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Surveillance of the rabies-related lyssavirus, Mokola, in small non-volant mammals in South Africa and Mozambique
Published 2020Subjects: “…Animal reservoirs…”
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Evaluation of macro-invertebrates as bio-indicators of water quality and the assessment of the impact of the Klein Plaas dam on the Eerste River by Bredenhand, Emile
Published 2008Subjects: “…Reservoirs -- Environmental aspects -- South Africa…”
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Page will reload when a filter is selected or excluded.- Core analysis 2 results 2
- Heterogeneous reservoir 2 results 2
- In formation evaluation, the knowledge of porosity, permeability and fluids saturation are very important in the determination of the hydrocarbon in place. These petro physical properties are necessary to understand the nature of the reservoir and help for proper field development planning. This was aimed at determining the petro physical properties (pore volume, bulk volume, grain volume, permeability and fluid saturation) of a reservoir from core plugs. A total of ten core plugs were used in this work. Archimedes immersion method was used in the determination of the bulk volume. Liquid saturation method was used in the determination of the porosity. The Dean-Stark extraction method was used in the determination of fluid saturation. From the results obtained in the core analysis, the sandstone reservoir has an average porosity of 14.9±5.1%, very good permeability with an average value of 349.77±0.3 mD and a very large water saturation value of 82±0.4%. Consequently the hydrocarbon saturation is approximately 18%. This implies that the formation is not commercially viable to develop based on the hydrocarbon saturation. The study shows that experimental work is one of the valid tools for making informed decisions on the development of a field in the petroleum industry and highlights the importance of the basic petrophysical properties in reservoir management. 2 results 2
- In recent years, mortality due to leptospirosis in dogs has been of major concern in Southwestern Nigeria, but the prevalent serovars, pathology and pathogenesis have not been fully documented. The purpose of this study was to investigate the disease in the dog and reservoir hosts (cattle and wild rats), and its pathogenesis and pathology in a guinea pig model. Between 2003 and 2010, 44 fresh and 60 formalin-fixed kidneys of tentatively diagnosed cases of canine leptospirosis obtained at necropsy from the two Veterinary Teaching Hospitals in Southwestern Nigeria, fresh kidneys of 108 asymptomatic cattle and 105 wild rats obtained from abattoirs were investigated histopathologically and for the presence of leptospiral organisms using Ellinghausen-McCullough-Johnson–Harris (EMJH) medium, microscopic agglutination test with monoclonal antibodies (MAT-Ab), polymerase chain reaction (PCR), Warthin Starry silver stain (WSss), and immunohistochemistry (IH). The chronicity of the canine infection was determined by renal histopathology. Forty guinea pigs were experimentally infected with 107 Leptospira interrogans serovar icterohaemorrhagiae, while 20 served as controls. The clinico-pathological changes, pathogenesis and pathology were investigated by sacrificing at 12, 24, 72, 96, 120 and 168 hrs post infection (p.i.). Data was analysed using descriptive statistics. Interstitial nephritis and tubular nephrosis were the most common renal lesions in dogs (88.4% and 76.7%), cattle (77.8% and 74.1%) and wild rats (62.9% and 67.6%), respectively. Leptospires were isolated from 84.1% dogs, 82.4% cattle and 68.9% wild rats. Serovars identified in dogs, cattle and wild rats were icterohaemorrhagiae (29.7%, 9.7%, 33.0%), pomona (18.5%, 3.2%, 23.8%), bratislava (11.1%, 22.6%, 4.8%), hardjo (0%, 29.0%, 0%), canicola (14.8%, 6.5%, 14.3%) and grippotyphosa (14.8%, 9.7%, 14.3%); unidentified isolates were 11.1%, 19.4%, 9.5% respectively. The virulence gene (285bp) was confirmed in 31.3% of canine, 81.8% of wild rat and 61.9% of bovine kidneys. The IH and WSss showed that in acute canine infections, leptospires were present in different renal tissues, but were only found attached to tubular epithelium in the more chronic infections. The guinea pig infection was characterized by anorexia, dullness, slight icterus, normocytic normochromic anemia, and thrombocytopenia. The detection of leptospires in different organs was time-dependent, but persisted only in the kidney after 120 hrs p.i. In the pancreas, the organism could only be detected by cultural isolation and PCR (12-72 hrs p.i.). Renal tubular necrosis and interstitial nephritis, hepatic necrosis and cord dissociation, pulmonary haemorrhages, acute pancreatitis, adrenal vacuolar degeneration, non-suppurative myocarditis and encephalitis were observed. Immunohistochemistry showed leptospiral antigens in the brain from 12-24 hrs p.i. Icterohaemorrhagiae and pomona were the two most frequently isolated serovars from canine leptospirosis in Southwestern Nigeria. Structural localisation of the organism within the kidney may be an indication of the stage of infection. Renal lesions of leptospirosis were present in asymptomatic reservoir hosts. In addition to the well documented renal, hepatic, and pulmonary pathology, lesions of leptospirosis were also found in several other organs. 2 results 2
- Modelling 2 results 2
- Oil recovery 2 results 2
- Permeability anisotropy 2 results 2
- Reservoir hosts 2 results 2
- Reservoir performance 2 results 2
- Understanding the basic mechanisms that govern flow of hydrocarbon in any given reservoir situation is necessary in developing reliable methods of predicting behaviour in that reservoir. Most reservoirs in Agbada Formation of the Niger Delta Basin are anisotropic and therefore heterogeneous, which is a vital parameter in the efficient production of hydrocarbons. This work looked at the effect of permeability anisotropy (Kv/Kh) or heterogeneous distribution and its effects on reservoir performance using windows based IPM-MBAL petroleum engineering software. Results analysis revealed that anisotropy makes reservoir production modelling more realistic than the isotropic scenarios, and degree of heterogeneity improves oil recovery from the reservoir (Kv/Kh = 1, R.F = 49.31%; Kv/Kh = 0.1, R.F = 49.95%; Kv/Kh = 0.001, R.F = 50.60%; Kv/Kh = 0.0001, R.F = 51.24%). Reservoir heterogeneity should be included in reservoir modelling practices because it has a significant effect on hydrocarbon production. 2 results 2
- Agricultural land-use 1 results 1
- Dandaru reservoir 1 results 1
- Desilting 1 results 1
- ELISA 1 results 1
- Eleyele Reservoir 1 results 1
- Environmental pollution 1 results 1
- Environmental pollution of water, which is a source of cheap and affordable protein in the form of fish on which the population depends on, is of great concern globally. The present study assesses the levels of polychlorinated biphenyls (PCBs) congeners in sediments and six commonly consumed cichlid species from Eleyele Reservoir, Southwestern Nigeria. The results indicate that the concentrations of heavier PCB congeners are higher than the lighter congeners in both sediment and fish tissue. The predominant PCB congeners in the sediment samples from this site were PCBs 8, 44, 114, 101, 189, 196, 206 and 209. The concentration of PCB congeners increased with increasing molecular weight from hepta-PCB to deca-PCB in all fish species. The trend in accumulation of total PCBs in fish was as follows: Tilapia guineensis (2,531.1 + 74.6 ng/g) > Sarotherodon galilaeus (1178.7+68.5 ng/g) > Oreochromis niloticus > (891.8+49.6 ng/g) > Tilapia zillii (832.8 + 38.2 ng/g) > Hemichromis fasciatus (475.7 + 28.5 ng/g) > Sarotherodon melanotheron (333.2 + 26.1 ng/g). In summary, data from this study shows that the levels of PCBs in cichlid species from Eleyele Reservoir are higher than the threshold level of 0.023–0.047 ng g_1 recommended by United States Environmental Protection Agency. Such elevated PCB levels present significant health implications for human consumers and a threat to the resident fish communities. 1 results 1
- Eutrophication 1 results 1
- Eutrophication of water bodies is mainly caused by influx of Nitrogen and phosphorus compounds from land-use. Understanding relationship water reservoirs and farmlands will foster management of ecological resources. This study examined the link between eutrophication and land-use at Dandaru reservoir at Agodi, Ibadan, Oyo State and effect (s) of mechanical clean up on the reservoir. The Vegetation, soil of Lawn (L), bush fallow (BF), vegetable farm (VF) and Agodi Gardens (AG), and water quality of Dandaru reservoir in Ibadan were systematically assessed pre- and post-desilting following standard procedures. Forty 0.25 m2 quadrats were floristically assessed for Relative importance values (RIV) and Shannon-Weiner index (H`). Three randomly extracted bulked and sub-sampled top soil of each land-use were analysed physiochemically. The reservoir was sampled for phosphate, Organic carbon (TON), nitrate (TN), dissolved oxygen (DO) and pH in three replicates at entry, mid and exit points of the river. Data were analysed using ANOVA at p=0.05. Means statistical differences followed Fisher’s LSD. Fifty one plant species were enumerated pre-desilting consisting of 15, 22, 29 and 11 species in L, BF, VF and AG respectively; 22 plants were enumerated post-silting consisting 10, 10, 8 and 8 species in L, BF, VF and AG respectively. legumes ranged in RIVs from 4.217-8.397 in BF and VF. Pre-desilting, VF had highest H` (3.334), while AG had lowest (1.988). Post-desilting, Lawn had highest H` (1.956) while VF had lowest (1.679). P, TOC, TN and pH were significantly different in all land-uses with TN (0.81±0.02g/kg) and TOC (7.83±0.05g/kg) in BF. Phosphorus (0.31±0.03g/kg) was high at AG pre-desilting. Post-desilting, TN (32.90±3.37g/kg) and TOC (2.24±0.04g/kg) were significantly high in lawn. Pre-silting, pH and DO were significantly different at all points, lowest at midpoint (6.73±0.04mg/l and 7.89±0.30mg/l respectively); post-silting, pH (7.87±0.00) and DO (9.54±0.0Img/l) increased at midpoint.The legumes in agricultural lands most likely contributed to eutrophication of Dandaru reservoir. However, desilting offered temporary restoration. Cessation of agricultural activities around Dandaru reservoir with its periodic assessment will prevent eutrophication 1 results 1
- Fluid saturation 1 results 1
- Leishmaniasis 1 results 1
- Leishmaniasis is an important tropical disease that is gradually gaining attention in Nigeria. The canine species which include domestic dogs have been named the reservoir host for the zoonotic form of leishmaniasis. The present study was carried out to determine the seroprevalence of canine leishmaniasis in three selected states of Nigeria using indirect enzyme linked immunosorbent assay (ELISA). Two hundred and seventy-three canine sera were tested for Leishnmnia IgG antibodies. Dogs sampled were grouped into young (<1 year) and adult (>1 year). Total prevalence recorded was 4.40 % (12/273). There was no significant difference (P > 0.05) between sera of hunting (4.83 %) and companion dogs (3.03 %). Furthermore, there was no significant difference (P > 0.05) between young and adults dogs. There was no correlation between sex and prevalence of canine leishmaniasis. However, significant difference (P < 0.05) was observed in the prevalence of each state with Kwara, Oyo and Ogun having 14.63, 3.33 and 1.32 % respectively. The result of this study established the presence of canine leishmaniasis in Oyo, Ogun and Kwara Slates of Nigeria making the zoonotic form of the disease a possibility 1 results 1
- Leptospiral serovars 1 results 1
- Leptospiral serovars, 1 results 1
- Mechanical clean up 1 results 1
- Niger Delta. 1 results 1
- Permeability 1 results 1
- Petrophysical properties 1 results 1
- Porosity 1 results 1
- Renal pathology 1 results 1
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