Browsing by Author "Osei-Atweneboana, M."
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Item Doxycycline Leads to Sterility and Enhanced Killing of Female Onchocerca volvulus Worms in an Area With Persistent Microfilaridermia After Repeated Ivermectin Treatment: A Randomized, Placebo-Controlled, Double-Blind Trial(Clinical Infectious Diseases, 2015-08) Debrah, A.Y.; Specht, S.; Klarmann-Schulz, U.; Batsa, L.; Mand, S.; Marfo-Debrekyei, Y.; Fimmers, R.; Dubben, B.; Kwarteng, A.; Osei-Atweneboana, M.; Boakye, D.; Ricchiuto, A.; Büttner, M.; Adjei, O.; MacKenzie, C.D.; Hoerauf, A.Background. Ivermectin (IVM) has been the drug of choice for the treatment of onchocerciasis. However, there have been reports of persistent microfilaridermia in individuals from an endemic area in Ghana after many rounds of IVM, raising concerns of suboptimal response or even the emergence of drug resistance. Because it is considered risky to continue relying only on IVM to combat this phenomenon, we assessed the effect of targeting the Onchocerca volvulus Wolbachia endosymbionts with doxycycline for these individuals with suboptimal response. Methods. One hundred sixty-seven patients, most of them with multiple rounds of IVM, were recruited in areas with IVM suboptimal response and treated with 100 mg/day doxycycline for 6 weeks. Three and 12 months after doxycycline treatment, patients took part in standard IVM treatment. Results. At 20 months after treatment, 80% of living female worms from the placebo group were Wolbachia positive, whereas only 5.1% in the doxycycline-treated group contained bacteria. Consistent with interruption of embryogenesis, none of the nodules removed from doxycycline-treated patients contained microfilariae, and 97% of those patients were without microfilaridermia, in contrast to placebo patients who remained at pretreatment levels (P < .001). Moreover, a significantly enhanced number of dead worms were observed after doxycycline. Conclusions. Targeting the Wolbachia in O. volvulus is effective in clearing microfilariae in the skin of onchocerciasis patients with persistent microfilaridermia and in enhanced killing of adult worms after repeated standard IVM treatment. Strategies can now be developed that include doxycycline to control onchocerciasis in areas where infections persist despite the frequent use of IVM.Item Efficacy of DEET and non-DEET-based insect repellents against bites of Simulium damnosum vectors of onchocerciasis(Medical and Veterinary Entomology, 2013-06) Wilson, M.D.; Osei-Atweneboana, M.; Boakye, D.A.; Osei-Akoto, I.; Obuobi, E.; Wiafe, C.; Kiszewski, A.Coping strategies including smoke screens are used against nuisance bites of Simulium damnosum Theobald (Diptera:Simuliidae) in onchocerciasis endemic communities. To find more effective alternatives, the efficacy of commercially available N,N-diethyl-3-methylbenzamide (DEET) products with active concentrations of 9.5, 13, 25, 50 and 98.1-100% and 'NO MAS,' (active component: para-menthane-3,8-diol and lemon grass oil) were tested at Bui-Agblekame, Ghana. A Latin square study design was implemented using eight groups of two vector collectors each, who used repellents (treatment), mineral oil or nothing each day until the end of the study. Flies were caught and their numbers each hour recorded using the standard methods for onchocerciasis transmission studies. T-tests were used to compare the mean duration of protection and a one-way analysis of variance controlling for catchers and repellents was performed. Tukey's test was used to compare protection by repellents and mineral oil. The highest percentage protection was 80.8% by NO MAS and the least 42.5% by the 13% DEET product. The period of absolute protection was 5 h by NO MAS and 1 h by 50% DEET product. No significant increase in protection was offered beyond 25% active DEET products and no significance was observed in terms of catcher × repellent effect (F = 1.731, d.f. = 48, P = 0.209). © 2012 The Royal Entomological Society.Item Efficacy of ivermectin against Onchocerca volvulus in Ghana - Authors' reply(Lancet, 2007-09) Osei-Atweneboana, M.; Eng, J.; Boakye, D.; Gyapong, J.; Prichard, R.Ed Cupp and colleagues suggest that an ivermectin resistance mechanism involving reduced suppression of reproduction by adult female Onchocerca volvulus would be unique. Although ivermectin resistance in trichostrongylids of livestock is manifested by the survival of the parasitic stages, including adult worms, the action of ivermectin against adult filariae is unique in that ivermectin mainly suppresses reproduction rather than killing adult filariae. Nevertheless, it is of interest that Caenorhabditis elegans unc-9 mutants share phenotypes of ivermectin resistance and an egg-laying defect.1 It has been suggested that low treatment coverage might explain the observed rapid skin repopulation with microfilariae, and Charles Mackenzie and Jan Remme and colleagues suggest treatment coverage of less than 50%. In fact, the average treatment coverage in the 5 years before the study, in the communities that showed poor parasitological responses, were: Jagbenbendo 71·5%, New Longoro and Kyingakrom 66·5% each, and Wiae 68·7%. These levels of coverage are in excess of the target of 65% set out by the African Programme for Onchocerciasis Control.2 Furthermore, the almost complete removal of skin microfilariae by 30 days after treatment confirms that treatment coverage was 100% for all patients in our study. A low treatment coverage cannot explain the rapid repopulation of skin microfilariae in these patients in the communities that showed poor parasitological response to ivermectin. Remme and colleagues point to the ivermectin-naive community and suggest that incoming infections could cause newly maturing adult worms to rapidly repopulate the skin with microfilariae. Ivermectin-naive communities are rare in Ghana and the naive community found in this study was in the East Gonja district. This area is remote from Kyingakrom and New Longoro (Kintampo district), two of the communities in which skin repopulation with microfilariae was alarming.Item Expanding molecular diagnostics of helminthiasis: Piloting use of the GPLN platform for surveillance of soil transmitted helminthiasis and schistosomiasis in Ghana(PLoS Neglected Tropical Diseases, 2018-01) Cunningham, L.J.; Odoom, J.; Pratt, D.; Boatemaa, L.; Asante-Ntim, N.; Attiku, K.; Banahene, B.; Osei-Atweneboana, M.; Verweij, J.J.; Molyneux, D.; Stothard, R.J.; Adams, E.R.The efforts to control and eradicate polio as a global health burden have been successful to the point where currently only three countries now report endemic polio, and the number of cases of polio continues to decrease. The success of the polio programme has been dependant on a well-developed network of laboratories termed the global polio laboratory network (GPLN). Here we explore collaborative opportunities with the GPLN to target two of the 18 diseases listed as a neglected tropical diseases (NTD) namely soil transmitted helminthiasis (STH) and Schistosomiasis (SCH). These were chosen based on prevalence and the use of faecal materials to identify both polio, STH and SCH. Our study screened 448 faecal samples from the Ghana GPLN using three triplex TaqMan assays to identify Ascaris lumbricoides, Necator americanus, Ancylostoma spp, Trichuris trchiura, Strongyloides stercoralis and Schistosoma spp. Our results found a combined helminth prevalence of 22%. The most common helminth infection was A. lumbricoides with a prevalence of 15% followed by N. americanus (5%), Ancylostoma spp. (2.5%), Schistosoma spp. (1.6%) and S. stercoralis (1%). These results show that it is possible to identify alternative pathogens to polio in the samples collected by the GPLN platform and to introduce new diagnostic assays to their laboratories. The diagnostic methods employed were also able to identify S. stercoralis positive samples, which are difficult to identify using parasitological methods such as Kato-Katz. This study raises the possibility of collaboration with the GPLN for the surveillance of a wider range of diseases which would both benefit the efforts to control the NTDs and also increase the scope of the GPLN as a diagnostic platform. © 2018 Cunningham et al.Item Onchocerciasis Control: Vision for the future from a Ghanaian perspective(Parasites & Vectors, 2009) Taylor, M.J.; Awadzi, K.; Basáñez, M.G.; Biritwum, N.; Boakye, D.A.; Boatin, B.; Bockarie, M.; Churcher, T.S.; Debrah, A.; Edwards, G.; Hoerauf, A.; Mand, S.; Matthews, G.; Osei-Atweneboana, M.; Prichard, R.K.; Wanji, S.; Adjei, O.Since 1987 onchocerciasis control has relied on the donation of ivermectin (Mectizan(R), Merck & Co., Inc.) through the Mectizan Donation Programme. Recently, concern has been raised over the appearance of suboptimal responses to ivermectin in Ghana - highlighting the potential threat of the development of resistance to ivermectin. This report summarises a meeting held in Ghana to set the research agenda for future onchocerciasis control. The aim of this workshop was to define the research priorities for alternative drug and treatment regimes and control strategies to treat populations with existing evidence of suboptimal responsiveness and define research priorities for future control strategies in the event of the development of widespread ivermectin resistance.Item Onchocerciasis control: vision for the future from a Ghanian perspective(2009-01-21) Taylor, M.J.; Awadzi, K.; Basáñez, M.; Biritwum, N.; Boakye, D.; Boatin, B.; Bockarie, M.; Churcher, T.S.; Debrah, A.; Edwards, G.; Hoerauf, A.; Mand, S.; Matthews, G.; Osei-Atweneboana, M.; Prichard, R.K.; Wanji, S.; Adjei, O.Abstract Since 1987 onchocerciasis control has relied on the donation of ivermectin (Mectizan®, Merck & Co., Inc.) through the Mectizan Donation Programme. Recently, concern has been raised over the appearance of suboptimal responses to ivermectin in Ghana – highlighting the potential threat of the development of resistance to ivermectin. This report summarises a meeting held in Ghana to set the research agenda for future onchocerciasis control. The aim of this workshop was to define the research priorities for alternative drug and treatment regimes and control strategies to treat populations with existing evidence of suboptimal responsiveness and define research priorities for future control strategies in the event of the development of widespread ivermectin resistance.