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Biomedical subjects

R W Snow

Publications and source records attributed to R W Snow.

At least 91 records · Page 5Linked to original sources
PubMed1994

Factors influencing admission to hospital during terminal childhood illnesses in Kenya.

BACKGROUND: Access to essential clinical services offered by district hospitals or health centres forms an important component of primary health care activities in the developing world. Utilization of hospital facilities during life-threatening childhood illnesses will affect survivorship. METHODS: We have examined clinical, geographical, social, economic and demographic features of families of 49 children who consulted a hospital facility during a terminal illness and 88 who did not during a 1-year prospective demographic and hospital-based surveillance of a rural community on the Kenyan Coast. RESULTS: Of children who died without admission, 15% had symptoms which lasted only 1 day compared to no children who were admitted (P = 0.004). Furthermore, those who died without admission tended to live further away from the nearest bus stage (P = 0.01) and had made greater use of traditional healers (P = 0.08). Mothers' education or household socioeconomic status did not influence admission to hospital. CONCLUSION: Health education is required to improve early recognition of clinical signs warranting hospital care and traditional healers should be included in any community-based education programmes.

Child↗
PubMed1994

Death registration on the Kenyan Coast.

District level statistics provide health care planners necessary information for both identifying priority areas and evaluating existing health care programmes. Since 1986 an upgraded civil registration system has been in operation in Kilifi district on the Kenyan Coast. For a one-year period (1992-1993) an independent, prospective surveillance for mortality events in a defined population of approximately 51,000 people was conducted as part of intensive demographic studies. Comparisons between the active surveillance and the civil registration system revealed marked under-reporting of deaths, particularly childhood deaths, to the civil authorities. Consideration needs to be given to methods of increasing the coverage of civil registration or of developing supplementary alternative methods of collecting the same information.

Adolescent↗
PubMed1994

The prevalence of epilepsy among a rural Kenyan population. Its association with premature mortality.

During a two year community-based investigation of mortality 3.5% of the deaths to individuals over the age of 5 years were reported by bereaved relatives to have occurred to epileptics and 77% of these deaths were thought to have occurred whilst the patient was in status epilepticus. This prompted us to determine the prevalence of epilepsy in this rural population by interviewing 7,450 residents of a pre-defined study area. The prevalence of 'Kifafa' or 'Vitsala', two local words used to describe epilepsy, but later confirmed through detailed interviews, was 0.4%. This prevalence is clearly an underestimate of the true prevalence of epilepsy in this population but is probably higher than prevalences reported in developed countries. Anti-convulsant prophylaxis is available at the district hospital but this service is only sporadically used by epileptics in this population. Uncontrolled and poorly managed epilepsy may result in an increased risk of premature mortality among epileptics living in this community.

Adolescent↗
PubMed1993

Maternal recall of symptoms associated with childhood deaths in rural east Africa.

Verbal autopsies (VA) are frequently used to determine causes of death for individuals for whom there is no reliable clinical information regarding the terminal illness. VA interviews are used to note key symptoms and signs recalled by relatives of the deceased and diagnoses ascribed according to the symptom complexes. The VA technique assumes that individual disease entities have discrete symptom complexes and that these can be accurately recognized and recalled by the interviewees. We have examined the accuracy with which specific symptoms are recalled over time by mothers or normal guardians of 491 children who died on the paediatric wards of two district hospitals in East Africa. Kwashiorkor, measles, trauma, generalized convulsions and neonatal tetanus were all reported with a high degree of accuracy for children who died of these conditions and had low false positive rates for children without these conditions. Recall was similar within 1 month of death compared to recall after 6 months for most symptoms and signs except neonatal tetanus where false positive reports by mothers increased with time since death. Symptoms and signs commonly used to describe malaria, respiratory tract and diarrhoea-related deaths were reported by mothers to have been present during the terminal illness in 43% of cases where these features were absent. Recall abilities differed between the two communities studied for some symptoms and signs highlighting the importance of such studies in every setting where VA are applied.

Bereavement↗
PubMed1993

Low-level Plasmodium falciparum transmission and the incidence of severe malaria infections on the Kenyan coast.

The transmission of Plasmodium falciparum was studied in relation to the incidence of severe malaria infections at Sokoke and Kilifi town, Kilifi District, Kenya. Intensive mosquito sampling during a one-year period yielded Anopheles gambiae s.l., An. funestus, and An. coustani. Anopheles gambiae s.l. was the predominant vector, comprising 87.9% and 97.9% of the total anophelines collected in Sokoke and Kilifi town, respectively. The proportion of An. gambiae s.l. with P. falciparum sporozoite infections was 4.1% (20 of 491) in Sokoke and 2.2% (3 of 138) in Kilifi town; no infections were detected in An. funestus or in An. coustani. Entomologic inoculation rates indicated that residents were exposed to only 8.0 infective bites per year in Sokoke and 1.5 in Kilifi town. Transmission was detected during only six months in Sokoke and three months in Kilifi town despite low-level, year-round vector activity. The yearly incidence of severe P. falciparum infections in children, 1-4 years of age was 24.1 per 1,000 in Sokoke and 4.2 per 1,000 in Kilifi town. Monthly patterns of transmission corresponded closely with the incidence of severe infections. At these sites on the coast of Kenya, the spatial and temporal incidence of severe malaria infections is associated with low-level P. falciparum transmission by vector populations.

Animals↗
PubMed1992

Childhood deaths in Africa: uses and limitations of verbal autopsies.

The verbal autopsy (VA) is an epidemiological tool that is widely used to ascribe causes of death by interviewing bereaved relatives of children who were not under medical supervision at the time of death. This technique was assessed by comparison with a prospective survey of 303 childhood deaths at a district hospital in Kenya where medically confirmed diagnoses were available. Common causes of death were detected by VA with specificities greater than 80%. Sensitivity of the VA technique was greater than 75% for measles, neonatal tetanus, malnutrition, and trauma-related deaths; however, malaria, anaemia, acute respiratory-tract infection, gastroenteritis, and meningitis were detected with sensitivities of less than 50%. There may have been unwarranted optimism in the ability of VAs to detect some of the major causes of death, such as malaria, in African children. VA used in malaria-specific intervention trials should be interpreted with caution and only in the light of known sensitivities and specificities.

Cause of Death↗
PubMed1992

Case-control studies of severe malaria.

The majority of children infected with Plasmodium falciparum in areas of stable endemicity do not develop severe, life-threatening disease. It is important to identify risk factors for the minority who do. Case-control studies in which children with severe disease are compared with children with non-severe disease and with community controls, avoid some of the ethical and logistical problems inherent in such an undertaking. This paper discusses methodological aspects of case-control studies of severe malaria including case and control definitions, selection of cases and controls, potential risk factors, sample size calculations and analysis. Although specifically concerned with malaria, many of these issues are equally relevant to case-control studies of other infectious and parasitic diseases in a tropical environment.

Case-Control Studies↗
PubMed1990

Compliance with malaria chemoprophylaxis over a five-year period among children in a rural area of The Gambia.

We have reviewed a malaria chemoprophylaxis programme in which Maloprim (pyrimethamine and dapsone) has been administered fortnightly by village health workers (VHWs) to approximately 1500 children each year aged 6-59 months resident in 15 primary health care villages in a rural area of The Gambia over 5 years. Reasonable levels of compliance with chemoprophylaxis have been maintained by many children over this period. this has occurred despite minimal outside supervision and support of the programme. Factors which may have affected the level of compliance in individual villages are identified. Large villages and those where social or political factionalism were evident tended to have low levels of compliance. The attitudes of VHWs and mothers to the programme were determined. Most VHWs cooperated enthusiastically and kept accurate records of compliance, despite receiving no compensation from the villagers for administering chemoprophylaxis. The administration of a drug to prevent illness in children was complementary to the curative service provided by VHWs. The chemoprophylactic was widely acceptable and nearly all mothers stated that the tablets were good for their children's health. However, knowledge of the specific purpose of chemoprophylaxis in the prevention of malaria was limited. Improvements in the programme which may result in higher levels of compliance are discussed.

Antimalarials↗
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

T and B cell responses of Plasmodium falciparum malaria-immune individuals to synthetic peptides corresponding to sequences in different regions of the P. falciparum antigen Pf155/RESA.

The C-terminal (3') amino acid repeat region of the Plasmodium falciparum Ag Pf155/RESA, a vaccine candidate, contains immunodominant T and B cell epitopes. In order to identify additional T cell epitopes in the molecule, synthetic peptides corresponding to the centrally (5') located repeat region, as well as to four nonrepeated regions, were synthesized. T cells from 46 P. falciparum-primed individuals living in a holoendemic area of The Gambia where malaria transmission is seasonal were tested for their responsiveness to the peptides by thymidine incorporation and IFN-gamma release. There was a considerable variation in the response to different peptides. Proliferation and IFN-gamma release were not correlated in individual donors, underlining the importance of measuring both activities when screening donor populations for total T cell responsiveness to a given Ag. Whereas 72% of the donors responded with proliferation and/or IFN-gamma release to the intact protein the mean % responders to the peptides was 40%. The most frequent responses (up to 60%) were induced with peptides from the 3'- and 5'-repeat region of the protein. Analysis of some closely related sequences in the 3'-repeat region indicated that they contained at least two epitopes that were either distinct or cross-reacting in different donors, suggesting difference in the genetic control of these responses. When the same peptides were investigated for reactivity with antibodies, the best T cell inducing sequences also displayed the best antibody reactivities. However, in individual donors, T and B cell responses were not correlated. T cell responses were shown to persist after a period with no P. falciparum transmission, whereas antibody concentrations tended to decrease, suggesting differences in the requirements of boosting at the T and B cell levels, respectively.

Amino Acid Sequence↗
PubMed1989

Sporozoite antibodies and malaria in children in a rural area of The Gambia.

Sporozoite antibody levels were measured in a group of children aged one to nine years resident in a rural area of The Gambia, using an ELISA to the repeat peptide (NANP)40. The prevalence and titre of antibodies varied with age but not with sex or ethnic group. Significant variations in prevalence were recorded within a group of adjacent villages. Children who were seropositive at the beginning of the dry season had higher spleen and parasite rates both at this time and at the end of the subsequent rainy season than did seronegative children, suggesting that they were exposed more frequently to infection. However, seropositive children had fewer episodes of fever accompanied by high levels of parasitaemia than did seronegative children, suggesting that they had a greater degree of clinical immunity. No differences were found in seroprevalence rates or in mean antibody titres between children who slept under conventional or Permethrin treated bed nets and those who did not, even though bed nets significantly reduced the number of bites by vector mosquitoes.

Age Factors↗
PubMed1989

Responses of Anopheles gambiae complex mosquitoes to the use of untreated bednets in The Gambia.

Population dynamics of the Anopheles gambiae complex of malaria vector mosquitoes were studied in four small hamlets in The Gambia. Bednets were used to reduce man/vector contact in two of the hamlets. High densities of An. gambiae, sensu lato, were present for only 3-8 weeks during the rainy season, depending on the position of the hamlet within the study area. The proportions of blood-fed mosquitoes caught indoors (83.0%) and existing from houses (11.6%) were lower in hamlets where bednets were used than in hamlets without (96.5% and 33.1% respectively). Fewer of the blood-fed mosquitoes had fed on man in houses where people slept under bednets (68.2%) than in those without (81.5%). However, the average number of infective bites received by children was still greater than one a year in hamlets where bednets were used. Consequently bednets are considered unlikely to be an effective malaria control measure so long as they are untreated with insecticide.

Animals↗
PubMed1989

Impact of permethrin-treated bednets on malaria transmission by the Anopheles gambiae complex in The Gambia.

Malaria vector mosquitoes belonging to the Anopheles gambiae complex were studied in four hamlets in The Gambia. All inhabitants were given bednets treated either with a placebo (milk) in two hamlets or with the pyrethroid insecticide permethrin (500 mg/m2) in two other hamlets. Malaria transmission occurred mainly during a few weeks of the rainy season, in September and October 1987. The indoor resting densities of mosquitoes in permethrin-treated hamlets were reduced, and we estimated over 90% reduction in biting on man by An. gambiae Giles sensu stricto in these hamlets. No mosquitoes were found under permethrin-treated bednets compared with eighty-one recovered from placebo-treated bednets. Mosquitoes exited more readily from rooms where permethrin-treated bednets were used than from rooms with placebo-treated nets. The annual mean probability that a child would receive an infective bite was estimated to be 0.09 in hamlets with insecticide-treated bednets, compared with 1.9 where placebo-treated bednets were used. Permethrin-treated bednets are therefore recommended as a means of effectively reducing the risk of exposure to malaria transmission, particularly in areas of low seasonal transmission.

Animals↗
PubMed1989

Permethrin-impregnated bednets reduce nuisance arthropods in Gambian houses.

The prevalence of bedbugs (Cimex hemipterus L.), chicken ticks (Argas persicus Oken) and headlice (Pediculus capitis De Geer) was surveyed in a rural area of The Gambia. At the beginning of the study 37.5% of children's beds were infested with bedbugs and 3.9% with chicken ticks, whilst the prevalence rate of pediculosis in children under 10 years old was 28.8%. Both bedbugs and headlice were clustered within compounds. Headlice prevalence increased with hair length and they were more common on girls than boys. Following this cross-sectional survey all bednets in the sixteen hamlets were either dipped in permethrin or a placebo. About 4 months later it was found that bedbugs and chicken ticks had disappeared from homes in which the bednets had been impregnated with permethrin. There was no reduction in hamlets with placebo-treated bednets. The rate of acquiring headlice between the two surveys was reduced by 91.1% in children who slept under insecticide-treated bednets compared with children with placebo-treated bednets. There were also significantly fewer day-flying and crawling insects, except earwigs, in homes of children who slept under insecticide-treated bednets compared with those with placebo-treated nets. These additional benefits of permethrin-treated bednets should contribute to their widespread acceptance and utilization by the community for personal protection.

Animals↗
PubMed1989

Use of insecticide-impregnated bed nets in Gambian primary health care: economic aspects.

Village-wide use of permethrin-impregnated bed nets, compared with placebo-treated nets, has reduced clinical attacks of malaria by 63% in the Gambia. Costs were calculated for nets made by local tailors and for their treatment with insecticide in the villages, as well as for targeted chemoprophylaxis and back-up treatment for fever, in a comprehensive malaria control strategy through primary health care. The villagers' preferences for bed net fabrics and willingness to pay for them, and their preferences for various items of expenditure by ranked order, age group, and sex are given. Ethnic differences in the use of bed nets are also discussed.

Adolescent↗
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↗