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Nditanchou R, Agyemang D, Dixon R, D'Souza S, Selby R, Opare J, Tettevi EJ, Asiedu MD, Idun B, Chailloux A, Schmidt E, Hamill L, Senyonjo L, Osei-Atweneboana MY. Persistent transmission of onchocerciasis in Kwanware-Ottou focus in Wenchi health district, Ghana. BMC Infect Dis 2024; 24:1156. [PMID: 39402497 PMCID: PMC11475550 DOI: 10.1186/s12879-024-10071-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 10/09/2024] [Indexed: 10/19/2024] Open
Abstract
BACKGROUND This study examined onchocerciasis transmission in Kwanware and Ottou in the Wenchi Health District of Ghana, where persistent onchocercal microfilariae (mf) levels have been reported since 2012. METHODS This study was conducted from 2019 to 2021 and involved the following: (i) reviewing past records of ivermectin mass drug administration (MDA); (ii) conducting a treatment coverage evaluation survey (CES); (iii) conducting key informant interviews; (iv) prospecting blackfly breeding sites; (v) collecting and dissecting blackflies; and (vi) conducting parasitological and serological surveys. RESULTS (i) The review indicated ongoing MDA treatment for the past 27 years, with a reported coverage of over 65% in the last 17 yearly rounds; (ii) estimated treatment coverage by the CES in 2019 was 71.3%, with most of those not taking medicine stating that they were not offered; (iii) however, the key informant interviews revealed insufficiencies in reaching a significant number of people for treatment due to remote settlement, mobility, transport logistical issues, failure to register some people for treatment, leading to a false impression of good coverage, and a short distribution time; (iv) the most productive breeding was found within 5 km of Kwanware-Ottou; and (v) blackfly daily biting rates were highest in Kwanware and Ottou, with 199 and 160 bites per day, respectively. Infection in blackflies was found only in Kwanware and Ottou, with infectivity rates of 5.9‰ (per 1000) and 6.7‰, respectively. (vi) The mf prevalence in Ottou and Kwanware, respectively, was 40.0% and 30.0% among adults aged ≥ 20 years, and the anti-(Onchocerca volvulus) Ov16 IgG4 antibodies seroprevalence rates were 8.3% and 13.3% among children aged 5-9 years. These values were reduced to undetectable levels at a radius of 10 km from Ottou. CONCLUSIONS This study confirms that active onchocerciasis transmission centres on Kwanware/Ottou and is confined to a 10 km radius despite 27 yearly treatment rounds. The main contributing factors are suboptimal coverage and high biting rates. Identifying and targeting such a focus with a combination of interventions will be cost-effective in accelerating onchocerciasis elimination in Ghana.
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Affiliation(s)
- Rogers Nditanchou
- Sightsavers Cameroon Country Office, Immeuble No 1067 bis Rue 1750 Nouvelle Route Bastos, P.O. Box 4844, Bastos, Yaoundé, Cameroon.
| | - David Agyemang
- Sightsavers Ghana Country Office, The Elizabeth, No. 39, Senchi Link Airport Residential Area, P.O. Box 18190 KIA, Accra, Ghana
| | - Ruth Dixon
- Technopolis Group, 3 Pavilion Buildings, Brighton, BN1 1EE, UK
| | - Susan D'Souza
- Sightsavers, 35 Perrymount Road, Haywards Heath, RH16 3BW, UK
| | - Richard Selby
- Sightsavers, 35 Perrymount Road, Haywards Heath, RH16 3BW, UK
| | - Joseph Opare
- Neglected Tropical Diseases Programme, Ghana Health Service, PMB, Ministries, P.O. Box MB-190, Accra, Ghana
| | - Edward Jenner Tettevi
- The Council for Scientific and Industrial Research (CSIR), P. O. Box AH 38, Achimota, Accra, Ghana
| | - Manfred Dakorah Asiedu
- The Council for Scientific and Industrial Research (CSIR), P. O. Box AH 38, Achimota, Accra, Ghana
| | - Bright Idun
- The Council for Scientific and Industrial Research (CSIR), P. O. Box AH 38, Achimota, Accra, Ghana
| | | | - Elena Schmidt
- Sightsavers, 35 Perrymount Road, Haywards Heath, RH16 3BW, UK
| | - Louise Hamill
- Sightsavers, 35 Perrymount Road, Haywards Heath, RH16 3BW, UK
| | - Laura Senyonjo
- Sightsavers, 35 Perrymount Road, Haywards Heath, RH16 3BW, UK
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Post RJ, Laudisoit A, Mandro M, Lakwo T, Laemmer C, Pfarr K, Hoerauf A, Tortosa P, Gomard Y, Ukety T, Mande C, Farovitch L, Amazigo U, Bakajika D, Oguttu DW, Awaca N, Colebunders R. Identification of the onchocerciasis vector in the Kakoi-Koda focus of the Democratic Republic of Congo. PLoS Negl Trop Dis 2022; 16:e0010684. [PMID: 36331979 PMCID: PMC9668120 DOI: 10.1371/journal.pntd.0010684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 11/16/2022] [Accepted: 10/17/2022] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND The objective of this study was to characterise the vector in a small hyper-endemic focus of onchocerciasis (the Kakoi-Koda focus) which has recently been discovered on the western slopes of the rift valley above Lake Albert. METHODOLOGY/PRINCIPAL FINDINGS Aquatic stages of blackflies were collected by hand from streams and rivers, and anthropophilic adult females were collected by human landing catches. Using a combination of morphotaxonomy and DNA barcoding, the blackflies collected biting humans within the focus were identified as Simulium dentulosum and Simulium vorax, which were also found breeding in local streams and rivers. Simulium damnosum s.l., Simulium neavei and Simulium albivirgulatum were not found (except for a single site in 2009 where crabs were carrying S. neavei). Anthropophilic specimens from the focus were screened for Onchocerca DNA using discriminant qualitative real-time triplex PCR. One specimen of S. vorax was positive for Onchocerca volvulus in the body, and out of 155 S. dentulosum, 30% and 11% were infected and infective (respectively). CONCLUSIONS/SIGNIFICANCE Simulium dentulosum currently appears to be the main vector of human onchocerciasis within the Kakoi-Koda focus, and S. vorax may be a secondary vector. It remains possible that S. neavei was the main (or only) vector in the past having now become rare as a result of the removal of tree-cover and land-use changes. Simulium vorax has previously been shown to support the development of O. volvulus in the laboratory, but this is the first time that S. dentulosum has been implicated as a probable vector of onchocerciasis, and this raises the possibility that other blackfly species which are not generally considered to be anthropophilic vectors might become vectors under suitable conditions. Because S. dentulosum is not a vector in endemic areas surrounding the Kakoi-Koda focus, it is probable that the Kakoi-Koda focus is significantly isolated.
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Affiliation(s)
- Rory J. Post
- Disease Control Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Anne Laudisoit
- EcoHealth Alliance, New York, New York, United States
- Global Health Institute, University of Antwerp, Wilrijk, Belgium
- Evolutionary Ecology group (EVECO), University of Antwerp, Wilrijk, Belgium
| | - Michel Mandro
- Provincial Health Division Ituri, Ministry of Health, Bunia, Democratic Republic of Congo
| | - Thomson Lakwo
- Division of Vector Borne and Neglected Tropical Diseases Control, Ministry of Health, Kampala, Uganda
| | - Christine Laemmer
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn
- German Center for Infection Research (DZIF), partner site Bonn-Cologne, Germany
| | - Kenneth Pfarr
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn
- German Center for Infection Research (DZIF), partner site Bonn-Cologne, Germany
| | - Achim Hoerauf
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn
- German Center for Infection Research (DZIF), partner site Bonn-Cologne, Germany
| | - Pablo Tortosa
- Université de La Réunion, UMR PIMIT "Processus Infectieux en Milieu Insulaire Tropical", CNRS 9192, INSERM U 1187, IRD 249. Plateforme de Recherche CYROI, Saint-Denis, France
| | - Yann Gomard
- Université de La Réunion, UMR PIMIT "Processus Infectieux en Milieu Insulaire Tropical", CNRS 9192, INSERM U 1187, IRD 249. Plateforme de Recherche CYROI, Saint-Denis, France
| | - Tony Ukety
- Centre de Recherche en Maladies Tropicales (CRMT), Rethy, Democratic Republic of Congo
| | - Claude Mande
- Department of Ecology and Wildlife Management, University of Kisangani, Kisangani, Democratic Republic of Congo
- Biodiversity Monitoring Centre (CSB), University of Kisangani, Kisangani, Democratic Republic of Congo
| | - Lorne Farovitch
- School of Medicine and Dentistry, University of Rochester Medical Center, Rochester New York, United States of America
| | - Uche Amazigo
- Pan-African Community Initiative on Education and Health, Enugu, Nigeria
| | - Didier Bakajika
- Expanded Special Project for Elimination of NTDs, World Health Organization Regional Office for Africa, Brazzaville, Republic of Congo
| | - David W. Oguttu
- Division of Vector Borne and Neglected Tropical Diseases Control, Ministry of Health, Kampala, Uganda
| | - Naomi Awaca
- Ministry of Health, National Programme for Neglected Tropical Diseases & Preventive Chemotherapy, Kinshasa, Democratic Republic of Congo
| | - Robert Colebunders
- Global Health Institute, University of Antwerp, Wilrijk, Belgium
- * E-mail:
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Takaoka H. 5) Review of the Biology and Ecology of Adult Blackflies in Relation to the Transmission of Onchocerciasis in Guatemala. Trop Med Health 2016; 43:71-85. [PMID: 26744575 PMCID: PMC4652670 DOI: 10.2149/tmh.2015-s12] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Recent studies on the biology and ecology of adult blackflies in relation to the transmission of human onchocerciasis in Guatemala are reviewed. First, earlier studies on the transmission of the disease since its discovery by Dr. R. Robles in 1915 are outlined. Second, eleven blackfly species caught on humans are evaluated for vector status on the basis of their natural and experimental infections with third-stage larvae of Onchocerca volvulus, and Simulium ochraceum,* S. metallicum* and S. callidum are confirmed as natural vectors of the disease in Guatemala in descending order of importance, whereas S. gonzalezi, S. haematopotum, S. veracruzanum and S. horacioi are potential vectors. Third, the migration and fate of O. volvulus microfilariae ingested by female blackflies are highlighted on the basis of the findings of the cibarial armature of S. ochraceum and physiological incompatibility of S. metallicum as main barriers against microfilariae, both of which greatly decrease the number of ingested O. volvulus microfilariae developing to the third-stage larvae per female. Fourth, among many ecological factors of female blackfly populations, geographical and altitudinal distributions, habits of blood feeding, host preferences for blood feeding, preference for human body parts, parous rates, daily and seasonal fluctuations of biting activities, in particular, of parous females, gonotrophic cycle, longevity, flight range, and annual transmission potential are reviewed, and their influences on the transmission dynamics of the disease agents are considered. Fifth, effects of air temperatures on the O. volvulus–S. ochraceum complex are examined, with a special reference to the characteristic altitudinal distributions of the disease. The importance of reliable identification of both the vector blackfly species and filarial larvae found in female blackflies is emphasized to understand the transmission of the disease. [*It is now known that these two species are actually species complexes.]
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Affiliation(s)
- Hiroyuki Takaoka
- Institute of Biological Sciences, Faculty of Science, University of Malaya , Kuala Lumpur, 50603 Malaysia
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Neary JM, Trees AJ, Ekale DD, Tanya VN, Hetzel U, Makepeace BL. Onchocerca armillata contains the endosymbiotic bacterium Wolbachia and elicits a limited inflammatory response. Vet Parasitol 2010; 174:267-76. [PMID: 20850932 PMCID: PMC3038270 DOI: 10.1016/j.vetpar.2010.08.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 08/16/2010] [Accepted: 08/23/2010] [Indexed: 11/27/2022]
Abstract
Human onchocerciasis, also known as River Blindness, is a debilitating disease caused by the filarial nematode Onchocerca volvulus. Many, but not all, filarial nematodes carry within their tissues endosymbiotic, Rickettsia-like bacteria of the genus Wolbachia. Onchocerca spp. infections in cattle offer the most relevant, analogous host–parasite model system. West African cattle are commonly co-infected with four Onchocerca spp.; two of these are Wolbachia-positive (Onchocerca gutturosa and Onchocerca ochengi), and the remainder are of unknown Wolbachia status (Onchocerca dukei and Onchocerca armillata). Previous studies have suggested that worm survival is dependent on this bacterium. O. armillata, an abundant parasite of African cattle that has received little attention, is a primitive species that may lack Wolbachia. The objectives of this study were to determine if O. armillata carries Wolbachia and to provide preliminary descriptions of the host inflammatory cell environment around the adult worms. The findings may support or refute the hypothesis that a prime contribution of Wolbachia is to permit long-term survival and reproduction of certain Onchocerca spp. (including O. volvulus in humans). O. armillata adult worms were found in the aorta of 90.7% of cattle (n = 54) slaughtered at an abattoir in Ngaoundéré, Adamawa Region, Cameroon. The presence of Wolbachia in O. armillata was confirmed by a specific anti-Wolbachia surface protein antibody detected using a peroxidase conjugate (immunohistochemistry) and PCR for detection of Wolbachia-specific sequences within DNA extracts from frozen worms. Tissue sections stained with haematoxylin and eosin showed the host cell response to be dominated by macrophages and fibroblasts. This is unusual compared with nodule-dwelling Wolbachia-positive Onchocerca spp., where the host response is typically characterised by granulocytes, and suggests that the mechanisms for worm survival employed by this species (which is probably motile) may differ.
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Affiliation(s)
- Joseph M Neary
- Liverpool School of Tropical Medicine and Faculty of Veterinary Science, University of Liverpool, Liverpool, UK
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ATTENBURROW DP, DONNELLY JJ, SOULSBY EJL. Periodic ophthalmia (recurrent uveitis) of horses: An evaluation of the aetiological role of microfilariae of Onchocerca cervicalis and the clinical management of the condition. Equine Vet J 2010. [DOI: 10.1111/j.2042-3306.1983.tb04559.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Faísca P, Morales-Hojas R, Alves M, Gomes J, Botelho M, Melo M, Xufre A. A case of canine ocular onchocercosis in Portugal. Vet Ophthalmol 2010; 13:117-21. [DOI: 10.1111/j.1463-5224.2010.00763.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Affiliation(s)
- Shelley G Rhodes
- Veterinary Laboratories Agency, Addlestone, Surrey KT15 3NB, UK.
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Stevens L, Giordano R, Fialho RF. Male-Killing, Nematode Infections, Bacteriophage Infection, and Virulence of Cytoplasmic Bacteria in the GenusWolbachia. ACTA ACUST UNITED AC 2001. [DOI: 10.1146/annurev.ecolsys.32.081501.114132] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Lori Stevens
- Department of Biology, University of Vermont, Burlington, Vermont 05405; e-mail:
| | - Rosanna Giordano
- Department of Biology, University of Vermont, Burlington, Vermont 05405; e-mail:
| | - Roberto F. Fialho
- Department of Biology, University of Vermont, Burlington, Vermont 05405; e-mail:
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10
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Abstract
An adult male mongrel dog that had spent its entire life in Hungary, was found to have infection with filaroid nematodes of the genus Onchocerca. The gravid male and female parasites were embedded in bean-sized granulomatous masses on the conjunctiva and the sclera of both eyes. The cuticle of females consisted of two separated layers in longitudinal sections, the external layer bearing ridges and the internal layer showing striations. The ridges were marked, rounded in shape, and the ratio of body diameter to the distance between ridges varied between 7:1 and 10:1. At midbody of the worms, two striations could be seen between each pair of ridges: one under every ridge and one between neighbouring ridges. Numerous exceptionally small (96.4 microm x 6.4 microm) microfilariae were seen in the uteri of females and the surrounding tissues and isolated from skin biopsy materials. The morphology and location of the parasite and histopathological lesions of the Hungarian case were similar to that described in dogs in the United States. This case is the first documented ocular Onchocerca infection in dogs outside the western United States. Thus, onchocercosis should be considered in the differential diagnosis of ocular and periocular nodules in dogs also in Europe.
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Affiliation(s)
- Z Széll
- Department of Pathology and Zoology, Faculty of Veterinary Science, Szent István University, H-1400, P.O. Box 2, Budapest, Hungary
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Pearson CA. Femoral hernia--a not so unusual presentation of onchocerciasis. Trop Doct 1996; 26:199-200. [PMID: 8937254 DOI: 10.1177/004947559602600439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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McKechnie NM, Braun G, Kläger S, Connor V, Kasp E, Wallace G, Whiston R. Cross-reactive antigens in the pathogenesis of onchocerciasis. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 1993; 87:649-52. [PMID: 8122928 DOI: 10.1080/00034983.1993.11812824] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The ocular disease associated with infection with Onchocerca volvulus is unique in that there is a wealth of epidemiological evidence to support the casual nature of the association but there is little known about the pathogenic mechanisms involved. We have identified a 44,000 M(r) component of ocular tissues that shows immunological cross-reactivity with an O. volvulus antigen. This immunological cross-reactivity between parasite and a component of host tissues may underlie the development of ocular disease in onchocerciasis. Preliminary experiments indicate that it is possible to initiate ocular disease in susceptible rats using the recombinant parasite antigen. This should allow the development of a laboratory model of ocular onchocerciasis and further our understanding of the mechanisms by which an infective organism can produce an auto-immune-like disease in the host.
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Affiliation(s)
- N M McKechnie
- Department of Pathology, University of Cambridge, U.K
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Nelson GS. Human onchocerciasis: notes on the history, the parasite and the life cycle. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 1991; 85:83-95. [PMID: 1888224 DOI: 10.1080/00034983.1991.11812534] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- G S Nelson
- Liverpool School of Tropical Medicine, U.K
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Abstract
Sowda, the localized asymmetrical lesion of onchocerciasis endemic in Yemen and Southern Saudi Arabia, is characterized by hyperpigmented lichenified papular lesions on one leg with intense pruritus. There is enlargement of femoral and inguinal lymph glands. In our study, even the long standing cases do not show elephantiasis of the leg or genitalia. Microfilaria appeared to be scarce and adult worms could not be detected clinically, as well as by ultrasonography (except in one case). There was no significant lymphatic obstruction; such cases were studied by contrast lymphangiography and isotope lymphangiography.
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Affiliation(s)
- M A Siddiqui
- Department of Medicine, King Khalid University Hospital, Riyadh, Saudi Arabia
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Hussein HS, el Sammani SE. Onchocerca raillieti: release from skin snips, maintenance in vitro and periodicity of microfilariae. Vet Res Commun 1990; 14:31-9. [PMID: 2316189 DOI: 10.1007/bf00346381] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Several media were tested for the release of Onchocerca raillieti microfilariae from skin snips and for their subsequent in vitro maintenance. Tyrode's solution containing 20% equine serum and antibiotics was the best medium tested, followed by phosphate buffered saline. Tyrode's solution alone or distilled water were poor media. A temperature 7-12 degrees C lower than the host's body temperature favoured release of the microfilariae from skin snips. The microfilariae were best maintained at 4-10 degrees C, when they remained alive for up to 5 days. O. raillieti microfilariae had an evening periodicity which could be related to a possible vector's peak of feeding activity.
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Affiliation(s)
- H S Hussein
- Zoology Department, College of Science, King Saud University, Riyadh, Saudi Arabia
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al-Khawajah MM, Siddiqui MA. Onchocerciasis: an unusual presentation as eczema. Int J Dermatol 1990; 29:73-4. [PMID: 2329030 DOI: 10.1111/j.1365-4362.1990.tb03764.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Hay RJ, Mackenzie CD, Guderian R, Noble WC, Proano JR, Williams JF. Onchodermatitis--correlation between skin disease and parasitic load in an endemic focus in Ecuador. Br J Dermatol 1989; 121:187-98. [PMID: 2775644 DOI: 10.1111/j.1365-2133.1989.tb01798.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Onchocerciasis is a chronic parasitic infection in which infiltration of the skin by microfilariae has been associated with a number of different pathological changes. This survey compared the prevalence of different forms of skin disease in two villages, one of which was located within the endemic zone for onchocerciasis (Zapallo Grande), in a lowland rain forest area of western Ecuador. The commonest skin diseases in both villages were scabies, pyoderma and pityriasis versicolor. In addition changes closely correlated with the presence of microfilariae in skin snips were found in Zapallo Grande--such as atrophic gluteal changes, and acute and chronic papular dermatitis. The only other skin disease associated with onchocerciasis was widespread tinea corporis due to T. rubrum. The Amerindians in the endemic onchocerciasis area were more likely than Negroes to have generalized atrophic changes of the skin, whereas in the latter group significant numbers of individuals had no obvious skin lesions but large numbers of microfilariae were detected in skin snips. Acute papular dermatitis was common in both groups and in biopsied lesions microfilariae could usually be identified within the epidermis or close to the dermo-epidermal junction. One patient had developed severe reactive onchodermatitis (Sowda). Swabs taken from onchocercal skin lesions showed no evidence of skin surface carriage of Staphylococcus aureus. Changes classically associated with onchocerciasis such as pretibial hypopigmentation (leopard skin) and hanging groin were notably absent in this population.
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Affiliation(s)
- R J Hay
- London School of Hygiene and Tropical Medicine, U.K
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Abstract
Human filarial infections afflict over 150 million persons worldwide and are major causes of morbidity in many developing countries. Onchocerca volvulus infection is a leading preventable cause of blindness, while bancroftian and brugian filariasis may produce lymphatic obstruction of the genitalia and extremities (elephantiasis). Definitive diagnosis of these helminthic infections currently depends on demonstration of microfilariae in host tissues, i.e., the skin in the case of O. volvulus and the bloodstream in the cases of Wuchereria bancrofti and Brugia malayi. Many investigations are now directed at developing specific and sensitive serum antigen assays that will allow diagnosis of active infection (i.e., presence of adult-stage parasites) in the absence of detectable microfilariae. With respect to the immunology of these parasitic infections, efforts are being directed at elucidating the role of T- and B-cell responses in the development of pathologic lesions and resistance to reinfection. These data as well as molecular biologic approaches to identify and study filarial molecules which are immunogenic are discussed. Finally, since treatment of filariases at present depends on antiparasitic drugs, the clinical indications and dosages of diethylcarbamazine and ivermectin are summarized.
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Affiliation(s)
- J Nanduri
- Department of Medicine, Case Western Reserve University, Cleveland, Ohio
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Murray KA, Post RJ, Crampton JM, McCall PJ, Kouyate B. Cloning and characterization of a species-specific repetitive DNA sequence from Onchocerca armillata. Mol Biochem Parasitol 1988; 30:209-15. [PMID: 3185612 DOI: 10.1016/0166-6851(88)90089-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Two clones, pOA1 and pOA5, have been isolated from a genomic DNA library prepared from pools of Onchocerca armillata adults in the plasmid vector pUC12. In dot-blot hybridisations, these two clones do not cross-hybridise significantly with total genomic DNA from O. volvulus, O. gutturosa, O. ochengi, O. gibsoni, O. lienalis, bovine, human, Culicoides nubeculosus, Simulium species or Brugia pahangi, but do hybridise with as little as 100 pg of DNA from two separate geographic isolates of O. armillata. The sequence of pOA1 and pOA5 has been determined and found to contain a repetitive DNA sequence 147 bp in length. These clones can be used as specific and sensitive DNA probes for the identification of O. armillata capable of identifying a single L3 larva.
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Affiliation(s)
- K A Murray
- Wolfson Unit of Molecular Genetics, Liverpool School of Tropical Medicine, U.K
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Behnke JM. Evasion of immunity by nematode parasites causing chronic infections. ADVANCES IN PARASITOLOGY 1987; 26:1-71. [PMID: 3314404 DOI: 10.1016/s0065-308x(08)60294-8] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- J M Behnke
- Department of Zoology, University of Nottingham, England
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22
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Perler FB, Karam M. Cloning and characterization of two Onchocerca volvulus repeated DNA sequences. Mol Biochem Parasitol 1986; 21:171-8. [PMID: 3024001 DOI: 10.1016/0166-6851(86)90020-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Two repeated sequences, plasmids pOV8 and pOV26, were cloned and characterized from the filarial parasite Onchocerca volvulus. Both clones can be used to distinguish O. volvulus DNA from other Onchocerca species or other nematodes by restriction fragment length polymorphisms, but neither clone can differentiate between DNA from savanna (Mali) or forest (Ivory Coast) O. volvulus isolates. DNA from one O. volvulus infective larva can be detected by both clones in dot blot hybridization assays. Neither clone cross hybridizes with DNA from host or vector species (human or simuliid, respectively). pOV26 is a member of an interspersed repeated DNA family composed of at least 100 members, and is only observed in the genus Onchocerca. Repeated DNA clone pOV8 cross reacts with DNA from other parasitic filarial nematodes, and is also present in at least 100 copies per O. volvulus genome. pOV26 is a potential tool in the diagnosis of human onchocerciasis, since it is specific for the genus Onchocerca. In the future, we plan to look for regions of these repeated sequences which may serve as a basis for the development of probes to discriminate among Onchocerca species and strains using a simple dot hybridization test.
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Flockhart HA, Cibulskis RE, Karam M, Albiez EJ. Onchocerca volvulus: enzyme polymorphism in relation to the differentiation of forest and savannah strains of this parasite. Trans R Soc Trop Med Hyg 1986; 80:285-92. [PMID: 3024365 DOI: 10.1016/0035-9203(86)90037-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Isozyme analysis was carried out on Onchocerca volvulus worms collected from Liberia, Ivory Coast, Burkina Faso and Sudan to see whether this technique could detect differences between forest and savannah populations of this parasite. A total of 243 forest and 189 savannah individual female worms were electrophoresed and stained for seven enzymes. Four showed some polymorphism, LDH, MDH, PGM and MPI and the other three, GAPDH, PEP and GPI were invariant. Statistical analysis of the results showed that the relative proportions of genotypes from within the different countries conformed to Hardy-Weinberg expectations. Pairwise comparisons of allele frequencies between countries showed that populations from Liberia and Ivory Coast had a very similar composition; there was some divergence between all the other pairs of populations and the genetic distance was calculated to summarize the degree of divergence. The number of loci examined was small and the genetic distances were within the range expected for separate geographical populations of the same species. The usefulness of this technique in worm identification is discussed.
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Abstract
Onchocerca raillieti was found to be prevalent in Sudanese donkeys. The parasite was reported from Central, Northern, Western and Eastern Sudan and was most predominant in the last locality. The pathological changes produced by adult worms in the ligamentum nuchae are mostly chronic and do not seem to cause any clinical manifestations. Likewise, the microfilariae, though found in high densities in the skin with a "spill over" into the eyes, produce no pathological changes in either the skin or eyes.
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Cheema AH, El-Bihari S, Ashour NA, Ali AS. Onchocerciasis in camels (Camelus dromedarius) in Saudi Arabia. J Helminthol 1984; 58:279-85. [PMID: 6520373 DOI: 10.1017/s0022149x0002513x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
During a survey in 1980-81, 125 of 478 (26.2%) camels in Saudi Arabia were found infected with onchocerciasis. The prevalence rates in local and imported camels were 93/272 (34.2%) and 32/206 (15.5%), respectively. The disease was characterized by hard nodules in the connective tissue around the nuchal ligaments and in the subcutis. The nodules consisted of cavities containing live, degenerate or dead Onchocerca fasciata, inflammatory cells, fibrosis and calcification. The microfilariae were concentrated in the skin over the head and neck regions and often caused mild non-suppurative dermatitis.
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Nonaka S, Hashiguchi Y, Kawabata M, Aoki Y, Tada I, Marroquin HF, Flores GZ. Dermatological survey of onchocerciasis in Guatemala. J Dermatol 1980; 7:61-70. [PMID: 15462077 DOI: 10.1111/j.1346-8138.1980.tb01944.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A comprehensive survey of onchocerciasis was performed on 1259 inhabitants in San Vicente Pacaya and the surrounding area. The total number of inhabitants examined was 1259, 763 males and 496 females. An examination of microfilarial density was carried out by the skin snip method. There were 610 microfilarial positives (50.4%) out of 1211 persons, 448 males (60.9%), and 162 females (34.1%). Nodules were examined by palpation, and there were 404 (32.8%) positives for nodule out of 1232 persons, 299 males (40.3%), and 105 females (21.4%). Eczematous dermatitis was seen in 149 persons, the generalized type in 13, and other types in 136. Depigmentation on the lower extremities was seen in 290 persons, the severity was graded from 0 to 4, and grade 1 depigmentation was seen in 91; grade 2, in 143; grade 3, in 52 and grade 4 in 4 persons out of 1159 individuals examined. The positives for lymphadenopathy (above grade 2) were 464 (41.2%) out of 1127 individuals. Itching was seen in 129 (18.3%) of 705 individuals examined by the inquiry card method. The correlation between skin changes and onchocerciasis was also analyzed. Those individuals who were microfilarial positive in the skin snip and eyes, and who had palpable nodules were defined as being onchocerciasis patients. There was a high frequency of eczematous dermatitis, depigmentation on the lower extremities and lymphadenopathy in the onchocerciasis infected group, compared with the non-infected group, but there was no difference in the rate of itching between them. Hanging groin, elephantiasis and "erisipela de la costa" were not seen in this endemic area, and the degree of skin changes was slight, compared with that reported in Africa thus far.
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Affiliation(s)
- S Nonaka
- Laboratorio de Investigaciones Cientificas-Dr. Isao Tada para control de la Oncocercose, Servicio Nacional de Erradicacion de la Malaria, 5a Avenida, 11 40, Zona 11, Ciudad de Guatemala, Guatemala
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Reid GD. The development of Onchocerca volvulus in two temperate blackfly species, Simulium ornatum Meigen and Simulium lineatum Meigen. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 1979; 73:577-81. [PMID: 539857 DOI: 10.1080/00034983.1979.11687299] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In view of the promise shown by temperate simuliids for laboratory colonization, the ability of Simulium ornatum and S. lineatum to support the development of Onchocerca volvulus was investigated. An injection technique is described for the introduction of O. volvulus microfilariae from a chimpanzee into female simuliids in the absence of a bloodmeal. RPMI 1640 medium, with penicillin, streptomycin and foetal calf serum, proved satisfactory as an inoculation medium. Third stage larvae were obtained in both S. ornatum and S. lineatum after seven days at 27 degrees C. The rate of development of the parasite in S. ornatum is recorded.
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Abstract
Onchocerca armillata was found in 284 (28%) of 1,016 aortas, and O. gutturosa in 82 (28.87%) of 284 nuchal ligaments and in 11 (7.85%) of 140 rumenosplenic areas in specimens from cattle slaughtered during a 12-month period. Adult parasites were not found in 600 hides. Gross lesions included parasitic tunnels, nodules, roughening and calcification in the aortic walls. The connective tissue of nuchal ligaments and rumenosplenic areas was increased in amount, was gelatinous and brown and had afew nodules, Microscopically there were acute changes with oedema, haemorrhages and cellular infiltrations predominatly by eosinophils. There were chronic granulomatous reactions characterized by accumulation of macrophages, lymphocytes, plasma cells, giant cells, calcification and fibrosis around degenerate and dead parasites. Neutral fat was in parasites and surrounding cells. Both changes often occurred in the same specimen and many samples had parasites but no tissue reaction. Hypersensitivity, foreign-body reactions and parasitic toxins apparently were involved in the genesis of these lesions.
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Gibson DW, Connor DH. Onchocercal lymphadenitis: Clinicopathologic study of 34 patients. Trans R Soc Trop Med Hyg 1978; 72:137-54. [PMID: 653785 DOI: 10.1016/0035-9203(78)90049-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Clinicopathological studies on lymph nodes of 32 Africans with onchocerciasis--some complicated by hanging groin and elephantiasis of the genitalia--revealed atrophic lymphoid tissue, lymphoedema, chronic inflammation and fibrosis. We identified microfilariae of Onchocerca volvulus in nodes of 24 of 32 Africans (75%). There microfilariae were most numerous in the capsule and in the fibrous tissue of the medulla, but smaller numbers were also found within lymphoid tissue, in dilated lymphatics and in blood vessels. We believe that in Africians, antigens released from microfilariae of O. volvulus lead to the deposition of immune complex in tissues, which in turn causes inflammation and fibrosis and eventually obstructive lymphadenitis. This causes hanging groin and, possibly, also elephantiasis. A distinctive pattern of perivascular fibrosis contains "fibrinoid material" that we interpret as immune complexes involving microfilarial antigens. In contrast, nodes from two Yemenites with severe onchocercal dermatitis of the lower limbs (sowda) had hyperplastic follicles, minimal fibrosis and no microfilariae.
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Ali-Khan Z. Tissue pathology and comparative microanatomy of Onchocerca from a resident of Ontario and other enzootic Onchocerca species from Canada and the U.S.A. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 1977; 71:469-82. [PMID: 596957 DOI: 10.1080/00034983.1977.11687213] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The microanatomy of one male and one female specimen of a zoonotic Onchocera sp in a fibrous nodule excised from the wrist of an Ontario resident, two bovine Onchocerca from Saskatchewan and Manitoba, Canada, and O. cervicalis from the ligamentum nuchae of a horse in Georgia, U.S.A., were compared. In dimensions and cuticular morphology, the three Canadian specimens of Onchocera shared certain features and closely resembled both O. cervicalis and O. gutturosa. The number of cuticular striae in some species of Onchocerca, particularly in male worms, is briefly discussed and its taxonomic value questioned. The Canadian patient visited Radlett, Hertfordshire, England, and then her summer cottage in the Muskoka region, Ontario, prior to the appearance of her symptoms, so that it is uncertain where she acquired the infection. Zoonotic onchocerciasis has yet to be described from Ontario. All nine cases of bovine onchocerciasis (the two described here and seven others) have occurred in Manitoba and Saskatchewan.
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Abstract
One hundred patients with onchocerciasis were treated with diethylcarbamazine: a single course of treatment led to clinical cure in 48% of the patients; no means of anticipating which patients might require only a single course of treatment was found.
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Colbo MH, Fallis AM, Reye EJ. The distribution and biology of Austrosimulium pestilens, a serious biting-fly pest following flooding. Aust Vet J 1977; 53:135-8. [PMID: 869802 DOI: 10.1111/j.1751-0813.1977.tb00139.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The distribution of A. pestilens is expanded with records from the southern Gulf of Carpentaria Rivers. The value of sampling specific adult resting sites for the assessment of host range and vector potential is recorded. The value of CO2 as an attractant and the truck trap, or modifications thereof, as a collector of A. pestilens is also demonstrated.
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Kolstrup N. ONCHOCERCA GUTTUROSA IN Danish cattle. Prevalence, geographic distribution and host-vector relationships. Acta Vet Scand 1975. [PMID: 1136899 DOI: 10.1186/bf03546690] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Mellor PS. Studies on Onchocerca cervicalis Railliet and Henry 1910. I. Onchocerca cervicalis in British horses. J Helminthol 1973; 47:97-110. [PMID: 4702889 DOI: 10.1017/s0022149x00023774] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
1. 903 horses were examined at 3 abattoirs in South East England. 10(22–7%) of the horses at the London Colney abattoir, 23(13–9%) of those at the Braintree abattoir, Essex, and 90(12–9%) of those at the Islington abattoir, London, were infected with O.cervicalis. All 105 horses examined in Southern Ireland were found to be negative.2. The adult worms of O.cervicaliswere found without exception, in the ligamentum nuchae of infected horses. The suspensory ligaments of the fetlock and flexor tendons were always negative.3. The microfilariae of O.cervicalisconcentrate along the abdominal mid-line of the host. In 5 complete horse hides, 95% of the microfilariae were found within 6 inches of the linea alba. The examination of 31 other horses infected with O.cervicalisconfirmed this pattern of microfilarial distribution.4. The microfilariae were concentrated along the ventral mid-line, of the host; presumably an adaption to accommodate the habits of the vector C.nubeculosus, which bites preferentially in this area.5. Seasonal variations in the number of microfilariae in horse skin, as reported by Japanese workers, was not observed. Evidence was found, however, to suggest that the microfilariae migrate into the deeper levels of the dermis during the Winter. Histological examination of infected horse skin showed that the microfilariae have a very uneven distribution in the dermis. They congregate together in isolated “clumps” or “nests” and are frequently found in close proximity to the sweat glands or hair follicles.
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