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Search Results: 1 - 10 of 377 matches for " Basile Kamgang "
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Entomological profile of yellow fever epidemics in the Central African Republic, 2006–2010
Ngoagouni Carine,Kamgang Basile,Manirakiza Alexandre,Nangouma Auguste
Parasites & Vectors , 2012, DOI: 10.1186/1756-3305-5-175
Abstract: Background The causative agent of yellow fever is an arbovirus of the Flaviviridae family transmitted by infected Aedes mosquitoes, particularly in Africa. In the Central African Republic since 2006, cases have been notified in the provinces of Ombella-Mpoko, Ouham-Pende, Basse-Kotto, Haute-Kotto and in Bangui the capital. As the presence of a vector of yellow fever virus (YFV) represents a risk for spread of the disease, we undertook entomological investigations at these sites to identify potential vectors of YFV and their abundance. Findings Between 2006 and 2010, 5066 mosquitoes belonging to six genera and 43 species were identified. The 20 species of the Aedes genus identified included Ae. aegypti, the main vector of YFV in urban settings, and species found in tropical forests, such as Ae. africanus, Ae. simpsoni, Ae. luteocephalus, Ae. vittatus and Ae. opok. These species were not distributed uniformly in the various sites studied. Thus, the predominant Aedes species was Ae. aegypti in Bangui (90.7 %) and Basse-Kotto (42.2 %), Ae. africanus in Ombella-Mpoko (67.4 %) and Haute-Kotto (77.8 %) and Ae. vittatus in Ouham-Pende (62.2 %). Ae. albopictus was also found in Bangui. The distribution of these dominant species differed significantly according to study site (P < 0.0001). None of the pooled homogenates of Aedes mosquitoes analysed by polymerase chain reaction contained the YFV genome. Conclusion The results indicate a wide diversity of vector species for YFV in the Central African Republic. The establishment of surveillance and vector control programs should take into account the ecological specificity of each species.
Genetic Structure of the Tiger Mosquito, Aedes albopictus, in Cameroon (Central Africa)
Basile Kamgang,Cécile Brengues,Didier Fontenille,Flobert Njiokou,Frédéric Simard,Christophe Paupy
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0020257
Abstract: Aedes albopictus (Skuse, 1884) (Diptera: Culicidae), a mosquito native to Asia, has recently invaded all five continents. In Central Africa it was first reported in the early 2000s, and has since been implicated in the emergence of arboviruses such as dengue and chikungunya in this region. Recent genetic studies of invasive species have shown that multiple introductions are a key factor for successful expansion in new areas. As a result, phenotypic characters such as vector competence and insecticide susceptibility may vary within invasive pest species, potentially affecting vector efficiency and pest management. Here we assessed the genetic variability and population genetics of Ae. albopictus isolates in Cameroon (Central Africa), thereby deducing their likely geographic origin.
Notes on the blood-feeding behavior of Aedes albopictus (Diptera: Culicidae) in Cameroon
Basile Kamgang, Elysée Nchoutpouen, Frédéric Simard, Christophe Paupy
Parasites & Vectors , 2012, DOI: 10.1186/1756-3305-5-57
Abstract: Analysis of ingested blood in outdoor-resting females showed that Ae. albopictus preferentially fed on humans rather than on available domestic animals (95% of the blood meals contained human blood). Our results further showed that Ae. albopictus is a day-biting species in Yaoundé, with a main peak of activity in the late afternoon.This is the first report on the feeding behavior of Ae. albopictus in Central Africa. The species is highly aggressive to humans and might therefore be involved in human-human virus transmission in this setting.Aedes albopictus (Skuse, 1894) is an invasive mosquito species that originated in Asian forests [1] and expanded to temperate and tropical regions of America, Africa and Europe, mainly during the last three decades [2]. Aedes albopictus is widely considered as a secondary vector of human arboviruses such as dengue virus (DENV), because it is thought to preferentially feed on animals rather than humans, contrary to the highly anthropophilic Aedes aegypti (L., 1762) [3]. Yet, Ae. albopictus has been incriminated as a primary vector in recent chikungunya virus (CHIKV) epidemics in the Indian Ocean, Central Africa and Europe [4-6], suggesting sustained man-vector contact in these settings. In Cameroon (Central Africa), Ae. albopictus was first recorded in the early 2000s [7] and rapidly spread throughout the south of the country [8]. In Cameroonian urban centers such as Yaoundé, the species now pullulates [9] and is gradually replacing autochthonous Ae. aegypti populations. Concomitant with the spread of Ae. albopictus in Central Africa, an increase in DENV and CHIKV outbreaks was reported in a number of countries, including Cameroon [10], Gabon [5,11] and the Republic of Congo [12]. Indeed, Cameroonian Ae. albopictus populations were shown to be orally susceptible to DEN-2 virus and CHIKV infection [5], and the species was recognized as the main vector of both viruses in 2007 in Libreville, Gabon [5,11].Although Ae. albopictus prefere
Temporal Patterns of Abundance of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) and Mitochondrial DNA Analysis of Ae. albopictus in the Central African Republic
Basile Kamgang,Carine Ngoagouni,Alexandre Manirakiza,Emmanuel Nakouné,Christophe Paupy,Mirdad Kazanji
PLOS Neglected Tropical Diseases , 2013, DOI: 10.1371/journal.pntd.0002590
Abstract: The invasive Asian tiger mosquito Aedes albopictus (Diptera: Culicidae) was first reported in central Africa in 2000, in Cameroon, with the indigenous mosquito species Ae. aegypti (Diptera: Culicidae). Today, this invasive species is present in almost all countries of the region, including the Central African Republic (CAR), where it was first recorded in 2009. As invasive species of mosquitoes can affect the distribution of native species, resulting in new patterns of vectors and concomitant risk for disease, we undertook a comparative study early and late in the wet season in the capital and the main cities of CAR to document infestation and the ecological preferences of the two species. In addition, we determined the probable geographical origin of invasive populations of Ae. albopictus with two mitochondrial DNA genes, COI and ND5. Analysis revealed that Ae. aegypti was more abundant earlier in the wet season and Ae. albopictus in the late wet season. Used tyres were the most heavily colonized productive larval habitats for both species in both seasons. The invasive species Ae. albopictus predominated over the resident species at all sites in which the two species were sympatric. Mitochondrial DNA analysis revealed broad low genetic diversity, confirming recent introduction of Ae. albopictus in CAR. Phylogeographical analysis based on COI polymorphism indicated that the Ae. albopictus haplotype in the CAR population segregated into two lineages, suggesting multiple sources of Ae. albopictus. These data may have important implications for vector control strategies in central Africa.
Insecticide susceptibility of Aedes aegypti and Aedes albopictus in Central Africa
Basile Kamgang, Sébastien Marcombe, Fabrice Chandre, Elysée Nchoutpouen, Philippe Nwane, Josiane Etang, Vincent Corbel, Christophe Paupy
Parasites & Vectors , 2011, DOI: 10.1186/1756-3305-4-79
Abstract: Aedes aegypti and Ae. albopictus were sampled in six urban localities of Cameroon (Garoua, Bertoua, Yaoundé, Bafia, Buea) and Gabon (Libreville). Larval bioassays, carried out to determine the lethal concentrations (LC50 and LC95) and resistance ratios (RR50 and RR95) suggested that both vector species were susceptible to Bti (Bacillus thuringiensis var israeliensis) and temephos. Bioassays were also performed on adults using WHO diagnostic test kits to assess phenotypic resistance to deltamethrin, DDT, fenitrothion and propoxur. These experiments showed that one population of Ae. aegypti (Libreville) and two populations of Ae. albopictus (Buea and Yaoundé) were resistant to DDT (mortality 36% to 71%). Resistance to deltamethrin was also suspected in Ae. albopictus from Yaoundé (83% mortality). All other field mosquito populations were susceptible to deltamethrin, DDT, fenitrothion and propoxur. No increase in the knockdown times (Kdt50 and Kdt95) was noted in the Yaoundé resistant population compared to other Ae. albopictus populations, suggesting the possible involvement of metabolic resistance to deltamethrin and DDT.In view of the recent increase in dengue and chikungunya outbreaks in Central Africa, these unique comparative data on the insecticide susceptibility of Ae. aegypti and Ae. albopictus could help public health services to design more effective vector control measures.Dengue virus (DENV, Flaviviridae, Flavivirus) and chikungunya virus (CHIKV, Togaviridae, Alphavirus) are mosquito-borne viruses of medical concern in most tropical regions. With about 50-100 million reported cases annually, including 500 000 severe cases of dengue haemorrhagic fever (DHF) or dengue shock syndrome (DSS), DENV is the most prevalent mosquito-borne human virus worldwide [1]. In West and Central Africa, where DENV epidemics remained limited until 5 years ago, the number of outbreaks or case reports has increased significantly in several areas, including Cameroon in 2006 [2,3],
Evidence of Dengue Virus Transmission and Factors Associated with the Presence of Anti-Dengue Virus Antibodies in Humans in Three Major Towns in Cameroon
Maurice Demanou ,Régis Pouillot,Marc Grandadam,Pascal Boisier,Basile Kamgang,Jean Pierre Hervé,Christophe Rogier,Dominique Rousset,Christophe Paupy
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0002950
Abstract: Background Dengue is not well documented in Africa. In Cameroon, data are scarce, but dengue infection has been confirmed in humans. We conducted a study to document risk factors associated with anti-dengue virus Immunoglobulin G seropositivity in humans in three major towns in Cameroon. Methodology/Principal Findings A cross sectional survey was conducted in Douala, Garoua and Yaounde, using a random cluster sampling design. Participants underwent a standardized interview and were blood sampled. Environmental and housing characteristics were recorded. Randomized houses were prospected to record all water containers, and immature stages of Aedes mosquitoes were collected. Sera were screened for anti-dengue virus IgG and IgM antibodies. Risk factors of seropositivity were tested using logistic regression methods with random effects. Anti-dengue IgG were found from 61.4% of sera in Douala (n = 699), 24.2% in Garoua (n = 728) and 9.8% in Yaounde (n = 603). IgM were found from 0.3% of Douala samples, 0.1% of Garoua samples and 0.0% of Yaounde samples. Seroneutralization on randomly selected IgG positive sera showed that 72% (n = 100) in Douala, 80% (n = 94) in Garoua and 77% (n = 66) in Yaounde had antibodies specific for dengue virus serotype 2 (DENV-2). Age, temporary house walls materials, having water-storage containers, old tires or toilets in the yard, having no TV, having no air conditioning and having travelled at least once outside the city were independently associated with anti-dengue IgG positivity in Douala. Age, having uncovered water containers, having no TV, not being born in Garoua and not breeding pigs were significant risk factors in Garoua. Recent history of malaria, having banana trees and stagnant water in the yard were independent risk factors in Yaounde. Conclusion/Significance In this survey, most identified risk factors of dengue were related to housing conditions. Poverty and underdevelopment are central to the dengue epidemiology in Cameroon.
Eliciting Guilty Feelings: A Preliminary Study Differentiating Deontological and Altruistic Guilt  [PDF]
Barbara Basile, Francesco Mancini
Psychology (PSYCH) , 2011, DOI: 10.4236/psych.2011.22016
Abstract: Guilt has been identified as both an intrapsychic and an interpersonal emotion. The current study presents evidence of the existence of two senses of guilt, deontological and altruistic guilt, induced through different experimental paradigms. Deontological guilt evolves from having slighted moral authority or norms, while altruistic guilt arises from selfish behavior and the distress of others. We hypothesize that specific stimuli would evoke, separately, deontological guilt and altruistic/interpersonal guilt feelings. Two different procedures were used to test our hypothesis, adding two emotions as control conditions (i.e. anger and sadness). Results clearly indicate that two different guilt emotions can be evoked separately, by appropriate stimulation. Findings and possible clinical implications are discussed.
Regolith Geochemistry and Mineralogy of the Mbalam Itabirite-Hosted Iron Ore District, South Eastern Cameroon  [PDF]
M. T. Nforba, V. Kamgang Kabeyene, C. E. Suh
Open Journal of Geology (OJG) , 2011, DOI: 10.4236/ojg.2011.12003
Abstract: Mbalam is a major emerging iron ore district in Cameroon. The regolith over the Mbalam itabirite, consists of relict, erosion and depositional units. Itabirite rock fabric is preserved in the relict regolith, the erosion unit is marked by erosion of the carapace cap regolith, with the depositional unit dominated by canga (loose fragments of hematite and/or itabirite cemented by goethite) or loose scree. Fe concentration increases from average of 46.18 wt% in the depositional soil material to as much as 79.08 wt% in the relict regolith regime with variation due to supergene weathering. Fe is the least mobile of the major elements, and the Fe oxides become significant phases and control the distributions of many elements. Absorption of P by iron oxides or oxyhydroxides appears to be the major mechanism of P retention in the different regolith environment. Au dispersion in the weathering profile occurs by two possible mechanisms (mechanical and hydromorphic) and it distribution is sporadic. Zr maintains a positive correlation with Al and Ti indicating extensive chemical weathering in the source area and resulting in a relative concentration of those residual elements. The weathered material show relatively high ΣREE; this is due to upward remobilisation from the lower primary itabirite, and the downward leaching of the upper mineralisation horizons by the descending epigenetic solutions.
Modeling the Dynamics of Malaria Transmission with Bed Net Protection Perspective  [PDF]
Jean Claude Kamgang, Vivient Corneille Kamla, Stéphane Yanick Tchoumi
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.519298
Abstract: We propose and analyze an epidemiological model to evaluate the effectiveness of bed nets as a prophylactic measure in malaria-endemic areas. The main purpose in this work is the modeling of the aggressiveness of anopheles mosquitoes relative to the way humans use to protect themselves against bites of mosquitoes. This model is a system of several differential equations: the number of equations depends on the particular assumptions of the model. We compute the basic reproduction number\"\", and show that if\"\", the disease free equilibrium (DFE) is globally asymptotically stable on the non-negative orthant. If\"\", the system admits a unique endemic equilibrium (EE) that is globally and asymptotically stable. Numerical simulations are presented corresponding to scenarios typical of malaria-endemic areas, based on data collected in the literature. Finally, we discuss the relative effectiveness of different kinds of bed nets.
Revolta e cidadania na Corte regencial
Basile, Marcello;
Tempo , 2007, DOI: 10.1590/S1413-77042007000100003
Abstract: this article analyzes the rebellion that took place in the s?o pedro de alcantara theatre, rio de janeiro, in september 1831. that was a political uprising conducted by the liberais exaltados in which several different social layers also took part. the movement was similar to others that took place in the beginning of the regency period. it is also understood as one of a set of axles for informal citizenship development and an incipient sense of nacionality. both were forged from below in an emergent political action public space.
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