Studies on the periodicity and intravascular distribution of <i>Wuchereria bancrofti</i> microfilariae in paired samples of capillary and venous blood from Recife, Brazil

Dreyer, Gerusa; Pimentael, Agueda; Medeiros, Zulma; Béliz, Fátima; Moura, Izolda; Coutinho, Amaury; Andrade, Luiz Dias de; Rocha, Abraham; Silva, Luiz Mauricio da; Piessens, Willy F.

doi:10.1111/j.1365-3156.1996.tb00037.x

Cited by 49 publications

(25 citation statements)

References 18 publications

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“…The apparent low prevalence might be due to the small volume of blood used in preparing the thick smear. It has been reported by Dreyer et al (1996) that 20-60 μl blood films do not reliably detect microfilaraemic individuals with low parasitaemia levels; in addition thick smears grossly underestimate the prevalence of filariasis (Faris et al 1993). The annual treatment with ivermectin that has been administered in these communities for the past 7 years might have also contributed to the low prevalence rate.…”

Section: Discussionmentioning

confidence: 87%

Current status of bancroftian filariasis in rural communities of the lower cross river basin, Nigeria: parasitological and clinical aspects

et al. 2008

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Background and objectives There is a dearth of information on the geographical distribution of bancroftian filariasis in Africa on which to establish elimination programmes. The aim of this study is to assess the prevalence and density of microfilaraemia and the prevalence of clinical manifestations of bancroftian filariasis in six rural communities of Lower Cross River Basin, Nigeria. Methods A total of 829 finger prick blood smear samples were collected from volunteers between 22.00 and 02.00 h and were examined for presence of helminth parasite Wuchereria bancrofti using standard parasitological method of diagnosis. All the volunteers were also screened for clinical manifestations of lymphatic filariasis. Results Forty-six (5.6%) of the 829 samples collected were found to be microscopically positive for W. bancrofti. The prevalence of microfilaraemia was significantly (P<0.05) higher in females (8.4%) than males (3.6%). There is a significant variation (P<0.05) in the age-specific prevalence, with the age group 41-60 years being the most affected (10.2%). The overall geometric mean microfilarial density of the infected persons was 9 mf/50 μl. It was higher in males (11 mf/50 μl) than females (7 mf/50 μl) (P>0.05). The prevalence of infection and geometric mean density showed large variations; there was a trend towards increasing prevalence and density with increase in age in both sexes. The overall disease prevalence was 9.2%; the most important clinical manifestation was hydrocele (10.5%) and lymphoedema (2.9%). These chronic disease manifestations increased with age (P<0.05). Conclusion These baseline data would be useful in planning for the elimination of lymphatic filariasis in Africa as per the WHO goal to eliminate lymphatic filariasis by the year 2020.

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Section: Discussionmentioning

confidence: 87%

Current status of bancroftian filariasis in rural communities of the lower cross river basin, Nigeria: parasitological and clinical aspects

et al. 2008

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“…Another problem is the between-study variation in the sensitivity of the method used to detect microfilaraemias. Sensitivity may be affected, for example, by the volume of blood tested/subject, the time when the blood samples are collected, and the way in which the samples are checked for mff (Dreyer et al, 1996b).…”

Section: Discussionmentioning

confidence: 99%

Children and adolescents infected withWuchereria bancroftiin Greater Recife, Brazil: a randomized, year-long clinical trial of single treatments with diethylcarbamazine or diethylcarbamazine–albendazole

Rizzo

Belo

Lins

et al. 2007

Annals of Tropical Medicine & Parasitology

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In filariasis-endemic areas beyond sub-Saharan Africa, the World Health Organization's recommended strategy for interrupting transmission of the causative parasites is annual, single-dose, mass treatment with a combination of diethylcarbamazine (DEC; given at 6 mg/kg) and albendazole (ALB; given at 400 mg) for 4-6 years (the minimum estimated life-span of the adult parasites). In an open, hospital-based, randomized and controlled trial, with a blinded evaluation of outcome, 82 children and adolescents from Recife, all with Wuchereria bancrofti microfilaraemias, were given either DEC alone (6 mg/kg) or the same dose of DEC combined with ALB (at 400 mg/patient). Every 90 days for 1 year after the single treatment, each patient was checked for microfilaraemia by the filtration of up to 5 ml of venous blood collected at night. One year post-treatment, 16 (39%) of the 41 patients given DEC alone and 20 (49%) of the 41 given DEC-ALB were found microfilaraemic (relative risk=0.8, with a 95% confidence interval of 0.49-1.31) and the corresponding geometric mean levels of microfilaraemia were 2.0% and 1.8% of the levels recorded immediately pre-treatment, respectively (P>0.05). In terms of the prevalences and intensities of microfilaraemia, therefore, the addition of ALB to the DEC appeared to offer no significant benefit.

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“…Prior to analysis, all mf prevalence values were standardized to reflect sampling of 1 ml blood volumes using a transformation factor of 1.95 and 1.15 respectively for values originally estimated using 20 µl or 100 µl blood volumes. These factors were derived using comparative prevalence data from the parallel application of these different diagnostic methods on the same individuals [14]–[18], and the function, , where P * ML is the mean mf prevalence obtained using the 1 ml blood filtration method and P * 20 and P * 100 denote the mf prevalences obtained using 20 ul and 100 ul blood volumes [5].…”

Section: Methodsmentioning

confidence: 99%

Global Eradication of Lymphatic Filariasis: The Value of Chronic Disease Control in Parasite Elimination Programmes

et al. 2008

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The ultimate goal of the global programme against lymphatic filariasis is eradication through irrevocable cessation of transmission using 4 to 6 years of annual single dose mass drug administration. The costs of eradication, managerial impediments to executing national control programmes, and scientific uncertainty about transmission endpoints, are challenges to the success of this effort, especially in areas of high endemicity where financial resources are limited. We used a combined analysis of empirical community data describing the association between infection and chronic disease prevalence, mathematical modelling, and economic analyses to identify and evaluate the feasibility of setting an infection target level at which the chronic pathology attributable to lymphatic filariasis - lymphoedema of the extremities and hydroceles - becomes negligible in the face of continuing transmission as a first stage option in achieving the elimination of this parasitic disease. The results show that microfilaria prevalences below a threshold of 3.55% at a blood sampling volume of 1 ml could constitute readily achievable and sustainable targets to control lymphatic filarial disease. They also show that as a result of the high marginal cost of curing the last few individuals to achieve elimination, maximal benefits can occur at this threshold. Indeed, a key finding from our coupled economic and epidemiological analysis is that when initial uncertainty regarding eradication occurs and prospects for resolving this uncertainty over time exist, it is economically beneficial to adopt a flexible, sequential, eradication strategy based on controlling chronic disease initially.

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Studies on the periodicity and intravascular distribution of Wuchereria bancrofti microfilariae in paired samples of capillary and venous blood from Recife, Brazil

Cited by 49 publications

References 18 publications

Current status of bancroftian filariasis in rural communities of the lower cross river basin, Nigeria: parasitological and clinical aspects

Current status of bancroftian filariasis in rural communities of the lower cross river basin, Nigeria: parasitological and clinical aspects

Children and adolescents infected withWuchereria bancroftiin Greater Recife, Brazil: a randomized, year-long clinical trial of single treatments with diethylcarbamazine or diethylcarbamazine–albendazole

Global Eradication of Lymphatic Filariasis: The Value of Chronic Disease Control in Parasite Elimination Programmes

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