Données préliminaires sur le paludisme humain en zones rurale et sémi-urbaine du département du Nkam (Littoral-Cameroun)

Objectif : Cette étude évalue les connaissances et les pratiques des populations sur le traitement et la prévention du paludisme et détermine la transmission du paludisme en zones rurale et sémi-urbaine du département du Nkam.Méthodologie et résultats : Un questionnaire a été administré aux populations de Bodiman et Yabassi, localités rurale et semi-urbaine, en mai 2015. Les captures de moustiques sur volontaires ont été effectuées à l’intérieur de 7 habitations par site, de juillet à septembre 2015, au rythme de 2 nuits consécutives par mois. L’infectivité des vecteurs a été déterminée par le test ELISA-CSP. 73,17% (n= 513) d’interviewés connaissaient les vecteurs du paludisme alors que seulement 9,46% (n= 63) connaissaient le germe. La moustiquaire était l’outil de prévention le plus utilisé à Bodiman (100%) et Yabassi (38,46%). Le montant mensuellement dépensé par les ménages contre le paludisme s’élevait à 2,31€ et 16,01€ en moyenne, respectivement à Bodiman et Yabassi. La majorité d’interviewés à Bodiman (n= 98 ; %=49,49) et Yabassi (n=198 ; %= 42,31) se rendaient à l’hôpital en cas de paludisme. En outre, 37 833 moustiques dont 35 961 à Bodiman et 1 872 à Yabassi ont été capturés. An. gambiae (81,82%) et An. coluzzii (18,18%) étaient les membres du complexe Gambiae identifiés ; An. coluzzii (59,26%) étant le plus représenté à Yabassi, et An. gambiae (81,82%) à Bodiman. Les indices sporozoïtiques d’An. gambiae s.l. étaient de 0% à Bodiman et de 2,15% à Yabassi.Conclusion et application : L’association de la lutte antilarvaire aux méthodes existantes de lutte antivectorielle par les pouvoirs publics contribuerait à baisser les fortes densités agressives observées à Bodiman de manière à réduire le budget alloué au paludisme par les ménages.Mots-clés : Connaissances, pratiques, transmission, paludisme, Bodiman, Yabassi

The In Vitro Effects of Aqueous and Ethanolic Extracts of the Leaves of Ageratum conyzoides (Asteraceae) on Three Life Cycle Stages of the Parasitic Nematode Heligmosomoides bakeri (Nematoda: Heligmosomatidae)

A comparative in vitro study was carried out to determine the ovicidal and larvicidal activity of aqueous and ethanolic extracts of Ageratum conyzoides (Asteraceae) leaves on the eggs (unembryonated and embryonated), first and second larval stages of Heligmosomoides bakeri. Four different concentrations (0.625, 1.25, 2.5, and 3.75 mg·mL−1) of both aqueous and ethanolic extracts were tested. Distilled water and 5% tween were used as negative controls in the bioassay. In fact, they did not affect development of eggs, hatching, and larval survival. The extract activities were dose dependent. The ethanolic extract was more potent against embryonation (39.6 ± 2.9%) than the aqueous extract (53.3 ± 10.9%) at the highest concentration (3.75 mg·ml−1). Both types of extracts killed larvae. Mebendazole proved more lethal (EC50 of 0.745 and 0.323 mg·mL−1, resp., for L1 and L2 larvae). The aqueous extracts were the least lethal (EC50 of 4.76 and 2.29 mg·mL−1, resp., for L1 and L2 larvae). The ethanolic extracts showed intermediate activity (EC50 of 1.323 and 1.511 mg·mL−1, resp., for L1 and L2 larvae). It is concluded that the ovicidal and larvicidal properties of aqueous and ethanolic extracts of Ageratum conyzoides leaves are demonstrated in this work

Climatic and cultural changes in the west Congo Basin forests over the past 5000 years

Central Africa includes the world's second largest rainforest block. The ecology of the region remains poorly understood, as does its vegetation and archaeological history. However, over the past 20 years, multidisciplinary scientific programmes have enhanced knowledge of old human presence and palaeoenvironments in the forestry block of Central Africa. This first regional synthesis documents significant cultural changes over the past five millennia and describes how they are linked to climate. It is now well documented that climatic conditions in the African tropics underwent significant changes throughout this period and here we demonstrate that corresponding shifts in human demography have had a strong influence on the forests. The most influential event was the decline of the strong African monsoon in the Late Holocene, resulting in serious disturbance of the forest block around 3500 BP. During the same period, populations from the north settled in the forest zone; they mastered new technologies such as pottery and fabrication of polished stone tools, and seem to have practised agriculture. The opening up of forests from 2500 BP favoured the arrival of metallurgist populations that impacted the forest. During this long period (2500–1400 BP), a remarkable increase of archaeological sites is an indication of a demographic explosion of metallurgist populations. Paradoxically, we have found evidence of pearl millet (Pennisetum glaucum) cultivation in the forest around 2200 BP, implying a more arid context. While Early Iron Age sites (prior to 1400 BP) and recent pre-colonial sites (two to eight centuries BP) are abundant, the period between 1600 and 1000 BP is characterized by a sharp decrease in human settlements, with a population crash between 1300 and 1000 BP over a large part of Central Africa. It is only in the eleventh century that new populations of metallurgists settled into the forest block. In this paper, we analyse the spatial and temporal distribution of 328 archaeological sites that have been reliably radiocarbon dated. The results allow us to piece together changes in the relationships between human populations and the environments in which they lived. On this basis, we discuss interactions between humans, climate and vegetation during the past five millennia and the implications of the absence of people from the landscape over three centuries. We go on to discuss modern vegetation patterns and African forest conservation in the light of these events.Peer reviewe

Reconstructing Asian faunal introductions to eastern Africa from multi-proxy biomolecular and archaeological datasets

Human-mediated biological exchange has had global social and ecological impacts. In subS-aharan Africa, several domestic and commensal animals were introduced from Asia in the pre-modern period; however, the timing and nature of these introductions remain contentious. One model supports introduction to the eastern African coast after the mid-first millennium CE, while another posits introduction dating back to 3000 BCE. These distinct scenarios have implications for understanding the emergence of long-distance maritime connectivity, and the ecological and economic impacts of introduced species. Resolution of this longstanding debate requires new efforts, given the lack of well-dated fauna from high-precision excavations, and ambiguous osteomorphological identifications. We analysed faunal remains from 22 eastern African sites spanning a wide geographic and chronological range, and applied biomolecular techniques to confirm identifications of two Asian taxa: domestic chicken (Gallus gallus) and black rat (Rattus rattus). Our approach included ancient DNA (aDNA) analysis aided by BLAST-based bioinformatics, Zooarchaeology by Mass Spectrometry (ZooMS) collagen fingerprinting, and direct AMS (accelerator mass spectrometry) radiocarbon dating. Our results support a late, mid-first millennium CE introduction of these species. We discuss the implications of our findings for models of biological exchange, and emphasize the applicability of our approach to tropical areas with poor bone preservation