under-reporting. Chief cancers are those of the oesophagus, liver and cervix. In Mali, stomach cancer is very common. As to trends, among South African Blacks, a population in transition, rates are rising, albeit slowly, of cancers of prosperity--prostate, lung, breast and colon-rectum. Salient questions are: can the number of cancers of underprivilege be lessened, and can cancers linked with rising socioeconomic states be restrained? Discussions of common risk factors, including diet, reproduction, smoking and drinking practices, indicate that for Africans as a whole, continuing poverty will prevent major changes in cancer pattern and rises in occurrence of the disease. However, should prosperity increase for Africans in big cities, rates are ultimately likely to attain those prevailing in the US Black population. Significant avoiding action seems almost impossible.

The effect of inflammatory and hypersensitive reactions, in response to the feeding of the tick Amblyomma variegatum, on the progression of experimental dermatophilosis infections

Initial infestations of Amblyomma variegatum larvae and nymphs, on rabbits and sheep respectively, produced inflammatory reactions in the host's skin; repeated infestations resulted in an increase in development of delayed type hypersensitive reactions. Dermatophilus congolensis cocci were applied in titrated doses to hosts at sites of inflammatory or hypersensitive reactions to ticks, and to control hosts with no exposure to ticks. We assessed the resulting infections for three weeks and found no significant difference between the infections on the three groups. We conclude that the local effects of the feeding of immature stages of this tick do not influence the pathogenesis of dermatophilosis.

Nutritional and non-nutritional factors for 'healthy' longevity

The far-reaching effects of the ageing of populations is being increasingly appreciated. Lengthening longevity, associated with decreasing family size, evokes rising charges, socioeconomically, and on health services. Information on these and other parameters is presented for developed and developing populations. Examples are given, with lessons to be learned, of long-living segments of populations, past and present. The roles of diet, physical activity, and smoking and alcohol consumption also of attitudes, are discussed. It is concluded that if the middle-aged and elderly could be persuaded to follow long-term practices associated with good public health, then morbidity could be compressed, and disability-free years extended. However, this goal could only be achieved with a high level of motivation.

Can the risk of colon cancer be lessened?

Colon cancer was rare or uncommon in the past, and still is in traditionally-living third world populations. It now affects 3-5% of western populations. Epidemiological, case control, experimental and other studies suggest that proneness to colon cancer can be lessened by major dietary changes, principally decreasing fat intake by a third, and doubling the intake of fiber-containing foods, especially vegetables and fruit--recommendations similarly advocated for the avoidance of coronary heart disease and other degenerative diseases. Among nondietary factors, evidence indicates familiality, obesity and atmospheric pollution to be contributory, while parity, physical activity, solar radiation, high social class, estrogen use, and aspirin use, appear protective. Despite insufficiencies of knowledge of prevention, avoiding action should certainly be taken by those familially prone. For the rest, conceivably a prudent life-style could benefit a proportion avoiding colon cancer.

Experiments on the relationship between feeding of the tick Amblyomma variegatum (Acari: Ixodidae) and dermatophilosis skin disease in sheep

Experiments on the systemic effect of feeding adult Amblyomma variegatum (F.) on dermatophilosis caused by Dermatophilus congolenis in six sheep were performed by feeding ticks at sites separate from sites of experimental infection with D. congolensis. Comparisons were made with D. congolensis infections on six control sheep without ticks. Tick-infested sheep developed chronic dermatophilosis lesions; tick-free sheep healed rapidly. On two tick-infested and two control sheep a chronological sequence of D. congolensis infection sites were made for histological comparisons. Dermatophilosis lesions on tick-infested sheep were characterized by chronic cellular infiltration and accumulation of plasma cells. Lesions on control sheep healed in association with transient cellular infiltration including plasma cells. In neither test nor control sheep was there evidence of effective phagocytosis of D. congolensis. It was concluded that feeding of these ticks had a systemic effect on the host such that dermatophilosis was aggravated via an effect on immunological reactions in the skin. Control of dermatophilosis by tick control is advocated.

Effect of subject age on costs of screening for colorectal cancer

STUDY OBJECTIVE

The aim was to estimate costs and yields of faecal occult blood screening and rescreening for colorectal cancer, for differing age cohorts.

DESIGN

Cost and clinical data were used as the basis for modelling the expected costs, and cost savings, resulting from the treatment of screen detected cancers, as compared with cancers detected by symptomatic presentation.

SETTING

Data were derived from the MRC screening trial currently in progress in Nottingham.

PARTICIPANTS

Approximately 140,000 subjects, age 50-79 years, were randomly allocated to a test (screened) and a control (unscreened) group.

MAIN RESULTS

The net costs of detecting and treating a cancer following colorectal screening fall as the age of the target population increases, owing principally to the increasing incidence of the disease with age. Generally, the marginal detection and treatment costs falls for all age groups with the first screening round, but rises considerably with the second. If allowance is made for cancers prevented as a result of early detection and excision of adenomas, the costs of screening are substantially reduced for all age groups.

CONCLUSIONS

Assuming a cost per QALY (quality adjusted life year gained) equivalent to that derived for the breast cancer screening programme, and a QALY gain from colorectal screening of one year, three screens, each separated by two years, appear economically justified for populations aged 60 years and above. Expected gains from cancer prevention make two screens justifiable for those between 45 and 59 years of age.

Screening for colorectal carcinoma: an analysis of the sensitivity of haemoccult

The sensitivity of Haemoccult for asymptomatic colorectal carcinoma has been estimated in a large randomized controlled trial of mass population screening, with a minimum follow-up of 2 years. A total of 111 cancers were diagnosed in those who completed the screening tests; of these, 36 appear to have been missed by Haemoccult and 75 were detected by the test, giving an overall sensitivity of 67.6 per cent. Haemoccult was shown to be significantly more sensitive for carcinoma of the sigmoid and descending colon than for rectal or right-sided cancers (81 versus 45 and 47 per cent, respectively). The sensitivity was higher when tests were completed over 6 rather than 3 days (74 versus 65 per cent), but this difference was not statistically significant. There was no evidence for a detrimental effect on tumour stage of a false-negative Haemoccult test; indeed, a higher proportion of the interval cancers were Dukes' A tumours than cancers in the control group.

Perplexing features in the occurrence of dental caries and its relationship to sugar intake

Epidemiologically, there are numerous perplexing features, insufficiently appreciated, in the occurrences of degenerative diseases, and in the roles of their risk factors. This applies particularly to dental caries, the commonest of all diseases, and the risk factor, sugar intake. In some contexts, caries scores are much lower, or are much higher, than expected. Moreover, even in contexts where outwardly the same risk factors are widespread, ranges of scores are much wider than would be expected. In all contexts, among groups and more especially among individuals, the association of caries experience and dietary intakes, particularly that of sugar intake, is limited. Accordingly, caution must be exercised in the over-blaming of sugar and in the overclaiming of benefits to be derived from reducing intake.

Cost-effective screening strategies for colorectal cancer

This paper models a range of feasible strategies for mass population screening for colorectal cancer. It uses both clinical and economic data derived from the major colorectal cancer screening trial currently under way in Nottingham, supplemented by data from concurrent Scandinavian trials. Costs and yields for 12 strategies are modelled, and optima are identified according to a number of evaluation criteria. The cost-effectiveness condition for the desirability of introducing a programme of colorectal screening is also established.

Malabsorption of carbohydrate foods by urban blacks

Prevalences of non-infective bowel diseases are very low in South African urban blacks compared with the white population. In seeking elucidation, using breath hydrogen measurements in series of black and white subjects, small-bowel transit time was determined, and the malabsorption of maize, wheat, and rice investigated. Median transit times in both ethnic groups were similar. Rice was fully, but wheat incompletely absorbed by both groups. Maize, the staple food of blacks, was incompletely absorbed by them, although completely absorbed by the white subjects. Carbohydrate consumption is high in the black population (60-65% of total energy intake). It is probable that in blacks, despite their now eating a low-fibre diet, an expected increase in large-bowel diseases has been inhibited in part by the protective mechanism of fermentation of malabsorbed maize and wheat.

Glycaemic responses to different carbohydrate foods in healthy and diabetic blacks in Soweto

Diabetes mellitus is uncommon in rural southern African blacks. With urbanisation and lifestyle changes, incidence rises to that in western populations. To assess associated changes in carbohydrate metabolism, glycaemic responses to glucose, refined maize, refined rice and bread were studied in 8 healthy and 8 non-insulin-dependent diabetic urban blacks. Additionally, in the healthy group serum insulin responses were measured. In the healthy, maize (the staple food of blacks) elicited the highest glucose response (207 mmol/l/min) and bread the lowest (107 mmol/l/min). The glycaemic indices of maize and glucose were similar. Serum insulin responses to maize were significantly lower than that of bread at 90 minutes (maize 66 muU/ml; bread 93 muU/ml; P = 0.02). In diabetics, maize and glucose elicited similar glycaemia (928 mmol/l/min and 921 mmol/l/min respectively). The high glucose response to maize could relate to its processing and physical form. The low insulin secretion could be due to inadequate stimulation by the 'entero-insular' axis. Moreover, variability in glucose insulin responses could stem from ethnic or genetic reasons. In the dietary management of black diabetics, refined maize should be replaced by other cereals.

Combating protein-energy-malnutrition in a rural/peri-urban southern African black population

PROTEIN-ENERGY-malnutrition (PEM) is a major cause of morbidity and mortality in young children in Africa. In South Africa, in 1987, to help combating and preventing PEM in the rural black population, the Gold Fields Nutrition Unit was inaugurated at the Medical University of Southern Africa. In 1987-9, 442 patients (rural/peri-urban) plus their mothers or child carers were admitted, and 406 attended as outpatients. Average age was 15.4 +/- 7.6 months, weight 7.0 +/- 1.6kg, stay in hospital, 12 +/- 10.8 days, and daily weight gain during treatment was 31 +/- 48g. Mothers mainly were young and unmarried. Primary causative factors were infections, ignorance, and insufficiency of food. Since results from rehabilitation are usually poor, mothers and carers were taught how best to prepare meals using local foodstuffs. The interventions included teaching and demonstrations of how to grow vegetables, maintain an orchard, a fowl-run, and improve kitchen and laundry facilities. In 1990, in a follow-up of 73 patients, no deaths had occurred within a 12 month period. This far better than usual outcome is being furthered by setting up satellite nutrition clinics.

Histopathology of attachment sites of Amblyomma variegatum and Rhipicephalus appendiculatus on zebu cattle of varying resistance to ticks

Mature, unimproved East African Zebu cattle (Bos indicus) naturally exposed to ticks from birth were ranked for resistance to ticks by repeated whole-body counts of infesting ticks. Four cattle of high resistance, four of low resistance and two of intermediate resistance were artificially infested with nymphs of Amblyomma variegatum and Rhipicephalus appendiculatus. Two Friesian cattle (Bos taurus) with less exposure to ticks were similarly infested. Biopsies of tick attachment sites were examined histologically. All attachment sites showed acute inflammatory lesions, and sites of both tick species on high resistance cattle showed delayed hypersensitive reactions with intra-epidermal pustulation and significant increases in the numbers of granulocytes. The predominant cells infiltrating attachment sites on high resistance cattle were eosinophils with A. variegatum and neutrophils with R. appendiculatus. Such differences need to be taken into account in developing immunological tests for selecting cattle for resistance but there are sufficient common features of reactions to the two infesting tick species to justify dermal hypersensitivity tests.

Limitations of faecal chymotrypsin as a screening test for chronic pancreatitis

Faecal chymotrypsin was measured in patients with chronic pancreatitis and in healthy black urban and rural control subjects. In the patients, significantly lower values of faecal chymotrypsin were obtained (mean (SD) 2.4 1.79 U/g stool) whereas in urban control subjects, values were within the normal range (mean (SD) 13.2 (11.9)). In rural black control subjects, however, the faecal chymotrypsin value was significantly lower (mean (SD) 7.1 (5.1)) than in urban black control subjects. It is suggested that faecal pH may influence faecal chymotrypsin values. The mean faecal pH in rural black subjects (pH 6.14) was significantly lower than that in urban control subjects (pH 6.77) and in patients with chronic pancreatitis (pH 6.61). Moreover, mean faecal chymotrypsin is high (20.0 U/g stool) at a pH greater than 7. Between pH 6 and 7 the mean value drops to 8.6 U/g stool and below pH 6 mean faecal chymotrypsin is in the abnormal range (4.4 U/g stool). Hence, low values for faecal chymotrypsin may be due to lower faecal pH (less than 6) in healthy control subjects. For diagnostic purposes, the faecal pH value should be determined if a low faecal chymotrypsin value is obtained.

Body image and eating behaviour in interethnic adolescent girls

Reports of major dissatisfaction among adolescent girls over body shape and their associated eating behaviour, prompted determining anthropometric and questionnaire studies on series of rural and urban black, Indian, and white girls aged 14-19 years. Variables were concern over weight, desired weight loss, also practices regarding binge eating, fasting, vomiting and laxative use. Black girls have low weight-for-age, yet experience more obesity than white girls; yet weight reduction, although desired, is seldom seriously attempted. Indian girls have low weight-for-age, principally for genetic, not social class, reasons; they also, even some underweight, desired weight reduction. White girls are also dissatisfied, although less acutely than girls in the US. The current attitudes of South African adolescent girls, apart from extremes, are unlikely to seriously prejudice their health.

Rehydration of guaiac-based faecal occult blood tests in mass screening for colorectal cancer. An economic perspective

Owing to dehydration during storage, faecal occult blood tests have been found to lose sensitivity; accordingly, test rehydration before development has been advocated, although this practice has yet to be subjected to an economic evaluation. In this paper, the results from two major screening trials in Sweden and England, one using rehydration and the other not, are so evaluated, based on a costing model developed within the English trial. The higher sensitivity resulting from rehydration was found to be accompanied by losses in specificity, such that, although more cancers are detected, the costs of screening and of cancer detection are actually considerably higher under the rehydration regimen than with non-hydration.

The hospital costs of diagnostic procedures for colorectal cancer

Diagnosis for colorectal cancer is commonly made using either colonoscopy or double contrast barium enema techniques. To data, little attention has been paid to the comparative costs of these two procedures and the paper presents estimates of hospital costs for each, using data from the colorectal study being undertaken in Nottingham, U.K. Consideration is also given to procedure sensitivity and the frequency of referral to the alternative technique in cases of incomplete diagnosis. The paper presents the conditions under which a given technique may be considered cost-superior to its alternative but concludes that the absence of conclusive clinical trial data and other considerations precludes the identification of a definitively optimum technique from the economic point of view.

Interethnic physiological and pathological diversities in southern African populations

The African continent accommodates a diversity of races--Arabs, Berbers, Nilo-Saharan, Bantu, Pygmies, as well as immigrant white and Indian populations, especially in Central, East and Southern Africa. In these populations and sub-populations, differences prevail in physiological variables, in biological disorders, in measurements made by laboratory and associated means, and in disease patterns. A salient question is: which differences will persist, and which become modified or even disappear as a result of progressive urbanisation, a rise in prosperity, and changes in lifestyle, particularly when these occur in populations previously poor or who have lived in a rural traditional manner.

The costing of nursing care: a study of 65 colorectal cancer patients

Nursing care is a major factor in the cost of most medical treatments. This paper reports on two alternative techniques for estimating the costs of nursing care, in the context of colorectal cancer treatment on a surgical ward in the University Hospital, Nottingham. The simpler, but cruder, technique is based on average patient costs, whilst the other is patient-specific and incorporates the use of nursing dependency data. Results from the two estimation methods are compared and the implications for the proper costing of nursing care are discussed.

Alternative pathways for hydrogen disposal during fermentation in the human colon

Hydrogen gas, which is produced during fermentation in the human colon, is either excreted in breath or metabolised by gut bacteria through a variety of pathways. These may include methanogenesis, dissimilatory sulphate reduction, and acetogenesis. To determine which of these routes predominates in the large intestine, stools were taken from 30 healthy subjects and incubated as 5% (w/v) slurries with Lintner's starch. In 23 of 30 subjects, methane production was the main method of hydrogen disposal. In the remaining seven, high rates of sulphate reduction were recorded together with raised production of H2S. All samples showed relatively low rates of hydrogen evolution and of acetate formation from CO2 and H2. Sulphate reduction and methanogenesis seem to be mutually exclusive in the colon and this is probably linked to sulphate availability. Sulphate reduction, methanogenesis, and acetogenesis were strongly influenced by pH. Sulphate reduction was optimal at alkaline pH values whereas methane production was maximal at a neutral pH and acetogenesis favoured acidic conditions. Faecal H2S values were related to carriage of sulphate reducing bacteria. These data show that a number of competing pathways for hydrogen disposal are possible in the large gut and that a variety of factors such as colonic pH and sulphate availability can determine which of these mechanisms predominates.