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Query: UMLS:C0042961 (volvulus)
 4,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Serum samples from persons who lived in areas where onchocerciasis occurred or who had filariasis were examined with the complement fixation test and the indirect hemagglutination test for the presence of antibodies against crude extracts from Dirofilaria immitis, Onchocerca volvulus, Dipetalonema viteae, and Ascaris suum. The results could be interpreted as follows: 1. The indirect hemagglutination test was more sensitive than the complement fixation test for the demonstration of antibodies in sera from European and indigenous inhabitants of endemic areas. 2. There were no differences between the responses to the four crude worm extracts among the groups of 21 patients with Loa loa, 12 patients with Onchocerca volvulus, 11 patients with Dipetalonema perstans, and 22 patients with clinical filariasis in whom no microfilaria had been found. It was concluded that the examination with crude extracts cannot give any information about the antigens that had caused the stimulation of antibodies.
Infection 1977
PMID:[Immunological diagnosis of filariosis in persons returning from tropical countries and in European and indigenous inhabitants of endemic areas (author's transl)]. 27 33

Infection due to Onchocerca volvulus was investigated in the Nimiyama Chiefdom, Kono District, Sierra Leone, where Simulium damnosum s.l. is known to breed but no data on the prevalence and intensity of O. volvulus infection exists. Of the 735 individuals sampled by the skin snip method in five villages, 471 (64%) were infected. The infection rate for males was significantly (p less than 0.05) higher than that of the females. Two hundred and ninety-one (70.0%) of the 416 males skin snipped and 180 (56.0%) of the 323 of their female cohorts were infected. The intensity of infection increased with age, with the younger cohorts presenting lower microfilarial density (MFD). Palpable nodules were observed in 230 (48.4%) of individuals found positive for skin microfilariae and in 37 (5.0%) individuals found negative for skin microfilariae. It is concluded that O. volvulus infection is mesoendemic in the Nimiyama Chiefdom, with the intensity of infection increasing with age.
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PMID:Parasitologic survey of Onchocerca volvulus infection in the Nimiyama Chiefdom, Kono District, Sierra Leone. 259 98

The Beffa form of Simulium soubrense Vajime & Dunbar, a member of the S. sanctipauli sub-complex of the S. damnosum complex, was found breeding throughout rivers in the Togo-Benin Gap, as far north as 9 degrees 30'N. Its distribution changed with the season. In southern Togo there were seasonal fluctuations in the relative abundancies of the Beffa form and of S. damnosum/S.sirbanum. There was considerable temporal and regional variation in the frequencies of different colour morphs of adult flies. The flies in Benin tended to be darker. Infections with Onchocerca volvulus (Leuckart) appeared to be independent of the host's colour morph category. Larger flies harboured significantly more first stage Onchocerca larvae but no significant relations with fly size were found for second and third stage larvae.
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PMID:The Beffa form of Simulium soubrense of the S. damnosum complex in Togo and Benin. 297 17

Adult female Simulium damnosum s.l. were caught at human and cattle bait at Djodji in Togo. Two members of the Simulium damnosum complex, the Djodji form of S. sanctipauli (74.9% of the total catch) and S. squamosum (25.1%), were identified and both were mainly anthropophilic. Although each species was also recorded feeding on cattle or turkey baits, most flies which were caught at animal baits did not take blood from them. Flies caught unfed at the cattle bait tended to be larger and have higher parous rates than those caught on man. S. sanctipauli flies were on average larger than S. squamosum but the sizes of both species varied seasonally. Infections with Onchocerca volvulus were found in both species. The infection rates varied seasonally with the highest levels occurring in the wet season. The Djodji form of S. sanctipauli is potentially a much more efficient vector (162 L3/1000 biting flies) than both S. squamosum (48 L3/1000 biting flies) and the S. sanctipauli s.l. found in the Cote d'Ivoire.
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PMID:Anthropophily, zoophily and roles in onchocerciasis transmission of the Djodji form of Simulium sanctipauli and S. squamosum in a forest zone of Togo. 317 68

Human onchocerciasis is found along the Nile in Northern Sudan, on the border with Ethiopia and in the Southern and Western Sudan--all areas where there is fast flowing water suitable for S. damnosum S.L. (in Sudan, the only fly in which the O. volvulus has been found) to breed. Epidemiological studies of this disease are still in progress however it is clear that in the huge area between Bahr El-Arabe and the white Nile, which is the most serious focus with blindness rates equalling or exceeding those in the worst affected foci elsewhere in Africa. Infection rates and parasite populations are highest in villages situated on rivers--near the probable breeding sites. Intensity of infection is generally highest in skin snip taken from the pelvi region, where the palpable nodules are more frequent. Microfilariae are commonly detected in the anterior chamber of the eye and in the peripheral blood. Fundus oculi lesions have been also detected in significant numbers causing impairment of vision and blindness, specially in the group of old people. Males are more commonly infected than females. These data provide a reasonable, though far from complete, account of the present situation concerning the importance and severity of onchocerciasis in this part of Sudan.
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PMID:[Onchocerciasis in Sudan: epidemiological situation in the south-west]. 343 81

The prevalence, intensity and clinical manifestations of onchocerciasis were investigated in three village communities along the Bahr El Arab and its tributaries in Southern Darfur, Western Sudan. Onchocerca volvulus has not been reported from this region before. Over 300 people were examined and the selection of patients was aimed at obtaining a cross-sectional view of the disease at all ages and in both sexes. Prevalence rates were high (67.5%, 28.6% and 32% in Titribi, Radom and Kafia Kingi, respectively). The intensity of infection in young adults was generally about 30 mf/mg, but ranged up to 100 mf/mg. Infections were detected in subjects as young as two years old; about one quarter of those sampled in Titribi had nodules, mostly in the pelvic region. Clinical signs of acute and chronic dermal changes were especially marked in Titribi. This village was located closest to the breeding sites, which appear in the rainy season only. More than a third of those samples had severe pruritus and showed many self-inflicted excoriations. Both anterior and posterior eye segment changes were detected in each community, and cases of onchocercal blindness were attributed to sclerosing keratitis and to optic and chorioretinal atrophy. One case typical of intensely localized disease was seen, where the affliction was unilateral and severe with oedema and pigment changes, but very few microfilariae present. Onchocerciasis appears to be well established in this region and has apparently caused abandonment of some settlements in recent years.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Onchocerciasis in Sudan: the Southern Darfur focus. 360 40

The model of Onchocerca lienalis microfilariae (mff) injected into CBA and T.O. strains of mice has been used to examine immunity to skin-dwelling microfilariae following exposure to a range of species of helminths. Mice which had received a primary infection with O. cervicalis mff were significantly resistant to challenge with O. lienalis mff (58% reduction relative to challenge controls). Immunization with the uterine contents (eggs and mff) of O. lienalis, O. gutturosa or O. volvulus conferred equivalent levels of protection against challenge with O. lienalis mff (66 to 75%). Similar results were obtained with immunizations in mice that employed either fresh or freeze-killed eggs of O. gutturosa. Significant reductions in the recoveries of O. lienalis mff were also demonstrated following the intraperitoneal implantation of adult male worms of O. gutturosa (30 to 52%), the adults of either sex of Dipetalonema viteae (60%), or after infection with Trichinella spiralis (27 to 81%). Infections with the trematode, Schistosoma mansoni, had a negligible effect on mff recoveries. It is concluded that partial resistance in mice to Onchocerca mff may be stimulated by factors, yet to be determined, that are neither stage nor species-specific.
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PMID:Immunity to Onchocerca lienalis microfilariae in mice. II. Effects of sensitization with a range of heterologous species. 393 54

Onchocerciasis is one of the major filarial diseases affecting humans and a leading cause of blindness. Control of the disease by chemotherapy and by elimination of the vector is not feasible in most areas of endemicity. The host immune response is thought to play a major role in the pathogenesis of complications. However, there is no clear evidence of protective immunity to reinfection in individuals who continue to be exposed to infective larvae. Antigens of Onchocerca volvulus are complex and show extensive cross-reactivity with other filarial parasites of humans and animals. Infection in humans results in the production of precipitating and reaginic antibodies to the parasite and in increases in levels of immunoglobulins that have no apparent specificity for parasitic antigens. Chronic antigenic stimulation in the presence of an antibody response leads to increased levels of circulating immune complexes. Cell-mediated immunity to parasite-derived antigens, as measured by migration inhibition, lymphocyte blastogenesis, and delayed skin-test reactivity, is decreased during infection. In addition, there is a decrease in delayed skin-test reactivity and in lymphocyte blastogenesis in response to unrelated antigens.
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PMID:Humoral and cellular immune responses to Onchocerca volvulus infection in humans. 407 Sep 16

Two species of Simulium were used to examine the effect of experimental Onchocerca lienalis infections on their fecundity and oviposition rates. S. ornatum s.l. was chosen as a natural vector of bovine onchocerciasis in Britain, and S. lineatum was selected because of its suitability as an experimental model for oviposition studies. Infection was either by feeding with blood containing microfilariae, or by intrathoracic injection of the parasites. Using the blood feeding technique, reductions in the fecundity of S. lineatum were observed at rates of 21 to 76%, depending on the concentration of parasites. A reduction of 21% in the fecundity of S. ornatum s.l. (P less than 0.05) was achieved when flies were fed on microfilariae at 69,000 per ml. Although individual flies feeding on infected blood may take as much as those in control groups, the feeding rates were reduced in several instances. S. lineatum also showed a depression of oviposition rate when infected by O. linenalis larvae. Fecundity was also significantly reduced when the route of infection was intrathoracic. Reductions for S. lineatum depended on the inoculum, but were either 36% (10 microfilariae per fly) or 54% (50 microfilariae per fly). S. ornatum s.l. showed a 13% reduction in fecundity when given 20 microfilariae per fly. It was concluded that similar experimental studies could be usefully performed with S. damnosum s.l. infected with O. volvulus microfilariae.
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PMID:The effect of experimental Onchocerca infections on the fecundity and oviposition of laboratory reared Simulium sp. (Diptera, Simuliidae). 671 Jun 3

Three species of British blackflies, Simulium ornatum s.l., S. erythrocephalum and S. lineatum, were infected with the cryopreserved microfilariae of Onchocerca volvulus obtained from human skin-snips in the Sudan. Doses of 5 or 10 microfilariae per fly were administered by intrathoracic injection into females, 1-2 days after eclosion from pupae. After 7 days at 27.5 degrees C and 85% relative humidity, microfilariae had completed development to third-stage larvae. Fly survival rates were highest for S. ornatum (96%) and lowest for S. lineatum (56%), and fell only marginally in each species when the larger dose of microfilariae was given. Infection rates ranged from 42% in S. lineatum up to 58% in S. ornatum following the lower dose of microfilariae, and 58% in S. lineatum up to 79% in S. ornatum following the higher dose. The proportion of microfilariae which completed development was relatively constant in each species of fly, ranging from 3.1-4.2% in S. lineatum to 10.5-16.8% in S. erythrocephalum. The greatest number of third-stage larvae recovered came from S. erythrocephalum at the higher dose of microfilariae, with a mean of 2.4 larvae per infected fly. As S. erythrocephalum has been successfully colonized through several generations in the laboratory, it is concluded that this is a promising species for reselection for increased susceptibility to O. volvulus.
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PMID:Development of Onchocerca volvulus from cryopreserved microfilariae in three temperate species of laboratory-reared blackflies. 687 7


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