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

Ivermectin, a recently developed macrocyclic lactone with broad antiparasitic activity, has been shown by a series of clinical trials to be safe and effective in the treatment of human infection with Onchocerca volvulus. Although it is rapidly microfilaricidal, it does not cause a severe reaction as is seen with diethylcarbamazine treatment. In patients with onchocerciasis, a single oral dose of ivermectin (150 micrograms/Kg) repeated once a year leads to a marked reduction in skin microfilaria counts and ocular involvement, although ivermectin has no known long-lasting effects on the adult worms. With treatment there is no significant exacerbation of either anterior or posterior segment eye disease even in those with severe ocular disease. Treatment leads to a marked and prolonged improvement in ocular status. Because of its safety and efficacy, ivermectin can be used on a mass scale and promises to revolutionize the treatment of onchocerciasis.
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PMID:Ivermectin treatment of ocular onchocerciasis. 219 51

Onchocerciasis--infection by Onchocerca volvulus--has four cardinal manifestations: dermatitis, subcutaneous nodules, sclerosing lymphadenitis, and eye disease. The first three are discussed here. The dermatitis begins when microfilariae degenerate in the dermis. This process is accompanied by inflammation, with degranulation of eosinophils and deposition of the major basic protein of the eosinophil granules on the cuticle of the microfilariae. So far as is known, the chronic effects of onchocerciasis are all a consequence of the degeneration of microfilariae. Subcutaneous nodules contain coiled adult worms and have an outer layer of fibrous scar and a central inflammatory cell exudate, which may cavitate. Perfusion of India ink reveals arborization of capillaries around adult worms, which derive nutrition from these networks. Onchocercal lymphadenitis is characterized initially by histiocytic hyperplasia and follicular atrophy and later by fibrosis and obstruction of lymph flow, a condition causing adenolymphocele ("hanging groin") and elephantiasis of the genitalia. Some patients appear to have immune tolerance to degenerating microfilariae, perhaps as a result of exposure in utero to microfilarial antigens in the maternal circulation. In contrast, other patients (Yemenites, for example) have a localized but intense response to a few microfilariae; these patients are hypersensitive--perhaps because they were not exposed to microfilarial antigens in utero. Autopsy data on infection of deep organs are limited.
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PMID:Pathologic changes of human onchocerciasis: implications for future research. 407 Sep 19

To provide quantitative information on the epidemiology of infection with Onchocerca volvulus and to define the association between indicators of infection and onchocercal eye disease, skin snips were obtained and skin and ocular examinations were performed on 892 persons living on seven Guatemalan coffee plantations. Skin-snip positivity and the density of microfilariae in the skin increased with age, reaching highest levels at 15-19 years, and both were greater in males than females. A history of nodulectomy was given by 67% of long-term residents and this percentage also increased with age. Over 90% of skin-snip positive subjects and 39% of skin-snip negative subjects had previous or present nodules. Microfilariae were detected in the cornea of 35.1% and in the anterior chamber of 18.9% of all persons examined and the frequencies increased with age, reaching peak levels at 10-19 years. Onchocercal eye lesions were found in 52 persons, causing bilateral blindness in six. Skin-snip positivity, microfilarial skin density, number of nodules, eye infection, and onchocercal eye lesions all correlated significantly with each other. Onchocercal blindness in one or both eyes was found only on fincas with a high prevalence (greater than 80%) and intensity of infection (greater than 22 microfilariae/mg skin).
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PMID:Onchocerciasis in Guatemala. Epidemiology in fincas with various intensities of infection. 697 10

To characterize the clinical and laboratory features of onchocerciasis in visitors to endemic areas and to compare them with those seen in endemic subjects, 20 returned visitors and 21 endemic subjects with onchocerciasis were evaluated. Dermatitis was the most frequent clinical finding among the returned visitors. None had nodules or eye disease and, in contrast to the endemic subjects, microfiladermia was often absent or of low density. All persons studied had antibody responses measurable by ELISA to both soluble Onchocerca volvulus antigen and a panel of diagnostic recombinant antigens. Eosinophil and IgE levels were significantly higher in the endemic group, as was the capacity of peripheral blood mononuclear cells from this group to produce the T helper cell-like cytokines interleukin-4 and -5. It is likely that the chronicity and intensity of infection in endemic subjects account for the clinical and immunologic differences observed between the 2 groups.
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PMID:Onchocerciasis in endemic and nonendemic populations: differences in clinical presentation and immunologic findings. 807 40

Antigen Ov39, derived from Onchocerca volvulus, cross-reacts on both the T and B cell level with a nonhomologous human retinal antigen, hr44. Lewis rats were immunized to investigate the potential of these antigens to induce eye disease. Histologic and immunohistologic examination of ocular tissues revealed pathologic changes as early as day 12, which included induction or up-regulation of class II and CD68-like antigen on perivascular cells, ramified retinal microglia, dendritiform cells of the iris epithelium, and ciliary epithelium and significant breakdown of anterior and posterior blood-ocular barriers. Extravascular immunoglobulin and staining for CD68-like antigen was detected in the optic nerve after immunization with Ov39. Unrelated structural abnormalities of retina and lens seen in 8% of eyes examined significantly predisposed eyes to the development of Ov39- or hr44-induced pathology. These findings suggest a role for cross-reactive immune responses in the development of ocular onchocerciasis.
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PMID:Immunization with the cross-reactive antigens Ov39 from Onchocerca volvulus and hr44 from human retinal tissue induces ocular pathology and activates retinal microglia. 935 36

Onchocerciasis is a major cause of blindness. Although the World Health Organization has been successful in reducing onchocerciasis as a public health problem in parts of West Africa, there remain an estimated 17 million people infected with Onchocerca volvulus, the parasite that causes this disease. Ocular pathology can be manifested in any part of the eye, although disease manifestations are frequently characterized as either posterior or anterior eye disease. This review focuses on onchocerca-mediated keratitis that results from an inflammatory response in the anterior portion of the eye and summarizes what is currently known about human disease. This review also describes studies with experimental models that have been established to determine the immunological mechanisms underlying interstitial keratitis. The pathogenesis of keratitis is thought to be due to the host inflammatory response to degenerating parasites in the eye; therefore, the primary clinical symptoms of onchocercal keratitis (corneal opacification and neovascularization) are induced after injection of soluble O. volvulus antigens into the corneal stroma. Experimental approaches have demonstrated an essential role for sensitized T helper cells and shown that cytokines can regulate the severity of keratitis by controlling recruitment of inflammatory cells into the cornea. Chemokines are also important in inflammatory cell recruitment to the cornea, and their role in onchocerciasis is being examined. Further understanding of the molecular basis of the development of onchocercal keratitis may lead to novel approaches to immunologically based intervention.
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PMID:Pathogenesis of onchocercal keratitis (River blindness). 1039 75

Onchocerciasis, or river blindness, is a parasitic infection caused by the filarial nematode, Onchocerca volvulus. It infects 18 million people worldwide, but is rarely seen in the United States. It is one of the leading causes of blindness in the developing world. Although onchocerciasis is also known as river blindness, it is not just a disease of the eyes, but rather a chronic multisystem disease. Clinically, onchocerciasis takes three forms: 1) eye disease; 2) subcutaneous nodules; and 3) a pruritic hypopigmented or hyperpigmented papular dermatitis. We present an 18-year-old African female with a 5-year history of asymptomatic, hypopigmented, slightly atrophic macules on her anterior tibiae. Pathology revealed a scant perivascular inflammatory infiltrate with mononuclear cells, eosinophils, and rare microfilariae in the papillary dermis. Ivermectin is the treatment of choice for onchocerciasis and was initiated in this patient. We present this interesting patient with onchocerciasis to expand our differential of hypopigmented macules, especially in the African population. In addition, we discuss both the diagnosis and the treatment of onchocerciasis in expatriate patients living in nonendemic areas.
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PMID:Onchocerciasis presenting with lower extremity, hypopigmented macules. 1082 90

One of the most significant contributions to tropical medicine and ophthalmology was made by Jean Hissette: African ocular onchocerciasis. During his extensive investigations in the Babindi country, he found numerous adults with river blindness. Their eye disease was caused by the filaria Onchocerca volvulus Leuckart. He noticed the signs of interstitial keratitis and band keratopathy, faint iritis or iridocyclitis, posterior synechiae and often a downward distortion of the pupil. He was the first to describe chorioretinal scarring of the fundus, what became known as the Hissette-Ridley fundus. People reported to him their entoptic phenomena which he unequivocally interpreted to be the images of microfilariae in the patient's own eye. During his stay in Belgium in 1932, he elucidated the pathogenesis of blindness since he was able to provide histological proof of the presence of microfilariae in various ocular tissues of an enucleated eye from a patient living near the Sankuru river. Like other serious health impairments, the severe inflammatory lesions in the eye occurred only after the microfilariae had died. Hence he realized that dying microfilariae play a key role in the mechanisms leading to blindness. Hissette's precise descriptions were the logical fruit of his outstanding observational abilities and enabled him as a man of great intuition to speculate about causal relationships. He evidently benefited from the fact that he took the native Africans seriously and asked them their opinion. In 1933, his friend and teacher Dr. De Mets in Antwerp already wrote on Hissette's discovery in the Belgian Congo: "This study is of exceptional value to specialists which is not only a tribute to its author, but to our common native country (Belgium)."
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PMID:The significance of some observations on African ocular onchocerciasis described by Jean Hissette (1888-1965). 1854 27

Human onchocerciasis, caused by infection by the filarial nematode Onchocerca volvulus, is a major neglected public health problem that affects millions of people in the endemic regions of sub-Saharan Africa and Latin America. Onchocerciasis is known to be associated with skin and eye disease and more recently, neurological features have been recognized as a major manifestation. Especially the latter poses a severe burden on affected individuals and their families. Although definite studies are awaited, preliminary evidence suggests that neurological disease may include the nodding syndrome, Nakalanga syndrome and epilepsy but to date, the exact pathophysiological mechanisms remain unclear. Currently, the only way to prevent Onchocera volvulus associated disease is through interventions that target the elimination of onchocerciasis through community distribution of ivermectin and larviciding the breeding sites of the Similium or blackfly vector in rivers. In this review, we discuss the epidemiology, potential pathological mechanisms as well as prevention and treatment strategies of onchocerciasis, focusing on the neurological disease.
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PMID:Neurological manifestations in Onchocerca volvulus infection: A review. 3045 51

Many parasitic infections have different presenting features in endemic individuals (ENDs) and immunologically naive temporary residents (TRs). Temporary residents with loiasis often display acute symptoms and hypereosinophilia, in contrast to a parasite-induced subclinical state in chronically infected ENDs. Few studies have examined differences in ENDs and TRs infected with the related filarial parasite Onchocerca volvulus. We identified 40 TRs and 36 ENDs with imported onchocerciasis at the National Institutes of Health between 1976 and 2016. All study subjects received an extensive pretreatment medical history, physical examination, and laboratory investigations. We performed additional parasite-specific serologic testing on stored patient sera. Asymptomatic infection occurred in 12.5% of TRs and no ENDs (P = 0.06). Papular dermatitis was more common in TRs (47.5% versus 2.7%, P < 0.001), whereas more pigmentation changes occurred in ENDs (41.7% versus 15%, P = 0.01). Only endemic patients reported visual disturbance (13% versus 0%, P = 0.03). One TR (3.3%) had onchocercal eye disease, compared with 22.6% of ENDs (P = 0.053). Absolute eosinophil counts (AECs) were similar in ENDs and TRs (P = 0.5), and one-third of subjects had a normal AEC. Endemic individuals had higher filarial-specific IgG4 and were more likely to be positive for IgG4 antibodies to Ov-16. Temporary residents and ENDs with imported O. volvulus infection presented with different dermatologic manifestations; ocular involvement occurred almost exclusively in ENDs. Unlike Loa loa, clinical differences appear not to be eosinophil-mediated and may reflect chronicity, intensity of infection, or the presence of Wolbachia in O. volvulus.
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PMID:Differences in the Clinical and Laboratory Features of Imported Onchocerciasis in Endemic Individuals and Temporary Residents. 3076 81


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