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At least 271 records · Page 15Linked to original sources
PubMed1989

[Effects of diethylcarbamazine and ivermectin on the mobilization of microfilariae of Onchocerca volvulus].

Microfilaria of Onchocerca volvulus are localized in superficial dermis. However, they are sometimes noticed in the blood and urines, when there is an important infestation. Diethylcarbamazine (DEC) bring on an increase of microfilaria, successively in the blood and after, in the urines. This study of 30 patients, treated in double blind by placebo, DEC and ivermectin, a new molecule with spectacular action on this filariasis, allowed to compare effect of each one on apparition of microfilariae in the blood and urines. Ivermectin bring on very important increase of microfilaremia without microfilaruria, unlike diethylcarbamazine. This establishment bring to discuss very different physiologic mechanisms between them. It should have an incidence on diagnosis and treatment of this dangerous parasite.

Adult↗
PubMed1987

Characterization of immunosuppressive proteins of Brugia malayi microfilariae.

Inhibition of Concanavalin A-induced lymphocyte proliferation was used to monitor the partial purification and characterization of suppressor molecules from microfilariae of Brugia malayi. Suppressor activity was present in high molecular weight fractions of microfilarial extracts (Mr greater than 50 kd on SDS-PAGE) and was protease-sensitive but resisted treatment with sodium periodate, indicating that it is associated with parasite proteins. Suppressor activity was released by microfilariae cultured in vitro and could be detected in peritoneal exudates of intraperitoneally-infected jirds and in lymph and sera from athymic C3H/HeN mice with patent B. malayi infections. These findings indicate that immune unresponsiveness during patent filarial infections may result from the in vivo release by microfilariae of high molecular weight proteins that suppress host immune responses.

Animals↗
PubMed1988

Homologous and crossreacting immune response of the jird and cotton rat against microfilariae of Dipetalonema viteae and Litomosoides carinii (Nematoda: Filarioidea).

Consecutive injections of microfilariae of L. carinii and D. viteae were carried out in the homologous or heterologous sequence into the corresponding natural or into the experimental hosts. Microfilariae of D. viteae are imunogenic in Sigmodon specifically and crossreacting as well. However, in the natural host, Meriones, they are doubtlessly tolerogenic. The sojourn and level of microfilaraemia are prolonged resp. higher when living D. viteae-Mf are injected s.c. followed by an i.v. injection. However, freeze-killed microfilariae of D. viteae are immunogenic in Meriones. Obviously the two filarial worms living in small mammals realize the balance with their natural hosts in quite a different manner. Which one of the two possibilities, or if one of them at all, reflects the relationship in human pathogenic filariae remains open.

Animals↗
PubMed1987

[Cutaneous changes induced by a dose of DEC in rodents with skin microfilaria: relevance of these phenomena for understanding the Mazzotti reaction and the pathogenesis of human onchocerciasis].

A single dose of DEC was given to Lemniscomys striatus parasitized by Monanema martini. The histopathological analysis of ear-lobe skin sections shows: a massive escape of microfilariae from the lymph capillaries, a major vascular exudative reaction with edema and diapedesis of blood cells. This inflammatory process leads to the destruction of the extralymphatic microfilariae and it induces a subacute and chronic dermatitis at the 7th day. These findings explain the pathogenesis of Mazzotti reaction during treatment of human onchocerciasis. The use of DEC produces precisely the factor that is responsible for the severity of the human disease: inflammatory reactions around the extralymphatic microfilariae.

Animals↗
PubMed1988

Experimental ocular onchocerciasis in cynomolgus monkeys. II. Chorioretinitis elicited by intravitreal Onchocerca lienalis microfilariae.

Chorioretinitis due to onchocerciasis is a major cause of blindness, and the pathogenesis is poorly understood. We have developed an experimental model for onchocercal chorioretinitis using cynomolgus monkeys (Macaca fascicularis). Two normal monkeys and two monkeys which had received prior sensitization with subcutaneous injections of live Onchocerca lienalis microfilariae were given intravitreal injections of either 0, 10, 50 or 500 live microfilariae. Posterior segment changes included disc edema, venous engorgement, retinal vasculitis, intraretinal hemorrhage, and progressive retinal pigment epithelial (RPE) disturbances. Histopathological findings included perivascular infiltrates with eosinophils, eosinophilic choroiditis, and RPE hypertrophy, hyperplasia and loss of pigment. Microfilariae in the retina had no surrounding inflammation but were found adjacent to areas of RPE alterations. Overall the inflammatory reaction in the two unsensitized monkeys was more severe than that seen in the sensitized monkeys. The retinal appearance of the monkeys resembled that found in human onchocerciasis, and this model appears to be a promising one for future investigations.

Animals↗
PubMed1987

Rapid method for the purification of viable microfilariae from nodules of Onchocerca volvulus by Percoll gradient centrifugation.

Microfilariae of O. volvulus were purified from dissected nodules by centrifugation on discontinuous Percoll density gradients. Nodules were used freshly or after cryopreservation in liquid nitrogen. Highly purified and motile microfilariae were recovered from a layer of a density of 1.090 g/ml. The isolated microfilariae retained their motility up to 3 days when cultured in vitro.

Animals↗
PubMed1979

Notes on nematode larvae others than microfilariae found on filter membranes in blood surveys for bancroftian filariasis.

Among 741 people examined in a rural area in Liberia for microfilariae of Wuchereria bancrofti 39 (5,3%) were found to be infected with nematode larvae others than microfilariae. These larvae had more developed inner structures than microfilariae and could be classified into two different types, differing in length and shape. The larvae have not been identified yet, but it is believed that they have to be associated to parasitic nematodes of the intestine.

Adolescent↗
PubMed1979

Electron microscopical studies on onchocerciasis. II. Skin and microfilariae after treatment with metrifonate.

Skin snips of six patients with manifest onchocerciasis treated with a single dose of metrifonate (10 mg/kg) were examined by electron microscopy one, three, five and ten days after application of the drug. Compared to untreated cases 24 hours after treatment there is a marked increase in the extend of perivascular infiltrates which are composed not only of macrophages, lymphocytes and plasma cells, but also of eosinophils. Infiltrates directly around dead microfilariae are seen infrequently. This pattern of cellular reaction remains constant for the first ten days after treatment. Metrifonate obviously kills the microfilariae rapidly, already 24 hours after its application totally disintegrated parasites are to be found. On the other hand always a few intact microfilariae are seen, possibly they just hatched after treatment.

Adult↗
PubMed1985

Filariasis transmission in Samoa. II. Some factors related to the development of microfilariae in the intermediate host.

The developmental period of microfilariae of sub-periodic Wuchereria bancrofti in laboratory-bred Aedes polynesiensis and Ae. samoanus was shorter in the warm season (December to May) than in the cool season (June to November). In the warm season the microfilariae reached the 'sausage' stage in three days, cylindrical second stage in seven days and the infective stage in 12 days after the infecting meal. During the cool season the incubation period was extended to 14 days. Microfilariae persisting in a carrier recently treated with diethylcarbamazine citrate readily infected Ae. polynesiensis and Ae. samoanus and developed into the infective stage, but the proportion which became infected was significantly less than the proportion infected on an untreated carrier having comparable microfilarial density. Under the conditions of the experiments the survival of infected Ae. polynesiensis and Ae. samoanus was dependent on physical conditions. The average level of infective worm burden did not appear to affect the mortality of the vectors.

Adolescent↗
PubMed1985

Brugia malayi: serum dependent cell-mediated reactions to microfilariae.

Sheathed and exsheathed microfilariae of Brugia malayi are killed by normal rat cells in the presence of immune serum in vitro. Immune serum heated at 56 degrees C for 1 hour lost this activity which was largely restored by the addition of fresh normal rat serum. EDTA but not EGTA abolished this activity indicating the operation of complement by alternate pathway. Fresh normal rat serum alone promoted cellular adherence without exerting cytotoxicity to the microfilariae. The activity in the immune serum could be removed with Staphylococcus aureus cells containing Protein A or anti-IgG antiserum. The activity could also be absorbed to and eluted from Protein A--sepharose CL-4B suggesting the involvement of IgG. Neutrophils and macrophages participate in the antibody dependent cell-mediated cytotoxicity phenomenon. Eosinophils while adhering to the microfilariae exert cytotoxicity only to the exsheathed parasites.

Animals↗
PubMed1979

[Scanning microscopical observations on the foregut structures o mosquitoes and their role for the ingestion of microfilariae (author's transl)].

Experiments on the transmission of Brugia malayi by various mosquitoes had shown that microfilariae ingested by some species were badly damaged when they reached the stomach, but were much less hurt in others. The structures of the foregut likely to cause these injuries, were investigated and documented by scanning microscope techniques. In Anopheles albimanus, A. arabiensis, A. stephensi and A. pharoensis which have well developed armatures the microfilariae showed a high rate of destruction. In A. stroparvus as well as in Aedes aegypti, Ae. togoi and Culex fatigans in which these structures are missing or poorly developed the larvae were much less affected. From the size, shape and position of the different papillae, spines, rods and cones observed it can be concluded and confirmed that the pharyngeal armature (buccopharyngeal bar) will be by far the most important structure responsible for the injuries of the microfilariae. However, it appears that the characteristics of different filaria species can play an important role in preventing such damages.

Animals↗
PubMed1977

Localization of acid phosphatase in microfilariae of Loa loa and Dipetalonema perstans from Cameroun.

The histochemical pattern of acid phosphatase activity in the microfilaria of L. loa showed a diffuse red staining all over the body, with conspicuous staining of the excretory and anal vesicles, Innenkörper, amphids and phasmids. In D. perstans, the enzymatic activity was localized chiefly in four regions corresponding to the excretory and anal vesicles, amphids and phasmids of the microfilariae. A considerable loss of enzyme activity was observed in microfilariae that had been stored in a refrigerator for somedays prior to their fixation.

Acid Phosphatase↗
PubMed1979

Studies on Dipetalonema viteae (Filarioidea). 4. Passive transfer of immunity to circulating microfilariae by spleen cells.

Passive transfer experiments provided clear evidence for a role of spleen cells in the immunity of hamsters against Dipetalonema viteae microfilariae. 106 or more spleen cells from postpatent (amicrofilaraemic) hamsters suppressed incipient microfilaraemia in syngeneic recipients when transferred at either week 2 or week 6 of a primary infection. Spleen cells from microfilaraemic donors (week 15-16 post infection) were also capable of transferring immunity against microfilariae. The spleen cell transfer never affected the survival of adult worms. After transfer of spleen cells from either patent or postpatent hamsters, antibodies to the cuticle of microfilariae could be found in the sera of recipients as early as week 8 of a primary infection.

Animals↗
PubMed1983

Acid phosphatase patterns in microfilariae of Onchocerca volvulus s.l. from the Upper Orinoco Basin, Venezuela.

The patterns of acid phosphatase in strains of Onchocerca volvulus s.l. which parasitize an Amerindian population (Yanomami) in Venezuela's Upper Orinoco Basin were examined by using the naphthol AS-TR phosphate method. The study sample consisted of 40 Yanomami inhabiting a savannah area at 950 m above sea level and 21 Yanomami residents of a tropical rainforest area at an altitude of 250 m. Stained intrauterine microfilariae, still within the egg case, exhibited a diffuse distribution of the enzyme in the early stages of embryonic development and a negative reaction at a more developed stage. Four of the five enzyme staining patterns described by Omar (1978) were found in the 3157 microfilariae examined from skin snips. Their distribution was: Type I--17.2%, Type III--0.5%, Type IV--75.6% and Type V--6.6%. No examples of Type II were observed. The results indicate that acid phosphatase patterns of the Upper Orinoco Onchocerca strain most resemble those of strains from Guatemala and Yemen, and are different from the African strains found in Upper Volta and Liberia. The relative frequency of acid phosphatase patterns was modified by cryopreservation of microfilariae.

Acid Phosphatase↗
PubMedDate not supplied

Microfilariae in association with neoplasms. Report of six cases.

Microfilariae were observed during routine cytopathologic or histopathologic examination of tumor tissue from six neoplasms. Subsequent to the detection of the parasite in smears or sections, repeated examination of night blood smears from these patients demonstrated microfilariae in only one case of squamous-cell carcinoma of the cervix. Histopathologic examination of the serial sections revealed different types of unrelated tumors, but no microfilariae could be demonstrated except in one case of hemangioblastoma of the cerebellum.

Adult↗
PubMed1980

Studies on Dipetalonema viteae (Filarioidea). 5. Ultrastructural aspects of the antibody-dependent cell-mediated destruction of microfilariae.

The antibody-dependent cell-mediated destruction of Dipetalonema viteae microfilariae was followed by electron microscopy both in vitro and within micropore chambers in vivo. There was a correlation between the degree of adherence (1% mf with adhered cells) and the degree of microfilarial damage. Polymorphonuclear leukocytes, predominantly neutrophils, seemed to be responsible for the destruction of microfilariae in vivo. An in vitro assay indicated that eosinophils also have a role as potent effectors against microfilariae. The first sign of microfilarial damage is the disintegration of cuticular layers. In a later stage of destruction, lysis of the hypodermis or even of the whole microfilarial tissues was observed.

Animals↗
PubMed1995

Seasonal prevalence of Onchocerca-like microfilaria in camels in Kuwait.

Infection of the camel (Camelus dromedarius) with Onchocerca-like microfilaria is recorded for the first time in Kuwait. Throughout a period of 14 months, the blood of 284 camels were examined, of these 32 (11%) were found infected with the microfilaria. Infections were recorded in all months except during summer, July to September, and in February. The highest monthly incidence (27%) was detected in June at the end of spring. It is suggested that harsh environmental conditions in Kuwait during summer either arrest development of microfilariae or influence their diurnal distribution in tissues of the camel.

Animals↗
PubMed1995

The ultrastructure of the foregut and its influence on bancroftian microfilariae ingestion in three Egyptian mosquito species.

Laboratory observations on the uptake of bancroftian microfilariae (mf.) by three Egyptian mosquito species revealed that microfilariae ingested by some tested species were badly damaged during ingestion. The foregut structures in Culex pipiens, Aedes caspius and Anopheles multicolor were investigated by light and scanning microscope techniques. In Ae. caspius which have well developed pharyngeal armatures, and An multicolor which have well developed cibarial armatures, high proportion of microfilariae were scored and damaged. Vice virsa, Cx. pipiens, considered as the main vector of bancroftian filariaris have neither developed pharyngeal nor cibarial pumps, the percentage of damaged mf was very small. The relationship between the injury of mf. in mosquito midgut and the presence of the foregut armatures was discussed.

Aedes↗