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PubMed2003

Analysis of Wuchereria bancrofti infections in a village community in northern Nigeria: increased prevalence in individuals infected with Onchocerca volvulus.

Infections with Wuchereria bancrofti causing lymphatic filariasis still represent one of the major health problems in the tropics, with 120 million people infected and over 750 million exposed to this filarial parasite. We have studied lymphatic filariasis infections as part of a multi-parasite survey in a village community in the savannah of northern Nigeria. We analysed serum samples from 341 individuals aged 5-70 years, detecting a W. bancrofti circulating antigen using the commercially available ICT Filariasis card test. The prevalence of infections was 10% and clearly age-dependent, increasing from below 2% in children to over 20% in subjects older than 40 years. Measuring IgG4 antibodies against the recombinant W. bancrofti antigen SXP1 showed that 36% of all tested individuals had been at least exposed to the parasite. Antibody levels also increased very significantly with age. A further analysis measuring Onchocerca volvulus-specific IgG4 antibodies showed a very significant association between infections with O. volvulus and those with W. bancrofti. Our data show that infections with W. bancrofti in Nigeria are still a frequently occurring health problem, since they are more prevalent than previously reported, and that individuals with an O. volvulus infection are more often infected with W. bancrofti than expected statistically.

Aged↗
PubMed1994

Histochemical localization of key glycolytic and related enzymes in adult Onchocerca fasciata.

The activities of some key enzymes of the glycolytic and pentose phosphate pathways were investigated histochemically in adult female Onchocerca fasciata (Nematoda: Filarioidea). The distribution patterns of phosphofructokinase (PFK), aldolase (ALD), glyceraldehyde 3-phosphate dehydrogenase (G3PDH) and glucose 6-phosphate dehydrogenase (G6PDH) in different tissues of the worm were determined by employing NitroBlue Tetrazolium (NBT). The glycolytic enzymes PFK, ALD, and G3PDH were distributed throughout the hypodermal tissue, somatic muscles and reproductive organs. These enzyme activities were predominantly expressed in the hypodermal and reproductive tissues, both of which appeared to be metabolically more active than adjacent tissues. The high activities of the enzymes studied in the hypodermal tissue when compared with the minimal or low activity in the intestinal epithelium support the assumption that the worm's intestine, in contrast to the body wall, plays no significant role in the nutrient acquisition process. The results emphasize that both the glycolytic and hexose monophosphate pathways of carbohydrate metabolism are active components in energy production and biosynthetic processes in the various tissues of the worm. The functional significance of these glucose-metabolizing enzymes has been discussed with regard to their location in the tissues concerned.

Animals↗
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↗
PubMed1986

Optimization of culture conditions for the maintenance of Onchocerca gutturosa adult worms in vitro.

A series of experiments examined the effects of various media, serum supplements, gas phases and the incorporation of mammalian cell feeder layers on the survival of Onchocerca gutturosa adult worms in vitro. The survival of male worms was poor in all media tested that were not supplemented with inactivated foetal calf serum (IFCS), with improved but variable survival in media supplemented with 10-30% IFCS. Using a cell-free system in an atmosphere of 5% CO2 in air, good results were obtained in medium NCTC 135 + 10% IFCS (median survival time 39 days, range 25-41). Marginally better survival was obtained with the same medium in an atmosphere of 95% N2/5% CO2 (median 45 days, range 25-56) and with a 1:1 mixture of media NCTC 135 and IMDM + 10% IFCS (median 38 days, range 38-51). Survival was enhanced in culture systems which incorporated bovine kidney (MDBK) cells, bovine trachea (EBTR) cells and monkey kidney (LLCMK2) cells. Exceptionally long survival was obtained using medium MEM + 10% IFCS + LLCMK2 cells under a gas phase of 5% CO2 in air, in which male worms survived from approximately 6 to over 7 months. Under similar conditions, female worms were also maintained for periods of up to 6 months and 5 out of 18 specimens released microfilariae into the culture system. The long-term culture described in this study will be useful for basic biochemical, chemotherapeutic and immunological studies in vitro.

Animals↗
PubMed1989

Fate of developing larvae of Onchocerca lienalis and O. volvulus in micropore chambers implanted into laboratory hosts.

Infective larvae of Onchocerca lienalis and O. volvulus implanted subcutaneously within micropore chambers into laboratory hosts moulted to the fourth stage (L4) and underwent limited development and growth. Similar recoveries of O. lienalis L4 larvae in the range of 33-66% were obtained from chambers implanted into CBA and BALB/c strains of mice, jirds, and the natural bovine host. A relatively constant proportion of larvae survived up to 24 days post implantation and thereafter recoveries declined, although some worms were still alive after 96 days. Recoveries of O. volvulus L4 larvae from chambers given to normal or T-cell deprived mice were equivalent to one another and to those obtained with O. lienalis. Moulting of O. lienalis in chambers was observed on days 3 and 5, in close accordance with the timing of the third moult in cattle following systemic infection. Moulting of O. volvulus occurred between days 3-6. Morphological changes in developing larvae included a small but significant increase in length, a transient increase in width, and early development of the spicular primordia and genital tube. L4 larvae of O. lienalis, but not those of O. volvulus, exhibited 3 distinct caudal papillae not present on infective larvae.

Animals↗
PubMed1987

Chromosomes of Onchocerca volvulus (Spirurida: Onchocercidae): a comparative study between Nigeria and Guatemala.

Chromosomes of Nigerian Onchocerca volvulus were compared with those of Guatemalan O. volvulus. Both parasites had basically the same chromosomal construct (2n = 8, XY type). Autosomes consisted of a pair of large and two smaller pairs. Sex chromosomes were made up of medium sized X chromosome and very small Y chromosome. It was not possible to infer the position of the centromeres.

Animals↗
PubMed1987

Onchocerciasis in British cattle: a study of Onchocerca gutturosa and O. lienalis in North Wales.

Onchocerca gutturosa and O. lienalis infections in British cattle were studied by examination of cattle post-mortem originating from North Wales and Cheshire (north west England). In 463 adult animals, the microfilarial (mf) prevalence was 28.5%. In 95.3% of the mf infected animals, gravid worms could not be found at either the ligamentum nuchae or the gastro-splenic omentum. Dermal mf at the head were identified as O. gutturosa on the basis of their highly significant association with the presence of gravid O. gutturosa at the ligamentum nuchae, which were found in only 3.2% of cattle. Mfs were isolated from different skin sites and from adult worms and a minimum of 10 mfs from each isolate were examined for width and acid phosphatase (AP) staining pattern. The width of O. gutturosa dermal mf was less than 4 micron (4 isolations), narrower than that of putative O. lienalis mf isolated from umbilical skin of cattle without evidence of O. gutturosa, which were in 20/22 isolations greater than 4 micron wide. The dermal mf were also distinguished on the basis of different AP staining patterns which, for each species, correlated closely with that of hatched intrauterine mf from their respective adult female worms. Based on the criteria of morphology and AP staining patterns the mf species prevalences in the survey population were estimated as O. lienalis 24.1% and O. gutturosa 2.2%, with a further 2.2% of cattle infected with both species. The results indicate that the predilection site of adult O. lienalis is not the gastro-splenic omentum. In North Wales, the distribution of the two species was different; O. lienalis was widely distributed in all cattle rearing areas both lowland and upland, whereas O. gutturosa was largely restricted to valleys close to major rivers.

Acid Phosphatase↗
PubMed1991

Chromosome numbers in Onchocerca dukei and O. tarsicola.

Testicular examination of male Onchocerca dukei and German O. tarsicola revealed five pairs of chromosomes, which is typical of most filariae. In contrast to German O. tarsicola, specimens from Sweden had only three pairs of chromosomes.

Animals↗
PubMed1988

Surface carbohydrate changes on Onchocerca lienalis larvae as they develop from microfilariae to the infective third-stage in Simulium ornatum.

Use was made of seven FITC labelled lectins as tools to investigate the surface of Onchocerca lienalis larvae as they develop through to the infective third-stage in a natural vector, Simulium ornatum. The lectins were derived from Canavalia ensiformis (Con A), Lens culinaris (lentil), Triticum vulgaris (wheat germ), Arachis hypogaea (peanut), Helix pomatia, Phaseolus vulgaris (kidney bean) and Tetragonolobus purpureus (asparagus pea). Between 70 and 100 living parasites were examined for each developmental stage; i.e. skin microfilariae, late first-stages, second-stages, preinfective third-stages and infective third-stages isolated from the mouth parts of the flies. None of the lectins used bound to the surface of the microfilariae. However, progressive binding to the cuticle of the first- and second-stages was observed using Con. A, lentil lectin and wheat germ agglutinin (WGA). Following moulting to the third-stage, binding of these three lectins declined. Furthermore, as these lectins decreased, peanut and Helix pomatia lectins progressively increased in their binding, despite the fact that they showed little or no binding to the first- and second-stages; stages at which Con A, lentil and WGA were at their maximum. Asparagus pea and kidney bean lectins failed completely to bind to any of the larvae examined. Carbohydrate inhibition tests showed that the lectin was indeed binding specifically to glycoconjugates on the parasite surface. WGA binding was not inhibited by prior incubation with N-acetyl-D-glucosamine, even at high concentrations, but neuraminic acid did completely inhibit its binding. Judging from the patterns of binding on the nematodes themselves, the carbohydrates may not be vector in origin, but derive from the worms. The lectin specificities indicate that initially mannose/glucose type derivatives are present on the surface. Following moulting to the third-stage these are progressively replaced, or overlaid with galactosamine type derivatives, also present on the infective third-stage as it enters the bovine host. The availability of these surface glycoconjugates to attack mediated by natural insect lectins may be of importance in the parasite regulatory mechanisms of the blackfly. Variability in these surface carbohydrates, and in the response to them could well be a contributing factor in the cytospecific variation in S. damnosum susceptibility to geographical variants of O. volvulus.

Animals↗
PubMed1988

Morphological differences between Venezuelan and African microfilariae of Onchocerca volvulus.

Comparative morphological and biometric characteristics of microfilariae of Onchocerca gutturosa and O. volvulus from different geographical areas (Upper Orinoco, Venezuela; Togo; Liberia) were assessed. "Stepwise" discriminant analysis and Mahalanobis estimators were applied to measure distance between populations. The results indicate a strong similarity between the two strains from the Upper Orinoco (Venezuela) and the Togo strain, as well as a clear separation between these strains and that of O. gutturosa. The Liberian strain was easily distinguishable from microfilariae from Togo and Venezuela. Discriminant analysis showed the Liberian deme to be as different from the Venezuelan and Togo demes as these demes were from microfilariae of the reference species, O. gutturosa. Although it is necessary to confirm these data using formalin-fixed specimens obtained from the skin, the present findings suggest the existence of geographically-different strains of O. volvulus in America and Africa.

Animals↗
PubMed1993

A probable case of vertical transmission of Onchocerca volvulus microfilariae.

A probable case of vertical transmission of Onchocerca volvulus microfilariae in Dass Bauchi State, Nigeria is presented. A 28-week-old male child delivered by a 39-year-old Fulani woman suffering from onchocerciasis was positive for O. volvulus microfilariae based on skin snip examinations. The child had general body pruritic rash and intermittent fever. Although the child's skin snip on re-examination five weeks later was also positive, the fever had gradually subsided.

Adult↗
PubMed1996

Onchocerca fasciata: histochemical demonstration of succinate and NADH dehydrogenase.

The activities of selected enzymes of the respiratory chain system in Onchocerca fasciata (Filarioidea: Onchocercidae) have been investigated histochemically. Thus, the localization and distributions of NADH dehydrogenase (EC 1.6.99.3), succinate dehydrogenase (SDH) (EC 1.3.99.1) and cytochrome oxidase (EC 1.9.3.1) were investigated in various tissues of the adult female worm by employing MTT, Nitro BT (dehydrogenases) and DAB (cytochrome oxidase). Different tissues varied considerably in their enzymatic activities. The hypodermis and reproductive tissues showed strong and identical localization of NADH and SDH dehydrogenase activities reflecting high metabolic rates. Little or no dehydrogenase activities were observed in the intestine and cuticle. In contrast to the two dehyrogenases, no activity was observed for cytochrome oxidase in any of the tissues in adult or embryonic stages of the worm. The significance of these results with respect to the energy metabolism of the worm is discussed. It is suggested that O. fasciata lacks a classical, mammalian-type respiratory pathway and that oxidative phosphorylation is of no importance as an energy generating pathway in this essentially anaerobic parasite.

Animals↗
PubMed1976

[Onchocerca raillieti n.sp. (Filarioidea) from a domestic donkey in Africa].

Onchocerca raillieti sp. n. (Filarioidea), from the domestic donkey (Equus asinus) in Africa, is described. The species is compared to O. bohmi (Supperer, 1953) n.comb, O. reticulata Diesing, 1841, O. cervicalis Railliet et Henry, 1910, O. flexuosa (Wedl, 1856) and O. armillata Railliet et Henry, 1909 and can be differentiated by numerous characters of which the most important are the anterior region of the female (which is straight and slender, 6 to 8 cm long, and bears longitudinal striae) and the 10 symmetrically arranged pairs of caudal papillae. O. raillieti seems to be a primitive species by several characters (caudal papillae, cervical papillae, oesophagus, vulva and cuticle.)

Animals↗
PubMed1976

The anthelmintic effects of a new compound "E" (Friedheim) on Onchocerca gutturosa in the cow--a possible tertiary screening system for drug action against O. volvulus in man.

Three cows were treated with different levels of compound "E" which is known to have strong filaricidal activity. In all three animals the number of microfilariae of Onchocerca gutturosa declined after treatment. At autopsy most of the adult worms found were dead and in those still living embryogenesis appeared to have ceased. It is concluded that, despite the disadvantages, this system represents a possible way of assessing onchocercicidal activity before undertaking human trials.

Animals↗
PubMed1984

Identification of an antigen of Onchocerca volvulus of possible diagnostic use.

Adult Onchocerca volvulus worms obtained by enzyme digestion from nodules of infected Mexicans were radio-isotope labelled by the chloramine-T or Bolton-Hunter methods. No antigenic determinants were detected in extracts of worms labelled by the chloramine-T method but 3 antigens were detected in extracts of the Bolton-Hunter labelled worms. Two were present in such small amounts that it was impractical to investigate them further, but a major component of mol. wt 20 kDa was purified by gel filtration and used in a serological survey of inhabitants of villages in Southern Mexico. Using the 20 kDa antigen, which is superficially located on both sexes of O. volvulus, sera from both non-endemic and endemic regions were analysed by radio-immunoprecipitation of this antigen. In Southern Mexico, the average sensitivity of the test was 92%, and the specificity 98%. Whilst the 20 kDa antigen did not detect antibodies in the sera of Trinidadians infected with Wuncheria bancrofti or Mansonella ozzardi, this antigen detected high levels of antibodies in Indians exposed to W. bancrofti.

Animals↗
PubMed1981

An improved technique for the cryopreservation of Onchocerca microfilariae.

Experimental describe the use of ethanediol to store Onchocerca microfilariae in liquid nitrogen. The technique involves a 2-stage incubation of the parasites at 37 degrees C and 0 degrees C in ethanediol, before rapid cooling to -196 degrees C. Viability has been assessed by motility, by migration in a proxy host and by development to the infective stage in the insect vector. A total of 71-79% of the cryopreserved microfilariae was shown to be viable compared to unfrozen controls. The technique is simple, inexpensive and very effective when compared to previous cryopreservation procedures for microfilariae and should be particularly suited for use under field conditions.

Animals↗
PubMed1986

Identification of non-cross-reacting antigens of Onchocerca volvulus with lymphatic filariasis serum pools.

Onchocerca volvulus proteins labelled with 125I were immunoprecipitated with onchocerciasis and lymphatic filariasis human serum pools in order to differentiate between cross-reacting and non-cross-reacting antigens. Analysis of the immunoprecipitates by two-dimensional gel electrophoresis revealed that all high molecular weight (Mr) O. volvulus antigens cross-reacted with the lymphatic filariasis serum pools. We observed, however, that at least 8 O. volvulus antigens were specifically immunoprecipitated only by the onchocerciasis serum pools, with Mr ranging from 20,000 up to 43,000 Daltons. These results suggest that the lower Mr O. volvulus antigens are more species specific than the other antigens. The significance of these findings for the immunodiagnosis of onchocerciasis is discussed.

Adult↗
PubMed1982

Experimental infection of mice with the microfilariae of Onchocerca lienalis.

Microfilariae of Onchocerca lienalis were obtained from the umbilical skin of naturally infected cattle and were injected into mice. Maximum numbers of microfilariae were recovered from the skin and ears of mice when using the subcutaneous route of inoculation. Microfilariae were distributed throughout the pinna of the ear but were concentrated towards the tip where histological sections showed them to be in the dermis and adipose tissue. Using the number of parasites recovered from the ears as an index of the intensity of infection it was found that inbred CBA/H T6T6 mice were one of the most susceptible of 11 strains of mice examined. No difference in susceptibility was found between male and female CBA mice of the same age, but marked differences were demonstrated between male CBA mice of different ages. After infection with 5 000 microfilariae the recovery of parasites from the ears increased rapidly to a peak at day 35 when 10% of the inoculum was recovered, and thereafter declined up to day 242. Over a range of inoculation doses examined it was found that there was a direct, linear relationship between the number of microfilariae recovered from the ears and the number in the inoculated dose. CBA mice showed marked resistance to reinfection with microfilariae. Six days after challenge with a secondary infection recoveries of microfilariae from the ears were only 26% of the level in challenge controls and fell to 3% of the level of controls by day 35. It is concluded that the model of O. lienalis microfilariae in CBA mice shows considerable promise as a tool for research into immunological responses to skin-dwelling microfilariae, which are the principal cause of pathology in onchocerciasis.

Aging↗