BackgroundHighland areas of Africa are mostly malaria hypoendemic, due to climate which is not appropriate for anophelines development and their reproductive fitness. In view of designing a malaria control strategy in Western Cameroon highlands, baseline data on anopheline species bionomics were collected.MethodsLongitudinal entomological surveys were conducted in three localities at different altitudinal levels. Mosquitoes were captured when landing on human volunteers and by pyrethrum spray catches. Sampled Anopheles were tested for the presence of Plasmodium circumsporozoite proteins and their blood meal origin with ELISA. Entomological parameters of malaria epidemiology were assessed using Mac Donald's formula.ResultsAnopheline species diversity and density decreased globally from lowland to highland. The most aggressive species along the altitudinal transect was Anopheles gambiae s.s. of S molecular form, followed in the lowland and on the plateau by An. funestus, but uphill by An. hancocki. An. gambiae and An. ziemanni exhibited similar seasonal biting patterns at the different levels, whereas different features were observed for An. funestus. Only indoor resting species could be captured uphill; it is therefore likely that endophilic behaviour is necessary for anophelines to climb above a certain threshold. Of the ten species collected along the transect, only An. gambiae and An. funestus were responsible for malaria transmission, with entomological inoculation rates (EIR) of 90.5, 62.8 and zero infective bites/human/year in the lowland, on the plateau and uphill respectively. The duration of gonotrophic cycle was consistently one day shorter for An. gambiae as compared to An. funestus at equal altitude. Altitudinal climate variations had no effect on the survivorship and the subsequent life expectancy of the adult stage of these malaria vectors, but most probably on aquatic stages. On the contrary increasing altitude significantly extended the duration of gonotrophic cycle and reduced: the EIR, their preference to human blood and consequently the malaria stability index.ConclusionMalaria epidemiological rooting in the outskirts of Western Cameroon highlands evolves with increasing altitude, gradually from stable to unstable settings. This suggests a potential risk of malaria epidemic in highlands, and the need for a continuous epidemiological surveillance.
La composition et la structure du zooplancton de deux lacs du complexe lacustre Ossa (Ossa et Mwembè), site protégé UNESCO situé dans une plaine inondable, ont fait l'objet d'une étude entre septembre 2009 et février 2010. 37 et 41 espèces de zooplancton ont été recensées respectivement dans les lacs Ossa et Mwembè. Les deux milieux, oligotrophes, sont soumis à l'influence du fleuve Sanaga qui leur apporte en temps de crue de nouvelles espèces. La présence de Mesocyclops leuckarti dans ces eaux amène à considérer l'existence de cette espèce sur le continent africain. La densité des organismes zooplanctoniques augmente entre septembre et novembre et chute rapidement en décembre, ce qui s'accorde avec une succession saisonnière des communautés. Les paramètres physico-chimiques, qui permettent de caractériser les plans d'eau comme oligotrophes, ne diffèrent pas significativement entre les deux milieux, ni avec la profondeur de prélèvement, ce qui justifie la valeur de 82 % trouvée pour l'indice de similitude de SÖRENSEN. Quant à la structure des populations de zooplancton, elle est influencée principalement par la saison et par la profondeur de prélèvement, le mois et la station n'ayant pas d'influence sur cette distribution.
The composition and the structure of the zooplankton of two lakes of the Ossa lake complex (Ossa and Mwembe) were studied between September 2009 and February 2010. 37 and 41 species of zooplankton were inventoried respectively in the lakes Ossa and Mwembe. The two environments are oligotrophic but subjected to the influence of the river Sanaga that brings them in swelling time new species. Mesocyclops leuckarti found in these lakes suggests the presence of this species on the African continent. The density of the zooplankton organisms increases between September and November and falls quickly in December, in accordance with a seasonal impact on communities. The physicochemical parameters do not differ significantly between the two environments and with the sampling depth. This justifies the value of 82 % obtained with the SÖRENSEN index. The structure of the populations of zooplankton is principally influenced by the season. The sampling depth, the month and the station do not influence this distribution
Market gardening, in the swampy lowlands of the Dschangcity, plays an important role in terms of providing employment, and supply the city with fresh products. However, waterborne diseases, which occur in the city, are both attributed to the bad quality of drinking water and sanitation practices. This work aims to characterize watering waters of crop, to assess the health risks associated with the use of these waters. Water from eleven streams and five wells used to irrigate crops were sampled and analyzed once a week for a month. Analyses focused on physico-chemical parameters (temperature, suspended matter, pH, electrical conductivity, COD, BOD5, NO-3 , Al, Fe, Cu, Ni), parasitological (helminthes eggs) and bacteriological (total coliforms, fecal coliforms, fecal streptococcus). The results show that, the physico-chemical quality of well waters generally approaches the WHO standards of crop watering water. The physico-chemical of streams waters and bacteriological quality of wells and streams waters are bad, according to WHO guide. These bad quality waters could contaminate crops, some of which are eaten raw, which is surely a cause of the outbreak of waterborne diseases in the city. The waters from streams are more affected. The pretreatment of the water before use for irrigation of vegetables is highly recommended
In Dschang City, as in Cameroon's secondary cities, waterborne diseases are increasing. Stream waters are used for watering crops. The purpose of this work was to evaluate the health risk of irrigating vegetables (lettuce, carrots and eggplants) in the Dschang lowlands. Escherichia coli, Entamoeba spp. cysts, Ascaris lumbricoides eggs, major elements and trace elements were looked for in the vegetables collected from 18 plots. The results show that market gardening is practised mainly in the lowlands that receive all the untreated waste from the city. Stream waters used for spraying crops contains approximately 4.2 Log (CFU of E. coli) in 100 ml, regardless of the season. Eggs and parasite cysts were detected. The vegetables analysed have a low and acceptable chemical content. Regardless of the season, E. coli found on crops was far above the standards (103 UFCg−1 DM), 5–58 times above. Eggs and parasite cysts were also detected. These parasites and bacteria represent a real risk to consumers and would be partly responsible for the upsurge of waterborne diseases in Dschang City. © 2019 John Wiley & Sons, Ltd.
Ce travail a bénéficié du soutien de la Fondation Internationale pour la Sciences à travers les bourses W5005-1, W5005-2, W4006-1 et W4006-2 à qui les auteurs adressent un grand merci. RESUME Le risque lié à l'utilisation des eaux usées en agriculture dépend de la durée de survie des microorganismes pathogènes sur les cultures. Ce travail a pour objectif de suivre in situ la durée de survie de E. coli, des oeufs et des kystes de parasites sur la carotte, l'aubergine et la laitue. Les cultures ont reçu de l'eau polluée à la maturité, et elles ont été échantillonnées et analysées pendant une semaine. En saison pluvieuse, une chute de 73%, 83%, 97% de E. coli a été obtenu sept jours après sur la laitue, la carotte et l'aubergine respectivement. En saison sèche, cette baisse a été respectivement de 97%, 95% et 99%. Malgré le fort pourcentage de chute, excepté l'aubergine, le taux de E. coli est resté supérieur aux seuils sanitaires (10 3 E. coli/g). Le pourcentage d'échantillon positif en oeufs et en kyste, varie entre 0 et 25% sur la laitue et la carotte, et entre 0 et 8% sur l'aubergine. Ce qui est un danger pour les consommateurs de ces légumes qui se consomment cru. Afin d'éviter ou de réduire le risque lié à cette pratique, les maraîchers devrait arrêter l'arrosage des cultures au moins une semaine avant la récolte.
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