Filling the Gap 115 Years after Ronald Ross: The Distribution of the Anopheles coluzzii and Anopheles gambiae s.s from Freetown and Monrovia, West Africa

Souza, Dziedzom K. de; Koudou, Benjamin G.; Bolay, Fatorma K.; Boakye, Daniel; Bockarie, Moses J.

doi:10.1371/journal.pone.0064939

Cited by 12 publications

(12 citation statements)

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“…gambiae s.s . in Monrovia, Liberia [ 21 ]. The relative dominance of one species over another is believed to be associated with breeding site characteristics [ 43 ].…”

Section: Discussionmentioning

confidence: 99%

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Low prevalence of Plasmodium and absence of malaria transmission in Conakry, Guinea: prospects for elimination

Kouassi

Souza

Goépogui³

et al. 2016

Malar J

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BackgroundOver the past 15 years, mortality and morbidity due to malaria have been reduced substantially in sub-Saharan Africa and local elimination has been achieved in some settings. This study addresses the bio-ecology of larval and adult stages of malaria vectors, Plasmodium infection in Anopheles gambiae s.l. in the city of Conakry, Guinea, and discusses the prospect for malaria elimination.MethodsWater bodies were prospected to identify potential mosquito breeding sites for 6 days each in the dry season (January 2013) and in the rainy season (August 2013), using the dipping method. Adult mosquitoes were collected in 15 communities in the five districts of Conakry using exit traps and indoor spraying catches over a 1-year period (November 2012 to October 2013). Molecular approaches were employed for identification of Anopheles species, including An. coluzzii and An.gambiae s.s. Individual An.gambiae mosquitoes were tested for Plasmodium falciparum and P. vivax sporozoites using the VecTest™ malaria panel assay and an enzyme-linked immunosorbent assay. A systematic research of Ministry of Health statistical yearbooks was performed to determine malaria prevalence in children below the age of 5 years.ResultsCulex larval breeding sites were observed in large numbers throughout Conakry in both seasons. While Anopheles larval breeding sites were less frequent than Culex breeding sites, there was a high odds of finding An.gambiae mosquito larvae in agricultural sites during the rainy season. Over the 1-year study period, a total of 14,334 adult mosquitoes were collected; 14,135 Culex (98.6 %) and 161 (1.1 %) from the An.gambiae complex. One-hundred and twelve Anopheles mosquitoes, mainly collected from rice fields and gardens, were subjected to molecular analysis. Most of the mosquitoes were An. gambiae s.s. (n = 102; 91.1 %) while the remaining 10 (8.9 %) were An.melas. The molecular M form of An. gambiae s.s. was predominant (n = 89; 79.5 %). The proportions of kdr genotype in the An. gambiae s.s. M and S form were 65.2 and 81.8 % (n = 9), respectively. No sporozoite infection were detected in any of the mosquitoes tested. The prevalence of Plasmodium recorded in children aged below 5 years was relatively low and varied between 2.2 and 7.6 % from 2009 to 2012.ConclusionsThe low density of larval and adult stages of Anopheles mosquitoes, the absence of infected An.gambiae species and the low prevalence of Plasmodium in under 5-year-old children are important features that might facilitate malaria elimination in Conakry. The heterogeneity in species composition and resistance profiles call for vector control interventions that are tailored to the local bio-ecological setting.

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“…gambiae s.s . in Monrovia, Liberia [ 21 ]. The relative dominance of one species over another is believed to be associated with breeding site characteristics [ 43 ].…”

Section: Discussionmentioning

confidence: 99%

“…Genomic DNA was extracted from the legs of the mosquitoes, morphologically identified as An. gambiae , using the boiling preparation method [ 21 ]. Briefly, the legs were crushed in 100 ml of distilled water and boiled at 95 °C for 10 min.…”

Section: Methodsmentioning

confidence: 99%

Low prevalence of Plasmodium and absence of malaria transmission in Conakry, Guinea: prospects for elimination

Kouassi

Souza

Goépogui³

et al. 2016

Malar J

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“…The latter has been widely used in sampling Anopheles mosquitoes in malaria intervention programmes [ 29 ] and remains the ‘gold’ standard for collecting indoor-resting, blood-fed and gravid mosquitoes [ 29 , 30 ]. In West African cities and urban areas with high pollution levels, Culex mosquitoes are the predominant mosquito species [ 22 , 31 ]. Likewise, the use of the same collection methods in rural areas reveals higher proportions of Anopheles compared to Culex [ 32 ].…”

Section: Discussionmentioning

confidence: 99%

Assessing the presence of Wuchereria bancrofti in vector and human populations from urban communities in Conakry, Guinea

et al. 2015

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BackgroundThe Global Programme to Eliminate Lymphatic Filariasis was launched in 2000 with the goal of interrupting transmission of lymphatic filariasis (LF) through multiple rounds of mass drug administration (MDA). In Guinea, there is evidence of ongoing LF transmission, but little is known about the most densely populated parts of the country, including the capital Conakry. In order to guide the LF control and elimination efforts, serological and entomological surveys were carried out to determine whether or not LF transmission occurs in Conakry.MethodsThe prevalence of circulating filarial antigen (CFA) of Wuchereria bancrofti was assessed by an immuno-chromatography test (ICT) in people recruited from all five districts of Conakry. Mosquitoes were collected over a 1-year period, in 195 households in 15 communities. A proportion of mosquitoes were analysed for W. bancrofti, using dissection, loop-mediated isothermal amplification (LAMP) assay and conventional polymerase chain reaction (PCR).ResultsCFA test revealed no infection in the 611 individuals examined. A total of 14,334 mosquitoes were collected; 14,135 Culex (98.6 %), 161 Anopheles (1.1 %) and a few other species. Out of 1,312 Culex spp. (9.3 %) and 51 An. gambiae (31.7 %) dissected, none was infected with any stage of the W. bancrofti parasite. However, the LAMP assay revealed that 1.8 % of An. gambiae and 0.31 % of Culex spp. were positive, while PCR determined respective prevalences of 0 % and 0.19 %.ConclusionsThis study revealed the presence of W. bancrofti DNA in mosquitoes, despite the apparent absence of infection in the human population. Although MDA interventions are not recommended where the prevalence of ICT is below 1 %, the entomological results are suggestive of the circulation of the parasite in the population of Conakry. Therefore, rigorous surveillance is still warranted so that LF transmission in Conakry would be identified rapidly and adequate responses being implemented.

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“…If available, sample weights could help in improving the accuracy of the association between conflict variables and changes in malaria prevalence; however, at the inferential stage their effects are limited by the use of thousands of conflict-to-malaria point associations. Additionally, data quality represents a potential source of uncertainty because, in conflict situations, it can be difficult to collect reliable data on malaria prevalence and transmission [ 22 , 74 ], though here the analysis is applied to pre- and post-conflict prevalence at same locations, so this issue is limited. In terms of conflict data, there are alternative databases, but each has their own limitations for a point-based spatiotemporal analysis.…”

Section: Discussionmentioning

confidence: 99%

A geostatistical analysis of the association between armed conflicts and Plasmodium falciparum malaria in Africa, 1997–2010

Sedda

Tatem

2015

Malar J

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BackgroundThe absence of conflict in a country has been cited as a crucial factor affecting the operational feasibility of achieving malaria control and elimination, yet mixed evidence exists on the influence that conflicts have had on malaria transmission. Over the past two decades, Africa has seen substantial numbers of armed conflicts of varying length and scale, creating conditions that can disrupt control efforts and impact malaria transmission. However, very few studies have quantitatively assessed the associations between conflicts and malaria transmission, particularly in a consistent way across multiple countries.MethodsIn this analysis an explicit geostatistical, autoregressive, mixed model is employed to quantitatively assess the association between conflicts and variations in Plasmodium falciparum parasite prevalence across a 13-year period in sub-Saharan Africa.ResultsAnalyses of geolocated, malaria prevalence survey variations against armed conflict data in general showed a wide, but short-lived impact of conflict events geographically. The number of countries with decreased P. falciparum parasite prevalence (17) is larger than the number of countries with increased transmission (12), and notably, some of the countries with the highest transmission pre-conflict were still found with lower transmission post-conflict. For four countries, there were no significant changes in parasite prevalence. Finally, distance from conflicts, duration of conflicts, violence of conflict, and number of conflicts were significant components in the model explaining the changes in P. falciparum parasite rate.ConclusionsThe results suggest that the maintenance of intervention coverage and provision of healthcare in conflict situations to protect vulnerable populations can maintain gains in even the most difficult of circumstances, and that conflict does not represent a substantial barrier to elimination goals.

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Filling the Gap 115 Years after Ronald Ross: The Distribution of the Anopheles coluzzii and Anopheles gambiae s.s from Freetown and Monrovia, West Africa

Cited by 12 publications

References 19 publications

Low prevalence of Plasmodium and absence of malaria transmission in Conakry, Guinea: prospects for elimination

Low prevalence of Plasmodium and absence of malaria transmission in Conakry, Guinea: prospects for elimination

Assessing the presence of Wuchereria bancrofti in vector and human populations from urban communities in Conakry, Guinea

A geostatistical analysis of the association between armed conflicts and Plasmodium falciparum malaria in Africa, 1997–2010

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