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Background and Objective: Nigeria still remains a major endemic area despite concerted efforts by the World Health Organization to reduce the burden of Schistosomiasis. This study aimed to determine the current prevalence of the infection and its associated risk factors among elementary school children in Osun State. Materials and Methods: The study purposively recruited 504 elementary students from eight schools across three senatorial districts of Osun State, Nigeria. A parasitological assessment of urine samples was done for the detection of S. haematobium eggs. A semi-structured questionnaire was administered to elicit information on the risk factors associated with urinary schistosomiasis. Bivariate and multivariate logistic regression was used to estimate the likelihood of infection among the various factors associated with urinary schistosomiasis. All statistics were performed at p< 0.05. Results: The mean (SD) age of respondents was 11±1.93 years with a preponderance of age range between 11 and 16 years (54.0%). The overall prevalence of schistosomiasis was 4.4%. The highest prevalence (12.1%) was recorded in a school located in Osun West while the lowest (1.5%) was recorded in a school located in Osun East. The regression model showed that environmental activities such as fishing (aOR 7.0, 95% CI 1.59-31.14), fetching water from river bodies (aOR 23.3, 95% CI 1.59-42.22) and open defecation (aOR 8.4, 95% CI 2.10-23.82) were independently associated with urinary schistosomiasis. Conclusion: This study revealed a low prevalence of urinary schistosomiasis and this is an indication of ongoing transmission. [ABSTRACT FROM AUTHOR]

Background: Rapid urbanization in Nigerian cities may lead to localized variations in malaria transmission, particularly with a higher burden in informal settlements and slums. However, there is a lack of available data to quantify the variations in transmission risk at the city level and inform the selection of appropriate interventions. To bridge this gap, field studies will be undertaken in Ibadan and Kano, two major Nigerian cities. These studies will involve a blend of cross-sectional and longitudinal epidemiological research, coupled with longitudinal entomological studies. The primary objective is to gain insights into the variation of malaria risk at the smallest administrative units, known as wards, within these cities. Methods/results: The findings will contribute to the tailoring of interventions as part of Nigeria's National Malaria Strategic Plan. The study design incorporates a combination of model-based clustering and on-site visits for ground-truthing, enabling the identification of environmental archetypes at the ward-level to establish the study's framework. Furthermore, community participatory approaches will be utilized to refine study instruments and sampling strategies. The data gathered through cross-sectional and longitudinal studies will contribute to an enhanced understanding of malaria risk in the metropolises of Kano and Ibadan. Conclusions: This paper outlines pioneering field study methods aimed at collecting data to inform the tailoring of malaria interventions in urban settings. The integration of multiple study types will provide valuable data for mapping malaria risk and comprehending the underlying determinants. Given the importance of location-specific data for microstratification, this study presents a systematic process and provides adaptable tools that can be employed in cities with limited data availability. [ABSTRACT FROM AUTHOR]

The need for evidence-based data, to inform policy decisions on malaria vector control interventions in Nigeria, necessitated the establishment of mosquito surveillance sites in a few States in Nigeria. In order to make evidence-based-decisions, predictive studies using available data becomes imperative. We therefore predict the distribution of the major members of the Anopheles gambiae s.l. in Nigeria. Immature stages of Anopheles were collected from 72 study locations which span throughout the year 2020 resulted in the identification of over 60,000 Anopheline mosquitoes. Of these, 716 breeding sites were identified with the presence of one or more vector species from the An. gambiae complex and were subsequently used for modelling the potential geographical distribution of these important malaria vectors. Maximum Entropy (MaxEnt) distribution modeling was used to predict their potentially suitable vector habitats across Nigeria. A total of 23 environmental variables (19 bioclimatic and four topographic) were used in the model resulting in maps of the potential geographical distribution of three dominant vector species under current climatic conditions. Members of the An. gambiae complex dominated the collections (98%) with Anopheles stephensi, Anopheles coustani, Anopheles funestus, Anopheles moucheti, Anopheles nilli also present. An almost equal distribution of the two efficient vectors of malaria, An. gambiae and Anopheles coluzzii, were observed across the 12 states included in the survey. Anopheles gambiae and Anopheles coluzzii had almost equal, well distributed habitat suitability patterns with the latter having a slight range expansion. However, the central part of Nigeria (Abuja) and some highly elevated areas (Jos) in the savannah appear not suitable for the proliferation of these species. The most suitable habitat for Anopheles arabiensis was mainly in the South-west and North-east. The results of this study provide a baseline allowing decision makers to monitor the distribution of these species and establish a management plan for future national mosquito surveillance and control programs in Nigeria. [ABSTRACT FROM AUTHOR]

The study evaluates the resistance and susceptibility of adult female Anopheles gambiae s. l., Aedes aegypti and Culex quinquefasciatus mosquitoes sourced within Osogbo metropolis, Osun State, Nigeria to four groups of insecticides [Permethrin, Deltamethrin, Pirimiphos-methyl and DDT (Dichlorodiphenyltrichloroethane)] and the distribution of their larval habitat within the metropolis. Mosquito larvae of the three genera were collected during the wet season and reared to adult stage in the laboratory. Emerged adult female mosquitoes were exposed to insecticide impregnated papers of the four insecticide groups for 60mins using WHO kits to determine the knock down rate (kdr). Thereafter, they were transferred into holding tubes and left for 24hrs to assess their resistance and susceptibility according to the WHO protocol. Four types of larval habitats were identified (tires, ground pools, gutters and plastic containers). Anopheles gambiae s. l. showed the highest resistance to Permethrin (49%) (p = 0.04, p<0.05) while the highest susceptibility was recorded with Pirimiphos-methyl (69%) with the lowest against Permethrin (16%) (P = 0.002; p<0.05). The highest resistance of A. aegypti was against OC-Control (45%) (p = 0.031; p<0.05). Permethrin had the highest susceptibility (60%) against A. aegypti while OC-control had the lowest (11%) (p = 0.005; p< 0.05). Culex quinquefasciatus had a lower resistance to OC-control (38%) as compared with Aedes aegypti (45%). However, it was least susceptible to Pirimiphos-methyl (52%) and DDT (17%) respectively (p = 0.013; p<0.05). The susceptibility of A. gambiae s. l. and C. quinquefasciatus to Pirimiphos-methyl and A. aegypti to Permethrin is an indication of the possibility of success if employed for vector control of A. gambiae s. l., C. quinquefasciatus and A. aegypti respectively. This could be through their inclusion as active ingredients in insecticide treated nets (ITNs) and indoor residual spray (IRS) with a view to abating malaria and other life-threatening mosquito-borne diseases constituting global public health scourge. [ABSTRACT FROM AUTHOR]

Simulium damnosum sensu lato (Diptera: Simuliidae) commonly known as black fly transmits Onchocerca volvulus, the parasite which causes onchocerciasis (river blindness) in Africa. The medical and socio-economic importance associated with the biting of this fly is enormous, hence, the need to devise effective means of breaking man-fly contact. The present study examined repellent activities of formulated topical creams prepared from white soft paraffin and two concentrations (5.0% and 7.5%) of essential oils of three plants, namely Monodora myristica, Eugenia caryophyllus and Xylopia aethiopica against Simulium damnosum s.l. vectors of human onchocerciasis in Nigeria. The chemical characterization of the oils was determined using gas chromatography and mass spectrometry. Fly collectors that applied the formulated creams at both concentrations caught lower numbers of black flies compared with the control. The difference in the number of flies caught between each of the three essential oils and the control was statistically significant at 7.5% concentration, whereas only E. caryophyllus was significantly different from the control at 5.0% concentration. Eugenia caryophyllus had the highest repellent activities, with the protection of 47.1% and 50.6%, followed by X. aethiopica (37.1% and 36.1%), whereas M. myristica had the least (28.7% and 34.1%) for concentrations of 5.0% and 7.5%, respectively. Trans-13-octadecenoic acid, Eugenol and Alpha-pinene were found to be the principal chemical constituents in M. myristica, E. caryophyllus and X. aethiopica, respectively. The active agents in the essential oils could be useful in providing low-cost repellents to prevent human-vector contact in black fly-infested communities. [ABSTRACT FROM AUTHOR]

Onchocerciasis caused by infection with Onchocerca volvulus is a disease of public health importance and is highly associated with disability. As Nigeria is aiming at eliminating onchocerciasis by 2030, there is a need to develop newer tools to map disease prevalence and identify environmental factors driving disease prevalence, even in places that have not been previously targeted for preventive chemotherapy. This study produced predictive risk-maps of onchocerciasis in Ogun State. Georeferenced onchocerciasis infection data obtained from a cross-sectional survey at 32 locations between March and July 2015 together with remotely-sensed environmental data were analyzed using Ecological Niche Models (ENM). A total of 107 field occurrence points for O. volvulus infection were recorded. A total of 43 positive occurrence points were used for modelling. ENMs were used to estimate the current geographic distribution of O. volvulus in Ogun State. Maximum Entropy distribution modeling (MaxEnt) was used for predicting the potential suitable habitats, using a portion of the occurrence records. A total of 19 environmental variables were used to model the potential geographical distribution area under current climatic conditions. Empirical prevalence of 9.3% was recorded in this study. The geospatial distribution of infection revealed that all communities in Odeda Local Government Area (a peri-urban LGA) showed remarkably high prevalence compared with other LGAs. The predicted high-risk areas (probability > 0.8) of O. volvulus infection were all parts of Odeda, Abeokuta South, and Abeokuta North, southern part of Imeko-Afon, a large part of Yewa North, some parts of Ewekoro and Obafemi-Owode LGAs. The estimated prevalence for these regions were >60% (between 61% and 100%). As predicted, O. volvulus occurrence showed a positive association with variables reflecting precipitation in Ogun State. Our predictive risk-maps has provided useful information for the elimination of onchocerciais, by identifying priority areas for delivery of intervention in Ogun State, Nigeria. [ABSTRACT FROM AUTHOR]

Mosquito larval surveys were conducted in two urban neigbourhoods, Surulere and Apapa, in Lagos State, Nigeria from July to October 2021. The aim was to investigate mosquito species composition and habitats utilized by these species with the overall goal of generating useful information to guide mosquito surveillance and control activities targeting vector species. Immature mosquitoes (larva and pupa) found were collected using dipping technique and emerged adults were identified using standard morphological keys. Mosquito abundance, diversity and habitat types were also assessed. A total of 2,696 immature mosquitoes were collected from both areas with 90.3% (2,434) collected from Surulere. Three species of mosquitoes; Aedes aegypti, Culex pipiens complex and Anopheles gambiae complex were found in both Surulere and Apapa. One species identified as Lutzia tigripes was found only in Apapa. In Surulere, Cx. pipiens complex had significantly (p < 0.05) the highest relative abundance (59.8%) while An. gambiae complex had the lowest (2.2%). In Apapa, Ae. aegypti had the highest abundance (68.7%) while Lt. tigripes had the lowest (6.9%) but there was no significant difference. Habitat types encountered in both areas included gutters (roadside ditches), ground pools and man-made containers especially used tyres. Larval densities varied significantly (p < 0.05) among species, and habitat types in Surulere but not in Apapa. The observed variations in species composition and abundance between the two urban neigbourhoods suggest different risk for specific mosquito-borne diseases. Integrated vector management tactics such as source reduction through larval habitat elimination and larviciding are recommended. [ABSTRACT FROM AUTHOR]

Background and objectives: This study reports knowledge of residents of Alabameta community, Osun State, Nigeria on the bioecology and socio-economic burden of black flies and onchocerciasis. Methods: Using structured questionnaires and Focus Group Discussion (FGD), a total of 150 community respondents participated in the study. Results: The knowledge of the residents on the existence of black flies in the community was significant (p<0.05) as all the 150 respondents confirmed the presence of black flies with the local name 'Amukuru' i.e causing itching. However, their lack of knowledge of the flies breeding site (104) (69%), prevention (134) (89%), cause (132) (88%), and treatment (133) (89%) of onchocerciasis was profound. Majority 147(98%) of the respondents reported that flies bite more in the wet season as against dry season 3(2%) and have a higher affinity (124) (82%) for biting the leg than any other part of the body. A larger percentage (89%) of the respondents are unaware of any medication for the treatment of onchocerciasis while 11% are aware. There had been no sensitization on onchocerciasis according to 89% of the respondents. Conclusion: Due to lack of resident's knowledge on black flies bioecology which may continuously expose them to the bite of the flies and ultimately infection, it is paramount that the Osun State government and the NTD implementing partner map out new public health education strategies during routine Mass Administration of Medicines with Ivermectin with a view to preventing onchocerciasis infection as well as man-vector contact. Author summary: The public health menace of parasites and their vectors is an issue of global public health concern. Black flies, the vector that transmit the dreadful parasite Onchocerca volvulus to its human host where it causes the debilitating disease, onchocerciasis, is a neglected tropical disease (NTD) with its greatest burden in sub-Saharan Africa. Nigeria is an endemic country for onchocerciasis. Despite efforts by health agencies globally in eradicating the disease through public health awareness, chemotherapy through community directed treatment with ivermectin (CDTI) and so on, it appears that inhabitants of Alabameta community, Osun State, southwestern, Nigeria are unaware of the bioecology of the vector as well as the public health implication of the disease according to the present study. Therefore, there is the urgent need for the government at the state and federal levels as well as health agencies to improve on public health awareness of the disease with a view to curbing exposure of residents and ultimately disease eradication. [ABSTRACT FROM AUTHOR]

A longitudinal study was carried out to investigate species composition, seasonal abundance, parity and transmission potential of Simulium damnosum complex in Alabameta community in Osun State, Southwestern, Nigeria. Adult Simulium damnosum complex were collected along Owena River, Alabameta, by two dark complexioned vector collectors from 07:00hr to 18:00hr weekly using collecting tubes from November 2014 to April 2015. The flies were morphologically identified and dissected for the purpose of detecting Onchocerca parasite using dissecting microscope. The Monthly Biting Rate (MBR) of flies was determined using World Health Organization standard formula. A total of four hundred and forty flies were collected during the study period with all of them identified as forest species of Simulium damnosum complex. There was significant variation in monthly collection of the flies with the month of November having the highest number of flies (194) (44%) while the month of April recorded the lowest number of flies (31) (7%) (p<0.05). The morning biting peak (09hr - 11hr) (137) was higher than the evening biting peak (15hr -17hr) (64) (p<0.05) while nulliparous flies (294) (67%) were more abundant than the parous flies (146) (33%) (p<0.05). There was absence of infection (zero infectivity) of the flies (p<0.05). The zero infectivity in the flies may plausibly indicate the possibility of zero transmission of Onchocerca parasite in the community which if sustained over a period of time may signify the possibility of onchocerciasis elimination. Also, the presence of forest species of the flies reduces the risk of resident's intense exposure to blinding savannah strain of onchocerciasis. [ABSTRACT FROM AUTHOR]

Simulium damnosum Theobald complex is a group of black flies which vector filarial worms that cause onchocerciasis in Africa. Studies were conducted to investigate the morphological composition of adult S. damnosum complex in three ecological zones of Osun State, Nigeria. Adult black flies were sampled between October 2014 and September 2016, and the wing tufts, antennae, fore coxae and other morphotaxonomic characters were observed and classified following standard methods. The results revealed a sympatric occurrence of both forest- and savannah-dwelling groups (morphotypes) of black flies at each zone with the Guinea savannah zone (Iwo) having significantly higher abundance of forest than savannah black flies. The derived savannah (Ede) had higher abundance of savannah than forest black flies while the rainforest (Obokun) had more forest than savannah black flies but there was no significant difference between them. In Iwo, the highest abundance of forest flies was obtained in October and June while savannah flies were highest in November. The monthly abundance of each morphotype of black flies was significantly different in Ede but not in Obokun. Wing tuft colours among forest flies varied significantly in Iwo and Ede. This study indicates that there is substantial morphological diversity among sibling species of black flies which is useful for identification and could be exploited in black fly control. The presence of savannah flies in the three zones calls for surveillance for potential incursion of blinding parasite strain which migrant savannah flies could introduce to the communities. [ABSTRACT FROM AUTHOR]

Simulium damnosum (Theobald) sensu lato (s.l.) is a complex of many species of black flies that transmit Onchocerca volvulus (Leuckart) to varying capacities based on their ecological zones in Africa. The presence of three ecological zones in Osun, an onchocerciasis endemic state in Nigeria, is the basis of this study that is aimed at determining the population dynamics of S. damnosum s.l. in the state. Adult S. damnosum s.l. were collected fortnightly in the wet and dry seasons for 2 yr between October 2014 and September 2016 in the Guinea savanna (Iwo), derived savannah (Ede), and rainforest (Obokun) zones. Temperature, relative humidity, and rainfall of the study area were measured. The results showed that in the first year, Ede had 62.8% of the total black fly population while Obokun had the lowest (1.5%). In the second year, Iwo had 94.1% of the total black fly population while Obokun had the least population. The black fly population was significantly higher during the wet season than dry season in Iwo and Ede, but was not significant in Obokun. The results further showed that black fly populations were strongly correlated with ambient temperature and rainfall in Iwo, whereas no relationships were recorded for Ede and Obokun. The results suggest that abundance of black flies during the wet season was due to increased rainfall which in turn created rapids and conditions suitable for development of preimaginal stages into adults. These vector surveillance findings will guide control decisions necessary for endemic communities to meet elimination targets. [ABSTRACT FROM AUTHOR]

Background: Loiasis is currently receiving attention as a disease of public health importance because of the possibility of increased risk of developing neurologic serious adverse event following mass ivermectin treatment against onchocerciasis in individual co-infected with Onchocerca volvulus and Loa loa. Methodology/Principal Findings: Rapid assessment procedure for loiasis (RAPLOA) was conducted in 12 communities covering the 3 senatorial districts of Osun State, Nigeria. A total of 960 people were interviewed for history of eye worm using the WHO guidelines for rapid assessment. The survey confirmed the presence of loiasis in all the 12 communities with 4 in Osun East/Ife south senatorial district being at high risk with a prevalence of over 40%. Based on the RAPLOA results, communities within Osun East/Ife south senatorial district were selected for microfilaraemic assessment of L. loa and O. volvulus. A total of 1115 and 1091 individuals were screened for L. loa and O. volvulus microfilaria worms respectively. 160 (14.3%) had L. loa microfilaria detected in their blood with 8 (5.0%) individuals having L. loa loads above 8000 mf/ml. 166 (15.2%) subjects had O. volvulus microfilaria (range 4-504 mf/ml) detected in their skin snip. 30 (2.69%) subjects were co-infected with both L. loa and O. volvulus. There was a significant variation in the prevalence (2.1% to 33.3%) of onchocerciasis in the communities studied (p = 0.001). Five (41.7%) of the studied communities had a prevalence that is equal to or greater than 20%. Conclusions/Significance: Low prevalence of onchocerciasis and loiasis co-infection in this study suggests that loiasis may not pose a serious epidemiological threat to the continuous distribution and sustainability of ivermectin for the treatment of onchocerciasis. Evaluation of the interruption of onchocerciasis transmissions in this region using all the indicators set forth by WHO is therefore suggested. Author Summary: Loiasis recently emerged as a disease of public health importance because of the risk of rare severe adverse events (SAEs) associated with the rapid killing of Loa loa microfilariae in heavily parasitized individuals following ivermectin treatment. for onchocerciasis. The possibility of developing these SAEs has been slowing down the control of onchocerciasis in some endemic communities. Based on information available at the Osun State Ministry of Health, the detailed geographic distribution of L. loa in Osun State is still awaiting elucidation. The results of this study revealed an overlap in geographic distribution of loasis and onchocerciasis in many communities in Osun State. The overall Community Microfilaria Load (CMFL) for L. loa was below the threshold level of endemicity that could be associated with the risk of SAEs after ivermectin treatment. Most individuals with slightly high L. loa microfilaria are either O. volvulus microfilaria free or have very low microfilaria load. The low prevalence of co-infection of both diseases in the study area is an indication that loiasis may not pose any serious epidemiological threat to the distribution and sustainability of ivermectin in the treatment of onchocerciaisis. [ABSTRACT FROM AUTHOR]

Background: Studies on biting behaviours and infectivity status of insect vectors are pre-requisites in understanding the epidemiology of the vector- borne diseases and planning effective control measures. A longitudinal study was carried out to investigate the transmission index of Simulium damnosum complex species along Osun River, South Western Nigeria. Adult flies were collected on human attractants from 07:00 to 18:00 hours for two consecutive days from February 2008 to June 2009 at three communities: Osun Eleja, Osun Ogbere and Osun Budepo. The infectivity rate was determined by dissection and Polymerase Chain Reaction amplification (PCR) of 0-150 genes of Onchocerca parasite using the pool screening technique. Results: The results indicated that the majority of the flies collected at the three sampling points were nulliparous as they accounted for 53.90%, 57.86% and 59.58% of the flies dissected at Osun Budepo, Osun Ogbere and Osun Eleja, respectively. The parous rate was higher during the dry season than the wet season but the difference was not statistically significant (p < 0.05). The biting activity of the parous flies showed two peaks at Osun Budepo and three peaks at Osun Eleja and Osun Ogbere. Of the 1,472 flies dissected and 1,235 flies screened by molecular method, none was infected with Onchocerca parasite at the three sampling points however the annual biting rates at the three communities were higher than 1,000 considered as tolerable value for a person living in an onchocerciasis zone by Word Health Organization. Conclusion: The study has provided the baseline data for further study on onchocerciasis transmission dynamics and the need to intercept man- simuliid vector contact at the study area. [ABSTRACT FROM AUTHOR]

Mosquito-borne diseases (MBDs) are major public health burdens in tropical nations, including Nigeria. This study assessed mosquito larval species composition, abundance, and abiotic factors influencing mosquito breeding in slum communities of Lagos with the goal of informing MBD control measures. Three slum communities-Bariga, Makoko, and Ajegunle-were selected along with the nonslum community of Ikeja, which served as a control site. Larval sampling was done using the standard dipping technique between December 2021 and July 2022 across the dry and wet seasons. Mosquito larvae were raised to adults and identified using morphological keys and molecular assays. A total of 57,753 immature mosquitoes were collected from all study sites, with a significantly (P < 0.05) greater abundance in the dry season than the wet season. The majority (98.1%) of the mosquitoes collected belonged to Culex pipiens s.l., the only species found during the dry season in almost all locations. In the wet season, species identified from all sites combined were Anopheles gambiae ss., Anopheles arabiensis, Aedes aegypti, Aedes albopictus, Cx. pipiens s.l., and Lutzia tigripes, with Ajegunle having the greatest species diversity (H = 0.593). Among physicochemical parameters measured, only water temperature had a significant positive correlation (r = 0.934, P = 0.020) with larval densities in Ajegunle only. Permanent mosquito-breeding habitats had significantly greater larval densities than temporary habitats within the slum communities. These findings could inform the development of integrated vector control strategies that address the different species of mosquitoes in the fight against MBDs in urban slums.

The Simulium damnosum Theobald complex transmits Onchocerca volvulus Leuckart (Spirurida: Onchocercidae), the causative agent of onchocerciasis. Recent evidence suggests that control efforts have strongly suppressed parasite populations, but vector surveillance is needed in parts of Africa where the disease remains endemic. Here, studies on biting rates and infectivity status of suspected vector species were conducted in three onchocerciasis-endemic areas, namely Iwo, Ede, and Obokun, in Osun State, Nigeria. A total of 3,035 black flies were collected between October 2014 and September 2016, and examined for parity and parasites using standard methods. A separate collection of 2,000 black flies was pool-screened for infectivity using polymerase chain reaction (PCR) amplification of the O-150 marker. Results showed that parous flies were significantly less common than nulliparous flies with overall parous rates of 8.02% in Iwo and 35.38% in Ede at the end of the study period. Obokun had a parous rate of 22.22% obtained in the first year only. None of the dissected parous flies were infected with O. volvulus and PCR assays showed no amplification of O-150 O. volvulus-specific repeats in head and body pools. However, annual biting rates exceeded the World Health Organization threshold of 1,000 bites/person/yr. Thus it appears that, with such high rates of biting, even low levels of vector infection can sustain onchocerciasis in African communities., (© The Author(s) 2020. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Objective: To determine the larval habitats of mosquito fauna and possible impact of land use/ land cover changes on the epidemiology of mosquito-borne diseases in Osogbo metropolis, Southwestern, Nigeria., Methods: All accessible larval habitats were surveyed between May and September, 2011 in Osogbo metropolis while Land Use/ Land cover of the city was analyzed using 2 Lansat Multispectral Scanner satellite imagery of SPOT 1986 and LANDSAT TM 2009., Results: A total of six species namely, Aedes aegypti, Aedes albopictus, Aedes vittatus, Anopheles gambiae complex, Culex quinquefasciatus and Eretmapodite chrysogaster were encountered during the study. The occurrence and contribution of disused tyres was significantly higher (P<0.05) than the other habitats encountered, while there were no significant differences in the contribution of gutters/run-offs, septic tanks/ drums, ground pools/open drains and discarded containers to the breeding of mosquitoes (P>0.05). The accessible land use/ land covered of the study area between 1986 and 2009 showed that the wet land coverage and settlement area increased from 0.19 to 9.09 hectare and 1.00 to 2.01 hectare respectively while the forest area decreased from 60.18 to 50.14 hectare., Conclusion: The contribution of the habitats coupled with the increasing rate of flooded environment which could provide ample breeding sites for mosquitoes call for sustained environmental sanitation and management in Osogbo metropolis.

Background: The biting preference of Simulium vectors has been known to influence the distribution of Onchocerca nodules and microfilariae in human body. There is, however, variation in biting pattern of Simulium flies in different geographical locations. This study investigates the biting pattern on human parts by Simulium vectors along Osun river system where Simulium soubrense Beffa form has been implicated as the dominant vector and its possible implication on the distribution of Onchocerca nodules on human body along the river., Methods: Flies were collected by consented fly capturers on exposed human parts namely head/neck region, arms, upper limb and lower limb in Osun Eleja and Osun Budepo along Osun river in the wet season (August-September) and the dry season (November-December) in 2008. The residents of the communities were also screened for palpable Onchocerca nodules., Results: The results showed that number of flies collected below the ankle region was significantly higher than the number collected on other exposed parts (p <0.05) while the least was collected on head/neck region in both seasons. The lower trunk was the most common site (60%) for nodule location at Osun Eleja followed by upper trunk (40%). Nodules were not found in the head and limb regions. At Osun Budepo, the upper trunk was the most common site of the nodule location (53.8%) followed by the lower trunk (38.5%) and head region (7.7%)., Conclusion: Though, most of the flies were caught at the ankle region, the biting of other parts coupled with the presence of nodules at the head and upper trunk regions showed that Simulium vectors could obtain microfilariae from any part of the body, thus increasing the risk of onchocerciasis transmission.

The root and leaf extracts of four plants, Occimum gratissimum, Azadirachta indica, Pterocarpus santalinoides, and Pistia hyptis, were studied for repellent activities against the adults of Simulium damnosum sensu lato. The leaves and roots were extracted with 95% ethanol and the stocks were diluted with paraffin. The repellent activities of the extracts were investigated using human baits along the banks of River Oyan and River Ogun in southwestern Nigeria. The results showed that the root extract of O. grattissium and leaf extract of P. hyptis had highest repellent potentials with 78% and 78.1% protection against S. damnosum sensu lato, respectively, whereas the root and leaf of P. santalinoides recorded the least. Although there were significant differences in the percentage of protection of the extracts of the plants (p < 0.05), the variations in the percentage of protection of the leaf and root extracts were not statistically significant (p > 0.05). The study concludes that there exist some repellent efficacies in the extracts of the plants, most importantly O. grattissimum and P. hyptis. The plant extracts can further be developed in the prevention of man-vector contact in onchocerciasis endemic communities.