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

This study reports the clinical, ophtalmological and parasitological examination for onchocerciasis in 4 882 people, living in 23 villages located in 8 different areas of west Africa. The disease is hyperendemic in the whole sample and no major differences occur when comparing the indices of Onchocerca volvulus infection. However, all the complications (eye, skin and lymph node lesions) are less common in the four forest clusters than in to the four savanna clusters. The disease seems to be relatively well tolerated in areas where transmission of Onchocerca volvulus is carried out by Simulium species other than S. damnosum s.s. and S. sirbanum. The striking epidemiological differences of onchocerciasis is probably associated with several vector-parasite complexes, which may indicate the existence of different strains of O. volvulus.
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PMID:[The different types of human onchocerciasis in west Africa (author's transl)]. 745 61

Onchocerciasis affects 7% of Uganda's population and 1.5 million more people are at risk of infection with Onchocerca volvulus, the nematode that causes the disease. This paper reports the results of part of a multi-centre study whose objective was to determine the prevalence of onchocercal skin disease and its associated psychosocial importance in Uganda. The study employed a standardised clinical dermatological survey method along with the use of structured questionnaires, focus group discussions and key informant interviews. Out of a total of 993 persons examined to determine the prevalence of onchocercal skin lesions 253 persons were interviewed to determine the psychosocial importance of the disease. The results indicate that onchocercal skin disease is associated with a variety of psychosocial, physical and economic effects. The disease also leads to stigmatisation of affected persons and their families. It is suggested that dermatological effects of onchocerciasis should be recognised as an important cause of morbidity in Uganda.
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PMID:Social and psychological aspects of onchocercal skin disease in Nebbi district, Uganda. 749 28

Onchocerciasis is an infection with the nematode Onchocerca volvulus. The main clinical symptoms are caused by the microfilariae. They include ocular lesions leading to blindness. Onchocerciasis is widely distributed in Africa from the Sahara to the southern tip, and is also found in some areas of South and Central America. Ivermectin was shown to be an effective treatment in the early 1980's, and is safe and better tolerated than diethylcarbamazine. We report the results of ivermectin treatment of onchocerciasis, and various features of the control obtained by large-scale ivermectin treatment programs. In large-scale programs, ivermectin (150 micrograms/kg) is administered once a year. This dose paralyses the microfilariae, such that they are carried away by the lymph to the lymph nodes where they are destroyed. This dose thereby reduces the load of microfilaria by 90%. The effects of a dose of ivermectin last about two or three years, and the lesions in the anterior segment of the eye can be cured or substantially reduced. Regular treatment prevents severe lesions of the posterior segment of the eye. The effects of repeated treatment on lesions of the retina are currently under investigation. Frequent doses of ivermectin prevent the development of embryo parasites in the females, and reduces the number of adults by attrition. Large-scale treatment programs reduce the transmission of the parasite by its vectors. There are several problems impeding large-scale treatment programs. Choosing patients for priority treatment requires expensive and sometimes aggressive methods of diagnosis. Thus new techniques for the identification of communities in which onchocerciasis is a serious public health problem are required. The choice of strategies for distribution, to optimize the cost, benefit ratio and feasibility, remain controversial. Wide distribution by mobile teams is effective, but expensive. Active distribution by trained community distributors is a cheaper potential alternative. Clinic-based or passive distribution requires the population to present to be able to obtain ivermectin. Thus, although cheap, this approach is generally poorly effective. A further complication is the clearly defined criteria on which these methods should be evaluated.
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PMID:[The use of ivermectin in the control of onchocerciasis]. 764 Aug 97

Onchocerciasis is a systemic disease caused by the filarial parasite Onchocerca volvulus. It is endemic in Central Africa and South America and causes blindness which is directly related to the severity of the infection. World-wide, there are about 18 million suffering from onchocerciasis, of whom 2 million are blind. The most common symptom is pruritus, which appears early in the disease. Ocular manifestations appear later, and when present, life expectancy is less than 10 years. We present a 31-year-old male Ethiopian immigrant with this disease, which was brought to Israel with the Ethiopian immigration of the past decade. In this population can be found the various manifestations of the disease in all its stages. Patients are treated with oral Ivermectin, once a year, the safest of known medications for this disease. The need for early detection and treatment is emphasized because of the potential for ocular destruction.
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PMID:[Ocular onchocerciasis in Israel]. 772 Nov 79

The Onchocerciasis Control Programme (OCP) in West Africa, launched in 1974, includes 11 participating countries and covers more than one million square kilometres. The aim of the OCP is to control blinding onchocerciasis (river blindness) which is caused by the savannah strain of Onchocerca volvulus transmitted by the Simulium damnosum complex. There is no effective macrofilaricide, so vector control to prevent the transmission of the parasite remains the method of choice, despite the availability of ivermectin, a drug which controls ocular morbidity. The potential value of vector control has been demonstrated by the original programme: 14 years activity has eliminated the disease as a public health problem in the areas included. This strategy requires adapted logistical support involving (i) widespread insecticide coverage (27,000 km of river are treated by the OCP during the rainy season), (ii) frequent (weekly) application of larvicide and (iii) prolonged intervention due to the life-span of the worm in the human reservoir, estimated to be approximately 14 years. We describe the vector control operations and their organisation 20 years after the initiation of the OCP. The OCP can be divided into 5 areas of logistic activity. The first covers activities involving insecticide and fuel management for the OCP as a whole: assessment of the requirements for the following year, ordering from insecticide and petrol suppliers, stocking fuel and insecticide at the depots covering the area. The second activity is the treatment of rivers with insecticide. This includes treating the ground with larvicide, the aerial operations run by an independent company supplying 12 helicopters on contract to the OCP, and use of satellite beacons for retransmitting of hydrological data. The third activity is monitoring the impact of larvicides on both the target (adult and larval S. damnosum) and on other fauna (fish, crustaceans and other insects). The fourth activity is field data collection and its processing. This involves a data transmission network to facilitate stock management insecticide application and entomological and hydrological surveillance using computer systems. The fifth activity is the coordination of vector control operations, technical and administrative staff and estimations of the funds available to the Vector Control Unit. The logistic aspects of other large-scale-insect-control programmes world-wide are considered, and the possibility of using the OCP as a model for such programmes (both public health and agricultural) is assessed.
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PMID:[Control of onchocerciasis vectors in West Africa: description of the logistics adapted for a large-scale public health program]. 785 Jan 90

This paper examines the extent to which onchocercal skin lesions affect the age at marriage and the duration of lactation among infected women in forest areas of Nigeria. In a retrospective study, 145 multiparous women were asked about their breast-feeding behaviour. Ninety-seven per cent routinely breast-fed after delivery, although the duration of lactation for 75 infected and 70 non-infected women was different. Of the 75 women with Onchocerca volvulus infection, 73% experienced itching during breast-feeding; 26% breast-fed for not more than 3 months compared to 2.1% of non-infected women who breast-fed for the same period (p < 0.005). A multiple regression model showed severity of onchocercal lesions as an independent predictor of shorter duration of lactation for women with O. volvulus infection. Duration of breast-feeding was reduced by more than 9 months for 6 (25%) out of 24 infected women who breast-fed infants before and after the onset of itching from lesions. Also, while the minimum age at marriage was 9 years for non-infected women, it was 17 years for women whose lesions appeared before marriage. This preliminary study suggest that incessant itching and severe onchocerciasis lesions may be important predictors of failure of women to breast-feed for longer periods in rain-forest areas of Nigeria.
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PMID:Detrimental effects of onchocerciasis on marriage age and breast-feeding. 785 22

Onchocerciasis or "river blindness" is a vector-borne tropical disease resulting from infection with the filarial nematode Onchocerca volvulus. Disease manifestations include dermatitis, rheumatic complaints, and blindness. Recent findings have suggested an autoimmune etiology for the occurrence of chorioretinopathy, a disease of the eye which together with sclerosing keratoconjunctivitis is responsible for approximately 400,000 onchocerciasis-related cases of blindness. The identification of onchocerciasis as an important cause of tropical rheumatism prompted us to evaluate serologically the presence of systemic autoimmune disease in onchocerciasis patients and local controls from a hyperendemic area in Sierra Leone. In both groups there was a marked autoimmune response against cytoplasmic non-RNA-associated proteins consisting of autoantibodies against five major Ag with respective m.w. of 35, 51, 64, 83, and 110 kDa. These five proteins are novel autoantigens that could be distinguished from calreticulin, the human homologue of the onchocercal Ag RAL-1, and known autoantigens such as the 50-kDa La/SS-B or 52- and 60-kDa Ro/SS-A proteins by immunoblotting and ELISA assays. Furthermore, autoantibody reactivity against calreticulin was significantly higher in O. volvulus-infected individuals than in endemic controls. Autoantibody reactivity against the five major autoantigens, anti-calreticulin reactivity, and antibody reactivity against the 65-kDa arthritis-associated mycobacterial heat shock protein were intercorrelated as parts of an onchocerciasis-associated autoimmune response. The implication of autoimmunity in the disease pathogenesis of onchocerciasis could have important consequences for future research on therapeutical regimens, pathogenetic mechanisms, and serological diagnosis of onchocerciasis.
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PMID:Autoimmunity and filariasis. Autoantibodies against cytoplasmic cellular proteins in sera of patients with onchocerciasis. 790 Dec 81

As part of the return of savanna migrants installed since a long time in forest regions, in the south of Sierra Leone, we carried out an experimental study about a cross-transmission between Simulium sirbanum from Missira (West-Mali) and the forest strain of Onchocerca volvulus in the south-west of Sierra Leone. This study will allow to know if there is a risk of onchocerciasis transmission recrudescence in relation to the reinstallation of these migrants in their native region. Because of the very high limitation to the forest strain of O. volvulus microfilariae output of the peritrophic membrane reduction with savanna black-flies and according to the very low mature parasite out put of S. sirbanum with this strain observed along this experimentation, the forest strain of O. volvulus from the south Sierra Leone appears maladjusted to S. sirbanum, the main vector of onchocerciasis in savanna regions. This observation implicates a very low intensity of transmission for this forest strain by savanna onchocerciasis vectors. The return of savanna migrants in their native region, installed in the south Sierra Leone since several decades, could not be, in a short time, an origin of onchocerciasis recrudescence in savanna regions of the Onchocerciasis Control Programme area cleaned by an effective vector control carried out since 1975 sustained now by a chemotherapeutic treatment reducing the human parasite reservoir. However, the preservation of this acquired necessitates an epidemiological supervision increased, because the interactions between the vector and the parasite for a long time could carry away a mutual adaptation and a sickness recrudescence.
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PMID:[ Onchocerciasis control program in West Africa: socioeconomic development and risk of recrudescence of transmission. 1. Experimental study of the transmission of Onchocerca volvulus strains from Southwestern Sierra Leone by Simulium sirbanum]. 794 48

The movements of human populations towards the mining wealth of the northern parts of Sierra Leone are favorable to a high contact rate between onchocerciasis patients coming from the south-western area of this country and the vector species Simulium yahense and Simulium squamosum which assume the essential of onchocerciasis transmission in the above-mentioned mining area. In fact, the Onchocerca volvulus strains concerned by this contact seem to be more pathogenic than those locally transmitted. In order to assess the danger it could represent for the Onchocerciasis Control Programme in West Africa, we carried out the experimental study of transmission which may result from this contact when more or less infected onchocerciasis patients are involved. The results indicated that this transmission by S. yahense may reach high proportions only when heavily infected onchocerciasis patients are implicated. We took also notice of the low capacity of S. squamosum to transmit the O. volvulus strains from the south-western Sierra Leone, irrespective of the microfilarial load of patients. Thus, in the most favorable conditions of a high parasite-vector contact of the study, involvement of S. yahense and onchocerciasis patients with high skin microfilarial loads is the only occurrence to which a high risk of intensive transmission may be related. The authors consider that the probability of such a risk occurring will be drastically reduced, due to the considerable decrease of skin microfilarial loads in human communities which regularly have the advantage of ivermectin (Mectizan) mass treatments.
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PMID:[Onchocerciasis control program in West Africa: socioeconomic development and risk of recrudescence of transmission. 2. Experimental study of the transmission of Onchocerca volvulus strains from Southwestern Sierra Leone by Simulium yahense and Simulium squamosum]. 794 49

The development of polymerase chain reaction-based methods using strain- and species-specific DNA probes for Onchocerca volvulus has permitted classification of individual parasites from every stage of the parasite's life cycle. This technology has been applied on a large scale basis by Onchocerciasis Control Program (OCP) in West Africa. The primary objective of the OCP in using the DNA probes was to obtain accurate estimates of the annual transmission potential of the blinding strain of O. volvulus. The DNA probe classification of larvae collected throughout the OCP area demonstrated that larvae of less pathogenic strains of O. volvulus and other filarial parasites carried by Simulium damnosum s.l. have resulted in a significant overestimation of the annual transmission potential for blinding onchocerciasis. This effect is particularly pronounced along the southern border of the OCP, where the blinding and less pathogenic strains of O. volvulus coexist, and in the north of the control area, where animal parasites, particularly O. ochengi, may even predominate. A second objective of the OCP in applying the DNA probe technology was to determine the distribution of blinding and less pathogenic O. volvulus in infected individuals along the southern border of the control area. Results obtained from these studies have generally confirmed the distribution pattern established by previous epidemiologic studies. In addition, DNA probe classifications have demonstrated that in areas where the blinding and less pathogenic strains of O. volvulus coexist, a single individual may simultaneously be infected with both strains of the parasite.
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PMID:DNA probe-based classification of Simulium damnosum s. l.-borne and human-derived filarial parasites in the onchocerciasis control program area. 798 61


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