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A M Polderman

Publications and source records attributed to A M Polderman.

At least 73 records · Page 4Linked to original sources
PubMed1995

An attempt to quantify the role of existing health facilities in controlling vesical schistosomiasis in rural northern Cameroon.

Around the artificial reservoir in the Benue River near Lagdo in Northern Cameroon, Schistosoma haematobium and S. mansoni are prevalent. The primary health care structure has been reinforced in recent years, but no special attention has been paid to schistosomiasis. This setting was considered ideal to estimate the contribution of the existing health facilities in the control of morbidity due to schistosomiasis. The patients locally diagnosed as having vesical schistosomiasis, were subsequently examined with a standardized quantitative filtration method. Furthermore, surveys were carried out in the surrounding villages to estimate the age-specific prevalences of vesical schistosomiasis in the health centre's catchment area. The number of heavily infected people is low in the region (12%), but heavy infections represented 64% of the visitors with vesical schistosomiasis at the health centre. The data suggest that the health centre is efficacious in 'passively' detecting the most heavy infections. It was also possible to identify villages with large numbers of heavily infected people from the health centre's records. Finally, a calculation model is presented to estimate the expected number of visitors to the health centre, based on data from the field survey.

Adolescent↗
PubMed1995

Quantitative interpretation of coprocultures in a population infected with Oesophagostomum bifurcum.

Coproculture is used in northern Togo and Ghana in the research on Oesophagostomum bifurcum, a common parasite of man in these regions. Prior to a follow-up study to investigate patterns of reinfection in Oesophagostomum and hookworm, it was attempted to evaluate the relevance of counting larvae for the assessment of the intensity of infection at the population level. Of 102 samples, one egg count (Kato-smear) and three coprocultures were carried out. Frequency distributions of counts of larvae of Oesophagostomum and of hookworm isolated in three coprocultures, showed log-normality. There was a highly significant correlation between egg counts and the combined number of Oesophagostomum and hookworm larvae (Spearman rank correlation test, r = 0.74, p < 0.01). It is concluded that the mean larval counts of three coprocultures can be interpreted quantitatively, as normally done for egg counts. A quantitative classification of larval counts is proposed.

Ancylostomatoidea↗
PubMed1995

Reinfection patterns of Oesophagostomum bifurcum after anthelmintic treatment.

Subjects infected with the adult worms of Oesophagostomum bifurcum, diagnosed through semiquantitative detection of characteristic third stage larvae, were treated in the middle of the dry or in the middle of the rainy season with two different dosages of albendazole. A third group was not treated. The pattern of reinfection after treatment was analysed. Transmission of Oesophagostomum infection appeared to be limited to the rainy season and the rate of reinfection was independent of the dose of albendazole received. The impact on transmission of developing stages that might survive in the nodules in the intestinal wall is discussed.

Adolescent↗
PubMed1994

[Strongyloides infections in former prisoners of war in South-East Asia in the second World War; additional information from serological diagnosis].

OBJECTIVE: To analyse the efficacy of ELISA serology in patients with Strongyloides infection acquired during World War II and maintained through repeated autoinfection. DESIGN: Descriptive. SETTING: Laboratory of Parasitology, Faculty of Medicine, Leiden, the Netherlands. METHODS: Parasitological and clinical data on 193 ex-prisoners of war (South-east Asia) were presented previously (1990) by Verburg and De Geus. ELISA using L-3 S. ratti antigen was carried out with sera of these patients and the results were compared with those of repeated stool examinations using Baermann's method. RESULTS: All subjects harbouring larvae in repeated stool examinations (26) were positive in serology. In 21 out of 167 patients in whom no larvae could be demonstrated, specific antibodies were detected. Anamnestic information together with data on eosinophilia and IgE levels suggested that the majority of these subjects were actually infected. The serological prevalence of infection with Strongyloides stercoralis was 33% for those imprisoned in Burma and 4% for those who were prisoners of war in the former Netherlands East Indies. CONCLUSION: In the group of subjects studied, in whom Strongyloides infection was apparently maintained through a process of autoinfection for a period of over 40 years, serology appears a sensitive and specific diagnostic tool. Larvae could be detected in no more than 26 out of 47 serologically positive subjects.

Aged↗
PubMed1994

A sedimentation-selective filtration method for the diagnosis of light infections with Schistosoma mansoni.

An epidemiological survey for infection with Schistosoma mansoni was carried out in the community of Catharina Sophia in northern Surinam. The merits of a more sensitive diagnostic system, the Sedimentation-Selective-Sieving (SSF) method, were evaluated; the results were compared with those obtained with the standard Kato-Katz thick smear technique. Examination of a duplicate Kato smear (2 x 25 mg) resulted in a prevalence of 22% while the real prevalence was shown to be more than 42%. The SSF procedure was shown to have a comparatively high sensitivity although the egg counts per gram (calculated on the basis of examining samples of 2-3 g) were considerably lower than those derived from Kato smears. The implications for epidemiological surveillance of communities with excretion of low numbers of S. mansoni eggs are discussed and the observations are compared with those one might expect on the basis of mathematical modelling (De Vlas et al., 1992).

Animals↗
PubMed1994

Quantitative determination of circulating soluble egg antigen in urine and serum of Schistosoma mansoni-infected individuals using a combined two-site enzyme-linked immunosorbent assay.

Two enzyme-linked immunosorbent assays (ELISA-5B1 using monoclonal antibody [MAb] 114-5B1-A [IgG1] and ELISA-4D12 using MAb 114-4D12-A [IgG3]) that detect circulating soluble egg antigen (CSEA) of Schistosoma mansoni were combined into one assay. This assay showed better performance than either of the two MAbs alone in detecting egg antigen, which was demonstrated with 80 urine samples from patients infected with Schistosoma mansoni from Zaire. The lower detection limit of the combined ELISA was 90 pg of the trichloroacetic acid-soluble fraction of soluble egg antigen (SEA-TCA) per milliliter. Thirty-two serum samples and 107 urine samples from uninfected Dutch individuals were negative when tested with the combined ELISA. This assay showed the same sensitivity (86.3%) with patients' urine samples as parallel testing with ELISA-5B1 and ELISA-4D12 (85%), while ELISA-5B1 and ELISA-4D12 showed sensitivities of 81.3% and 75%, respectively. The sensitivity of the combined ELISA with 51 serum samples was 84.3%, and three of five serum samples available from the seven patients with negative urine were positive for CSEA. The concentration of CSEA calculated from a four-parameters logistic curve for samples tested showed a correlation with egg output and serum circulating anodic antigen (P < 0.0001). Circulating soluble egg antigen in urine showed a significant decrease with an increase in age of the patients in relation to serum CSEA and egg output.

Age Factors↗
PubMed1993

Field trials to control schistosome intermediate hosts by the plant molluscicide Ambrosia maritima L. in the Senegal River Basin.

Several field experiments were carried out in Senegal to evaluate the molluscicidal activity of Ambrosia maritima L. Applications of 400 mg L-1 of dry leaves of the plant in creeks of the Lampsar river did result in a reduction of Bulinus spp of 54-56% 2 weeks after treatment. Treatment of a closed irrigation canal caused a reduction of the density of Biomphalaria pfeifferi up to 77% 2 weeks after the application of 150 mg L-1 and 300 mg L-1. In both trials, however, a quick increase in the snail density was observed after treatment. It is concluded that the large amounts of crude plant material required to achieve snail reductions of less than 80% compromise the use of A. maritima in schistosomiasis control programmes.

Animals↗
PubMed1993

Observations on the morphology of adults and larval stages of Oesophagostomum sp. isolated from man in northern Togo and Ghana.

Infection with Oesophagostomum sp. appears to be extremely common in man in northern Togo and Ghana. Adult specimens were recovered from the intestinal lumen by treatment with pyrantel pamoate and the morphological characteristics of oesophagostomes of man could for the first time be compared with information available on the morphology of oesophagostomes of monkeys. The observations and measurements demonstrated that the species involved is Oesophagostomum bifurcum and that the eggs of this species cannot be differentiated from those of Necator americanus. Both infections occur simultaneously in the population involved. The L1 larvae, too, cannot be differentiated from hookworm L1 larvae. The L3 larvae, however, are characteristic. Diagnoses of human Oesophagostomum infections is based on the detection of these larvae in coprocultures. In the present paper, the eggs, the L1 and L3 larval stages and the adults, are carefully described and photos are given.

Animals↗
PubMed1993

A pocket chart to estimate true Schistosoma mansoni prevalences.

In a recent paper, Sake de Vlas and Bruno Gryseels have explored the extent and implications of the underestimation of Schistosoma mansoni prevalences, as measured by faecal screening. Together with Gernt van Oortmorssen, Anton Polderman and Dik Habbema, they now present a practical and generally applicable chart to infer 'true' prevalences from simple egg count surveys.

Journal Article↗
PubMed1992

A model for variations in single and repeated egg counts in Schistosoma mansoni infections.

Faecal egg counts are often used to measure Schistosoma mansoni infection, but the considerable variation between successive counts complicates their interpretation. The stochastic model described in this paper gives a description of observed egg counts in a population and can be used as a tool to gain an insight into the underlying worm load distribution. The model distinguishes between two sources of variation in egg counts: (1) variation caused by the difference in worm load between individuals, and (2) the variability of egg counts for an individual with a given worm load. Empirical data, single and repeated measurements, from surveys in five villages in Burundi and Zaire have been used to fit and validate the model. We have discussed possible mechanisms that explain the differences in estimated values between the villages. The model indicates that the expected number of eggs in a stool sample per S. mansoni worm pair is lower than suggested by autopsy data and that, possibly as a consequence of immunity, the inter-individual variation in worm loads decreases with age.

Adolescent↗
PubMed1992

Human Oesophagostomum infection in northern Togo and Ghana: epidemiological aspects.

Recently, it has been established that human infection with Oesophagostomum bifurcum is common in northern Togo and northeastern Ghana. Two surveys were conducted in this area. In a regional survey, O. bifurcum infection appeared to occur in 38 of 43 villages. The highest prevalences (up to 59%) occurred mostly in small isolated villages and were usually associated with high hookworm infection rates. The infection was relatively rare in children under five years of age (7% infected). In older individuals, females showed higher prevalences than males (30% vs. 24%). In a second survey, the entire population of two high-prevalence villages was examined. Infection rates were low in children under three years of age, but rose quickly thereafter, suggesting intense transmission. A stable level of infection was reached by 10 years of age. Oesophagostomum larvae were found more frequently in hookworm-positive than in hookworm-negative coprocultures, and possible explanations for the association between infection with Oesophagostomum and hookworm are discussed.

Adolescent↗
PubMed1992

Experiences with the control of schistosomiasis mansoni in two foci in central Africa.

Experiences with population-based chemotherapy and other methods for the control of schistosomiasis mansoni in two subsaharan foci are described. In the forest area of Maniema (Zaire), intense transmission of Schistosoma mansoni, high prevalences and intensities of infection, and important morbidity have been documented. Taking into account the limited financial means and the poor logistic conditions, the control strategy has been based mainly on targeted chemotherapy of heavily infected people (> 600 epg). After ten years of intervention, prevalences and intensities have hardly been affected, but the initial severe hepatosplenic morbidity has almost disappeared. In Burundi, a national research and control programme has been initiated in 1982. Prevalences, intensities and morbidity were moderate, transmission was focal and erratic in time and space. A more structural control strategy was developed, based on screening and selective therapy, health education, sanitation and domestic water supply. Prevalences and intensities have been considerably reduced, though the results show focal and unpredictable variations. Transmission and reinfection were not significantly affected by chemotherapy alone, and the eventual outcome of repeated selective treatment appears to be limited by the sensitivity of the screening method. Intestinal morbidity was strongly reduced by community-based selective treatment, but hepatosplenic enlargement was hardly affected; this is possibly due to the confounding impact of increasing malaria morbidity. The experiences show the importance of local structures and conditions for the development of an adapted control strategy. It is further concluded that population-based chemotherapy is a highly valid tool for the rapid control of morbidity, but should in most operational conditions not be considered as a tool for transmission control.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Egg production of Oesophagostomum bifurcum, a locally common parasite of humans in Togo.

In northern Togo and northeastern Ghana, Oesophagostomum bifurcum is a common parasite in humans. Diagnosis is based on coproculture because the eggs of hookworm and Oesophagostomum are indistinguishable. To determine the level of egg production, 12 subjects were treated with 2 x 10 mg/kg of pyrantel pamoate and the worms they evacuated were then counted. Pretreatment and post-treatment species-specific egg counts were calculated on the basis of larval and total egg counts. The median worm burden was 81 (range 12-300) per person. The calculated median egg production was 33.7 egg/gram of feces per female worm. Assuming a total daily stool production of 150 g/day, this amounts to 5,055 eggs/day, which is comparable with the production of other nematodes of the same superfamily.

Ancylostomatoidea↗
PubMed1992

Schistosomiasis in the Yemen Arab Republic. Prevalence of Schistosoma mansoni and S. haematobium infection among schoolchildren in the central highlands and their relation to altitude.

A study was carried out in March/April 1988 to determine the prevalence of Schistosoma haematobium and S. mansoni among schoolchildren in the Jebal ash Sharq District, Dhamar Governorate, Yemen Arab Republic. The average percentage of schoolchildren infected with schistosomies (one or both species) was 34.5%. The prevalence of S. mansoni was found to be 22.6% and S. haematobium was present in 16.8% of the urine samples. A negative correlation was found between prevalence and altitude.

Adolescent↗