Browsing by Author "Abiodun Obembe"

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    ABUNDANCE AND DIVERSITY OF NON-MOSQUITO INSECTS OF IMPORTANCE FOUND DURING MOSQUITO SURVEILLANCE IN SELECTED RURAL HOUSES IN KWARA STATE, NIGERIA
    (2021) Abiodun Obembe
    ABSTRACT: Insects control interventions in rural communities usually focus on malaria mosquitoes, neglecting other inimical entomological species. This study gives an account of abundance and diversity of non-mosquito insects of importance found during Pyrethrum Spray Collection (PSC) of endophilic mosquitoes in two rural communities in Kwara State, Nigeria. Non-mosquito insects found during mosquito surveillance in the two communities between August and October 2014 were collected and identified. Webbing clothes moths Tineola spp and Phorid flies Megaselia spp represented at least 20% of the non-mosquito insect species collected in each community. Phorid flies (28.8%), clothes moths (28.2%), silverfish Lepisma spp (38.7%) and carpenter ants Camponotus spp (4.3%) were found in both communities. Association of phorid flies with human myiasis and potential economic damage the cloth moth and silverfish could bring to scarcely available resources such as clothing and starch-based materials call for the sensitization of rural community residents on the economic importance of these insects. Indoor residual spraying of insecticides which is usually conducted against mosquitoes may as well control these other insects. However, improved housing and living conditions remain the permanent solution.
  • Thumbnail Image
    Item
    Genetic identity, human blood indices, and sporozoite rates of malaria vectors in Gaa-Bolorunduro, Kwara State, Nigeria
    (2022) Abiodun Obembe
    Abstract Introduction: To identify the specific Anopheles mosquito sibling species responsible for malaria transmission, determine their vectorial potential, and predict suitable control measures, this study investigated genetic identities, human blood feeding, and sporozoite infection rates of endophilic Anopheles mosquitoes in Gaa-Bolorunduro, a cattle rearing community in Kwara State, Nigeria. Methodology: Monthly pyrethrum spray collections of Anopheles mosquitoes were conducted for one year in addition to PCR characterization of sibling species and ELISA probing of human blood meal and sporozoite infections. Mean numbers and human blood indices (HBI) of the different Anopheles sibling species identified were compared. Results: The total of 668 PCR-identified mosquitoes comprised 50.8% An. arabiensis, 46.7% An. gambiae, and 2.5% An. coluzzii. Annual mean numbers of An. arabiensis was significantly higher (p = 0.001) than An. coluzzii but not An. gambiae (p = 0.602). Proportions of An. arabiensis found with human blood (0.29) were lower compared to An. gambiae (0.72) and An. coluzzii (0.75). However, the annual mean HBI of An. arabiensis was not significantly higher than An. gambiae (p = 0.195) and An. coluzzii (p = 0.249). Plasmodium falciparum sporozoite infection rate was 1.6% in An. gambiae, 0.9% in An. arabiensis and 0% in An. coluzzii. Conclusions: The prevalent An. arabiensis and An. gambiae mosquitoes found indoors, despite the outdoor cattle population barrier, could be targeted by community-scale utilization of long-lasting insecticide-treated bed nets. Further studies on outdoor mosquito surveillance and bovine blood meal identification are required for the recommendation of suitable complementary vector control measures for the community.
  • Thumbnail Image
    Item
    Lessons from the implementation of LLIN distribution campaign in Ilorin Kwara State, Nigeria
    (http://www.biomedcentral.com/1471-2458/14/514, 2014) Abiodun Obembe
    Abstract Background: Studies implemented to evaluate the success of Long-lasting insecticidal nets (LLIN) distribution campaigns are often limited to ownership and utilization rates, neglecting other factors that directly affect the efficacy of the tool in malaria control. This study investigates sleeping habits and net maintenance behaviour in addition to LLIN ownership, utilization and the challenges associated with LLIN use among residents in Ilorin City where the tool has been massively distributed. Methods: A cross-sectional survey was conducted using pre-tested interviewer-administered questionnaire to obtain information from randomly selected household respondents in Ilorin, the Kwara State Capital. The study was conducted in July 2012, about sixteen months after the March 2011 distribution of LLIN in the locality. The results were analyzed using the EPI INFO 2007 version. Results: LLIN ownership (85%) and utilization (37%) rates improved compared to earlier reports, though 29% of net users have noticed holes in the nets even as 26% claimed to have actually experienced mosquito bites under it. Most (92%) of the respondents who slept under LLIN the previous night before the study spent the first five hours of the night (19.00-23.00 hr) outdoors while 88% also engage in inappropriate net washing practices. All the LLIN users claimed to have experienced at least one malaria episode while 43% have had two or more episodes within the past twelve months. Conclusion: The use of LLIN among the respondents in this study was accompanied by chancy sleeping habits, inappropriate net maintenance practices and repeated experience of mosquito bites under the nets. This shows the need to sustain the will and confidence of LLIN users in this area through frequent monitoring and surveillance visits targeted at enlightening the people on habits that increase malaria exposure risks as well as proper use and maintenance of LLIN for maximum malaria vector control benefits. Keywords: Malaria, Long-lasting insecticidal nets, Sleeping habits, LLIN maintenance
  • Thumbnail Image
    Item
    Malathion and Pirimiphosmethyl susceptibility of bendiocarb resistant Anopheles gambiae s.l. mosquito populations in urban Lagos, Nigeria
    (2021) Abiodun Obembe
    Abstract: This study assessed susceptibility status of Anopheles mosquito populations to organophosphate insecticides in selected areas within Lagos metropolis. The study also provides an update on the earlier established Anopheles mosquito resistance to some insecticides such as pyrethroids and carbamate. Adult Anopheles mosquito populations reared from larval collections at natural breeding sites in Yaba and Lekki areas in Lagos were exposed to World Health Organization (WHO) insecticide test papers. The insecticides used for the test include: two organophosphates (Malathion and Pirimiphos methyl), two pyrethroids (deltamethrin and permethrin) and one carbamate (bendiocarb). All the mosquitoes used in this study were identified as An. gambiae sensu lato. Results from the study showed that Anopheles populations from the two sites were fully susceptible (100% mortality rates) to the organophosphates (Malathion and Pirimiphos methyl). The Anopheles populations exhibited resistance to pyrethroid (permethrin and deltamethrin) (≤ 60% mortality rates) and carbamate bendiocarb (≤ 38% mortality rates). The resistance levels were higher compared to the reports of earlier studies.
  • Thumbnail Image
    Item
    Mind the weather: a report on inter-annual variations in entomological data within a rural community under insecticide-treated wall lining installation in Kwara State, Nigeria
    (biomedcentral, 2018) Abiodun Obembe
    Abstract Background: Entomological indices within a specific area vary with climatic factors such as rainfall, temperature and relative humidity. Contributions of such weather parameter fluctuations to the changes in entomological data obtained within a community under implementation of a promising vector control intervention should be taken into account. This study reports on inter-annual changes in entomological indices within two rural communities, one of which was under insecticide-treated durable wall lining (DL) installation. Methods: Community-wide DL installation was followed by monthly meteorological data and pyrethrum spray mosquito collections for 2 years in intervention and a similar neighbouring community (control). Human blood meal and sporozoite ELISA tests were conducted on female mosquitoes collected alongside PCR identification of subsamples. Mosquitoes collected at the intervention site were tested in cone susceptibility assays against subsamples of installed DL materials collected on a 6-monthly basis for 2 years. Deltamethrin susceptibility of Anopheles mosquitoes from the intervention site was determined before and after DL installation. Entomological indices in the first and second years were compared within each site. Results: Rainfall in the study area increased significantly (t = -3.45, df = 11, P = 0.005) from first to second year. Correlation between rainfall and Anopheles densities in both sites were significant (r = 0.681, P < 0.001). Mosquitoes collected at the intervention site were susceptible (100%) to deltamethrin at baseline but resistant (92%) in the second year. However, subsamples of installed DL materials remained effective (100% mortality) against Anopheles mosquitoes from the intervention site throughout the 6-monthly cone assay exposures. Monthly pyrethrum spray collections showed significant increase in Anopheles densities from first to second year in the control (6.36 ± 1.61 vs 7.83 ± 2.39; t = -3.47, df = 11, P = 0.005), but not in the intervention (2.83 ± 1.86 vs 4.23 ± 3.31; t = -2.03, df = 11, P = 0.067) community. However, mean annual mosquito man-biting rates increased significantly in both intervention (0.88 ± 0.18 vs 1.06 ± 0.38; F(1, 10) = 9.50, P = 0.012) and control (1.45 ± 0.31 vs 1.61 ± 0.34; F(1, 10) = 10.18, p = 0.010) sites along with increase (≥ 1.6 times) in sporozoite rates within intervention (0–2.13%) and control (2.56–4.04%) communities. Conclusions: The slight increase in vector density, induced by significant increase in rainfall, led to increased sporozoite infection and significantly increased man-biting rates within the intervention site. These reveal the need for incorporation of integrated vector management strategies to complement DL installation especially in regions with high rainfall and mosquito density. Promising vector control tools such as DL should be evaluated on a long-term basis to reveal the possible effect of weather parameters on control performance and also allow for holistic recommendations.
  • Thumbnail Image
    Item
    Molecular characterization and Plasmodium falciparum transmission risks of Anopheles mosquitoes in Malete, Nigeria
    (2023) Abiodun Obembe
    ABSTRACT. Introduction: Studies on malaria vector surveillance are useful for evidence-based control in specific communities. Such studies are lacking in Malete, a rapidly growing peri-urban community in Nigeria. Objective: To assess sibling species identity, human blood indices, and Plasmodium falciparum transmission risks by Anopheles mosquitoes, in Malete. Methods: I collected endophilic mosquitoes quarterly from inhabited houses using the pyrethrum spray catch technique. I identified the mosquitoes, and probed for the presence of human blood and P. falciparum, using standard PCR and ELISA methods, respectively. Results: Anopheles mosquitoes (90%) were the most abundant compared to Culex (10%) and Mansonia (0,5%). Specifically, A. gambiae (85%) were predominant over A. coluzzii (11%) and A. arabiensis (3%). The Anopheles sibling species had generally high human blood indices (≥0,82). However, A. gambiae man-biting rates (0,92-3,64) were higher than A. coluzzii (0-0,84) and A. arabiensis (0-0,27). Plasmodium falciparum sporozoite infection (3%) was found only in A. gambiae. Conclusion: While P. falciparum infection was 3%, long-lasting insecticidal nets should be deployed for control in Malete, particularly of A. gambiae.
  • Thumbnail Image
    Item
    Significant 24 h recovery and survival of Culex mosquitoes exposed to pyrethroid insecticides using the CDC bottle bioassay
    (2023) Abiodun Obembe
    Insecticides deployed for mosquito vector control rely on the susceptibility of the targeted vector population for continued efficacy and public health protection. The Centers for Disease Control and Prevention (CDC) bottle bioassay is a standard method used for rapid mosquito insecticide resistance assessment without measuring sublethal or delayed insecticidal effects. Ignored sublethal or delayed mortality effects may affect the accuracy of susceptibility test outcomes and appropriateness of insecticide selection decisions. This study found significant recovery and survival among Culex mosquito populations initially immobilized after pyrethroid insecticide exposures using the CDC bottle bioassay. Adult female Culex mosquitoes, reared from three different larval collection sites, were exposed to x1 and x2 intensities of deltamethrin and alphacypermethrin insecticides using the CDC bottle bioassay method. Exposed mosquitoes were held for 24 hours for comparison of 30 min exposure time and 24 h post-exposure mortalities. Subsamples of exposed mosquitoes were identified with Polymerase Chain Reaction (PCR) technique. For both x1 (P ≤ 0.009) and x2 (P ≤ 0.048) insecticide intensities, the percentage mosquito mortalities at 30 min exposure time (20-24%, 21-27%) reduced significantly after the 24 h postexposure period (3-9%, 6-13%) respectively. However, after both 30 min (P ≥ 0.475) and 24 h (P ≥ 0.090) periods, mosquito mortalities at x2 intensity (21-27%, 6-13%) were not significantly higher than mortality at x1 (20-24%, 3-9%). All PCR-identified samples were found to be Culex quinquefasciatus. The significantly reduced mortality at 24 h post exposure time indicates delayed recovery and survival of mosquitoes, usually not captured when using the CDC bottle bioassay method. This result provides evidence to suggest further discussions and review of the CDC bottle bioassay procedures for improved measure of mosquito susceptibility/resistance.