Evaluation of aquifer hydraulic conductivity and transmissivity of Ezza/Ikwo area, Southeastern Nigeria, using pumping test and surficial resistivity techniques.

Aquifer hydraulic parameters including hydraulic conductivity and transmissivity play a very important role in the assessment and management of groundwater. Conventionally, these parameters are best estimated employing pump test, which is usually expensive and time-consuming. The use of surficial electrical resistivity data integrated with few available pumping test data provides a cost-effective and efficient alternative. A total of thirty-five (35) vertical electrical soundings with a maximum half-current electrode spacing of 150 m using the Schlumberger array were used in this study. Five (5) of these soundings were parametric soundings carried out in the vicinity of monitoring wells for correlation and comparative purposes. The empirical relationships between the hydraulic parameters derived from the pump test data and the aquifer resistivity data were established for the Ebonyi and Abakaliki Formations, respectively, and, in turn, used to estimate aquifer hydraulic parameters in areas away from wells. Aquifer hydraulic conductivity estimated across the study area varies from 0.49 to 1.5735 m/day with a mean value of 0.9205 m/day for the Ebonyi Formation, while the Abakaliki Formation has hydraulic conductivity values that vary from 0.0775 to 1.3023 m/day, with a mean value of 0.2883 m/day. The transmissivity values estimated across the study area range between 0.29 and 57.27 m2/day with a mean value of 6.59 m2/day. Transmissivity values obtained were interpreted with Krásný's transmissivity classification, and this delineated the study area into three groundwater potential zones: very low, low, and intermediate zones. The study shows that the areas underlain by the Ebonyi Formation have a higher groundwater potential than those underlain by the Abakaliki Formation. These findings are supported by the geology of the area, which revealed that the Abakaliki Formation is dominated by shales with very low permeability, while the Ebonyi Formation consists of shales with alternations of sand/sandstones, which statistical analysis of the different model equations used in estimating the hydraulic parameters of the study area revealed that the new model empirical equations proposed and used in the present study proved to be the best alternatives to pumping test data.

Trematode infections of the freshwater snail Biomphalaria pfeifferi from a south-east Nigerian community with emphasis on cercariae of Schistosoma.

Knowledge of trematode infections in Biomphalaria pfeifferi from south-eastern Nigeria is scarce, due to the absence of Schistosoma mansoni infection in the region. Therefore, the present study sought to describe trematode infections in B. pfeifferi from the River Uzuru in the Nigeria Cement Factory area, Nkalagu, south-eastern Nigeria. Four hundred and sixty snails were checked for trematode infections, and mice were exposed to the Schistosoma cercariae shed from the snails. Adult worms were harvested from the mice 13 weeks post-infection, while sections of the liver and spleen were examined. Primary school children living in the area were screened for S. mansoni infection and assessed for activities involving water contact. The edges of the river were also searched for burrows and rodents. The five cercaria morphotypes found were armatae xiphidiocercariae, echinocercariae, Schistosoma cercariae, cystophorous cercariae and cercariaeum cercariae. The overall prevalence and mean intensity of trematode infections were 39.78% and 195.46, with the prevalence and mean intensity of most cercaria morphotypes higher in the hot-dry than in the cool-dry season. The infected mice showed S. mansoni-like characteristics but the stool samples of the schoolchildren were negative for S. mansoni eggs. Water-contact activities in the River Uzuru were minimal. Burrows were seen at the river edges but no Schistosoma eggs were recovered from captured rats. This is the first report of Schistosoma cercariae and other cercaria morphotypes in B. pfeifferi from south-eastern Nigeria. Additional molecular investigations are needed to identify correctly these Schistosoma cercariae, due to their public health implication.

Parasitological and histopathological effects of immunosuppression in guinea-pigs (Cavia porcellus) experimentally infected with Schistosoma haematobium.

The parasitological and histopathological effects of immunosuppression in guinea-pigs (Cavia porcellus) experimentally infected with Schistosoma haematobium were studied. A total of 16 guinea-pigs were divided into four groups (four per group): non-immunosuppressed, non-infected group (NN); immunosuppressed, non-infected group (IN); immunosuppressed, infected group (II); non-immunosuppressed, infected group (NI). The IN and II groups were immunosuppressed with 5 mg/kg prednisolone while the II and NI animals were infected with 200-300 S. haematobium cercariae. Excretion of eggs in urine/faeces, worm burden and histopathology of some vital organs of the guinea-pigs were studied. Eggs of S. haematobium were observed in the urine of the NI and II groups from 9 weeks post-infection and in faeces from 10 and 13 weeks post-infection for the NI and II groups, respectively. However, II animals excreted more viable eggs in urine and faeces than those of the NI group. Worm recovery at 14 weeks post-infection showed that NI and II guinea-pigs had more female worms than male worms and a greater proportion of worm recovery for NI animals was of immature worms. Significant differences (P < 0.05) existed between female, male and immature worm burden of the two groups but not in their total worm burden (P>0.05). Histological changes, which were notably reactions to adult S. haematobium worms, were observed in the organs of the NI and II groups but these changes were seen more in the organs of the immunosuppressed, infected (II) than in the non-immunosuppressed, infected (NI) guinea-pigs. The results suggest that immunosuppression before infection increased worm survival and had a moderate effect on liver and bladder histology of S. haematobium infected guinea-pigs.