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PubMed1985

[Morphology of adult and sub-adult Wuchereria bancrofti. Differential characteristics among the strains].

The description of the fourth stage larva of W. bancrofti provides an indication of the direction of morphological evolution in the genus showing in particular that W. kalimantani is more highly evolved than W. bancrofti and constitutes a "capture" by Presbytis of the species parasitic in man. No morphological character of adult W. bancrofti distinguishes the geographic origin of the different collections studied. By contrast, the morphological characters of the microfilariae and their biological features are significantly different, but are not inter-correlated. It therefore appears that in the genus Wuchereria, as in the other viviparous filarioids, the phenomenon of speciation is evident first of all in the morphology of the microfilaria, the stage most susceptible to selection pressures.

Aging↗
PubMed1986

Differentiation of infective larvae of Brugia malayi and Wuchereria bancrofti by scanning electron microscopy.

A comparative scanning electron microscopy of the infective (third stage) larva of Wuchereria bancrofti and Brugia malayi revealed the following features: The lateral caudal papillae in both species are rounded and the terminal papilla is relatively pointed and smaller. The caudal papillae in W. bancrofti are more protruding while in B. malayi they are flattened. The lateral caudal papillae in B. malayi have an indentation around their bases which is absent in W. bancrofti. This is the most useful distinguishing feature and easily recognizable. The oral opening and the cephalic papillae in both the species are similar and not useful for differentiation.

Animals↗
PubMed1982

Nondevelopment of Wuchereria bancrofti in nude (congenitally athymic) mice.

Infective larvae of Wuchereria bancrofti (Nematoda: Filarioidea) were harvested from Aedes aegypti mosquitoes fed in vitro on microfilaremic blood of Haitian volunteers. Larvae were inoculated either into the subcutaneous tissue (SC) or peritoneal cavity (IP) of congenitally athymic (nude) mice, C3H/HeN (nu/nu). Initially 15 male and two female mice received larval doses from 38-180, and necropsy was done between 11 and 75 days post-inoculation. No worms were found at necropsy. Four additional male mice given 75 larvae each were also injected daily with 0.3 ml of normal human serum, but again no worms were recovered at necropsy on days 13 through 17. Given the severe nature of the nude immunodeficiency, it seems unlikely that the total failure of W. bancrofti to develop in nude mice results from a T cell-dependent immune response. Perhaps either non-immune mechanisms actively destroy larvae or the mouse lacks a factor(s) essential for parasite development, but not found in human serum. In any case, the thymic independence of resistance to W. bancrofti is clearly unlike that shown to the related filaria, Brugia pahangi.

Animals↗
PubMed1987

In vitro cultivation of third stage larvae of Wuchereria bancrofti to the fourth stage.

Third stage larvae of Wuchereria bancrofti obtained from laboratory-infected mosquitoes grew and molted to the fourth stage in vitro. The culture medium which supported the best growth and development consisted of a 1:1 mixture (v/v) of two commercially available cell culture media, NCTC 135 and Iscove's modified Dulbecco's medium supplemented with 10% human serum or plasma and an antibacterial/antimycotic mixture. Cultures were incubated at 37 degrees C in an atmosphere of either 5% or 8% CO2 in air. After 35 days of culture, 65% to 100% of the larvae were fourth stage. They were motile and in excellent morphological condition with development of the reproductive system in males and females. This culture system will provide an important tool for biochemical and immunological studies.

Aedes↗
PubMed1988

Filarial antigen in circulating immune complexes from patients with Wuchereria bancrofti filariasis.

Detection of filarial antigen in circulating immune complexes from patient sera was performed by an enzyme immunoassay in which the immune complexes were precipitated in the cold with polyethylene glycol and then dissociated in an acid pH buffer before being added to an ELISA plate. The dissociated antigen bound to the plate where it could be detected by peroxidase-labeled polyclonal rabbit antifilarial antiserum. Control sera used for defining the specificity of the assay included sera with immune complexes not related to parasite infection with and without free parasite antigen added prior to polyethylene glycol precipitation as well as sera from normal individuals. Filarial antigen was detected in the circulating immune complexes from 10 of 28 patients with bancroftian filariasis residing in either the Cook Islands (subperiodic Wuchereria bancrofti) or India (periodic W. bancrofti). By immunoblotting, the most frequently identified filarial antigen in these complexes was an approximately equal to 200 kDa circulating antigen.

Adolescent↗
PubMed1989

Uptake and development of Wuchereria bancrofti in Culex quinquefasciatus that fed on Haitian carriers with different microfilaria densities.

In studies conducted between 1984 and 1986, the vector competency of Culex quinquefasciatus was assessed after bloodfeeding on 61 Haitian volunteers with different densities of Wuchereria bancrofti microfilariae (mf) and on 11 that were amicrofilaremic. Infected volunteers included persons previously given diethylcarbamazine citrate for 12 consecutive days and some that were untreated. Mosquitoes, derived from field-collected larvae, were released under bed nets and fed upon the volunteers while they slept. The mean mf uptake in mosquitoes that fed on 21 carriers with low to ultralow densities (1-28 mf/ml blood) was 0.2-4 mf/mosquito (mean = 1.7 mf). The observed infectivity rate of greater than 3,000 mosquitoes that fed on high (56-7,500 mf/ml blood; median = 525), low (11-49 mf/ml blood; median = 20), or ultralow (1-10 mf/ml blood; median = 3) density carriers was 4, 11, and 30 times higher, respectively, than the expected rate calculated from the estimated volume of the imbibed bloodmeal. These results indicate that "hidden" carriers (less than 50 mf/ml blood) may serve as a source of infection for mosquitoes, and support the increasing evidence that mosquitoes ingest more microfilariae than expected.

Animals↗
PubMed1975

[On the migration of the third stage larvae of Wuchereria bancrofti in Anopheles gambiae (author's tranls)].

The migratory pattern of the third stage larvae of Wuchereria bancrofti from the thorax into the head of Anopheles gambiae has been studied. A total of 1269 infected mosquitoes were dissected and examined from the 7th through the 19th day after the blood meal. The filarial worms migrated from the thorax through the abdomen before they reached the head of the mosquito. Third stage larvae first appeared in the abdomen on the 9th day after infection, where their number increased progressively up to the 13th day and then decreased steadily thereafter. In contrast, mature larvae were first found in the head on the 11th day, and a concentration of larvae could be observed in this region only from the 14th day onwards.

Abdomen↗
PubMed1990

Rapid diagnosis of Brugia malayi and Wuchereria bancrofti filariasis by an acridine orange/microhematocrit tube technique.

A microhematocrit tube technique for diagnosis of human filariasis has been previously described. A system incorporating heparin, EDTA, and acridine orange into a microhematocrit tube (Quantitative Blood Count, QBC) has been commercially developed for the quantitation of blood counts and has been used for the diagnosis of malaria. We evaluated this test for its usefulness in the diagnosis of filariasis. Upon centrifugation, the parasites were concentrated in the area of the buffy coat and could be observed through the wall of the tube. The parasites were concentrated further by a plastic float that expands the buffy coat and confines the parasites to the periphery of the tube. Acridine orange stains the DNA of the parasite, and morphologic characteristics can be examined by fluorescence microscopy. The terminal and subterminal nuclei and long cephalic space of Brugia malayi, as well as the short cephalic space and caudal nuclei of Wuchereria bancrofti, were easily recognized and differentiated from each other. Microfilariae were detected in samples diluted to a level of approximately 50/ml.

Acridine Orange↗
PubMed1990

Immunocytochemical localization of surface antigens in microfilariae of Wuchereria bancrofti.

Antigenic sites were localized on the surface structure (sheath and cuticle) of microfilariae of Wuchereria bancrofti using sera from microfilaraemic and amicrofilaraemic patients using antibodies associated to colloidal gold particles and transmission electron microscopy. No labeling was observed on the surface of intact parasites. Microfilariae without the sheath and isolated sheath were obtained by ultrasound treatment. Using these preparations labeling of the inner portion of the sheath was observed when sera from amicrofilaraemic patients were used. Labeling of the cuticle surface was observed mainly in the regions of the cuticular annulations.

Animals↗
PubMed1990

Evaluation of medium supplements for in vitro cultivation of Wuchereria bancrofti.

Third-stage larvae (L3) of Wuchereria bancrofti molt to the fourth stage in an in vitro culture medium composed of NCTC 135 and Iscove's modified Dulbecco's medium (1:1; v/v) supplemented with 10% human serum and a mixture of anti-bacterial and anti-mycotic agents. In the present investigation this culture medium was used to examine the effects of different concentrations of human serum, medium supplements, and serum replacements on larval growth, development, and molting. Several medium supplements and serum replacements were evaluated including hemin, Nutridoma, and a mixture of soybean lipids, bovine serum albumin, and transferrin. The supplements tested could not support larval growth and development in the absence of serum and they did not have an enhancing effect on larval growth and development in combination with human serum. A medium supplement of 30% human serum resulted in molting of 80-94% of L3s and optimum growth to the mid to late fourth stage. This culture system provides an excellent alternative to experimentally infected animals as a source of larvae undergoing the third molt and fourth-stage larvae for screening potential anti-filarial compounds and for immunologic and biochemical studies.

Animals↗
PubMed1990

Evaluation of in vitro released Wuchereria bancrofti third stage larval antigens for detection of Bancroftian filariasis.

Three types of in vitro released excretory, secretory and metabolic antigens of Wuchereria bancrofti third larval stage (L3ESM) are evaluated in ELISA test to detect infected individuals in the endemic area. A total of 104 reference sera are used to predict the sensitivity of these antigens. None of L3 ESM antigens, although homologous in nature, did not identify correctly the categorised reference sera. This study clearly indicated a need for defined antigens to detect W. bancrofti infection early in the endemic residents.

Animals↗
PubMed1989

Fine structure and localization of anionic sites on the surface of microfilaria of Wuchereria bancrofti.

The fine structure of the sheath and the cuticle of microfilaria of Wuchereria bancrofti was analysed and the results obtained were compared with those from other filarial parasites. Cationized ferritin particles bind to the surface of the sheath and the epicuticle. No binding of colloidal iron hydroxyde particles to the microfilaria surface was observed. Reaction product indicative of carbohydrates containing vic-glycol groups was not observed in thin sections of microfilaria submitted to the periodic acid-thiosemicarbazide-silver proteinate technique. The results obtained are discussed in relation to previous studies using lectins.

Animals↗
PubMedDate not supplied

Gravid adult female worms of Wuchereria bancrofti in fine needle aspirates of soft tissue swellings. Report of three cases.

Gravid adult female worms of Wuchereria bancrofti were observed in fine needle aspirates of soft tissue swellings from three patients. An inguinal lymph node was aspirated in two cases, and a breast nodule was the site of aspiration in the third case. In one of the inguinal lymph node aspirates, two adult gravid female worms were identified.

Adolescent↗
PubMed1989

Detection of Wuchereria bancrofti antigen in serum and finger prick blood samples by enzyme immunoassay: field evaluation.

We have recently reported that a monoclonal antibody-based enzyme immunoassay for detection of filarial antigen in human serum is sensitive and specific for active infection with Wuchereria bancrofti. The present studies were undertaken to assess the feasibility of testing whole blood collected by finger prick in this assay. A preliminary study was performed to compare antigen test results obtained with whole blood, blood dried on filter paper, and serum. Results obtained with anticoagulated whole blood specimens agrees with serum results in 94 of 97 cases. All whole blood and serum specimens from 28 people with positive microfilaria smears were positive in the test. Filter paper blood specimens were less satisfactory because of decreased sensitivity and specificity. A population-based survey of 1009 persons was conducted in a village near Calicut, India, to evaluate the use of finger prick blood specimens for filarial antigen detection in field studies. Thirty-eight of 39 microfilaria carriers had positive antigen tests. In addition, 10.7% of amicrofilaremic endemic controls had positive tests. Additional studies are needed to test the hypothesis that filarial antigenemia in endemic controls indicates the presence of subclinical infection.

Adolescent↗
PubMed1987

Lectin-binding characteristics of Wuchereria bancrofti microfilariae.

The binding of 10 different lectins to the surface of microfilariae of Wuchereria bancrofti has been investigated. Wheat germ agglutinin (WGA) and Helix pomatia lectin (HPA) bound specifically to the sheathed microfilariae indicating the presence of N-acetyl-D-glucosamine and N-acetyl-D-galactosamine respectively on the surface. Exsheathed microfilariae did not react with any of the lectins. Treatment of sheathed microfilariae with proteases resulted in increased binding of WGA and HPA. Such treated microfilariae showed a weak binding of Concanavalin A (Con A), and lectins of lentil (LCH) and of Limulus polyphemus (LPA). Sheathed microfilariae incubated with sera of people living in endemic zones of filariasis but with no apparent evidence of infection (endemic normals), or with sera of chronic elephantiasis patients, or with their respective gamma globulin fractions, bound Con A and LCH. These lectins bound weakly to exsheathed microfilariae under the same conditions. Binding was due to the mannose components of the specific immunoglobulins of the sera which coated the microfilariae. However, microfilariae when incubated with sera or their globulin fractions from non-endemic normals (NEN), or from microfilarial carriers, did not bind Con A and LCH, suggesting that specific immunoglobulins were neither present in NEN sera nor in significant amounts in sera of microfilarial carriers.

Acetylgalactosamine↗
PubMed1988

Circulating antibodies and antigens in Presbytis monkeys infected with the filarial parasite Wuchereria bancrofti.

Levels of circulating filarial antigen, and humoral antibody to other defined antigenic targets, were measured over the course of experimental infection of three Presbytis cristatus monkeys with Wuchereria bancrofti. Circulating antigen levels, measured with an anti-phosphorylcholine monoclonal antibody, varied widely although all animals were positive for some period of the infection. Circulating antigen levels tended to be inversely related to the titre of anti-phosphorylcholine antibody, and this trend was maintained even following acid dissociation and inactivation of immune complexed host antibody. Other antibody specificities were measured by Western blotting against somatic proteins and immunoprecipitation of surface antigens. Amongst somatic antigens, targets between 14,000 and 200,000 daltons were recognised by monkey antibodies, but no correlation with infection status could be discerned. Likewise when measuring the response to the 29,000 dalton major adult surface glycoprotein, one animal produced a rapid response but the others did not recognise it until late in infection. In general, the experimental findings are characterised by wide variability between individuals, as may perhaps be expected in a primate host for a human spectral disease.

Animals↗
PubMed1988

Uptake and development of Wuchereria bancrofti in Aedes aegypti and Haitian Culex quinquefasciatus that were fed on a monkey with low-density microfilaremia.

Colonized mosquitoes of Culex quinquefasciatus (Haitian strain) and Aedes aegypti (Liverpool strain) were blood fed on a patas monkey (Erythrocebus patas) that had been experimentally infected with the Haitian strain of Wuchereria bancrofti and harbored a consistently low microfilaremia (1-3 mf per 20 mm3). Both species ingested more than twice the expected number of microfilariae (mf), i.e. 1.9 and 0.77 mf per mosquito, respectively. However, at 10-16 hours post ingestion only 4.2% of the mf had migrated from the blood meal in Cx. quinquefasciatus versus 20.7% in Ae. aegypti. Subsequently, only 3.5% of the ingested mf developed to the third stage in Cx. quinquefasciatus versus 56% in Ae. aegypti.

Aedes↗
PubMed1988

Comparative densities of Wuchereria bancrofti microfilaria in paired samples of capillary and venous blood.

Concurrent finger-prick and venous blood samples were obtained from 43 patients infected with Wuchereria bancrofti. Microfilariae were counted in blood smears and on nuclepore filters. Based on the numbers of microfilariae in 20-microliters finger-prick samples, an expected (theoretical) number of microfilariae in venous samples was calculated. This expected value was compared to the actual number of microfilariae present in venous blood. The actual number of microfilariae present ranged from 0.7 to 30 times (median 3) less than expected. The exponential function y = 16.74e.17x, r2 = .69, where y = venous counts and x = capillary counts was found to accurately reflect the relationship between venous and capillary counts. Each unit (microfilaria) change in capillary blood would result in an expected 19% unit increase/decrease in venous blood. The results support strongly the theory that microfilariae are unevenly distributed in the blood system. The epidemiological implication is that persons with low or ultralow microfilaremia levels in venous blood may have a much greater pool of microfilaria available in capillaries. We believe that the present study explains, at least partially, why mosquitoes feeding on these kinds of microfilaria carriers (frequently) have a greater uptake fo microfilariae than expected.

Adolescent↗