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Development of resistance by different malaria vector populations to insecticides has become a big threat to malaria vector elimination. This study evaluated the susceptibility of Anopheles mosquito populations in Akwa Ibom State, Nigeria to permethrin (0.75%), deltamethrin (0.5%), lambdacyhalothrin (0.5%), alphacypermethrin (0.75%), Dichlorodiphenyltrichloethane (DDT), propoxur, bendiocarb and pirimiphosmethylin in World Health Organization (WHO) test tubes following standard protocols. The mosquitoes were obtained as aquatic forms and reared under laboratory conditions to adults. The adults were subjected to WHO susceptibility bioassays following standard procedures. Malaria vectors across the study sites were resistant to permethrin, deltamethrin, lambdacyhalothrin and alphacypermethrin insecticides. Full susceptibility to propoxur and bendiocarb was recorded across the sites. Full susceptibility to pirimiphosmethyl was recorded in populations from three sites. Nevertheless, population of the malaria vectors collected from Oron was resistant to pirimiphosmethyl. KDT50 and KDT95 estimated for each insecticide using a log-time probit model revealed that knockdown was more rapid for deltamethrin, lambdacyhalothrin, alphacypermethrin, propoxur, bendiocarb and pirimiphosmethyl than for DDT and permethrin across the study sites. Morphological identification of all the mosquito samples used revealed that they were female Anopheles gambiae s.l. Sustained susceptibility of malaria vectors to pyrethriod is necessary for successful malaria control with insecticide treated nets and Indoor Residual Spraying (IRS). Emergence of focal points with insecticide resistance gives serious concern especially with the scale-up in distribution of pyrethriod treated nets to these areas. This may increase selection pressures due to overexposure. Further study to identify the exact resistance mechanism(s) of malaria vectors from these sites is recommended.

Malaria is a major public health problem in Nigeria, accounting for about 60% of all outpatient attendances and 30% of all hospital admissions. Indoor residual spraying (IRS) was scaled up in Nigeria to supplement long lasting insecticide treated nets (LLINs) for malaria vector control. The success of IRS partly defends on the susceptibility of local anopheles mosquitoes to insecticides. The WHO standard insecticides-impregnated papers and tubes were used to conduct bioassay tests against local populations of Anopheles species in Misau Bauchi State Nigeria with a view of selecting the suitable insecticides for IRS. The tests papers include: Cyfluthrin (0.15%), DDT (4%), Deltamethrin (0.05%), Lambdacyhalothrin (0.05%), Malathion (5%), Permethrin (0.75%), Propoxur (0.01%), Alpha-cypermethrin (0.75%), Bendiocarb (0.1%), Bifenthrin (0.15%) and untreated (control). Twenty (20) two to three day-old, female Anopheles species, glucose fed, none blood fed, were exclusively used in the bioassay per treatments which was replicated three times. The post exposure 1 h knockdown and 24 h mortality was assessed. The results of the knockdown assessment indicate that Alphacypermethrin had the lowest KD50 (time taken to knockdown fifty percent of the exposed mosquitoes) value of 4.8 min. Relatively moderate KD50 values (minutes) were obtained with Propoxur (11.34), Deltamethrin (13.20), Malathion (15.82), Bendiocarb (17.29), Permethrin (18.43), Cyfluthrin (20.28) and Lambdacyhalothrin (23.11). Relatively higher KD50 values were obtained with Bifenthrin (27.29) and DDT (32.12) impregnated papers. The results of mortality assessment indicate that Anopheles mosquitoes were susceptible to Alphacypermethrin, Malathion and Propoxur with 100% mortality. The Anopheles species were less susceptible to Bifenthrin, Lambdacyhalothrin, Permethrin, Deltamethrin, Bendiocarb, Cyfluthrin and DDT. The Anopheles species used in the tests were morphological identified as Anopheles gambiae, Anopheles funestus and Anopheles nili. The public health significance of these findings is discussed. Key words: Nigeria, Anopheles mosquitoes, resistance, Misau, Bauchi State, indoor residual spraying (IRS).

Microsporidial infections have been recognized as an increasingly important infection in immunocompromized patients, particularly those infected with HIV/AIDS. This study was designed to study immune responses associated with experimental Encephalitozoon intestinalis infection in immunecompetent rats.Thirty-four rats in 3 groups, A (Control), B (Intraperitoneal) and C (Oral) were given injections of 0.5 ml of 2 x 10(6) of purified spores of Encephalitotozoon intestinalis spores and were observed for serum specific IgG for 21 days using both Direct and Indirect ELISA.In indirect ELISA, specific lgG were detected on days 7, 14 and 21 for the group B rats and on day 21 for group C and in direct ELISA method, specific lgG were detected in-group B rats on days 7 and 21, for group C rats on day 21 only, while in the control rats, specific lgG were not detected. There was no significant difference between the direct and indirect methods (df=1, X(2), P0.05). E. intestinalis was observed in stool samples of rats in 1/12 (08.33%) on days 14 and 21 in group B and in 4/10 (33.33%), 3/10 (25.00%) and 2/10 (16.67%) on days 7, 14 and 21 respectively in group C. In-group, A which is the control rats, no microsporidia were observed on days 0, 7, 14 and 21.There were no changes in the T-lymphocyte counts of rats prior to and after inoculation with spores. Extensive lesions were observed along the intestinal walls especially on the middle and lower sections of group C rats only.

Information is very scarce on the prevalence of hepatitis-B virus (HBV) infection among blood donors and patients with human immunodeficiency virus (HIV) infection in Nigeria. Hepatitis-B surface antigen (HBsAg) ELISA was used to determined the prevalence of HBsAg among 175 blood donors (aged 20-40 years) and 490 HIV-infected patients (aged 17-60 years) in Jos, Nigeria. Twenty-five (14.3%) of the blood donors and 127 (25.9%) of the HIV-infected individuals were HBsAg seropositive, indicating a higher HBV infection among HIV-infected persons than among healthy blood donors. A slightly higher HBsAg seroprevalence was recorded in the males (14.6%) than females (12.9%) of the blood donors. Among the HIV-infected patients, the males had considerably higher HBsAg seroprevalence than the females (31.8 vs 22.1%) with the highest prevalence of HBsAg occurring in the 51-60 years age group (44%), followed by those of 31-40 years (28.2%). Results confirmed the high endemicity of HBV infection in Jos, Nigeria and the significantly greater prevalence of HBV infection among HIV -infected patients than among blood donors.

Purpose: Microsporidial infections have been recognized as an increasingly important infection in immuncompromised patients, particularly those infected with HIV/AIDS. This study was designed to study immune responses associated with experimental Encephalitozoon intestinalis infection in immunocompetent rats. Materials and Methods: Thirty-four Rats in 3 groups, A (Control), B (Intraperitoneal) and C (Oral) were given injections of 0.5 ml of 2 x 10 6 of purified spores of Encephalitotozoon intestinalis spores and were observed for serum specific IgG for 21 days using both direct and indirect ELISA. Results: In indirect ELISA, specific lgG were detected on days 7, 14 and 21 for the group B rats and on day 21 for group C and in direct ELISA method, specific lgG were detected in-group B rats on days 7 and 21, for group C rats on day 21 only, while in the control rats, specific lgG were not detected. There was no significant difference between the direct and indirect methods (df=1, X 2 , P>0.05). E. intestinalis was observed in stool samples of rats in 1/12 (08.33%) on days 14 and 21 in group B, and in 4/10 (33.33%), 3/10 (25.00%) and 2/10 (16.67%) on days 7, 14 and 21 respectively in group C. In group A, which is the control rats, no microsporidia were observed on days 0, 7, 14 and 21. Conclusions: There were no changes in the T-lymphocyte counts of rats prior to and after inoculation with spores. Extensive lesions were observed along the intestinal walls especially on the middle and lower sections of group C rats only.