Conducting a descriptive survey: 2. Choosing a sampling strategy.
Explore the source record for details and available documents.
Developing Countries↗
Biomedical subjects
S B Macfarlane
Publications and source records attributed to S B Macfarlane.
Conducting a descriptive survey: 1. Planning the survey.
Explore the source record for details and available documents.
Data Interpretation, Statistical↗
Epidemiology training for primary health care: the use of computer-assisted distance learning.
The Liverpool Epidemiology Programme, based in the Liverpool School of Tropical Medicine, has designed a series of computer-based modules for use in distance learning. The purpose of this paper is to highlight the role of computers in training health workers in epidemiology in developing countries. The aim of the modules is to provide health workers with solutions to problems which they face in their everyday work. The modules are written in hypertext software for IBM compatible machines and interact with the epidemiological software Epi Info. Four modules are described: LEP-Nut which deals with nutritional surveillance, LEP-Ref which looks at the role of epidemiology within a refugee health care programme, LEP-Surv dealing with health surveillance and LEP-Rap which introduces the concept of rapid appraisal. They are also easily distributed, particularly with the development of the Internet. The modules are carefully evaluated before and after distribution. Issues related to their evaluation and subsequent revision are discussed, in particular is the content important, adequate, communicated and useful? A major advantage of computer-based learning materials is that they can be easily updated with new advancements of knowledge and experience from the field.
Computer-Assisted Instruction↗
Errors in calculating weight-for-height.
Weight-for-height is widely used as an index of recent malnutrition and often forms the basis on which major policy decisions are made about nutrition interventions. This article illustrates potential for error in the calculation of weight-for-height. Comparisons are made between results obtained using the international reference figures published by the World Health Organization, the plasticized cards distributed by Teaching-aids At Low Cost and by using the computer software package Epi Info (versions 5 and 6). An assessment is made of the errors introduced by treating supine measurements incorrectly as stature or by treating stature measurements as supine. Comparisons are also made between the use of standard deviation scores and percentages of the median. It is recommended that the international reference figures be published in a more convenient tabular form and that the plasticized cards and percentages of the median should not be used for studies involving international comparison. Investigators who plan to use Epi Info are advised to take into account the way in which it calculates weight-for-height when collecting and analyzing their height measurements.
Africa South of the Sahara↗
A universal growth reference or fool's gold?
Explore the source record for details and available documents.
Anthropometry↗
The use of hypertext: demonstration of the methods for investigating an epidemic of meningitis.
The Meningitis Hypertext Case Study is a computer-assisted learning module developed by the Liverpool Epidemiology Programme as part of a comprehensive set of modules and case studies to assist health workers to learn epidemiology. The objectives of the case study are to highlight important concepts in diagnosing an epidemic of meningitis. It has been developed using hypertext software (LINKWAY) which allows interactions with other epidemiological software (EPI INFO) for the analysis of the data. The case study makes extended use of graphical displays, has a 'user-friendly' presentation and can be used by individuals and groups. Our initial experience indicates that this form of computer-assisted learning has considerable potential by providing users with an organized path through a series of problems set in a realistic environment. This could prove to be potentially useful in developing countries where up-to-date learning materials are often unavailable.
Computer-Assisted Instruction↗
Protein-energy malnutrition in northern Sudan: prevalence, socio-economic factors and family background.
The socio-economic and family background and the nutrition of 145 children with kwashiorkor admitted to hospital in Khartoum over a 2-year period were compared with 113 marasmic kwashiorkor, 158 marasmic, and 186 nutritionally normal controls of similar age. Peak admissions for kwashiorkor were in the wet and post-wet season and the mean (SD) age was 1.6 (0.6) months. Mothers of malnourished children were more likely to be pregnant, and had poorer housing, sanitation and water supply, a lower income and food expenditure and less education than controls. Mothers of controls breastfed their children longer, introduced mixed feeding earlier, offered a wider variety of foods, and were more likely to have had their infants immunized. Neither family instability nor cultural practices which result in separation of children from their mothers appear to have an important role in protein-energy malnutrition in the Sudan. Families of kwashiorkor children had a higher food expenditure and better maternal education than marasmic children. There was no significant difference between the two groups in duration of breastfeeding or in the age of introduction of mixed diet. However, kwashiorkor children appeared to be offered more meat. Differences in food availability could account for the relative retardation of growth and lack of subcutaneous fat in marasmus compared to kwashiorkor.
Breast Feeding↗
Detection of cow's milk protein intolerance by an enzyme-linked immunosorbent assay.
Circulating IgG antibodies to cow's milk proteins have been quantified in 182 children using an enzyme-linked immunosorbent assay (ELISA). Antibody levels in children with cow's milk protein intolerance (CMPI) were compared with those in control groups comprising other diarrhoeal diseases, atopic children, and a "normal" sample including children with toddler diarrhoea. Mean IgG antibody levels in children with CMPI were significantly higher than in any of the control groups. There were clear differences in peak antibody levels between CMPI and all other groups for each of the protein fractions tested. There was some overlap in titres between CMPI and other enteropathies but the assay gave 88% sensitivity and specificity for the diagnosis of CMPI overall and was 100% specific against the combination of non-enteropathic controls in this study. These findings indicate that the assay could be applied as an outpatient screening test for CMPI and would be particularly useful in differentiating "toddler" diarrhoea from CMPI.
Adolescent↗
Protein-energy malnutrition in northern Sudan: clinical studies.
The medical history, clinical features and investigations of 145 children with kwashiorkor were compared with 113 marasmic kwashiorkor, 158 marasmic children and 186 nutritionally normal controls of similar age admitted to hospital in Khartoum. Factors in the group with protein-energy malnutrition (PEM) which could relate to aetiology include: a history of prolonged illness and anorexia, frequent and prolonged episodes of diarrhoea and recent measles. The delay in achievement of developmental milestones in PEM children probably reflects the frequent and chronic illnesses in this group. An episode of previous oedema was reported in 22 per cent of marasmic kwashiorkor, 12 per cent of kwashiorkor and 12 per cent of marasmic children. Though hair and mucosal changes and enlarged liver were more common in the marasmic kwashiorkor and kwashiorkor groups, they were also common in marasmic children. There was no significant difference in behaviour (apathy, irritability, anorexia) between kwashiorkor and marasmic children. The classical skin changes of kwashiorkor were only seen in the oedematous children. The mortality was 19 per cent in kwashiorkor, 35 per cent in marasmic kwashiorkor, and 14.5 per cent in the marasmic group. The major differences between marasmus and kwashiorkor children were that the kwashiorkor children were reported larger at birth, achieved more normal developmental milestones, were taller and had larger head circumference than the marasmic children. The implications of these findings in relation to aetiology are discussed.
Anthropometry↗
The interaction of alpha thalassaemia with malaria.
A controlled trial of iron dextran prophylaxis in infants 2 months old was carried out on the north coast of New Guinea, where malaria is holoendemic. These infants have a high carrier rate (80%) for alpha + thalassaemia. The neighbouring highland area has a low rate of both malaria and alpha + thalassaemia. The results of clinical and haematological examination of these infants at 6 and 12 months were analysed to determine the relationship between alpha thalassaemia and susceptibility to malaria. Infants were divided according to haemoglobin Bart's levels found at birth into 3 groups corresponding to probable genotypes. Homozygotes had higher slide malarial positivity and spleen rates at 6 and 12 month than the normal or heterozygote groups. Analysis of variance of haemoglobin levels showed that the anaemia associated with malaria was greatest in the normals and least in the homozygotes at 6 months. A possible protective mechanism of alpha thalassaemia is discussed.
Disease Susceptibility↗
Loperamide in acute diarrhoea in childhood: results of a double blind, placebo controlled clinical trial.
Fifty-three young children with acute diarrhoea were included in a hospital-based, double-blind trial of loperamide at two dose levels (0.4 and 0.8 mg/kg/day), given with standard oral rehydration therapy versus placebo plus oral rehydration therapy. The differences in the overall recovery rate were significant (P less than 0.05), the fastest being in the group given 0.8 mg/kg and slowest in the placebo group. Comparison between weights on admission and weights by day 3 showed that more children in the loperamide groups gained weight than in the placebo group (P less than 0.05). No serious side effects of loperamide were observed. The drug was withdrawn in one child because of excessive lethargy and sleep. The results indicate that loperamide in the doses employed is safe and may be a useful adjunct to oral rehydration in certain children.
Child, Preschool↗
The chemotherapy of onchocerciasis. XII. The prediction of microfilarial loads in patients with onchocerciasis after treatment with diethylcarbamazine in northern Ghana.
This paper presents some statistical problems of analysing changes in patterns of microfilarial loads in onchocerciasis patients after chemotherapeutic treatment. Analyses are made of a pooled set of data from ten separate studies of diethylcarbamazine (DEC) conducted at the Onchocerciasis Chemotherapeutic Research Centre, Tamale, between 1978 and 1983. Regression models of microfilarial load at different intervals post-treatment are fitted with initial microfilarial load, total dose of DEC, duration of treatment and age of the patient as the independent variables. Appropriate transformations of the variables are chosen by examination of plots of residuals for violations of the assumptions underlying the regression models. A dose response curve for DEC is produced.
Adult↗
Effect of iron prophylaxis on morbidity due to infectious disease: report on clinical studies in Papua New Guinea.
A controlled trial of iron prophylaxis (3 ml intramuscular iron dextran) to two-month-old infants was carried out on the north coast of Papua New Guinea where there is high transmission of malaria. The initial hypothesis was that iron deficiency increased susceptibility to infections and thus iron supplementation in a situation of actual or potential iron deficiency would diminish this susceptibility. Findings detailed elsewhere indicate that the placebo control group became relatively iron deficient and that the iron dextran group had adequate iron stores and a higher mean haemoglobin; however, prevalence of malaria recorded in the field was higher in the iron dextran group. Analysis of field and hospital infectious morbidity in the trial indicated a deleterious effect of iron dextran for all causes and for respiratory infections (the main single reason for admission). Total duration of stay in hospital was significantly increased in the iron dextran group. Analysis of other factors showed a deleterious effect of low weight for height at the start of the trial; a significant positive correlation between birth haemoglobin and hospital morbidity rates and a positive interaction between haemoglobin and iron dextran on hospital morbidity. A possible association between malarial experience and other infectious morbidity is discussed.
Body Weight↗
Iron supplementation increases prevalence and effects of malaria: report on clinical studies in Papua New Guinea.
A placebo-controlled trial of intramuscular iron dextran prophylaxis for two-month-old infants was carried out on the north coast of Papua New Guinea where there is high transmission of malaria. The results indicate that the placebo group became relatively iron deficient whereas the iron dextran group had adequate iron stores and, in the absence of malaria, a higher mean haemoglobin. However in the iron dextran group there was a higher prevalence of malaria, as judged by parasite and spleen rates at 6- and 12-month follow-up; a lower haemoglobin associated with malaria when compared with the placebo group and a greater reticulocytosis in response to malaria infection. Within the placebo group it was noticed that the malaria rates were lower at follow-up in those infants who had had a low birth haemoglobin. In neither group was there apparent suppression of marrow activity in the presence of malaria. Malaria infection in both groups was associated with a significantly raised serum ferritin level and transferrin saturation. Over-all these data give evidence for a protective role of iron deficiency against malaria and would argue against the injudicious use of iron replacement in areas where malaria is endemic.
Clinical Trials as Topic↗
Aflatoxins and kwashiorkor: clinical studies in Sudanese children.
Aflatoxin analysis of blood and urine by high performance liquid chromatography in 584 Sudanese children is reported. The results in 404 malnourished children comprising 141 kwashiorkor, 111 marasmic kwashiorkor and 152 with marasmus are compared with 180 age-matched controls and correlated with clinical findings. The aflatoxin detection rate and mean concentration were higher in serum of children with kwashiorkor than the other groups. The difference between the detection rate in kwashiorkor and controls was significant (p less than 0.05). The aflatoxin detection rate in urine was highest in the marasmic kwashiorkor group and the mean concentration was higher in the marasmic kwashiorkor and marasmic groups than in the kwashiorkor and control groups. There were important differences in the detection of certain aflatoxins between the groups. Aflatoxicol was detected in the sera of 16 (11.6%) kwashiorkor, in six (6.1%) marasmic kwashiorkor, but in none of the controls and only once in marasmus. These differences are highly significant (p less than 0.0001). The ratio of AFB1 to AFM1 was higher in the sera and urines of kwashiorkors than in controls, suggesting that the normal transformation of AFB1 to AFM1 may be impaired in kwashiorkor with consequent increase in transformation of AFB1 to aflatoxicol. The study therefore provides evidence of differences in the metabolism of aflatoxins in children with kwashiorkor compared with children with other forms of malnutrition and normally nourished children and confirms the association between aflatoxins and kwashiorkor contained in a preliminary report on this work.
Aflatoxin B1↗
Total dose iron infusion, malaria and pregnancy in Papua New Guinea.
A study was made of 544 mothers and their 556 newborns in an area of endemic malaria, to analyse effects of total dose intravenous iron infusion (TDI) to mothers during pregnancy. 34% of these mothers received TDI before delivery. A range of haematological tests was carried out on newborns and mothers in addition to anthropometry. 84% of mothers had had ante-natal care and data were also collected retrospectively from ante-natal records. TDI was associated with more slide positive peri-natal malaria in primipara (odds ratio: 5.46) but not in multipara. When all relevant factors were considered TDI was not associated with an overall improvement in haemoglobin status from the first ante-natal level recorded to the post-natal check. Post-natal malaria was associated with lower ante-natal and post-natal haemoglobin levels. There was no evidence of any effect of TDI in pregnancy or of maternal malaria on foetal maturity or birth weight. Gestational age, maternal weight, parity and maternal post-natal haemoglobin were all significantly correlated with birth weight. TDI to the mother was associated with higher neo-natal serum ferritins and lower neo-natal haemoglobins. Maternal post-natal malaria was associated with significantly lower iron in serum in newborns. It is suggested that routine total dose iron infusion to anaemic pregnant mothers in malaria endemic areas may be contraindicated.
Anemia, Hypochromic↗
Malumfashi Endemic Diseases Research Project XXI. Some aspects of the collection of demographic data.
This paper considers some of the procedures used and problems encountered in the collection of demographic data for a large-scale medical project: the Endemic Diseases Research Project at Malumfashi in northern Nigeria, 1974-1979. 43,216 people were enumerated and a subset of 26,100 were visited monthly for one year for the purpose of registration of vital events. The majority of problems encountered are relevant to similar studies in developing countries. Some difficulties cannot be avoided, but it is considered helpful to identify them. Other situations, however, deserve particular attention, such as the development of adequate on-site data-checking mechanisms, as these are areas in which future programmes could benefit from the experience of the demographic studies in Malumfashi. More effort still needs to be put into the improvement of data collection methods themselves.
Attitude to Health↗
Iron supplementation and malaria.
Explore the source record for details and available documents.
Age Factors↗