Browsing by Author "Addy, E.T."
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Item Epidemic acute haemorrhagic conjunctivitis due to coxsackie virus A24 variant in Ghana.(East African Medical Journal, 1990) Brandful, J.A.; Yoshii, T.; Addy, E.T.; Adiku, T.K.; Osei-Kwasi, M.; Mingle, J.A.An outbreak of acute haemorrhagic conjunctivitis (AHC) occurred in Accra, Ghana, reaching a peak in July 1987. Individuals ranging from infants to adults over 50 years were infected, with those between 20 and 30 years being the most affected group. There was a female preponderance. Clinical features included conjunctivitis, subconjunctival haemorrhage and ocular pain. Some patients reported of blurred vision due to mild keratitis. Isolation of virus from clinical specimens of AHC patients was successful only in cells of human origin such as HeLa and FL. Coxsackie virus A24 variant (CA 24v) was identified as the aetiologic agent. This is the first report to associate CA 24v with an epidemic of AHC in Africa, south of the Sahara, which is outside the endemic area of Southeast Asia and the Caribbeans. This finding suggests that earlier outbreaks of AHC in Ghana and Africa may have been due to CA 24v but went undetected. The results of various tests performed during this study suggest that, at least, two antigenically different viruses of CA 24v circulated during the course of this epidemic.Item An investigation of persistent microfilaridermias despite multiple treatments with ivermectin, in two onchocerciasis-endemic foci in Ghana(Annals of Tropical Medicine and Parasitology, 2004-05) Awadzi, K.; Boakye, D.A.; Edwards, G.; Opoku, N.O.; Attah, S.K.; Osei-Atweneboana, M.Y.; Lazdins-Helds, J.K.; Ardrey, A.E.; Addy, E.T.; Quartey, B.T. et. al.If ivermectin-based programmes for the control of human onchocerciasis are to be successful, the drug must remain effective for as long as necessary. In an open, case-control study, an attempt was made to determine if the persistent, significant, Onchocerca volvulus microfilaridermias seen in some individuals who had received at least nine treatments with ivermectin were the result of the development of drug resistance in the parasite. Twenty-one of these 'sub-optimal' responders (cases) were matched, by age, weight, number of treatments, locality and skin microfilarial counts, with seven amicrofilaridermic responders and 14 ivermectin-naive subjects. The number of treatments taken, any potential drug interactions and significant underlying disease were determined from detailed clinical and laboratory studies. Each subject was treated with ivermectin during the study, so that plasma concentrations of the drug could be determined for 72 h from the time of dosage. The microfilarial and adult-worm responses to this treatment were assessed from skin microfilarial counts (obtained before the treatment and at days 8, 90 and 365 post-treatment), day-90 embryogrammes, and the results of fly-feeding experiments. Parasite-sensitivity criteria for various time-points were derived from earlier data on skin microfilaridermias and the effects of ivermectin on the adult worms. The results indicate that the significant microfilaridermias that persist despite multiple treatments with ivermectin are mainly attributable to the non-response of the adult female worms and not to inadequate drug exposure or other factors. The possibility that some adult female worms have developed resistance to ivermectin cannot be excluded. These results justify the routine monitoring of treatment efficacy in any ivermectin-based programme of disease control.Item Thirty-month follow-up of sub-optimal responders to multiple treatments with ivermectin, in two onchocerciasis-endemic foci in Ghana(Annals of Tropical Medicine and Parasitology, 2004) Awadzi, K.; Attah, S.K.; Addy, E.T.; Opoku, N.O.; Quartey, B.T.; Lazdins-Helds, J.K.; Ahmed, K.; Boatin, B.A.; Boakye, D.A.; Edwards, G.The pathogenesis of the sub-optimal response of Onchocerca volvulus to ivermectin was investigated in a 30-month follow-up of 28 individuals who, in a previous study, had been found to show a sub-optimal (N = 15) or adequate response (N = 13) to multiple treatments with the drug. Verbal informed consent was obtained before each subject was given a general clinical and ocular examination. Skin snips were taken from both iliac crests and both calves. Seventeen nodule carriers were hospitalized for nodulectomy. Adult worms were harvested, embryogrammes were constructed and all developmental stages were counted; degenerate, stretched microfilariae were noted separately. All the subjects were in good general health and all except one had received at least one additional treatment with ivermectin since the earlier study. A large proportion of the adult female worms in 10 out of the 11 sub-optimal responders who were nodule carriers were in full embryonic production but most of the stretched microfilariae they carried were degenerate. This picture is similar to that found in adult worms exposed to the first dose of ivermectin. In one subject who had no viable worms in his nodules, the existence of occult but actively reproductive worms was inferred from the high level of microfilaridermia observed less than 12 months after treatment. These observations confirm the existence of populations of adult female O. volvulus that respond poorly to repeated doses of ivermectin. The use of suramin in the treatment of the sub-optimal responders is discussed.