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PubMed1981

The major radioiodinated cuticular antigens of Onchocerca gibsoni microfilariae are neither species nor onchocerca specific.

The possible role of microfilarial surface (cuticular) antigens in immuno-diagnosis of human filarial infections has been assessed using microfilariae (mf) of the cattle parasite Onchocerca gibsoni. A Triton X-100 extract of 125I-labeled O. gibsoni mf was reacted with a panel of sera from humans infected with Onchocerca volvulus, Wuchereria bancrofti and Schistosoma japonicum as well as sera from uninfected controls. Results of these immunoprecipitations indicated that sera from humans infected with O. volvulus or W bancrofti contain antibody specificities recognising certain of the radioiodinated cuticular proteins of O. gibsoni mf. Two-dimensional gel analysis and subsequent autoradiography of these immunoprecipitates showed that 8 radioiodinated proteins recognised by sera from calves injected with O. gibsoni mf were also immunoprecipitated by sera from humans infected with either O. volvulus or W. bancrofti. Thus there appear to be no major radioiodinated cuticular antigens of O. gibsoni mf which are species or onchocerca specific.

Animals↗
PubMed1982

Histochemical enzyme variation in Onchocerca volvulus microfilariae from rain-forest and Sudan-savanna areas of the Onchocerciasis Control Programme in West Africa.

Histochemical staining methods for acid phosphatase were used to study the differences among microfilariae of various West African strains of Onchocerca volvulus in both forest and Sudan-savanna onchocerciasis zones. The results have shown statistically significant differences in the staining patterns of microfilarial populations in the two zones. In the rain-forest areas, where onchocerciasis is transmitted by Simulium yahense, S. sanctipauli, S. soubrense and S. squamosum, there were no significant differences of microfilarial staining patterns in patients, by age and sex, between the three Simulium-Onchocerca complexes studied. There was a close relationship between the "strain differences", as revealed morphoenzymatically, and the clinical picture of the disease in both the forest and the Sudan-savanna zones. The present findings are in favour of the hypothesis that there are intrinsic differences in the strains of the parasite occurring in the two areas. The application of the histochemical means of parasite characterization appears to be a useful tool in differentiating strains of O. volvulus and could contribute towards a better understanding of the epidemiology of human onchocerciasis in different bioclimatic zones where the disease is endemic.

Adolescent↗
PubMed1978

Histochemical differentiation of Brugia, Wuchereria, Dirofilaria and Breinlia microfilariae.

Histochemical demonstration of acid phosphatase activity in microfilariae gives sufficiently characteristic and consistent results for the differentiation of even closely related species. No difference could be detected among nocturnally periodic, nocturnally subperiodic and diurnally subperiodic Brugia malayi, but they could readily be distinguished from B. pahangi. Similarly, Dirofilaria repens could be readily distinguished from D. immitis and B. booliati from B. sergenti. The enzyme distribution pattern of a Malaysian rural strain of Wuchereria bancrofti was different from those of other regions.

Acid Phosphatase↗
PubMed1981

Periodicity of microfilariae of human filariasis analysed by a trigonometric method (Aikat and Das).

The microfilarial periodicity of human filariae was characterized statistically by fitting the observed change of microfilaria (mf) counts to the formula of a simple harmonic wave using two parameters, the peak hour (K) and periodicity index (D) (Sasa & Tanaka, 1972, 1974). Later Aikat and Das (1976) proposed a simple calculation method using trigonometry (A-D method) to determine the peak hour (K) and periodicity index (P). All data of microfilarial periodicity analysed previously by the method of Sasa and Tanaka (S-T method) were calculated again by the A-D method in the present study to evaluate the latter method. The results of calculations showed that P was not proportional to D and the ratios of P/D were mostly smaller than expected, especially when P or D was small in less periodic forms. The peak hour calculated by the A-D method did not differ much from that calculated by the S-T method. Goodness of fit was improved slightly by the A-K method in two thirds of analysed data. The classification of human filariae in respect of the type of periodicity was, however, changed little by the results calculated by the A-D method.

Animals↗
PubMed1982

The examination--time/dose interval in the provocation of nocturnally periodic microfilariae of Wuchereria bancrofti with diethylcarbamazine and the practical uses of the test.

The administration of diethylcarbamazine (DEC) in the daytime in areas where microfilariae (mf) of Wuchereria bancrofti and Brugia malayi exhibit nocturnal periodicity provokes mf to enter the peripheral blood. The importance of relating the dose of DEC and time when the blood specimen is taken is emphasized. The main practical uses of this provocative day test are as a routine diagnostic tool, in estimating prevalence and density of mf in a community, as a preliminary screening method for assessing potential filaricides nd in evaluating the parasitological response to mass chemotherapy.

Blood↗
PubMed1982

Controlled studies on the effect of nodulectomy on the concentration of microfilariae in the skin of patients exposed o continuing transmission of Onchocerca volvulus in the rain-forest zone of Western Nigeria.

Two sets of controlled experiments were conducted, using 13 adult onchocerciasis patients from a village in the hyperendemic rain-forest zone of Western Nigeria, to determine the effect of the excision of one or two onchocercal nodules on the concentration of microfilariae in the skin. The results show that, in patients with established infections who are exposed to continuing reinfection, nodulectomy per se does not reduce the microfilarial density, overall or in the same anatomical region from which the nodule is excised, to any significant degree. It is therefore concluded that the indirect assessment of the activity of test drugs against the adult Onchocerca volvulus by serial estimation of microfilarial concentrations over a period of about 24 months is unlikely to be compromised by limited selective nodulectomy.

Adult↗
PubMed1982

IgE-dependent cellular adhesion and cytotoxicity to Litomosoides carinii microfilariae--nature of effector cells.

Albino rats immunized with sonicated microfilarial antigen incorporated in Freund's complete adjuvant, produce antibodies that promote cell-mediated adhesion and killing of Litomosoides carinii microfilariae in vitro. Using highly purified cell populations, it has been shown that macrophages and neutrophils are most active in this phenomenon. Eosinophils, while adhering readily to parasites in the presence of the antibody, did not affect the viability of the parasites when observed after 24 hr incubation.

Animals↗
PubMed1981

Enhanced adhesion of rat neutrophils to Litomosoides carinii microfilariae in the presence of culture supernatants from mitogen-stimulated lymph node cells.

Microfilariae of the rat filarial parasite Litomosoides carinii are killed by normal rat neutrophils which adhere to them in the presence of antibody and complement. Adherence and killing were increased in the presence of the fluid from 48-hr cultures of Con A- or PHA-stimulated normal rat lymph node cells. Both normal and augmented binding were inhibited by cytochalasin B. The factor(s) responsible for increased binding was non-dialysable, susceptible to heat (56 degrees C, 30 min) and freezing and thawing. Its production was inhibited by cycloheximide. Pretreatment of neutrophils with stimulated culture supernatant for 3 hr, followed by washing, also augmented adherence. Similar pretreatment also enhanced phagocytosis of opsonized sheep erythrocytes and latex particles but did not increase candidacidal activity. These experiments suggest that cell-mediated immune reactions leading to lymphokine production may potentiate anti-filarial antibody-dependent cellular cytotoxicity and general phagocytosis by neutrophils.

Animals↗
PubMed1980

[Studies of the numerical distribution of microfilariae in foci of lymphatic filariasis (author's transl)].

The frequency distribution of Wuchereria bancrofti microfilariae counts in capillary blood, at a community level, is shown to differ significantly from the log-normal distribution, commonly used (and recommended by WHO). A much better fit is obtained with a truncated negative-binomial distribution, the k exponent of which is estimated to 0.3. This value does not seem to be affected by the endemic level, by microfilaricide mass-treatments or by the blood sample volume. This result has immediate practical interests: 1) it facilitates a posteriori comparisons between surveys in which different volumes of blood were examined; 2) at a given density it allows calculation the change in sensitivity (detection rate) as a function of a change in the volume of blood examined, thus allowing better a priori planning of surveys. The paper provides the formulae required to calculate k, or, given k, to calculate the expected numbers in the various density classes. It also provides nomograms (fig. 4a & b) giving estimates of the true mean M and of the detection rate TD, given any one of the three following observations, made on observed positives: the median Dmf. 50, the mean m, or the percentage Pl having only 1 mf. The effect of changing the volume of blood on the rate of detection can then be read easily from the nomogram. These results, likely to apply to other important parasitic diseases, should instigate more elaborated statistical research in this direction.

Animals↗
PubMed1980

IgE-dependent adherence and cytotoxicity of rat spleen and peritoneal cells to Litomosoides carinii microfilariae.

Serum taken after the termination of microfilaraemia from rats infected with the filarial parasite Litomosoides carinii brought about adherence and cytotoxicity of normal rat spleen and peritoneal cells to microfilariae. The activity could be absorbed to, and eluted from, anti-rat IgE, but not anti-rat IgG, immunosorbent columns. Immune serum heated to 56 degrees C for 3 hr did not cause cellular adherence or cytotoxicity; the addition of fresh normal rat serum failed to restore activity. Fresh rat serum did, however, restore activity to immune serum which was inactive after being heated to 56 degrees C for 30 min. EDTA, EGTA and diethylcarbamazine inhibited adherence. It is concluded that IgE antibodies are responsible for cellular adherence and cytotoxicity and that complement may play a part, as yet undefined, in these reactions.

Animals↗
PubMed1995

Comparative exsheathment of microfilariae of Wuchereria bancrofti in certain mosquito species.

The exsheathment of ingested microfilariae (mf) of Wuchereria bancrofti in their vector Culex. (Cx.) pipiens and in a refractory mosquito species Aedes (Ae.) caspius was assessed. No exsheathed mf were encountered in the mid gut of tested mosquitoes, while they were observed in abdomen and thoracic muscles. All exsheathed mf migrated from the mid gut of both tested species. The lowest percentage of ingested mf was recorded in the mid gut of Cx. pipiens and the thoracic muscles of Ae. caspius one day post feeding. On the other hand, 94.2% out of the exsheathed mf reached the thoracic region of Cx. pipiens and one-tenth of this proportion was observed in the thorax of Ae. caspius. Failure of a large percentage of mf to exsheath after being ingested in the Ae. caspius indicates inefficient vector ability to support the filarial development to the infective stage.

Aedes↗
PubMed1994

Cytochemical analysis of the sheath of microfilariae of Wuchereria bancrofti and Brugia malayi.

Thin sections of Epon and Lowicryl embedded microfilariae of Wuchereria bancrofti and Brugia malayi were analyzed by transmission electron microscopy aiming at topochemical characterization of the sheath. Three layers could be distinguished. Some of the layers were labeled when incubated in the presence of antibodies, lectins and enzymes which recognize extracellular matrix components usually associated with the basal laminae lining epithelial cells.

Animals↗
PubMed1995

Effect of acetylcholine, L-glutamine and diethyl carbamazine citrate on the release of microfilariae from Setaria digitata.

Release of microfilariae from adult filarial parasite S. digitata was reversibly arrested in presence of 2 mM L-glutamine. Diethylcarbamazine also showed a similar effect, but at a lower concentration (0.26 mM). Both compounds inhibited activities of protease and leucine amino peptidase enzymes. The only difference being, different concentrations of the two materials were required for comparable effects. Levels of histamine and acetylcholine in parasite were lowered during incubation under in vitro conditions. Direct effect of L-glutamine on the release of mf was also confirmed.

Acetylcholine↗
PubMedDate not supplied

Microfilaria in bronchial aspirate.

A 65-year-old female was evaluated for suspected bronchogenic carcinoma. The chest x-ray revealed a left parahilar opacity with a raised left dome of diaphragm. Fiberbronchoscopy showed an oedematous and hyperemic left main bronchus but no growth was visualised. Bronchial biopsy did not show any evidence of neoplasm. However, the bronchial aspirate smear examination showed one microfilaria. Post bronchoscopic roentgenogram done on the next day revealed clearing of left parahilar shadow and a normal diaphragm. The patient responded well to 300 mg of diethylcarbamazine given in divided doses for 3 weeks.

Administration, Oral↗
PubMed1994

The fate of Brugia pahangi microfilariae in Armigeres subalbatus during the first 48 hours post ingestion.

In Armigeres subalbatus, 60% and 3% of the ingested Brugia pahangi microfilariae (mf) respectively migrated into the haemocoel and the thorax within 5 minutes post ingestion (p.i.). Most of the mf had migrated from the gut into the haemocoel within the first 10 minutes p.i. There was no correlation between the number of mf ingested and the migration rate though those in mosquitoes with a low mf burden tend to migrate earlier. At 24 hours p.i., 5-30% of the mf were still in the gut; 19% of these mf were immobile. At 48 hours p.i. only 2% of the mf were mobile. B. pahangi mf isolated from blood meals at 24 hours p.i., failed to develop when inoculated into Armigeres subalbatus. 54% and 73% of the mf isolated from a 24 hour old clotted blood of a B. pahangi-infected cat and fresh peripheral cat blood respectively developed into stage-1 larva. Probably mf left in the midgut at 24 hours p.i. are the young and immature worms and are physiologically incapable of penetrating the gut.

Animals↗
PubMed1993

Microfilaria prevalence of diurnally subperiodic Wuchereria bancrofti among people having a medical checkup in American Samoa in the past 17 years.

The yearly change of microfilaria (mf) prevalence rates from 1974 to 1990 was studied in American Samoa with people who had medical checkups. The mf rates were found to have been kept at a low level (0.8-2.6%) in the past 17 years. The continued low prevalence reduced clinical filariasis significantly in the past 8 years. The low level of endemicity, despite very close communication with neighbouring Western Samoa where filariasis is much more prevalent, could be explained by the urbanized living conditions in American Samoa.

Adolescent↗
PubMed1993

Immunocytochemical localization of surface and intracellular antigens recognized by human sera in microfilariae of Wuchereria bancrofti.

Sera from patients with various clinical pictures of lymphatic filariasis, including tropical pulmonary eosinophilia (TPE), were used for the localization of surface and intracellular antigens in microfilariae of Wuchereria bancrofti embedded in Lowicryl K4M. Very few or no antigenic sites were located on the outer face of the sheath. The most inner layer, as well as the space between the cuticle and the sheath, was intensely labeled. Sera from TPE patients intensely labeled the cuticle and the cytoplasm of muscle cells.

Animals↗
PubMed1977

The concentration of microfilariae in the skin near the eye as a simple measure of the severity of onchocerciasis in a community and as an indicator of danger to the eye.

The parsitological and ophthalmological findings in an onchocerciasis survey in 8 villages (832 persons) and 5 primary schools (285 children) in Cameroon are reportedl The use of the coneoscleral punch/microtiter plate quantitative skin snip technique greatly facilitated this study, and its advantages over the weighed skin snip method are discussed. This simple technique could be used by paramedical personnel to detect the number of people in a community who have more than 15 microfilariae in a snip near the eye. This is shown to be a measure of the intensity of infection, and a good indicator of the number of people at risk of developing ocular pathology.

Adolescent↗