Structural investigation of Zungeru-Kalangai fault zone and its environ, Nigeria using aeromagnetic and remote sensing data.

This study analysed aeromagnetic and satellite imagery data over parts of northern Nigeria to delineate magnetic and surface lineaments associated with fault system trends. The aeromagnetic data were analysed using the Fast Fourier transform technique for reduction-to-equator, total horizontal derivative, analytic signal amplitude and Euler deconvolution. Landsat-8 OLI and SRTM data have been enhanced using spatial filtering and hill-shading techniques for the delineation of lineament features. The extracted surface lineaments are denser on the satellite imageries than on the HRAD because the datasets respond to different physical properties of the geological units and features. The location and orientation of the Zungeru/Kalangai fault zone, which extends about 245 km from the Bida Basin Basement to the northern part of Nigeria, correlate with the existing fault on the published geological map and form a conjugate pair with a fault around Kaya. The derived maps revealed the presence of several previously undetected geological lineaments corresponding to faults and folded dyke, striking predominantly N-S, NNE-SSW, NE-SW and NW-SE lacking in previous geological maps. The application of 2D forward modelling revealed the 2D image of the nature of the subsurface, magnetic susceptibilities of rocks and the block boundaries coinciding with the geological lineaments.

Gene frequencies of ABO and Rh (D) blood group alleles in a healthy infant population in Ibadan, Nigeria.

The ABO and Rhesus blood group systems remain the most important blood group systems clinically. In order to provide gene frequency values for the ABO and Rh (D) alleles in a healthy infant population in south west Nigeria, 4748 healthy infants were typed for ABO and Rh (D) blood groups over a five year period (1988-1992). Overall, 2575 (54.2%) were blood group O, 1023 (21.6%) were blood group A, 1017 (21.4%) were blood group B and 133 (2.8%) were blood group AB. The distribution of the ABO blood groups did not differ significantly from those expected under the Hardy Weinberg equilibrium (Goodness-of-fit X2 = 6.09, df = 3, p = 0.1075). The proportions of the infants belonging to the various ABO blood groups did not vary significantly over the period of the study (X2 = 14.53, df = 12, p = 0.268). Overall gene frequencies for the O, A and B genes were 0.7398, 0.1305 and 0.1298 respectively. For the Rh (D) gene, 4520 (95.2%) were Rh-positive while 228 (4.8%) were Rh-negative. However, the proportions of Rh (D) negative infants varied significantly over the period of the study, with a particular year (1991) having nearly twice the usual frequency of Rh-negative individuals (X2 = 31.17, df =, p < 0.001). The frequency of the Rh (D) gene was 0.7809. These figures are reported in the hope that they may find some use as reference for studies of ABO blood groups in health and disease, especially since they were obtained in an infant population in which it is expected that selection pressures should not have started to act to any significant extent.

Routine screening for sickle cell haemoglobinopathy by electrophoresis in an infant welfare clinic.

The experience of a Nigerian infant welfare clinic in offering sickle cell haemoglo-binopathy (SCH) screening by electrophoresis to its clinic population over a 12-year period is reported. Overall 10,115 children were screened. Homozygous haemoglobin S was detected in 3.1% and haemoglobin S + C in 1.1%. Carriers of the sickle cell gene (haemoglobin A + S) comprised 23.7% of the children screened. Gene frequencies for the A, S and C genes were 0.814, 0.155 and 0.031 respectively. The gene frequencies of the S and C genes were higher than those reported in infants and under-five children from other parts of Nigeria. Screening for sickle cell haemoglobinopathy in the first year of life through infant welfare clinics and 'well-baby' clinics as described in this report is suggested as a viable approach to the problems of detection (and genetic counselling) of SCH in developing countries with their scant resources. The advantages and limitations of this approach are discussed.

Toxoplasma gondii antibodies in Nigerian goats.

Toxoplasma gondii antibodies were detected in 27 of 848 sera from Nigerian breeds of goats. The significance of this finding in relation to livestock production and human public health in Nigeria is briefly discussed.

A comparison of three serological tests in the diagnosis of caprine brucellosis.

The serum agglutination test (SAT), the Rose Bengal plate test (RBPT) and the milk ring test (MRT) were used in the diagnosis of caprine brucellosis. There was a close correlation between the SAT and RBPT when both tests were negative but the RBPT failed to detect 79.82 per cent of sera in excess of 50 iu. Also, owing to the relatively poor milking potential of the Nigerian goat and the false positive results with the MRT, it is concluded that the SAT offers a better serological diagnostic tool for caprine brucellosis in this locality.

Salmonellae isolated from captive animals in Ibadan, Western State of Nigeria.

Six serotypes of salmonellae, Salmonella offa, S. glostrup, S. wimborne, S. dublin, S. saint-paul and S. webridge were isolated from captive wild animals in Ibadan, Western State of Nigeria. S. wimborne and S. glostrup are reported for the first time in Nigeria. All strains were sensitive to nitrofurantoin (200 mcg) and chloramphenical (10 mcg) but there wasmarked resistance to sulphafurazole (100 mcg) and penicillin (1.5 units).

Anthrax in captive carnivores in Ibadan, Nigeria.

Between 20 and 22 June 1974, three captive carnivores (two genets, Genetta sp. and one caracal, Felis caracal) died suddenly in the University of Ibadan Zoological Garden without previous signs of illness. Bacillus anthracis was isolated from their blood and tissues. The organism was highly pathogenic to laboratory animals. The disease was believed to have been contracted from meat fed the animals.