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Biomedical subjects

P Byass

Publications and source records attributed to P Byass.

At least 19 recordsLinked to original sources
PubMed1991

A survey of the health of British missionaries.

The results of medical examinations carried out on 212 missionary personnel from one missionary society returning on leave to the UK are presented. The great majority of missionaries worked in developing countries. They served in 27 countries altogether and for a total of 488 person years. The commonest illnesses reported overseas were malaria (87.3 per 1000 person years at risk), diarrhoea (63.5), anxiety (63.5), depression (41.0) and giardiasis (38.9). More illnesses were reported from West Africa (698 per 1000 person years at risk) than from any other region. Ten people (4.7%) were repatriated for health reasons and 10 relatives also returned as a consequence. Sixty per cent of those returning did so because of psychiatric illness. The highest rates of immunization achieved were for yellow fever (100% of those travelling to affected countries), tetanus (93%), polio (85%), typhoid (71%) and tuberculosis (53%). The results of urinalysis (100% of adults), full blood counts (78% of adults) and stool tests (74% of all people) are reported. The study shows that the history and psychiatric examination are an important part of the medical examination of people returning from overseas. Physical examination and urinalysis did not contribute much information, although the full blood count and absolute eosinophil count were useful tests.

Adolescent↗
PubMed1991

Ability of Anopheles gambiae mosquitoes to transmit malaria during the dry and wet seasons in an area of irrigated rice cultivation in The Gambia.

The seasonality of malaria transmission was studied in a Gambian village situated in an area where rice was cultivated. Observations were made during two dry seasons, when pump-fed irrigation was used to grow rice, and in the intervening rainy season, when rice was cultivated using a combination of irrigated and rain-fed paddies. Clinical episodes of malaria were mainly confined to the months during and soon after the rainy season. In the wet season the prevalence of parasitaemia was higher in febrile subjects than in afebrile controls but the reverse applied during the dry seasons. However, the biting rates of Anopheles gambiae complex mosquitoes in the two dry seasons (2.5 and 0.8 bites/child/night respectively) were greater than or similar to that in the rainy season (0.6 bites/child/night). The proportion of human bloodmeals (0.53 vs 0.75) and the survival of mosquitoes (parity rates of 0.41 vs 0.58) were both lower in the dry seasons than in the rains. The low prevalence of morbidity due to malaria in the dry season and the observed fall in the sporozoite rate may therefore have been due to a reduction in the vectorial capacity of the An. gambiae population. However, reduced transmission in the dry season may also have been due to the direct effect of high temperatures on the parasite in the vector.

Age Factors↗
PubMed1991

Coincidence of malaria parasitaemia and abnormal chest X-ray findings in young Gambian children.

Weekly surveillance of Gambian children aged less than 5 years for both acute lower respiratory infections (ALRI) and clinical malaria showed a high rate of coincidence between abnormal chest X-ray findings and high levels of malaria parasitaemia. Generalized interstitial X-ray changes were particularly associated with these cases of malaria parasitaemia. It is suggested that such ALRIs in these children may be attributable to malaria.

Child, Preschool↗
PubMed1991

Evaluation of a computerized field data collection system for health surveys.

A customized field data collection system (FDCS) has been developed for a hand-held computer to collect and check questionnaire data. The data quality, preparation time, and user acceptability of the system were evaluated during a malaria morbidity survey in Bakau, the Gambia. Eight field-workers collected data with either the FDCS or on paper questionnaire forms in alternate weeks over a 6-week period. Significantly fewer item errors occurred with the FDCS, and by the end of the survey period interview times were significantly less with the FDCS than with the paper and pencil questionnaire. Advanced appropriate technology may have a useful role in providing accurate and rapid information, particularly in overcoming bottlenecks in data processing, and in obviating the need for costly expertise and equipment. In developing countries this could help to improve the quality of data on health care.

Data Collection↗
PubMed1990

Acute lower respiratory infections in Gambian children: maternal perception of illness.

A study of mothers' perceptions of childhood acute respiratory infections (ARI) was performed in a rural Gambian population. A total of 25,046 interviews were recorded over a 1-year period with mothers from three villages and four hamlets, and these were analysed together with the results of surveillance of their children for episodes of ARI. Mothers recognized acute lower respiratory infection as a severe disease and recognized fast and difficult breathing as features which discriminated it from upper respiratory infections (sensitivity 73%, specificity 73%). They sought treatment for their children on 51% of occasions when chest pain was reported and on 70% of occasions when 'open chest' was reported. We conclude that even in poorly educated populations in which traditional medical beliefs and practices are widespread, it may be possible to educate mothers to identify lower respiratory infections and to seek early treatment. Community education should play a major role in all national ARI programmes and may be a critical determinant of the success of case management strategies in preventing ARI-related mortality in children.

Acute Disease↗
PubMed1990

Serologic responses to an Haemophilus influenzae type b polysaccharide-Neisseria meningitidis outer membrane protein conjugate vaccine in very young Gambian infants.

Recent studies in the United States and Europe have shown that Haemophilus influenzae type b polysaccharide-protein conjugate vaccines can induce protective antibody levels in young infants, but it was not clear that this would be the case in African infants, to whom H influenzae vaccines must be given at a very early age to prevent disease caused by H influenzae. Therefore, antibody responses to an H influenzae type b polysaccharide-Neisseria meningitidis outer membrane protein conjugate vaccine were measured in very young Gambian infants. In the first group (n = 85), to whom the vaccine was given at the ages of 1 and 3 months, the geometric mean antibody level rose from a prevaccination level of 0.23 microgram/mL to a postvaccination level of 1.27 micrograms/mL, and in the second group (n = 56), vaccinated at the ages of 2 and 4 months, the prevaccination level of 0.16 microgram/mL rose to a postvaccination level of 1.59 micrograms/mL. These two final postvaccination levels did not differ significantly, and interpolation suggests that similar antibody levels were present in both groups of infants at the age of 3 months. This is the age by which protection would need to be achieved to protect against H influenzae meningitis in The Gambia and in other countries where the infection has similar epidemiologic characteristics. No significant side effects of vaccination were noted.

Antibodies, Bacterial↗
PubMed1990

Risk factors for malaria among British missionaries living in tropical countries.

Thirty-two episodes of malaria (10 confirmed by laboratory tests) were reported by 162 people living in 18 developing countries under the auspices of one British missionary society. Malaria was endemic in all countries involved, and a total of 367 person-years were observed. The overall incidence rate for malaria was 87.3 per 1000 person-years at risk. Important factors identified were residence in West Africa compared with elsewhere (relative risk (RR) = 13.0, P less than 0.001), being in the 20-39 year age group (RR = 3.2, P less than 0.002), history of gastroenteritis (RR = 3.1, P less than 0.002) and living in a rural area (RR = 1.7, n.s.). Chemoprophylaxis was taken by 119 people (73.5%).

Adolescent↗
PubMed1990

Evaluation of a primary health care programme in The Gambia. I. The impact of trained traditional birth attendants on the outcome of pregnancy.

In 1983 a primary health care (PHC) programme was introduced into the Farafenni area of The Gambia; an important component of this programme was the identification and training of a traditional birth attendant (TBA) in each village with a population of 400 or greater. The outcome of pregnancy has been documented among women resident in 15 villages which joined the PHC programme and in 26 which were too small to do so, for 1 year before and for 3 years after the start of the programme. In PHC villages 65% of women were assisted at delivery by a trained TBA during the post-implementation period and the proportion of women who delivered in a hospital or health centre increased. Both maternal and neonatal death rates fell in PHC villages during the post-intervention period, declining to about half the levels recorded during pre-intervention surveys during the last year of the study. In non-PHC villages there was also a fall in the maternal death rate but little change in the neonatal death rate. Trained traditional birth attendants probably played some part in improving the outcome of pregnancy in the Farafenni area but other factors, such as improvements in transport, may also have contributed.

Adolescent↗
PubMed1990

Evaluation of a primary health care programme in The Gambia. II. Its impact on mortality and morbidity in young children.

Mortality and morbidity in children under 5 years of age were measured in 41 villages and hamlets in a rural area of The Gambia for a 1-year period before and for a 3-year period after the introduction of a primary health care (PHC) programme into 15 of the larger villages in the area. Both infant mortality and child mortality rates fell during the post-intervention period but declines were similar in PHC and in non-PHC villages suggesting that factors such as an up-grading of the Farafenni dispensary, improvements in transport and the survey itself may have played an important part in bringing about these changes. Measurements of morbidity showed a lower prevalence of diarrhoea, vomiting or severe cough in PHC villages after the introduction of the PHC programme. Introduction of the PHC programme had no significant effect on nutritional status or on vaccine coverage. Significant improvements in the health of children in the Farafenni study area have taken place during the past 5 years but the PHC programme is probably only one of the factors that have brought about these changes.

Child Health Services↗
PubMed1989

Assessment of clinical criteria for identification of severe acute lower respiratory tract infections in children.

222 acute lower respiratory tract infections (LRI), as defined by the World Health Organisation, were identified during one year's surveillance of a cohort of 500 Gambian children aged 0 to 4 years. Symptoms and signs at presentation were related to radiological evidence of lobar consolidation, indicating severe LRI. In infants, a fever of greater than 38.5 degrees C, refusal to breast-feed, or the presence of vomiting were the best predictors of severe LRI. In children aged 1 to 4 years, a fever of greater than 38.5 degrees C or a respiratory rate greater than 60/min were the most accurate clinical signs for severe LRI. Chest indrawing did not discriminate severe LRI. These community-based findings differ from results of hospital-based studies.

Acute Disease↗
PubMed1989

Follow-up of Gambian children for a 1-year period after rotavirus infection.

To investigate the hypothesis that rotavirus infection in young children can trigger chronic diarrhoeal disease, a group of cases from a documented epidemic of rotavirus and a group of matched controls were followed for a 1-year period after infection. No evidence of excess chronic diarrhoea or vomiting in the group known to have been infected with rotavirus was found.

Diarrhea, Infantile↗
PubMed1989

Choosing and using a microcomputer for tropical epidemiology. II. Study implementation.

Continuing from the previous paper (Byass 1989), practical considerations in setting up a computer system to assist in the collection of data from an epidemiological project are discussed. Organizing field work so as to facilitate computer processing is considered, together with establishing data entry and checking procedures. The use of the hypothetical example in the first paper is continued here.

Data Collection↗
PubMed1989

Choosing and using a microcomputer for tropical epidemiology. I. Preliminary considerations.

Practical considerations involved in ascertaining data processing requirements, starting with the protocol of an epidemiological study, are discussed. These include assessments of both hardware and software requirements. Throughout the paper special emphasis is placed on the problems of conducting an epidemiological study in a tropical environment, with minimal infrastructural, logistic and expert support. The requirements of a hypothetical study protocol are used as an example. This paper covers aspects of data processing required in preparing a project proposal; its sequel considers getting the project under way.

Computers↗
PubMed1989

Tropical epidemiology: a system for continuous demographic monitoring of a study population.

Epidemiologists in many developing countries, where official demographic services are unavailable, have to include some demographic functions in their work. The usual method of documenting a study population for epidemiological research in a developing country consists of three stages: mapping, enumeration and vital registration. This paper considers the last element of this process, detailing the development of a suitable data system and explaining how its implementation using microcomputers and a database management system can help in the creation of an on-line continuous vital registration system for a study population as an epidemiological tool. The issues covered are data collection, entry and analysis, and the advantages of such a system for use in epidemiological research in developing countries are also discussed.

Africa, Western↗