Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0042961 (volvulus)
 4,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The presence of microfilariae of Onchocerca volvulus in the eye is associated with an increased risk of deterioration of existing eye lesions. An opthalmological and parasitological examination of 630 persons was carried out in a hyperendemic focus of onchocerciasis in northern Togo. The prevalence of microfilariae increased in the cornea as well as the anterior chamber up to the age of 40-50 years, then decreased. The prevalence of onchocercal punctate keratitis, on the other hand, showed a peak for the age group 10-20 years. In two-thirds of the cases microfilariae were present in the anterior chamber as well as in the cornea. The relative distribution of microfilariae between the anterior chamber and the cornea did not change with the development of severe anterior lesions but in cases with severe posterior lesions relatively more microfilariae were found in the anterior chamber than in the cornea. In all cases of severe ocular lesions the numbers of microfilariae both in the anterior chamber and in the cornea were increased. The average number of microfilariae in the eye can be used as a parameter to enumerate the severity of ocular onchocerciasis.
 ...
PMID:The microfilarial load in the anterior segment of the eye. A parameter of intensity of onchocerciasis. 30 97

Rabbits, pre-immunized by intravenous inoculations of live, or of freeze-killed microfilariae of Onchocerca volvulus, were later challenged by subconjunctival inoculation of live microfilariae. Those pre-immunized with live microfilariae showed a marked chemotic conjunctivitis and reactions in the cornea (stromal keratitis and limbal abscesses), starting within one day of challenge. They were classed as sensitized. Those pre-immunized with dead microfilariae produced minimal reactions also starting on day 1, and were classed as tolerant. Histologically the reactions were distinctly greater in sensitized than in tolerant animals. The predominant cells in the inflammatory exudate were polymorphonuclear leucocytes and lymphocytes. The immunological basis for the differences between sensitized and tolerant rabbits is discussed, together with its possible bearing on human onchocerciasis. The effects of long-term subconjunctival and sclerocorneal inoculation of microfilariae were compared in one sensitized, one tolerant, one previously exposed, and one sensitized control rabbit. The sensitized test animal showed lesions resembling the sclerosing keratitis of human onchocerciasis. Immature microfilariae taken from intra-nodular fluid showed little ability to penetrate the cornea of the rabbit, and were minimally pathogenic.
 ...
PMID:Reactions to subconjunctival inoculation of Onchocerca volvulus microfilariae in pre-immunized rabbits. 121 32

A two-year longitudinal study carried out in five villages in a forest region of Gorama Chiefdom, Kono District, Sierra Leone, revealed that infection with Onchocerca volvulus was hyperendemic, the overall rate of infection being 61.6%. Prevalence rose from 28.6% in the 1-5-year age group, peaking among the 21-30-year age group (82.5%) and then levelling off. The intensity of infection though low, peaked in the 31-40-year-old males and in the 41-50-year-old female cohorts. The iliac crest was more sensitive for microfilarial (mf) recovery than the shoulder and the outer canthus. The majority of the nodules were located in the pelvic region. Microfilariae invasion of the eye was low, with low anterior chamber lesions but high posterior chamber lesions comprising mainly optic atrophy and choroidoretinitis. The rate of blindness was 1.6%, ocular onchocerciasis being the leading cause of blindness followed by cornea opacities.
 ...
PMID:Onchocerca Volvulus infection in Sierra Leone: relation between prevalence, intensity of infection, and ocular problems in a 'forest' region. 148 96

The effect of chloroquine phosphate on Onchocerca volvulus in vivo was studied in Ecuadorians undergoing treatment for malaria. All persons with a diagnosis of acute malaria and treated with 2500 mg of chloroquine over 3 d showed a 100% reduction of dermal O. volvulus microfilariae 7 d after treatment. However, 28 d after treatment the microfilarial densities returned to their pre-treatment levels and at 35 d they had increased to 121.6% of their pre-treatment values. Treatment did not appear to have any effect on the adult O. volvulus examined histologically in extirpated nodules. Patients treated for acute malaria and subsequently kept on a prophylactic regimen of 500 mg chloroquine weekly showed a reduction of 56.7% from pre-treatment microfilarial density after 27 weeks. Patients who underwent nodulectomy as well as treatment for acute malaria and were given 500 mg of chloroquine prophylactically for 27 weeks showed a reduction in dermal microfilarial density of 93.6%. Symptoms of onchocerciasis were reduced in the latter group of patients, with the elimination of all acute dermatological changes within 6 weeks. Ocular examination of these surgically and chemotherapeutically treated individuals revealed reductions of 94.9% of microfilariae in the anterior chamber, 95.9% of live microfilariae in the cornea, and 95.1% of dead microfilariae in the cornea. There was a reduction of 69.8% in corneal fluffy opacities. No alteration in the visual acuity or in visible lesions in the posterior segment was recorded. The results suggest that a complex interaction between chloroquine and O. volvulus takes place in vivo, which can be beneficial to the patient over a long period.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:The effect of antimalarial chloroquine therapy and prophylaxis on concurrent infection with Onchocerca volvulus in Ecuador. 178 Sep 94

Hartley guinea pigs were injected with Onchocerca lienalis microfilariae (Mf) as a model for human infection with Onchocerca volvulus. Subconjunctival injection of guinea pigs with O. lienalis Mf results in penetration of Mf to the central cornea, and formation of acute inflammatory reactions resembling those of human onchocerciasis around dead Mf. Sera from these animals contain IgG autoantibodies directed against at least two components of 3M KC1 extracts of guinea pig cornea and liver. Components with apparent molecular weights of 94-99 and 110-120 kilodaltons (KD) were recognized in both cornea and liver extracts, while 100, 74 and 34 kD components were recognized in liver extracts only. Components of 140 kD and 84 kD were recognized in cornea extracts only. The guinea pig liver extract cross-reacted with homogenate antigens from O. lienalis Mf, while the guinea pig cornea extract did not. Autoantibody-mediated inflammatory mechanisms may contribute to immunopathologic processes in onchocerciasis.
 ...
PMID:Autoantibody induced by experimental ocular Onchocerca infection: identification and characterization of autoantigens. 297 19

Very little of the original primary forest remains in Sierra Leone and the savanna is mainly woodland or a forest-savanna mosaic. The prevalence of microfilariae of Onchocerca volvulus, nodules and moderate or severe skin lesions was higher in forest than savanna villages. In forest villages the prevalence of microfilariae was 71.8% at the iliac crest, 36.6% (outer canthus), 12.8% (cornea) and 34.1% in the anterior chamber of the eye. Corresponding figures for the savanna villages were 51.9%, 20.5%, 5.6% and 21.8%. The overall prevalence of nodules in the forest and savanna was 70.5% and 53.2% respectively, while the prevalence of head and upper body nodules was 14.8% (forest) and 11.0% (savanna). The prevalence of moderate or severe skin lesions was 17.7% in forest and 13.0% in savanna villages. Lesions of the groin and scrotum were few in both zones. In persons aged 30 years or more the prevalence rates of severe eye lesions--sclerosing keratitis, iritis, optic atrophy and choroidoretinitis--were 4.3%, 16.1%, 13.9% and 14.8% respectively in forest villages. Corresponding figures for the savanna villages were 3.7%, 8.7%, 14.2% and 11.3%. Males were more commonly affected than females. At least one of these lesions was found in 32% persons in forest and 24% in savanna villages.
 ...
PMID:Onchocerciasis in Sierra Leone.2: A comparison of forest and savanna villages. 325 13

The relationship between severe onchocercal eye lesions (iritis, sclerosing keratitis, optic atrophy and choroidoretinitis) and (i) the prevalence and intensity of microfilariae (mf) of Onchocerca volvulus in skin snips from the iliac crest and outer canthus, and (ii) the prevalence of mf in the cornea and anterior chamber of the eye, was studied in 1414 persons from forest and savanna villages and 312 attenders at eye clinics. Ecologically the savanna of Sierra Leone more closely resembles the forest than the dry Sudan-savanna areas of West Africa, and in persons aged 30 years or more the combined prevalence of anterior segment lesions (iritis and sclerosing keratitis) was higher in the forest villages (20.6%) than in the savanna (12.7%). The higher loads of mf found in the forest compared to savanna villages could explain these results. Prevalence rates for posterior segment lesions (optic atrophy and choroidoretinitis) were 28.1% and 22.6% in the forest and savanna respectively. Although in villages from both zones there was a close association between mf in the anterior chamber and optic atrophy, other associations between posterior segment lesions and mf were either not significant or weak. In contrast, there was a strong association between anterior segment lesions and mf in the eye and the concentration of mf at the outer canthus. This association was stronger for iritis than for sclerosing keratitis.
 ...
PMID:Onchocerciasis in Sierra Leone 3: Relationships between eye lesions and microfilarial prevalence and intensity. 325 14

This study is concerned with the relationship between palpable onchocercal nodules and Onchocerca volvulus microfilarial loads in the skin. The number of microfilariae in clinically normal skin decreases as the distance from the nodule increases. Surgical removal of nodules reduces the microfilarial loads in 40 of 46 patients studied over a period of five months, with an average reduction of 65.4% of the prenodulectomy microfilarial load at the iliac crest. Complete elimination of detectable parasites was seen in some patients. Five individuals had increased microfilarial loads, all of which had developed new palpable nodules. Also, nodulectomy had a significant effect on ocular tissue, reducing the levels of parasites in the cornea and anterior chamber in 10 of 15 patients observed with no new nodules developing during the observation period. Both dermal and ocular clinical manifestations of onchocerciasis were reduced in a proportion of the patients. These parasitological and clinical findings provide evidence that nodulectomy is a beneficial procedure to O. volvulus infected patients in Ecuador by reducing both microfilarial loads and the degree of pathology.
 ...
PMID:The reduction in microfilariae loads in the skin and eye after nodulectomy in Ecuadorian onchocerciasis. 344 33

Onchocerca volvulus infection of the residents of two villages in the Upper Atbara River region of Sudan (63.4% prevalence) was found to be medically and socially significant with a remarkable degree of pruritus and dermal pathology present. The severest skin changes, which were often confined to certain areas of the body, were most common in the teenage group (13-19 years). Quantitation of the clinical changes showed that the most severe alterations were present in patients with the lower levels of microfilariae in the skin (0.1-6 mf mg-1) rather than in those with higher levels. Nodules containing adult O. volvulus were found in many individuals, and often in clusters in older patients. Major losses of vision due to O. volvulus were not found, although microfilariae were frequently seen in the cornea and anterior chamber. The commonest corneal change was punctate keratitis, and this was most frequently seen in the teenage group. Trachomatous changes of eyelids and corneas were also seen. The prevalence values of O. volvulus infection in the two villages were significantly increased when, in addition to microfilarial presence in skin biopsies, onchocercal signs such as punctate keratitis, nodule presence and microfilariae in the anterior chamber were taken into consideration. This illustrates the need to consider factors other than skin snip parasitology in obtaining a diagnosis. This study also emphasizes the degree of severity that onchodermatitis can reach and that low levels of dermal microfilariae can be accompanied by very extensive skin changes without any loss of vision. The necessity of considering the severity of skin changes when defining tolerable levels of onchocerciasis in a community is discussed.
 ...
PMID:Severe onchocercal dermatitis in the Ethiopian border region of Sudan. 344 29

Parasitological and clinical observations were made on residents of Pongo Nuer, a village in the province of Bahr El Ghazal, southwestern Sudan. Of 202 skin biopsies, 189 (94%) were positive for microfilariae of Onchocerca volvulus. Nodules were most common around the pelvic girdle and rare on the limbs or head. Microfilarial intensities, ranging up to 1,094 mf/mg of skin, were highest at the iliac crest and shoulder; they increased rapidly in childhood but then appeared to reach a plateau maintained through adult life. Nodule presence and number, especially at multiple sites, was significantly related to skin microfilarial intensity. Dermal manifestations of O. volvulus infection were widespread and severe, ranging from acute maculopapular eruptions to chronic, diffuse, and degenerative changes, even in young adults. However, high skin microfilarial intensities were found in asymptomatic individuals; conversely, lowest intensities were in those with severest maculopapular lesions, suggesting that host response was a major determinant of disease outcome. Microfilariae were detected in the cornea or anterior chamber of the eyes of one third of those examined in all age groups, but lesions of the posterior segment, including optic neuritis, chorioretinitis, and pigmentary abnormalities, were considered responsible for visual deficits in the population sample. Some pathologic changes in the anterior segment attributable to microfilariae were more common in the young than in adults but there was no preponderance of sclerosing keratitis in adults, contrary to expectations in hyperexposed individuals in a Sudan savannah zone. The best correlate of the presence of microfilariae in the eye was the intensity of infection in shoulder skin snips. Little value could be derived from data on outer canthus samples, either in terms of severity of ocular infection or disease. Microfilaremia was common (76%) but in only one case was attributed to O. volvulus; the remainder were due to Mansonella perstans.
 ...
PMID:Onchocerciasis in southwestern Sudan: parasitological and clinical characteristics. 382 96


1 2 3 4 Next >>