Browsing by Author "McCall, P.J."
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Item Cohort trial reveals community impact of insecticide-treated net son malaria metric indices in urban Ghana(Transactions of the Royal Society of Tropical Medicine and Hygiene, 2010) Klinkenberg, E.; Onwona-Agyeman, K.A.; McCall, P.J.; Wilson, M.D.; Bates, I.; Verhoeffe, F.H.; Barnish, G.; Donnelly, M.J.The efficacy of insecticide-treated nets (ITNs) in prevention of malaria and anaemia has been shown in rural settings, but their impact in urban settings is unknown. We carried out an ITN intervention in two communities in urban Accra, Ghana, where local malaria transmission is known to occur. There was evidence for amassor community effect, despite ITN use by fewer than 35% of households. Children living within 300m of a household with an ITN had higher haemoglobin concentrations (0.5g/dl higher, P = 0.011) and less anaemia (oddsratio2.21, 95%CI1.08–4.52, P = 0.031atmonth6), than children living more than 300m away from a household with an ITN, although malaria parasitaemias were similar. With urban populations growing rapidly across Africa, this study shows that ITNs will be an effective tool to assist African countries to achieve their Millennium Development Goals in urban settings.Item Cohort trial reveals community impact of insecticide-treated nets on malariometric indices in urban Ghana(Transactions of the Royal Society of Tropical Medicine and Hygiene, 2010-07) Klinkenberg, E.; Onwona-Agyeman, K.A.; McCall, P.J.; Wilson, M.D.; Bates, I.; Verhoeff, F.H.; Barnish, G.; Donnelly, M.J.The efficacy of insecticide-treated nets (ITNs) in prevention of malaria and anaemia has been shown in rural settings, but their impact in urban settings is unknown. We carried out an ITN intervention in two communities in urban Accra, Ghana, where local malaria transmission is known to occur. There was evidence for a mass or community effect, despite ITN use by fewer than 35% of households. Children living within 300 m of a household with an ITN had higher haemoglobin concentrations (0.5. g/dl higher, P=0.011) and less anaemia (odds ratio 2.21, 95% CI 1.08-4.52, P=0.031 at month 6), than children living more than 300 m away from a household with an ITN, although malaria parasitaemias were similar. With urban populations growing rapidly across Africa, this study shows that ITNs will be an effective tool to assist African countries to achieve their Millennium Development Goals in urban settings. [Registered trial number ISRCTN42261314; http://www.controlled-trials.com/ISRCTN42261314]. © 2010 Royal Society of Tropical Medicine and Hygiene.Item The elimination of the onchocerciasis vector from the island of Bioko as a result of larviciding by the WHO African Programme for Onchocerciasis Control(Acta Tropica, 2009) Traoré, S.; Wilson, M.D.; Sima, A.; Barro, T.; Diallo, A.; Aké, A.; Coulibaly, S.; Cheke, R.A.; Meyer, R.R.; Mas, J.; McCall, P.J.; Post, R.J.; Zouré, H.; Noma, M.; Yaméogo, L.; Sékétéli, A.V.; Amazigo, U.V.The island of Bioko is part of the Republic of Equatorial Guinea and is the only island in the World to have endemic onchocerciasis. The disease is hyperendemic and shows a forest-type epidemiology with low levels of blindness and high levels of skin disease, and the whole population of 68,000 is estimated to be at risk. Control of onchocerciasis began in 1990 using ivermectin and this yielded significant clinical benefits but transmission was not interrupted. Feasibility and preparatory studies carried out between 1995 and 2002 confirmed the probable isolation of the vector on the island, the high vectorial efficiency of the Bioko form of Simulium yahense, the seasonality of river flow, blackfly breeding and biting densities, and the distribution of the vector breeding sites. It was proposed that larviciding should be carried out from January to April, when most of the island's rivers were dry or too low to support Simulium damnosum s.l., and that most rivers would not need to be treated above 500 m altitude because they were too small to support the breeding of S. damnosum s.l. Larviciding (with temephos) would need to be carried out by helicopter (because of problems of access by land), supplemented by ground-based delivery. Insecticide susceptibility trials showed that the Bioko form was highly susceptible to temephos, and insecticide carry was tested in the rivers by assessing the length of river in which S. damnosum s.l. larvae were killed below a temephos dosing point. Regular fly catching points were established in 1999 to provide pre-control biting densities, and to act as monitoring points for control efforts. An environmental impact assessment concluded that the proposed control programme could be expected to do little damage, and a large-scale larviciding trial using ground-based applications of temephos (Abate 20EC) throughout the northern (accessible) part of the island was carried out for five weeks from 12 February 2001. Following this, a first attempt to eliminate the vectors was conducted using helicopter and ground-based applications of temephos from February to May 2003, but this was not successful because some vector populations persisted and subsequently spread throughout the island. A second attempt from January to May 2005 aimed to treat all flowing watercourses and greatly increased the number of treatment points. This led to the successful elimination of the vector. The last biting S. damnosum s.l. was caught in March 2005 and none have been found since then for more than 3 years.Item Malaria and irrigated crops, Accra, Ghana(Emerging Infectious Diseases, 2005-09) Klinkenberg, E.; McCall, P.J.; Hastings, I.M.; Wilson, M.D.; Amerasinghe, F.P.; Donnelly, M.J.We investigated the prevalence of malaria and associated risk factors in children living in urban Ghana. Malaria prevalence was associated with low hemoglobin concentration, low socioeconomic status, and higher age. Our findings indicate that African urban poor are seriously affected by malaria and that irrigated agriculture may increase this risk.Item Species abundance and insecticide resistance of Anopheles gambiae in selected areas of Ghana and Burkina Faso(Medical and Veterinary Entomology, 2004-12) Yawson, A.E.; McCall, P.J.; Wilson, M.D.; Donnelly, M.J.The Ghanaian National Malaria Control Programme has prioritized insecticide-treated materials as a key strategy for malaria control. We report on a survey of the distribution of the molecular forms of Anopheles gambiae Giles (Diptera: Culicidae) and insecticide resistance (the kdr mutation), carried out by sampling mosquitoes from 11 locations in Ghana and one additional site in Burkina Faso. The molecular M and S forms of An. gambiae were found to occur in sympatry in southern Ghana. The S form predominated throughout its distribution in the coastal savannah, except at one location in the strand and mangrove zone where rice was cultivated. The M form was the only form collected in northern Ghana and was the predominant form (97.5%) in Burkina Faso. No M/S hybrids were detected. The kdr mutation was observed at very high frequencies (98-100%) within the S form but reached a maximum of only 3.38% in the M form in one population at an irrigation scheme in the Ghanaian coastal savannah zone.Item Urban malaria and anaemia in children: A cross-sectional survey in two cities of Ghana(Tropical Medicine and International Health, 2006-05) Klinkenberg, E.; McCall, P.J.; Wilson, M.D.; Akoto, A.O.; Amerasinghe, F.P.; Bates, I.; Verhoeff, F.H.; Barnish, G.; Donnelly, M.J.OBJECTIVE: To describe the epidemiology of urban malaria, an emerging problem in sub-Saharan Africa. METHOD: Cross-sectional surveys of communities in Accra and Kumasi, Ghana, determining risk factors for malaria infection and anaemia in children aged 6-60 months. RESULTS: Malaria prevalence rates ranged from 2% to 33% between urban communities. 47.1% of children were anaemic (Hb < 11.0 g/dl). Factors associated with malaria prevalence were low socio-economic status, age and anaemia. The attributable risks of anaemia and severe anaemia (Hb < 8.0 g/dl) caused by malaria were 5% and 23% respectively. CONCLUSIONS: Malaria in urban areas displayed a heterogeneity and complexity that differed from the rural environment, which has important implications for malaria control. Marked intra-city variation indicates the importance of targeting specific areas or districts. The most vulnerable group, the urban poor, should be prioritized when designing control measures. This would require careful assessment of the malaria risk pattern in any city to guide an integrated control program. © 2006 Blackwell Publishing Ltd.