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Biomedical subjects

P van der Stuyft

Publications and source records attributed to P van der Stuyft.

13 recordsLinked to original sources
PubMed2006

Towards active community participation in dengue vector control: results from action research in Santiago de Cuba, Cuba.

Community participation is advocated as essential for attaining effective dengue prevention, but knowledge of how to foster this is limited. In Santiago de Cuba, multiple small task forces were created at the neighbourhood level that included all stakeholders in the control of Aedes aegypti. The task forces assessed the perceived needs and elaborated action plans to promote specific behavioural change and to reduce environmental risks through social communication strategies and intersectoral local government activities. We monitored five dimensions of the participation process and assessed behavioural and environmental results and entomological outcomes. Participation was weak to good. At the household level, uncovered water storage containers decreased from 49.3% to 2.6% between 2000 and 2002, and removing larvicide from them dropped from 45.5% to 1%. There was a reduction of 75% in the absolute number of positive containers and a significant decrease from 1.23% to 0.35% in the house index. Local task forces, in which the interests of householders as well as vector control workers are directly represented, can lead to effective government-community partnerships that resolve problems of mutual concern.

Animals↗
PubMed2004

Accuracy of routine diagnosis of pulmonary tuberculosis in an area of high HIV prevalence.

SETTING: Gweru Provincial Hospital, Zimbabwe. OBJECTIVES: To evaluate the accuracy of the diagnosis of pulmonary tuberculosis (PTB) in routine circumstances. DESIGN: Prospective cohort study of routinely diagnosed PTB patients between September 2000 and September 2001. RESULTS: Of 300 patients started on treatment, 161 (53.7%) were positive on direct microscopy. Of the 139 sputum-negative patients, 51 (36.7%) were positive after concentration of specimens, an additional 30 (21.6%) were positive on culture only and 58 (19.3% of the total) were negative for all laboratory investigations. There was no difference in sex, human immunodeficiency virus (HIV) serostatus or treatment outcome between the culture-positive and culture-negative presumed PTB patients. Sputum-negative patients had an increased risk of dying during treatment (RR 2.39, P = 0.015). CONCLUSIONS: The laboratory findings reveal that PTB could be confirmed in more than 80% of patients put on treatment in this setting. The treatment outcomes of the remainder did not differ from those in patients with microbiologically confirmed PTB. In a high HIV-prevalent area, clinicians rightly consider the results of the sputum microscopy test as only one element in the decision making process to put a patient on TB treatment.

Adolescent↗
PubMed1999

Operational validation of the direct agglutination test for diagnosis of visceral leishmaniasis.

The validity of the direct agglutination test (DAT) for visceral leishmaniasis (VL) was studied with a standardized field kit on 148 clinically suspected persons and 176 healthy controls recruited between 1993 and 1994 from an endemic area in Gedaref State, Sudan. A sensitivity of 95.9% and a specificity of 99.4% were found at a 1: 8,000 cut-off titer when parasitologically confirmed cases were compared with healthy controls. While corroborating previously reported sensitivity and specificity estimates of this serodiagnostic test, this study examined the bias generated by commonly used test validation procedures. The fundamental methodologic problem in VL test validation is the absence of a reliable gold standard. Moreover, any operational guideline on DAT use has to consider the critical dependency of the predictive values of the test on VL prevalence rates. The DAT diagnostic cut-off titer depends upon many external factors, among which the prevalence of disease in the area and the case mix seem the most important.

Agglutination Tests↗
PubMed1997

Utilisation rates and expenditure for public and private, curative-care services in semi-urban Guatemala.

In November 1994, a retrospective survey was conducted for two purposes; to investigate patterns of health-care uptake for childhood and maternal illness in semi-urban Guatemala; and to gain an insight into the expenditure incurred by the subjects when they consulted the various health-care providers. The subjects, who all belonged to a semi-urban ladina community, had easy geographical access to the health-care providers, of all types, operating in Sacatepequez, in the central highlands of Guatemala. The community was divided into clusters of roughly equal population size and 20 of these were selected. Within each selected cluster, eight households that had at least one young child (< 5 years of age) were investigated. Mothers belonging to each household were asked whether, how frequently, and where they had sought outside help for any health problem that had possibly affected them or their children during the past year. Subsequently, they were also invited to recall the expenditure incurred on the last visit, if any, to each type of health-care provider established in the area. The crude utilisation rates, for all providers combined, were 1.0/women.year and 0.8/child.year. Overall, 61% of women had no uptake of curative care for themselves and 12% of families no such uptake for their children. Lay curers and clinics run by non-governmental organizations were hardly utilised. Drug vendors accounted for 38% of contacts by women and 26% by children, private physicians for 34% and 38%, and public services for 22% and 33%, respectively. The utilisation rate of the official sector attained roughly 0.3/person.year in both women and children. Dissatisfaction with the treatment received and the lack of drugs were often given as reasons for not attending public services. The median total expenditure incurred per curative, health-care contact ranged from 0 quetzales in the official health centres to 63 quetzales with private physicians (a U.S.$ being equivalent to 5.5 quetzales at the time of the study). Although for each type of provider (except the health centres), expenditure was nearly equal for a woman or for a child contact, it consisted of a different mix of cost elements (consultation fee, drugs and transport) for each of the various categories of provider. The willingness for a more prominent role of the public sector. It would seem that there is, in the socio-economic environment of semi-urban Sacatepequez, room for experimenting with alternative modes of health-care financing to increase the quality and attractiveness of public services and their utilisation.

Adult↗
PubMed1996

[Evaluation of the Ivory Coast sentinel surveillance system for antimalarial drug sensitivity].

This study was performed to assess the sentinel surveillance system on malaria resistance in Cote d'Ivoire using a new method. Evaluation was based on documentation describing routine products and on activity reports obtained from the surveillance system. A qualitative approach was used to assess system design and quantitative approach to assess its operation. Degree of satisfaction with evaluation criteria was scored on a scale of 1 to 5. Score reproducibility in this study was good. Overall the system was considered as satisfactory. The strong points of the system are relevance, functions, sustainability, and data quality. The weak points are poor planning, overcentralization, and underuse of information. Correction of these weakness will require concentration by all parties at the national level involved in the surveillance system. The evaluation method used was simple, cheap and reproducible and thus could serve as an alternative approach for evaluation of sentinel surveillance systems in areas with scarce resources.

Antimalarials↗
PubMed1994

A hundred per cent of fields positive in a thick film: a useful indicator of relative changes in morbidity in areas with seasonal malaria.

The classical method of estimating the density of Plasmodium falciparum in blood, by counting the number of trophozoites per leucocyte, is compared with a method in which the proportion of microscope fields in a thick film that include at least one asexual form is evaluated. Mean densities of 144 and 1920 trophozoites/microliters blood gave 9.5% and 99.5% positive fields, respectively, and < 5% of slides with 100% positive fields were of blood with < 2000 trophozoites/microliters. The proportion with high parasitaemia (PHP) in a population, defined as the proportion of individuals with 100% positive fields, is proposed as a simple and reliable indicator of relative changes in malaria morbidity due to seasonal fluctuations or control activities. However, the use of this index is limited to areas with intermediate malaria stability. Data from a longitudinal survey in Burundi, presented to illustrate the use of PHP, show that PHP undergoes important fluctuations related to transmission. In contrast to the parasite index, the amplitude of fluctuations in PHP decreases with age as a result of acquired protective immunity. Although two health centres, one in a vector control area and one in an area with no control, reported similar proportions of cases of clinical malaria among their patients, PHP was about three times lower in patients from the vector control area. The estimation of the efficacy of a malaria control programme from simple clinical information appears unreliable. Sentinel health centres, each equipped with a microscope to estimate PHP, may often be better indicators of changes in morbidity.

Adolescent↗
PubMed1994

[Relationship between Plasmodium parasitemia and febrile episodes in various population groups in Kinshasa, Zaire].

The objective of this study was to determine the relative importance of determinants of fever-episodes in an environment with perennial malaria transmission. In 6 neighbourhoods of Kinshasa with different degrees of urbanization, 120 clusters of children younger than 10 years were selected over a one year period and followed up for 2 weeks each. In the 4,816 children retained for analysis 906 fever episodes were registered, which corresponds to an average incidence rate of 4.9 episodes per child per year. Seven hundred (77.3%) of the fever cases had a positive thick film (IF) but of the 3,289 children with a positive TF only 21.3% presented fever during the observation period. Nevertheless, high parasite densities formed, without neglecting the role of other infectious etiologies, the mayor pathogenic mechanism associated with fever. The risk for a fever episode was, in multivariate analysis, 40 times higher in children with at least one positive TF than in children with a negative TF on both day 1 and day 14, and amongst the ones with a positive TF the risk was 3 times higher in children with a parasitemia above 3,000 trophozoites/microliter blood. The habitat constituted another important independent determinant: the relative risk for fever was 1.48 for non-urbanized neighbourhoods, which probably reflects the low malaria transmission in the urbanized ones, but 2.1 for semi-urbanized against peripheral neighbourhoods, where the parasite index is high. Low socio-economic status, the short dry season and young age formed, in this order, further factors to the take into account.

Animals↗
PubMed1994

[Diagnosis of anemia at high altitude: problems encountered in Tibet].

To test the hypothesis that Tibetans do not increase their haemoglobin concentration with increasing altitude, haemoglobin concentrations of children aged 6 to 72 months were analyzed. The mean haemoglobin concentrations in the different age groups are significantly lower than the mean concentrations expected at this altitude. Histograms and tests for normality show that the haemoglobin distributions are Gaussian. The probability plots confirm the coefficients of skewness, which indicate a superimposed subpopulation towards the lower range of haemoglobin values. A mixed distribution analysis identifies that the curvilinear deviation found in the probability plot encompasses 10 to 12% of the studied population. Together with the normality of the haemoglobin distributions, we are led to suppose that this is the anaemic population. These figures are considerably lower than those found using recommended cut-off values for this altitude; 40 and 46%. Two possible explanations are put forward: 1) the whole population is submitted to the same factor and hence the whole population should be considered anaemic, 2) Tibetans react differently to altitude than other mountain people and have adapted themselves without increase in haemoglobin.

Adaptation, Physiological↗