Dynamique des formes de résistance des amibes entéropathogènes en milieu aquatique pollué (Yaoundé, Cameroun)

Abstract

Dynamics of resistant entero-pathogenic amoeba in a polluted aquatic habitat (Yaoundé, Cameroon). A study aimed at assessing the infectious forms of entero-pathogenic amoeba and the impact of physico-chemical variables on their distribution in waste and surface water of the city of Yaoundé was carried out from December 2012 to May 2013. The bioecological assessment of the amoeba load was carried out in 2015-2016. Monthly sampling was carried out on six points, that is two on the Messa residential effluent (before and after the purification station) and four sampling points on the Mingoa river basin. The physico-chemical analyses, carried out by volumetry and spectrophotometry, revealed that the waste water and surface water were lowly acidic (6.97 ± 0.3 UC), lowly oxygenated (22.83 ± 17.15 %), highly mineralized (408.00 ± 292.07 μS/ cm) and presented a high DBO5 value (83.86 ± 69.28 mg/ L O2). The values of this physico-chemistry reveal a high domestic pollution at the effluent and an input of organic matter at the Mingoa stream, due to antropogenic activity. The observation of the cysts was done with an Olympus model CK2 microscope at objective 40X, after concentration of the samples according to the techniques of direct observation and Merthiolate-Iode-Formol. The analyses proof the spatial and seasonal presence of cysts (454.60 ± 625.57 cysts/ L) of enteropathogens such as Entamoeba coli, Entamoeba histolytica, Entamoeba hartmanni, Endolimax nana and Pseudolimax butschlii. High correlations were observed between some physico-chimical and biological parameters. There is thus a faecal pollution of waters and human populations are exposed to sanitary risks, particularly amoebioses.