Biotransformation and oxidative stress responses in relation to tissue contaminant burden in Clarias gariepinus exposed to simulated leachate from a solid waste dumpsite in Calabar, Nigeria.

In this study, we have investigated biotransformation and oxidative stress responses in relation to tissue contaminant burden in the African sharptooth catfish (Clarias gariepinus) exposed to simulated leachate from a solid waste dumpsite in Calabar, Nigeria. Fish were exposed to simulated leachate, diluted to 0:0 (negative control), 1:10, 1:50, 1:100 and phenanthrene (a PAH: 50 µg/L used as a positive control) for 3, 7 and 14 days. Hepatic transcripts for cat, sod1, gpx1, gr, gst, cyp1a, cyp2d3, and cyp27 were analyzed by real-time PCR, while enzymatic assays for ethoxyresorufin O-deethylase (EROD), buthoxyresorufin O-deethylase (BROD), methoxyresorufin O-deethylase (MROD), pentoxyresorufin O-deethylase (PROD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST), uridine diphospho-glucuronosyltransferase (UDPGT) and lipid peroxidase (LPO) were measured using standard methods. In addition, protein expression for CYP1A, CYP3A and metallotheionin (MT) were measured by immunoblotting. Fish muscle samples were analyzed for selected group of contaminants after 14 days exposure showing significantly high uptake of heavy metals (Cd, Hg and Pb), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), chlorophenols, organochlorine (OC) and organophosphate pesticides in exposed fish. We observed significant concentration- and time-specific increases in biotransformation and oxidative stress responses at transcript and functional (enzyme and protein) levels, that paralleled tissue contaminants bioaccumulation patterns, after exposure to the simulated leachates. Our results highlighted the potential environmental, wildlife and public health consequences from improper solid waste disposal. In addition, it also provides a scientific basis for local sensitization and inform legislative decisions and policy formulation towards sustainable environmental management of solid wastes in Nigeria and other developing countries.

Epidemiology of tree-hole breeding mosquitoes in the tropical rainforest of Imo State, south-east Nigeria.

The study of tree-hole breeding mosquitoes was carried out in the tropical rainforest of Imo State Nigeria (two rural areas and two forest reserves in some parts of Orlu Senatorial Zone) between May-October 2002. Using standard entomological procedures, two macrohabitats (natural tree-holes and bamboo traps) and two microhabitats (leaf axils of cocoyams/pineapples and leaf axils of plantain/banana) were sampled for various mosquito species. Mosquitoes were recovered from all the various biotypes sampled. Types of mosquitoes species encountered, their relative abundance, as well as genera varied significantly during the study (p<0.05). Four genera of mosquitoes: Aedes, Culex, Anopheles and Toxorhynchites were recovered while 16 species of mosquitoes encountered include: Aedes aegypti, Ae. africanus, Ae. simpsoni, Ae. albopictus, Ae. stokesi, Ae. taylori, Ae. apicoargenteus, Culex quinquefasciatus, Cx. nebulosus, Cx. trigripes, Cx. decens, Anopheles gambiae, An. funiestus, An. coustani and Toxorhynchites viridibasis. Most of the mosquitoes showed oviposition preferences for one or more habitats. The presence of Ae. africanus, Ae. simpsoni and Ae. aegypti indicate that the study areas were at risk of yellow fever epidemic. The presence of Anopheles and Culex species ensured endemicity of malaria and filariasis, while the recovery of Ae. albopictus in this region suggests a possible outbreak of dengue fever in future if not properly controlled.

Studies on vesical schistosomiasis among rural Ezza farmers in the southwestern border of Ebonyi State, Nigeria.

Studies on vesical schistosomiasis and its snail vectors were carried out between October 2001-May 2002 among rural Ezza farmers inhabiting the southwestern border of Ebonyi State, Nigeria. The people are predominantly farmers. Of the 2,104 urine specimens examined in 10 communities, 466 (22.1%) comprising 305 (23.7%) men and 161 (19.7%) women were infected with visible haematuria as the predominant presenting symptom. Ezza people associate bloody urine with sexually transmitted diseases. There were no significant differences in the prevalence rates amongst various villages and sexes (p > 0.05). There was a gradual increase in the disease prevalence as the subjects' age increases. About 78.3% of the infected persons are aged 0-20 years. Statistical analysis revealed that the prevalence, intensity and visible haematuria were significantly more ( p < 0.05) in subjects under the age of 20 than subjects above 20. Among the infected population, 183 (39.3%) and 283 (60.7%) were excreting 50 eggs/10 ml urine and above 50 eggs/10 ml urine respectively. Lack of visible haematuria is a more valid indicator of the absence of vesical schistosomiasis. Of the various snails collected during malacological survey, mainly B. globosus were infected. Possible control measures are discussed.

Lymphatic filariasis among the Ezza people of Ebonyi State, eastern Nigeria.

A total of 1,243 Ezza people living in 10 communities of Ebonyi State, eastern Nigeria were examined between July 2002-January 2003 for lymphatic filariasis. This is the first time a filariasis survey due to Wuchereria bancrofti has been carried out in this state. Of the 1,243 persons examined, 210 (16.9 %) had W. bancrofti microfilariae. Infection varied significantly among communities and ages (p < 0.05) but not sex-related (p > 0.05). The Ezza people are predominantly farmers and professional hired labourers. There was a close association between microfilaria rate and microfilaria -density in various age groups (r = 0.812; p < 0.01). Microfilaria density is an important measure in the epidemiology, treatment and control of human filarisis in this endemic foci. Clinical signs and symptoms of the disease include elephantiasis, hydrocoele, dermatitis and periodic fever. Clinical symptoms without microfilaraemia and microfilaraemia without clinical symptoms were also observed. Of 1,603 mosquitoes dissected, Anopheles gambiae, An. funestus and Culex quinquefasciatus showed infectivity rates of 6.3 %, 5.1 % and 6.0 % respectively. The affected persons and other key informants are unaware of the cause of the disease and attributed it to witchcraft, violation of taboo, bad water and food. Intervention strategies to be integrated into the on-going Community-Directed Treatment with Ivermectin (CDTI) project are discussed.