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PubMed2000

Regional genetic variation in the major sperm protein genes of Onchocerca volvulus and Mansonella ozzardi (Nematoda: Filarioidea).

Onchocerca volvulus and Mansonella ozzardi are two human filarial parasites present in South and Central America. In the Brazilian Amazonia they are found in sympatry, and the lack of clear morphological diagnostic characters in the microfilariae hinders their identification. The major sperm protein (MSP) gene of both species has been sequenced and characterised to determine its potential as a molecular diagnostic character. The length of the MSP gene is different in each species, and this could be used to detect and differentiate them by running the polymerase chain reaction (PCR) product in an agarose gel. Two major gene groups were identified in O. volvulus with a genetic distance of 6% between them. In M. ozzardi only one major group of genes was observed. The high similarity between the protein amino acid sequence of both filarial species confirms that the MSP has been highly conserved through nematode evolution.

Animals↗
PubMed2001

Characterisation of nuclear ribosomal DNA sequences from Onchocerca volvulus and Mansonella ozzardi (Nematoda: Filarioidea) and development of a PCR-based method for their detection in skin biopsies.

The internal transcribed spacer region (ITS1, 5.8S gene and ITS2) of the two filarial nematodes Onchocerca volvulus and Mansonella ozzardi was sequenced, and two species-specific primers designed in the ITS2 to develop a PCR-based method for their specific detection and differentiation. When used with a universal reverse primer, the two species-specific primers gave amplification products of different size, which were readily separated in an agarose gel. The PCR was tested on skin biopsies from 51 people from three localities in Brazil where M. ozzardi is present, and results have been compared with those of parasitological examination of blood. The species-specific PCR gave a higher percentage of detection of infection by M. ozzardi than the parasitological examination of blood. No infection with O. volvulus was detected by PCR. This PCR-based assay may assist in determining the nature of infection in areas where both filarial species exist in sympatry.

Animals↗
PubMed1998

Zoonotic Onchocerca (Nematoda:Filarioidea) in the cornea of a Colorado resident.

OBJECTIVE: A female patient, resident in the state of Colorado, presented with iritis of the right eye. Slit-lamp examination showed the presence of a thin, threadlike worm entwined in the cornea. The patient was taken to surgery for removal of the parasite. DESIGN: A case report. INTERVENTION: A 3-mm-long supertemporal incision was made in the cornea and further dissected until the worm could be grasped and removed by gentle traction. RESULTS: The worm, a filarial nematode, was identified as a member of the genus Onchocerca, most likely Onchocerca cervicalis, a natural parasite of horses. The patient had an uneventful recovery, and 1 week after surgery, her visual acuity, intraocular pressure, and corneal edema were all resolving. CONCLUSION: In the United States and elsewhere, most cases of zoonotic filarial infection involving the eye are caused by Dirofilaria or Dipetalonema-like worms. However, the current case was caused by a species of Onchocerca. This is the first case of zoonotic Onchocerca from the eye to be reported, only the second case of zoonotic Onchocerca in the United States, and the seventh case worldwide. The worm was removed surgically, and the patient had an uneventful recovery.

Animals↗
PubMed2000

Evidence of Onchocerca fasciata (Filarioidea: Onchocercidae) in camels (Camelus dromedarius): I-prevalence, nodular lesions appearance and parasite morphology.

Examination of 3376 imported and 200 local Egyptian camels was carried out during the period extending between September 1997 and August, 1998. These animals were carefully examined for the presence of Onchocerca fasciata nodules and subsequently for O. fasciata adult parasites. Results of this study revealed that imported camels had the higher infection rate (2.75%), while those of local origin showed no palpable or detected Onchocerca nodules. Distribution of these nodules was mainly on the two sides of abdomen, hind limbs (concentrated in thigh region) and fore limbs particularly on the shoulders and nuchal ligament. This distribution varied according to the degree of infection. Searches for microfilariae were also performed using either blood samples, or in the subcutis and fascial sheath near or around the detected nodules.

Abdomen↗
PubMed1978

Onchocerca sweetae (Nematoda: Filarioidea): notes on the intermediate host.

Microfilariae of Onchocerca sweetae are broadly distributed in the superficial layers of the dermis of the water buffalo (Bubalus bubalis). A total of 2855 insects representing 20 species were collected from O. sweetae-infected bait buffaloes. Only one species, Culicoides sp. "M", ingested microfilariae from buffalo skin. Larval development of O. sweetae was observed in the thorax of this species. Atotal of 829 insects, representing 7 species and including 749 parous Culicoides spp. were collected from light and Manitoba traps. Developing filarioid larvae were observed only in Culicoides sp. "M". It is concluded that Culicoides sp. "M" is a natural intermediate host of O. sweetae in the Northern Territory of Australia.

Animals↗
PubMed1983

Immunocytochemical and ultrastructural studies on Dipetalonema viteae (Filarioidea).

The antigenic properties of adult male and female of Dipetalonema viteae were studied by immunocytochemistry. Using antisera of the rodents Meriones unguiculatus and Mastomys natalensis infected with D. viteae, the binding of antibodies to sections of filariae embedded in Epon was assayed by the peroxidase-antiperoxidase (PAP) technique and by electron microscopy. The optimal staining intensity was obtained with an antiserum dilution of 1:5000. Control sera were obtained from sex and age matched uninfected animals. Female D. viteae showed maximal antigen-antibody reactions within the uterus: in the inner uterus wall, in the "nutrient channels" between the maturing eggs and the differentiating microfilariae, on the eggshells, in the cuticula of microfilariae and in the spermatheca on the cell membrane of the mature spermatozoa. Male filariae showed binding of antibodies in the vesicula seminalis: in the nucleus and the nuclear membrane of primary spermatocytes and on maturing spermatids. Less pronounced antigen-antibody reactions in the cuticula, muscle and intestine were observed in both sexes. The PAP-technique offers significant improvements in comparison with other techniques, e.g., immunofluorescence, used to detect antigens on filariae: the PAP-technique has an increased sensitivity with a concomitant reduction in nonspecific background and can be used for both light and electron microscopy; moreover, PAP-treated tissues can be stored indefinitely at room temperature.

Animals↗
PubMed1982

Protein composition of various developmental stages of dipetalonema viteae (Filarioidea).

The protein composition of various developmental stages of Dipetalonema viteae was analysed on polyacrylamide slab gels in the presence of sodium-dodecylsulphate. When the total proteins of adult male and female parasites, microfilariae, eggs, and third-stage larvae were compared, apparent qualitative similarities between mature and immature filariae were observed. However, several stage specific components were also identified.

Animals↗
PubMed1982

Comparison of surface iodination methods by electron microscopic autoradiography applied in vitro to different life-stages of Dipetalonema viteae (Filarioidea).

Different states of Dipetalonema viteae (males, females, microfilariae, and 3rd-stage larvae) have been iodinated in vitro under physiological conditions by chloroglycoluril, lactoperoxidase or chloramine T. The concentrations of the catalysts were correlated with the viability of the worms. Localization of the label with the different iodination methods had been visualized by electro microscopical autoradiography. Chloroglycoluril-mediated iodination is predominantly localized on the filarial cuticle. Lactoperoxidase-catalysed iodination is less specific and chloramine T catalyses iodination in a gradient decreasing from the cuticle to inner structures. It is necessary to visualize the labelling by electron microscopical autoradiography prior to biochemical and immunological experiments to avoid the extraction of structures iodinated by leakage of the catalyst into sub-cuticular regions.

Animals↗
PubMed1989

Egg production in Brugia pahangi (Nematoda: Filarioidea).

Oogenesis in Brugia pahangi has been studied by means of the aceto-orcein chromosomal squash technique and light-microscope autoradiography. The use of colchicine has demonstrated a 2-3 mm terminal germinative zone within the ovary, in which continuous and rapid mitotic division of germ cells occurs. In 80% of the gonads, oocytes within a 1-2 mm length of the ovary proximal to the germinative zone were at the prophase of meiosis I. Primary oocytes with markedly less condensed chromatin, apparently interphase cells, were observed in the corresponding region of the ovary in the remaining 20% of material examined. A cyclical or phased development of primary oocytes is suggested. Autoradiographic studies, concerned with the incorporation of [5-3H]uridine into germ cells of B. pahangi in vitro, further suggest that the onset of meiotic prophase is associated with the initiation of high RNA synthetic activity. Following meiotic prophase, oocytes complete meiosis I before entering a period of growth during which the chromatin material is decondensed. Recondensation of chromosomes prior to meiosis II is only observed after fertilization within the seminal receptacle. On completion of meiosis II, with the extrusion of a polar body, the haploid chromosome complement of the female unites with that of the male, re-establishing the diploid number of the zygote (2n = 10).

Animals↗
PubMed1994

Turnover of microfilariae in small mammals 2. Disintegration of microfilariae (Acanthocheilonema viteae) (Filarioidea: Nematoda) after intravenous injection into the jird, Meriones unguiculatus.

After i.v. injection of 305 x 10(3) microfilariae (mf) per animal (50 g) into naive jirds, 50.8% of them could be recovered at autopsy 15 min later. Of these, 65.8% were calculated to be in the peripheral circulating blood (PCB) and were completely intact; 18.6% were recovered by perfusion of the lungs and 13.6% from the liver. In both organs about half the mf were associated with adherent lymphocytes and neutrophils but a few were partly disintegrated. Only 2.6% were recovered from the kidneys and the spleen. In long-term injection experiments using the same inoculum size the autopsy was done 15 min and 1, 3 and 6 weeks post-injection (p.i.) of mf into naive jirds. Throughout the experimental period the density of mf remained more or less constant in the PCB, but 3 weeks p.i. the density in the lungs increased up to 14 times to that in the PCB, whereas in the liver it decreased at the same time to a density similar to that in the PCB. In patent animals with adult worms delivering mf these were distributed as follows: 34.7% were calculated to be in the PCB; 24.4% were obtained by perfusion from the lungs and 22.0% from the liver; the rest were found in the kidneys (16.6%) and spleen (2.3%). In the lungs and the liver about 5/6 were associated with adherent cells, partly disintegrated or as fragments. In view of the fact that very few mf become disintegrated immediately after i.v. injection and also from their extremely long sojourn in the PCB, a low turnover rate of mf is presumed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Induction of the prophenoloxidase-activating system of Simulium (Diptera: Simuliidae) following Onchocerca (Nematoda: Filarioidea) infection.

Trials were carried out to study the humoral immune response of blackflies to filariae following infection using the intrathoracic injection technique. An induced 66 kDa protein was abundant in the haemolymph of the European species Simulium ornatum following infection with bovine Onchocerca lienalis. This protein was apparently at higher concentrations in the haemolymph of sham-inoculated flies, i.e. flies that received sterile medium without the parasites. A molecule of the same size was also observed in the haemolymph of infected S. damnosum s.l. following infection with human O. volvulus or bovine O. ochengi. However, the level of this protein was lower in blackflies injected with microfilariae of bovine O. dukei. Unlike O. volvulus and O. ochengi this species is not transmitted by S. damnosum s.l. under natural conditions. No such reaction was observed if the African blackflies had received a sham inoculation. Feeding experiments with wild-caught nulliparous S. damnosum sl. on Onchocerca-infected cattle supported the results of the injection trials. The 66 kDa protein could only be found in the haemolymph of specimens infected via a blood meal. This 66 kDa molecule was identified as phenoloxidase. It appeared in the haemolymph due to the activation of the prophenoloxidase system following the filarial infection and we hypothesize that it may be sequestered by the parasites, as part of a non-self recognition system.

Animals↗
PubMedDate not supplied

[Description of Onchocerca dewittei n. sp. (Filarioidea), parasite of Sus scrofa, in Malaysia (author's transl)].

Onchocerca dewittei n. sp. was collected from a wild Boar at the metatarse level (tendons and subcutaneous connective tissue); it can be differentiated from other species by the female cuticle showing straight ridges which overlap in the lateral fields, and by its relatively thick microfilaria (length 228-247 mu and width 6-7 mu). This suidean Onchocerca displays some primitive characters such as straight ridges and persistency of ten pairs of caudal papillae in the male; but as a whole this species is undoubtedly more highly evolved than O. raillieti Bain, Müller and coll., 1976, a parasite of Equidae.

Animal Population Groups↗
PubMed1984

Mansonella (E.) rotundicapita sp.n. and Mansonella (E.) longicapita sp.n. (Filarioidea : Onchocercidae) from Venezuelan capybaras, Hydrochoerus hydrochaeris.

Mansonella (E.) longicapita sp. n. and Mansonella (E.) rotundicapita sp. n., two filarial nematodes from the dermis of Venezuelan capybaras, are described. The two species can be distinguished on the size of the spicules (M. longicapita 327 and 139 micron, ratio of 2.3 : 1 ; M. rotundicapita 405 and 120 micron, ratio of 3.4 : 1), the degree of lateral elongation of the cephalic shield and in the size and configuration of the microfilaria. The microfilaria of M. rotundicapita is large (280 micron long), and in specimens fixed in 2% formalin, the posterior end of the body is bent in a shepherd's crook, while the microfilaria of M. longicapita is short (195 micron long) and when similarly fixed, assumes a gently curved attitude. Within the subgenus M. (Esslingeria), the species M. longicapita and M. rotundicapita are intermediate in size. Morphologically they resemble M. streptocerca and M. rodhaini most closely, but can be distinguished on size, spicule morphology, and microfilarial morphology.

Animals↗
PubMed1989

Intracellular melanization in the mosquito Anopheles quadrimaculatus (Diptera: Culicidae) against the filarial nematodes, Brugia spp. (Nematoda: Filarioidea).

Intracellular melanization responses to developing larvae of Brugia species (B. malayi (Buckley), B. pahangi (Buckley and Edeson), and B. patei (Buckley, Nelson, and Heisch] in the thoracic muscle fibers of eight strains of Anopheles quadrimaculatus Say were first observed 48 to 72 h after an infective blood meal. Three to 4 d later, large numbers of melanized first-stage larvae were found within the thoracic muscle fibers. These intracellular responses were in addition to the extracellular responses to microfilariae and microfilarial sheaths of B. pahangi in the abdominal hemocoel of An. quadrimaculatus described in literature. Simultaneously, normal development of larvae of the three Brugia species also was observed in all eight strains of An. quadrimaculatus. Comparisons of melanized first-stage larvae and normally developing larvae of the three Brugia species in the thoracic muscle fibers of the eight strains of An. quadrimaculatus showed that there were distinct variations in numbers of melanized and developing larvae and percentage of females with melanized and developing larvae in different strains. Numbers of melanized first-stage larvae reflected the extent of refractoriness of An. quadrimaculatus strains. Fully melanized larvae showed no abnormalities in parasite organelles, indicating that refractoriness is due to an enhanced ability of the host to recognize the living parasite. Further comparison among the strains suggested that the mutants, Yellow Larvae and Vero Beach Colony were significantly more susceptible, and Red Stripe was the most refractory to all three Brugia species. Thus, the gene(s) controlling susceptibility and refractoriness to all three Brugia species probably occurs on the same autosomal chromosome as the mutations in these strains. The significance of intracellular melanization of filarial larvae is discussed with reference to the melanization responses to different parasites in other mosquitoes.

Animals↗