The study was to know the water enterobacteria likely to harm the health of people in the group of Irhambi. Bacteriological analyzes of water sources, streams and rivers have been made. The results of the study show that the water sources, streams and rivers run through inhabited areas and bacteriological analysis shows that the water is contaminated, while the population obtains this water for drinking Gram Negative Bacilli and Unidentified (BGNNI), Kligler and Escherichia coli are present in some sources, streams and rivers of the search sites in the group of Irhambi. Thus, the Arab latrine pit is in the vicinity of sources of water. Animal faeces, dung and waste (rest of the kitchen, crop tops, etc.), used as fertilizer by farmers are at the base of groundwater contamination in runoff and infiltration of water rain hence the pollution of the water. The population and the landscape assainisse the environment of water points, and respects the minium distance of 25m between wells and latrines and the development partners keep telling support the strengthening of the remediation work at the households and financially support activities against pollution of water in the grouping. That governmental authorities, by encouraging health education awareness campaigns on the media and make continuous monitoring of water consumption in said group.

An ecological study of the aquatic mollusk Pila ovata has been realized in the aquatic ecosystems of Katana region, south Kivu, East of the Democratic Republic of Congo, which shelters this species. Ten aquatic- ecosystems have been prospected in this region according to the current speed of water, the bottom's nature, the pH, the temperature, the depth, the aquatic vegetation, the altitude and the shade degree. Here, it's about the study of favorable ecological conditions to this species in the aquatic ecosystems of the Katana region. For ending at reliable results, the sampling of mollusks has been practiced using the standardized unity of time method. The harvesting of mollusks has been done generally with the help of cloudy water trickle with small stitch of 2 mm attached on an iron bar having a circular opening of 50cm of diameter fits with a lumber handle of 1.5m. The harvesting of mollusks has been done by manual picking, and then put back in their nature biotope after counting. The favorable ecological conditions which prevail to the proliferation and to the survival of the mollusk Pila ovata are respectively: a minimum lightning (minimum plant cover), an abundant died aquatic vegetation, a minimum current, a sandy bottom or muddy on the one hand and a moderate temperature (≥ 160C) on the other hand. A highly significant difference has been observed between aquatic ecosystems of the region all the more that the mollusks number differs between sites. The knowledge of the ecology of this mollusk is an asset for the study of the fight against the intermediate host mollusks of Schistosomiasis.

Monthly and seasonal fluctuations in densities of land snails were recorded in four different sites (forest, fallow, cultivated area and wetland) in Katana region during the period of January to December 2013. The aim of this survey is to study the population dynamics of the land snails of the Katana region considering some geo-physical factors (rainfall, relative humidity and temperature) in different habitats. The study revealed the occurrence of 31 species of land snails belonging to 9 families of class Gasteropoda. The land snail species and their total catch were: Limicolaria laeta medjensis (225 specimens), Limicolaria distincta (195 specimens), Ataxon faradjense (159 specimens), Achatina achatina (147 specimens), Lehmannia valentiana (118 specimens), Achatina tincta (108 specimens), Curvella bathytoma (98 specimens), Trichotoxon pardus (78 specimens), Trichotoxon ruwenzoriense (75 specimens), Burtoa nilotica emini (72 specimens), Nothapalus paucispira xanthophaes (69 specimens), Trichotoxon maculatum perforatum (68 specimens) ,Pachnodus rutshuruensis (66 specimens), Gymnarion aloysii-sabaudiae (65 specimens), Mesafricarion putzeysi (64 specimens), Cerastus bequaerti (60 specimens), Gullela pupa ituriensis (58 specimens), Helixarion insularis (58 specimens), Bukobia cockerelli (56 specimens), Mesafricarion maculifer pilsbry (56 specimens), Perideriopsis fallsensis (56 specimens), Achatina fulica (54 specimens), Burtoa nilotica obliqua (52 specimens), Pleuroprocta silvatica (52 specimens), Pseudoglessula walikalensis (35 specimens), Achatina osborni(31 specimens), Loevicaulis schnitzleri (17 specimens), Subulinuscus ruwenzorensis (6 specimens), Homorus amputatus (4 specimens) , Theba pisana (4 specimens) and Arion rufus (3 specimens) in a descending order. The densities of the recorded land snails varied seasonally and the general seasonal peak was recorded during rainy while the lowest density observed during dry. Ecological factors which may influence the distribution or variation of the recorded land snails were also determined (temperature, relative humidity and rainfall). We remarked that the rainfall and the relative humidity were the two main ecological factors which influence the distribution or variation of the land snails in Katana region.

We investigated land snail fauna of Katana region, along the Lake Kivu and the Kahuzi-Biega National Park in Democratic Republic of Congo, using a combination of direct search and leaf litter sieving techniques. Four plots, in different habitats (Forest, wetland, cultivated area and fallow) were studied, covering low altitude (1400 - 1590 m), middle altitude (1600 - 1790 m) and high altitude (1800 - 2000 m). A total of 31 species and 2209 individual land snails belonging to 9 molluscan families and 23 genera were collected from all habitats. Species richness was ranged from 25 to 10 at different habitats and different altitudes. The wetland has high species richness (25) and the fallow has low species richness (10). Achatina achatina and Achatina fulica (Achatinidae) were recorded in all the habitats in the region (constant species), where Arion rufus (Arionidae), Homorus amputatus (Achatinidae) and Subulinuscus ruwenzorensis (Achatinidae) are found in one habitat (25 %) and are uncommon in Katana region (accidental species).The land snail species inventories will increase our knowledge of the molluscan fauna of the Katana region and assist in conservation management.