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)

Soluble antigen was prepared from adult worms and microfilariae of Onchocerca volvulus. In 27 patients clinically characterized as having generalized type (17) and localized reaction type (10) onchocerciasis, the response to this antigen was assessed in vivo by skin testing and in vitro by leucocyte migration inhibition assay. Three varieties of skin hypersensitivity were observed: Immediate, Arthus-type and delayed or type IV hypersensitivity. The first 2 occurred in all patients, but type IV hypersensitivity was noted only in 10, eight of whom had localized reactive type onchocerciasis, whilst the other 2 had mild generalized lesions which had for the most part healed with treatment. The leucocyte migration inhibition assay showed a spectrum of responsiveness with significant inhibition in the presence of antigen in 8 patients with localized lesions and in 2 others with mild generalized disease which had largely healed.--The specificity of the skin reaction and leucocyte migration inhibition to the antigen used was confirmed by the results obtained when a control group of 18 subjects, with no evidence of previous filarial infection, was similarly tested. 16 of them showed no skin hypersensitivity and 2 had a doubtful immediate reaction. No significant inhibition of leucocyte migration in the presence of antigen was noted in this group.
 ...
PMID:Immunological studies on onchocerciasis. Varying skin hypersensitivity and leucocyte migration inhibition in a clinical spectrum of the disease. 3 81

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.
 ...
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

Skin snips were taken from 75 people living in four villages of northern Togo. The 7824 microfilariae that emerged were examined by staining for the presence of acid phosphatase. Four distinct patterns of enzyme staining were observed, and descriptions of the stained microfilariae are given. The study confirms the view that a number of biological strains or variants of Onchocerca volvulus coexist in West Africa, and suggestions are made for further research that could result in the practical application of these observations in onchocerciasis control programmes.
 ...
PMID:Preliminary studies on the histochemical differentiation of strains of Onchocerca volvulus microfilariae in Togo. 30 58

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

Well over 20 million people in the world are infected with Onchocerca volvulus and it is probable that 200 000-500 000 people are blind as a result of this infection, which is the most important cause of blindness in certain areas of Africa and Latin America.Treatment of the disease is difficult and often produces serious adverse reactions in the patient. Combined use of diethylcarbamazine citrate and suramin is still the most suitable form of treatment. Screening for the early detection of cases at high risk of ocular manifestations must be organized, and their treatment undertaken, if blindness is to be avoided.Prevention of ocular onchocerciasis is feasible, using vector control methods to reduce transmission, but the procedures are costly and may have to be maintained for many years.Research is needed to improve treatment and to find a chemoprophylactic agent or a preventive vaccine.
 ...
PMID:Ocular onchocerciasis. 30 48

This report concerns the host's reactions to the presence of the parasite both in the course of the natural disease and during drug treatment. The various stages of Onchocerca volvulus are discussed in terms of the type of tissue reaction seen. The discussion then turns to basic hypotheses concerning the etiology of these reactions, emphasis being placed on the fact that while pathological changes are considerable in some locations there is a remarkable lack of reaction in others. Some of the mechanisms possibly involved in this apparent absence of host response are discussed, including anti-complement factors, poor antigenicity, acquisition of host antigen, immune tolerance, and blocking antibodies. In any study of the inflammatory response it is recommended that critical evaluations be made of histological material, haematological studies, the definition of the antigenic nature of O. volvulus, characterization of immunological reactivity of patients, and the definition of the migratory pathways of the parasite.The marked host reactions seen following chemotherapy, especially those related to the interaction of the drug diethylcarbamazine with microfilariae, are discussed at some length. The etiology of these reactions is considered and recommendations are made for the experimental elucidation of the mechanisms involved. Emphasis is placed on the necessity for detailed sequential histopathological and immunopathological studies in the definition of the tissue lesions found in onchocerciasis. Characterization of these lesions will assist greatly the approach to control of the adverse reactions seen during treatment.The use of anti-inflammatory agents in clinical trials is discussed and comments are made concerning the most suitable clinical situations for testing drugs and the types of drug that should be tested.
 ...
PMID:Inflammatory reactions in onchocerciasis: a report on current knowledge and recommendations for further study. 39 50

A pilot study on onchocerciasis and sowda was carried out in the south-western region of the Yemen Arab Republic. Of 61 persons examined in eight villages 35 (= 57%) were found positive for microfilariae by the skin-snip method, 13 had typical manifestations of sowda, 17 had other onchocercal-suggestive skin lesions and five had subcutaneous nodules. A single larva of Simulium damnosum s.I. was collected in Wadi Barakani. Numerous larvae and pupae of S. ruficorne and S. hargreavesi were taken in fast-flowing streams in four localities. The examination of microfilariae and adult worms by scanning electron microscopy as well as the histochemical staining of microfilariae for the demonstration of acid phosphatase activity confirmed that the concerned filaria belongs to the species Onchocerca volvulus. No morphological differences could be detected between the smaller number of the examined worms from the Yemen and the extensive parasite material from Liberia, West Africa.
 ...
PMID:Some observations on onchocerciasis including sowda in the Yemen Arab Republic. 44 97

As the study of the association diethylcarbamazine-levamisole gave encouraging results on the dermal microfilarial density of Onchocerca volvulus (Leuckart, 1893), the authors followed it up in order to determine the optimum regimen for mass treatment. Two therapeutic schemes have been tested: A--Initial treatment: 14 days with the dayly dosis of respectively 200 mg of diethylcarbamazine and 120 mg of levamisole progressively reached in four days. After one year: a single dayly dosis of respectively 200 mg and 60 mg for five days. B--Initial treatment: 7 days with the same dosis as above. After one year: dayly dosis of respectively 200 mg and 60 mg for seven days. It appears that scheme A may be considered as the best baseline to achieve the optimum regimen for the mass treatment of onchocerciasis. The aim of such a treatment is to decrease the dermal microfilarial density to a level compatible with the patient good condition.
 ...
PMID:[Onchocerciasis chemotherapy. II. Evaluation of two therapeutic schemes on microfilarial density, utilising the association diethylcarbamazine and levamisole (author's transl)]. 53 49

Onchocerca volvulus microfilariae obtained from onchocercal nodules were used as antigenic material for a skin test. This antigen is as specific as those previously employed in skin tests, detecting 85.2% of the persons with positive diagnostic signs of onchocerciasis in endemic areas. A low rate of false positives was found in the control group in nonendemic areas. The positive rate of reactions in the persons without positive signs in the endemic areas might be due to the presences of cases not detected as a result of palpation for nodules and two skin biopsies. In the examination of the residents of several populations, a close correlation was found between the positive rates of skin tests and the presence of infection. From these findings, we conclude that the skin test using the microfilarial antigen is a suitable procedure for the diagnosis of onchocerciasis. The skin test could also be useful as an epidemiological tool in assessing the effectiveness of control programmes.
 ...
PMID:The use of an Onchocerca volvulus microfilarial antigen skin test in an epidemiological survey of onchocerciasis in Guatemala. 53 7

The history and structure of the WHO Onchocerciasis Control Programme in the Volta River Basin are described. An outline of the vector control operations is given, and the techniques and organisation of the entomological evaluation network are described in detail. During the course of the evaluation and related studies undertaken between November 1974 and October 1978 almost 1.2 million S. damnosum females have been taken in over 52,000 man days of catching, and 674,000 flies were dissected. An assessment based on this effort using Annual Biting Rates and Annual Transmission Potentials shows that the transmission of O. volvulus has been reduced to below a defined maximum permissible level over most of the central part of the Programme Area. The difficulties encountered in the remainder, and at certain problem sites are outlined and relevant data given. The benefits to be expected from extending the area further southwards and the possibilities of later reductions in control activity are discussed.
 ...
PMID:Entomological aspects of the first five years of the Onchocerciasis Control Programme in the Volta River Basin. 54 1


1 2 3 4 5 6 7 8 9 10 Next >>