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Glutathione-binding proteins of Setaria digitata: antibody responses in human infected with Wuchereria bancrofti.

Glutathione-s-transferase activity was determined in filarial parasites. The activity was detected in adult stages of cattle parasite Setaria digitata. It was absent in other stages of Setaria and also in infective larval stages of Wuchereria bancrofti and Brugia malayi. The activity was enhanced about twenty five fold following purification of adult setaria extracts on glutathione agarose column. Antibody (IgG and IgM) levels to the affinity purified proteins (SdGBP) were detected predominantly (90%) in Wuchereria bancrofti infected individuals compared with normal residents of endemic regions. IgA and IgE responses could not be detected. Filarial sera in contrast to non-filarial caused reduction in the enzymatic activities of Sd GBP. Microfilaraemic sera after diethylcarbamazine treatment resulted in enhanced reduction of enzymatic activity.

Animals↗

[Subconjunctival localization of a Wuchereria bancrofti adult female].

The authors describe a case of conjunctival localization of a living adult Wuchereria bancrofti female observed in a 6 year old native Haitian girl, two years after her arrival in France. The adult was surgically removed from the conjunctiva. Microfilariae were evidenced in blood samples obtained at midnight. This is the first case of sub-conjunctival localization of W. bancrofti. This case stresses the necessity to identify the filaria by studying the microfilariae in blood samples obtained at different times of the nycthemere and/or by observing the adult after surgical extraction. The presence of a Loa, a Dirofilaria, a Mansonella, or a Wuchereria calls for different medical therapies.

Animals↗

Single versus repeated doses of ivermectin and diethylcarbamazine for the treatment of Wuchereria bancrofti var. pacifica microfilaremia. Results at 12 months of a double-blind study.

In October 1989, 58 apparently healthy Polynesian Wuchereria bancrofti carriers in whom microfilarial (mf) density was greater than or equal to 100 mf/ml were randomly allocated to treatment groups receiving single doses of either ivermectin at 100 mcg/kg or diethylcarbamazine (DEC) at 3 and 6 mg/kg. Six months later, half of the carriers initially treated with ivermectin 100 mcg/kg or DEC 3 mg/kg were given a second similar dose while the rest were given a placebo. By day 360 (6 months after retreatment), comparison of adjusted geometric mean mf counts per group indicated that (i) among the 3 treatments given once a year the DEC 6 mg/kg dose resulted in the highest efficacy, (ii) nevertheless, regarding either ivermectin 100 mcg/kg or DEC 3 mg/kg, 2 successive doses resulted in higher efficacy than one annual dose and (iii) though no significant difference could be evidenced between efficacy of ivermectin 100 mcg/kg and DEC 3 mg/kg given twice a year, DEC seemed to sustain the mf reduction for a longer period of time. During the 3 days following retreatment, adverse reactions (mild to moderate) were observed in 46% of carriers treated with microfilaricidal drugs and in 20% of those treated with placebo. These results suggest that single dose therapy with either DEC or ivermectin is safe and effective for prevention of lymphatic filariasis due to Wuchereria bancrofti in French Polynesia. The real impact on transmission by the vector, Aedes polynesiensis, of the complete negativation of microfilaremia observed during the previous part of the trial in carriers treated with ivermectin should be evaluated in a community-based trial including entomological study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Comparative study of Dot-immunogold silver staining and Dot-ELISA for the detection of serum antibodies against Wuchereria bancrofti.

Dot-immunogold silver staining (Dot-IGSS) and Dot-ELISA, using the soluble antigen of Brugia malayi, were employed to detect anti-Wuchereria bancrofti antibodies in 50 cases of Wuchereria bancrofti microfilaremia. The positive rates were 100% and 90% in Dot-IGSS and Dot-ELISA respectively. The average titer in the 45 positive cases was 1:184 (1:10-1:2560) for Dot-IGSS and 1:150 (1:10-1:2560) for Dot-ELISA, with 30 cases showing the same titer in both tests, 13 cases showing higher titer in Dot-IGSS than in Dot-ELISA and 2 cases in the former showing lower titers than in the latter. There was a linear relationship between the titers of antibodies detected by Dot-IGSS and by Dot-ELISA (r = 0.8443). Dot-IGSS, similar to Dot-ELISA, is easy to carry out and the result is easy to read. It is seen that Dot-IGSS is highly sensitive and specific and is practicable for immunodiagnosis and surveillance of filariasis.

Animals↗

In vitro cultivation of third stage larvae of Wuchereria bancrofti to fourth stage: influence of some physico-chemical factors.

It has been reported that third stage larvae (L3) of Wuchereria bancrofti strain from Jakarta, molted to the fourth stage (L4) in vitro, in a simple culture medium supplemented with 10% human serum. In the present study, this culture medium has been used to examine the effects of some physico-chemical parameters on larval growth, development and molting of Wuchereria bancrofti from India. Lymph at 10% concentration enhanced the in vitro survival time of larvae. Molting of larvae from L3 to L4 stage has been obtained using human fetal lung cells in cellular co-culture and as a source of conditioned medium. Given these improvements in the medium supplementation, it has been observed that the age of L3s (duration of L3s maintenance within the mosquitos) is one of the most important parameters for the development of L3s in vitro. No molting was observed when one day L3s were used whereas, molting occurred with one or two weeks old L3s. On the contrary, when more than 3 weeks old L3s were used molting failed to occur even though duration of survival of L3s was improved and in this case, most of the larvae were degenerated.

Animals↗

A study of placentas from Wuchereria bancrofti microfilaraemic and amicrofilaraemic mothers.

The prevalence of transplacental transfer of microfilariae and structural lesions in the placentas of amicrofilaraemic (n = 10) and Wuchereria bancrofti microfilaraemic (n = 10) pregnant women from the prenatal care unit of the Hospital das Clinicas, Recife, Brazil, was investigated. Study participants were selected by filtration (3 microns/13 mm) of nocturnal (2300-0100 h) venous blood. A detailed histopathological examination was performed to detect abnormalities in the placenta, the cord and the foetal membranes. Both study groups had similar obstetric profiles. Parasitaemia was present during labour in nine of ten microfilaraemic women, but no microfilariae were found by filtration of 5-10 ml cord blood. No macroscopic abnormalities were seen in placentas from microfilaraemic mothers; two placentas from the amicrofilaraemic cases contained, respectively, infarcted areas and cysts at the cut surface. Microscopy failed to detect microfilariae in the intervillous spaces, chorionic and decidual vessels, or the umbilical cord. Thus, transplacental transfer of Wuchereria bancrofti microfilariae seems to be a rare phenomenon, and microfilaraemia does not appear to be a risk factor for placental pathology.

Animals↗

Studies on quantitative aspects of the transmission of Wuchereria bancrofti.

Feeding experiments with Anopheles gambiae and Culex fatigans infected with Wuchereria bancrofti showed that the mosquito females were losing about 20% of their worm burden when they were feeding on a blood chamber as well as on the guinea pig. 6.6% of all mature larvae found in the mosquitoes succeeded in entering the final host. A striking high infection rate was observed in those mosquitoes which refused to feed on a guinea pig. These mosquitoes have also to be considered when the loss of filarial larvae is calculated. Furthermore the experiments showed, that only very few larvae of Wuchereria bancrofti get lost when the mosquitoes are feeding only on sugar water solution.

Animals↗

Concomitant infections of Plasmodium falciparum and Wuchereria bancrofti on the Kenyan coast.

BACKGROUND: Anopheles gambiae s.l. and An. funestus are important vectors of malaria and bancroftian filariasis, which occur as co-endemic infections along the Kenyan Coast. However, little is known about the occurrence and prevalence of concomitant infections of the two diseases in mosquito and human populations in these areas. This study reports the prevalence of concomitant infections of Plasmodium falciparum and Wuchereria bancrofti in mosquito and human populations in Jilore and Shakahola villages in Malindi, Kenya. METHODS: Mosquitoes were sampled inside houses by pyrethrum spray sheet collection (PSC) while blood samples were collected by finger prick technique at the end of entomological survey. RESULTS: A total of 1,979 female Anopheles mosquitoes comprising of 1,919 Anopheles gambiae s.l and 60 An. funestus were collected. Concomitant infections of P. falciparum sporozoites and filarial worms occurred in 1.1% and 1.6% of An. gambiae s.l collected in Jilore and Shakahola villages respectively. Wuchereria-infected mosquitoes had higher sporozoite rates compared to non-infected mosquitoes, but multiple infections appeared to reduce mosquito survivorship making transmission of such infections rare. None of the persons examined in Shakahola (n = 107) had coinfections of the two parasites, whereas in Jilore (n = 94), out of the 4.3% of individuals harbouring both parasites, 1.2% had P. falciparum gametocytes and microfilariae and could potentially infect the mosquito with both parasites simultaneously. CONCLUSION: Concerted efforts should be made to integrate the control of malaria and bancroftian filariasis in areas where they co-exist.

Journal Article↗

Tests of susceptibility of Liberian Culex quinquefasciatus to Tanzanian Wuchereria bancrofti.

Culex quinquefasciatus strains of Liberian and Tanzanian origin were fed on Tanzanian donors with Wuchereria bancrofti microfilaraemias. 11 to 17 days later the mosquitoes were dissected and scored for the presence and numbers of immature and mature filarial larvae. In one experiment a significantly lower susceptibility was found in a Liberian compared with a Tanzanian strain, but in the other cases there was no significant difference. The susceptibility of the Liberian strains was higher than in published data on the same mosquito strains tested with Liberian W. bancrofti. It is doubtful whether the Liberian mosquito strains could be a useful source of genes for the construction of a refractory strain with which to replace an East African vector population.

Animals↗

Successful cryopreservation of Wuchereria bancrofti microfilariae.

A fast freezing technique developed by James (1981) significantly improved the yield of schistosome larvae that could be stored in liquid nitrogen. This was adapted by Ham et al. (1981) to the freezing of microfilariae of Onchocerca spp. with excellent results. They found 70 to 80% of the cryopreserved larvae remained viable using this method and since then Ham (personal communication) has successfully applied the same technique to Brugia malayi microfilariae. The further application to Wuchereria bancrofti is described.

Animals↗

Wuchereria bancrofti in Tanzania: immune reactions to the microfilarial surface, and the effect of diethylcarbamazine upon these reactions.

Immune reactions to the surface of microfilariae (mff) of Wuchereria bancrofti were investigated among persons living in an endemic filariasis area of Tanzania. The sera from a proportion of mff-negative persons contained antibodies to the microfilarial sheath, and a clear correlation was seen between presence of anti-sheath antibodies and the ability of the sera to mediate leucocyte attack on the mff in vitro. The anti-sheath antibodies were mainly of the IgG class and to a lesser degree of the IgM class. Only in some sera did the binding of antibody to the microfilarial sheath lead to deposition of C3 on the sheath. The cuticle of some of the sheathless mff activated complement without presence of anti-cuticle antibody. Further, the effect of diethylcarbamazine (DEC) administration in vivo (i.e., as full course treatment or as Day Provocative Test) and in vitro (i.e., applied directly to the immune tests) on the reactions to the microfilarial surface was examined. No interference of this anti-filarial drug was, however, observed, neither on the ability of sera to mediate leucocyte attack on mff in vitro, nor on complement activation and C3 deposition on the microfilarial sheath.

Antibodies↗

Efficiency of papain-treated microfilariae of Wuchereria bancrofti (var. pacifica) as antigen for serodiagnosis of bancroftian filariasis in French Polynesia.

Papain-treated microfilariae of Wuchereria bancrofti have been used as antigen for indirect fluorescent assay: 0% of non-endemic sera, 8% of healthy exposed Polynesians, 48% of clinical patients and 96% of microfilaraemic subjects were positive by this test. The geometric mean titres were 22, 41, 147 and 605 respectively. Untreated microfilariae were unsuitable for diagnostic purposes. Dirofilaria immitis adult sections showed low reactivity, giving poor discrimination between non-endemic and microfilaraemic sera. The geometric mean titres were 6 and 61 respectively.

Antigens, Helminth↗

Factors affecting transmission of Wuchereria bancrofti by anopheline mosquitoes. 2. Damage to ingested microfilariae by mosquito foregut armatures and development of filarial larvae in mosquitoes.

Microfilariae (mf) of Wuchereria bancrofti from the midgut of 639 Anopheles gambiae, 557 An. arabiensis, 117 An. melas and 9 An. funestus were examined immediately after the mosquitoes had fed on carriers with different densities of mf. The percentages of mf damaged during ingestion were 57.1-60.0 in An. gambiae, 33.3-50.6 in An. arabiensis and 38.7-55.7 in An. melas. In each species the percentage of mf damaged was independent of mf density in the human host. A further 3657 An. gambiae, 2875 An. arabiensis, 347 An. melas and 32 An. funestus were examined 7 d or more after feeding on mf carriers. In An. gambiae and An. arabiensis, mean numbers of larvae per mosquito were strongly correlated to mf blood density, with similar regression slopes to those obtained from the regression of mf blood density on mean uptake of mf/mosquito. The ratio of mean numbers of larvae per mosquito to mean numbers of intact mf ingested per mosquito increased as the density of mf in the human host increased in An. gambiae and An. arabiensis, but decreased in An. melas as host mf density increased.

Animals↗

Factors affecting transmission of Wuchereria bancrofti by anopheline mosquitoes. 3. Uptake and damage to ingested microfilariae by Anopheles gambiae, An. arabiensis, An. merus and An. funestus in east Africa.

Laboratory observations were made on the uptake of microfilariae (mf) of Wuchereria bancrofti by Anopheles gambiae, An. arabiensis, An. merus and An. funestus. Over host mf densities ranging from 450/ml to 1735 mf/ml neither the percentage of mosquitoes ingesting mf nor the mean number of mf per mosquito was correlated to host mf density. All mosquito species damaged mf during ingestion but the proportion harmed was independent of host mf density. The mean proportion damaged was 0.67 in An. gambiae, 0.51 in An. merus, 0.47 in An. Arabiensis and 0.26 in An. funestus. A comparison of the mean number of undamaged mf ingested and the number of larvae in the thoracic muscles revealed that not all undamaged mf were able to reach the thoracic muscles.

Africa, Eastern↗

Secreted and surface antigens from larval stages of Wuchereria bancrofti, the major human lymphatic filarial parasite.

Antigenic proteins of microfilariae and infective larvae of Wuchereria bancrofti have been identified by intrinsic and extrinsic radiolabelling, and specific immunoprecipitation with sera from filarial patients. From 125I surface-labelling experiments, the most prominent antigen on both stages is of relative molecular mass (Mr) 17 000, while a molecule of similar size is both synthesized and released in vitro following labelling with [35S]methionine. A second similarity between the two stages is the production and secretion of a Mr 21 000 component, which is, however, not detected on the worm surfaces. A series of additional proteins from larval W. bancrofti are described from each parasite compartment (secreted, surface and somatic) and the antigenicity and specificity of these components explored with serum from patients with filariasis due to W. bancrofti or Brugia species, and with onchocerciasis. Among additional molecules released in vitro we have found a Mr 51 000 antigen from both stages, and also several proteins which are not recognised by antibody from human filarial patients.

Animals↗

A description of adult Wuchereria bancrofti (rural strain) from an experimental infection in the long-tailed macaque, Macaca fascicularis (sny. M. irus).

Adult worms of the rural strain of Wuchereria bancrofti in Peninsular Malaysia obtained from a successful experimental transmission in an immunosuppressed Macaca fascicularis are described for the first time. Although the worms, especially females, were slightly smaller, they were similar in morphology to those of the periodic and non-periodic W. bancrofti previously described.

Animals↗

The prevalence of naturally acquired multiple infections of Wuchereria bancrofti and human malarias in anophelines.

Malaria and filaria infection rates were determined for anopheline mosquitoes collected whilst biting and resting in village houses in Papua New Guinea. The number of anophelines infected with both parasites was greater than expected from the infection rates of each parasite and this difference was significant in resting collections. The excess of multiply infected mosquitoes is probably a result of a vector population composed of individuals with differing numbers of opportunities to become infected. Malaria-positive Anopheles punctulatus from resting catches had a significantly greater number of Stage 3 Wuchereria bancrofti larvae than malaria-negative mosquitoes. However, multiply infected mosquitoes appear to suffer greater mortality than non-infected or singly infected mosquitoes when the filarial worm reaches the third stage. Any potential increase in transmission resulting from multiple infections is thereby offset by a greater mortality rate in these mosquitoes.

Animals↗

Antigenic characterization of adult Wuchereria bancrofti filarial nematodes.

Adult Wuchereria bancrofti were recovered from infected Presbytis cristatus monkeys and radio-isotope labelled extrinsically with 125I and in vitro with [35S]methionine. 125I labelling of the surface of adult W. bancrofti permitted a comparison between the major surface antigens of this species and those from the related lymphatic filariae, Brugia malayi and B. pahangi. All species bear a prominent Mr 29,000 surface antigen but among the differences observed were the strongly labelled molecules with Mr 58,000 and 67,000 in W. bancrofti which are extremely faint in the Brugia species. The [35S]methionine label was effectively incorporated into somatic parasite proteins in vitro although it was not possible to identify any secreted proteins in this way. The antigenicity of these products was investigated using a variety of sera from homologous and heterologous infections and the immunoprecipitation patterns highlighted particular differences between somatic proteins of male and female worms. One secreted antigen was detected, however, by virtue of its phosphorylcholine epitopes, in the culture medium of mixed adult worms; medium from male W. bancrofti adults was negative although homogenates of either sex of adult W. bancrofti were strongly positive in the same system.

Animals↗