Papers by Abiodun Obembe PhD
Pan African Journal of Life Sciences
Background: Male mosquito control through swarm spraying and Attractive Toxic Sugar Baits (ATSB) ... more Background: Male mosquito control through swarm spraying and Attractive Toxic Sugar Baits (ATSB) have been identified as potential strategies to complement the regular but insufficient female mosquito-based insecticide-treated net (ITN) approach. However, the effectiveness of these control strategies relies on under-standing the insecticide susceptibility status of the targeted male and female mosquito populations. Therefore, this study aimed to assess the insecticide susceptibility status of male and female An. gambiae s.l. Popu-lations in urban Ilorin, Nigeria. Methods: Using WHO kits and protocol, adult male and female mosquitoes reared from the same larval col-lections from different sites were exposed separately to permethrin, deltamethrin, and alphacypermethrin insecticides. Joint insecticide susceptibility tests, involving exposures of equal numbers of male and female mosquitoes to each insecticide, were also conducted in anticipation of joint insecticide exposure on the fiel...
Journal of Applied Sciences and Environmental Management, 2022
Entomological data gathering is essential for monitoring malaria vector disease risks and selecti... more Entomological data gathering is essential for monitoring malaria vector disease risks and selection of appropriate interventions for the protection of exposed human populations. This study assessed the relative abundance, species composition, and sporozoite infection rates of indoor resting An. gambiae s.l. malaria vectors in six communities across 3 Local Government Areas in Kwara State, Nigeria. Total number of mosquitoes collected by Pyrethrum Spray Catch method over a period of eighth months were correlated with rainfall values in the area. Plasmodium falciparum sporozoite infection rates and sibling species identification of collected An. gambiae s.l. mosquito samples were determined by ELISA and PCR respectively. Results showed a positive correlation (r = 0.639, p = 0.08) between rainfall and numbers of Anopheles mosquitoes in the study areas. The overall composition of the An. gambiae s.l sibling species in the collected samples from all the six communities showed the predomi...
Insecticides deployed for mosquito vector control rely on the susceptibility of the targeted vect... more 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.
Background: Male mosquito control through swarm spraying and Attractive Toxic Sugar Baits (ATSB) ... more Background: Male mosquito control through swarm spraying and Attractive Toxic Sugar Baits (ATSB) have been identified as potential strategies to complement the regular but insufficient female mosquito-based insecticide-treated net (ITN) approach. However, the effectiveness of these control strategies relies on understanding the insecticide susceptibility status of the targeted male and female mosquito populations. Therefore, this study aimed to assess the insecticide susceptibility status of male and female An. gambiae s.l. Populations in urban Ilorin, Nigeria. Methods: Using WHO kits and protocol, adult male and female mosquitoes reared from the same larval collections from different sites were exposed separately to permethrin, deltamethrin, and alphacypermethrin insecticides. Joint insecticide susceptibility tests, involving exposures of equal numbers of male and female mosquitoes to each insecticide, were also conducted in anticipation of joint insecticide exposure on the field. Exposed mosquitoes were identified to species level. Results: Higher kdt 50 s (52.5-641.3mins) and lower mortalities (permethrin 39-62%, deltamethrin 57-68%, alphacypermethrin 44-60%), indicating higher levels of resistance, were observed for the females compared to the male (22.1-42.2 mins, 60-94%) mosquitoes. The percentage mortalities of males (71-94%) were significantly (P ≤ 0.043) higher than those of the jointly exposed females (39-62%). However, separately exposed male mosquito mortalities (60-81%) were not significantly (P ≥ 0.067) higher than the females (55-68%). All the male mosquito populations were resistant to permethrin (75-94% mortality), deltamethrin (60-82%), and alphacypermethrin (74-86%) insecticides after joint and separate exposures. Resistant male and female mosquitoes were identified predominantly as An. arabiensis (74-84%). Conclusion: Multiple pyrethroid insecticide resistance detected in the male and female mosquito populations indicates the potential ineffectiveness of pyrethroid-based swarm spraying, pyrethroid ATSB and ITNs in the study location
PubMed, Dec 1, 2011
Background & objectives: An efficient larvivorous fish must show a predilection for mosquito larv... more Background & objectives: An efficient larvivorous fish must show a predilection for mosquito larvae in the presence of alternative preys. This study compares the feeding capacity and preference of Aphyosemion gularis exposed to different kinds of aquatic macroinvertebrates. Methods: Various prey organisms such as Anopheles larvae and pupae, Culex larvae, chironomid larvae and ostracods were either singly and/or jointly presented at different densities to the fish and the number of prey consumed in 12 h light and dark periods were recorded. Results: The result showed that in terms of capacity and preference, the fish significantly consumed (p <0.05) more Anopheles larvae than pupae and more Anopheles larvae compared to Culex and chironomid larvae. It was also found that the fish preferred Culex larvae to chironomids larvae while significantly (p < 0.05) more Anopheles larvae were consumed compared to the more abundant ostracods. Conclusion: The results indicate that A. gularis is adapted to feed more on Anopheles than Culex larvae on one hand and generally preferred mosquito larvae to non - mosquito macroinvertebrates. The implication of this observation is that the presence of other non - mosquito organisms considered in this study is unlikely to divert the attention of the fish from mosquito larvae, especially Anopheles larvae. The fact that the fish are able to feed on some of the non - mosquito organisms such as chironomids and ostracods, means that they can subsist on these organisms in the absence of mosquito larvae.
UNED Research Journal
Introduction: Studies on malaria vector surveillance are useful for evidence-based control in spe... more 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...
Journal of Allergy & Infectious Diseases
scientific reports
The need for evidence‑based data, to inform policy decisions on malaria vector control interventi... more 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.
Asian journal of ethnobiology, Jun 17, 2021
Tropical Biomedicine, 2020
Studies profiling community and zonal malaria entomological risk indices are required to identify... more Studies profiling community and zonal malaria entomological risk indices are required to identify high risk areas where targeted control resources are most needed or likely to have the greatest impact on reducing risk of malaria infection. This study presents a first report on malaria vector risk indices in two vegetation zones within Adamawa state, Nigeria. Endophilic mosquitoes were collected for one year in selected communities in the Guinea and Sudan savanna zones within the State. Plasmodium falciparum Sporozoite and human blood meal ELISA assays were carried out on the female Anopheles mosquitoes collected. Sibling species composition of the An. gambiae complex were determined using PCR assays. Mean numbers of mosquitoes in the Guinea savanna communities were significantly (t = 7.73, DF = 11, p < 0.001) higher than the Sudan. Man-biting rates (F = 2.76, p = 0.13) of Anopheles mosquitoes were higher in the Guinea but not significantly different from Sudan savanna. Sporozoite rates of mosquitoes within the Guinea savanna were 2.7 times higher than the Sudan. The predominant Anopheles coluzzii species encountered in the state had higher overall human blood indices (0.63) and sporozoite rates (6.9%) compared to An. gambiae (0.39, 1.9%) and An. arabiensis (0.58, 2.3%) respectively. Overall annual human blood indices (0.59) of mosquitoes in Adamawa were lower compared to reports from other States. Prevalence and higher transmission risks indices of endophilic An. coluzzii mosquitoes reveal the need for LLIN and management of relatively permanent An. coluzzii breeding sites in the State. Widespread cattle rearing lifestyle and lower human blood indices of mosquitoes in the study area suggest the need to investigate cattle blood indices of the mosquitoes in the state. Higher entomological risk indices in the Guinea Savanna zone provide baseline information for prioritization of malaria vector control supplies within the State.
International Journal of Recycling of Organic Waste in Agriculture, 2014
Background Over the years, the use of organic materials in farming has reduced due to the increas... more Background Over the years, the use of organic materials in farming has reduced due to the increase in the use of chemical fertilizers which are rich in readily available plant nutrients. Intensive use of inorganic fertilizers may have depressing effect on yield of watermelon. Field experiment was conducted at the Teaching and Research Farm, Kwara State University Malete, Kwara State, Nigeria, to study the effects of different rates of Organomineral fertilizer Grade A, un-amended compost Grade B and NPK mineral fertilizer on the growth and yield of Citrullus lanatus. Results There were significant differences (P \ 0.05) among the treatments in relation to vine length, number of leaves, average weight of fruits and yield. NPK at 200 kg/ ha had the highest vine length of 294.67 cm followed by organomineral fertilizer Grade A applied at 2.5 t/ha which had the value of 268.0 cm. Un-amended compost Grade B at 1.5, 2.0 and 2.5 t/ha had vine length values of 257.7, 259.0 and 259.7, respectively. All the fertilizer treatments significantly (P \ 0.05) had higher number of leaves than control. The highest fruit yield of watermelon (36.7 t/ha) was obtained from organomineral fertilizer Grade A at 2.5 t/ha and NPK. Conclusion From this study, the use of organomineral fertilizer in the cultivation of watermelon could be used as alternative to mineral fertilizer, although cost effective but difficult to procure and cannot substantially redress the physical fragility of the soil. It is recommended that organomineral fertilizer Grade A at 2.5 t/ha be adopted for watermelon cultivation in the study area.
The Journal of Infection in Developing Countries
Introduction: To identify the specific Anopheles mosquito sibling species responsible for malaria... more 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. ar...
Technoscience Journal for Community Development in Africa, 2021
This study assessed susceptibility status of Anopheles mosquito populations to organophosphate in... more 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.
J Infect Dev Ctries, 2022
Introduction: To identify the specific Anopheles mosquito sibling species responsible for malaria... more 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.
International Journal of Current Research and Applied Studies, 2022
ABSTRACT
Background: Malaria microscopy remains the gold standard for the diagnosis of malaria. ... more ABSTRACT
Background: Malaria microscopy remains the gold standard for the diagnosis of malaria. However, lack of laboratory consumables, standard microscopes and expertise in malaria microscopy, especially in the rural areas with high malaria transmission, limits its deployment. Rapid Diagnostic tests (RDT) which are alternatives to the gold standard must however be evaluated in comparison with the microscopy before massive deployment of such RDT product in the field. This study evaluated two RDT products (CareStart TM and Nova) using blood sample of symptomatic and asymptomatic health care seeking individual in a health care center in Ilorin. Capacities of the products were compared with the microscopy in the diagnosis of malaria.
Methods: A total of 122 blood samples were collected through venipuncture of post-cubical veins of the patients using a syringe. The blood samples collected from each patient were transferred to a clean prelabeled bottle containing ethylenediaminetetra acetic acid (EDTA). Two RDT products: CareStart TM Pf and Nova Pf/Pv were purchased for evaluation or comparison with microscopy.
Results: Overall, 122 health care seeking individuals were examined. The sensitivity and specificity forPlasmodium falciparum malaria were 47% and 82%, respectively for CareStartTM RDT while 52% and 83% were for Nova RDT respectively. There was no significant difference (p>0.05) in the sensitivity and specificity between the two RDTs. The positive and negative predictive values of the two test kits were not significantly different: CareStartTM (87% and 37%), Nova (90% and 36%). The Nova RDT however, performed better than the CarestartTM though with a close margin.
Conclusion: The two RDT products could be used as the first screening test for malaria diagnosis thereby improving on the current situation of treating patients for malaria without laboratory outcome to confirm clinical evaluation.
J. Appl. Sci. Environ. Manage., 2021
Entomological data gathering is essential for monitoring malaria vector disease risks and selecti... more Entomological data gathering is essential for monitoring malaria vector disease risks and selection of appropriate interventions for the protection of exposed human populations. This study assessed the relative abundance, species composition, and sporozoite infection rates of indoor resting An. gambiae s.l. malaria vectors in six communities across 3 Local Government Areas in Kwara State, Nigeria. Total number of mosquitoes collected by Pyrethrum Spray Catch method over a period of eighth months were correlated with rainfall values in the area. Plasmodium falciparum sporozoite infection rates and sibling species identification of collected An. gambiae s.l. mosquito samples were determined by ELISA and PCR respectively. Results showed a positive correlation (r = 0.639, p = 0.08) between rainfall and numbers of Anopheles mosquitoes in the study areas. The overall composition of the An. gambiae s.l sibling species in the collected samples from all the six communities showed the predominance of An. gambiae s.s 298 (75.3%) compared to An. coluzzii 94(23.7%) and An. arabiensis 4(1.0%). However, the sporozoite infection rate of An. coluzzii (22.3%) was higher compared to An. gambiae s.s (12.8%) and An. arabiensis (0%). Mean numbers of An. gambiae s.l mosquitoes were significantly higher in Ilorin west LGA compared to Asa (F = 17.81, P < 0.001) and Ilorin East LGAs (F = 22.81, P < 0.001). Sporozoite rates of both An. gambiae s.s and An. coluzzii sibling species were higher in Ilorin West communities (Aiyede 21%, Ogundele 32%) compared to Asa (Idi Emi 11.1%, Lasoju 5.1%) and Ilorin East (Oke Oyi 2.4%, Ote-efan 0%) communities. Prevalence of sporozoite-infected An. gambiae s.s and An. coluzzii indoors highlight the need for effective insecticide treated bed-nets interventions to protect the residents from malaria risks. Higher numbers of An. coluzzii in the swampy rice marshed Ilorin West LGA communities require larval source management as an additional strategy for effective malaria vector control.
Background Plant oils possess biological activities which offer tremendous potential for disease ... more Background Plant oils possess biological activities which offer tremendous potential for disease vector management. This study investigated the bioactivity of selected insecticidal plant oils against Anopheles gambiae s.s. Kisumu Susceptible Strain (KSS) mosquitoes. The plant oils from leaves of Hyptis suaveolens, Ocimum gratissimum, Nicotiana tabacum, Ageratum conyzoides and fruit peels of Citrus sinensis were extracted and the major chemical components analysed using coupled gas chromatography-mass spectrometry (GC-MS). The spatial toxicity effects of the plant oils were tested at different concentration (0.1 mg/ml, 0.3 mg/ml and 0.5 mg/ml) against An. gambiae s.s. KSS in a Peet-Grady Chamber. Deltamethrin was used as the positive control. Results D-Limonene was the major chemical component found in Ci. sinensis and Ni. tabacum. Prococene I was the major chemical component in Oc. gratissimum while P-Xylene had the highest percent composition in Ni. tabacum. The control (Deltamethr...
Table S3. Insecticide susceptibility results. Number of dead/alive mosquitoes at the end of holdi... more Table S3. Insecticide susceptibility results. Number of dead/alive mosquitoes at the end of holding period (24 h). (DOCX 13 kb)
Table S2. Human blood indices of female Anopheles mosquitoes in the intervention and control comm... more Table S2. Human blood indices of female Anopheles mosquitoes in the intervention and control communities. (DOCX 17 kb)
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Papers by Abiodun Obembe PhD
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.
Background: Malaria microscopy remains the gold standard for the diagnosis of malaria. However, lack of laboratory consumables, standard microscopes and expertise in malaria microscopy, especially in the rural areas with high malaria transmission, limits its deployment. Rapid Diagnostic tests (RDT) which are alternatives to the gold standard must however be evaluated in comparison with the microscopy before massive deployment of such RDT product in the field. This study evaluated two RDT products (CareStart TM and Nova) using blood sample of symptomatic and asymptomatic health care seeking individual in a health care center in Ilorin. Capacities of the products were compared with the microscopy in the diagnosis of malaria.
Methods: A total of 122 blood samples were collected through venipuncture of post-cubical veins of the patients using a syringe. The blood samples collected from each patient were transferred to a clean prelabeled bottle containing ethylenediaminetetra acetic acid (EDTA). Two RDT products: CareStart TM Pf and Nova Pf/Pv were purchased for evaluation or comparison with microscopy.
Results: Overall, 122 health care seeking individuals were examined. The sensitivity and specificity forPlasmodium falciparum malaria were 47% and 82%, respectively for CareStartTM RDT while 52% and 83% were for Nova RDT respectively. There was no significant difference (p>0.05) in the sensitivity and specificity between the two RDTs. The positive and negative predictive values of the two test kits were not significantly different: CareStartTM (87% and 37%), Nova (90% and 36%). The Nova RDT however, performed better than the CarestartTM though with a close margin.
Conclusion: The two RDT products could be used as the first screening test for malaria diagnosis thereby improving on the current situation of treating patients for malaria without laboratory outcome to confirm clinical evaluation.
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.
Background: Malaria microscopy remains the gold standard for the diagnosis of malaria. However, lack of laboratory consumables, standard microscopes and expertise in malaria microscopy, especially in the rural areas with high malaria transmission, limits its deployment. Rapid Diagnostic tests (RDT) which are alternatives to the gold standard must however be evaluated in comparison with the microscopy before massive deployment of such RDT product in the field. This study evaluated two RDT products (CareStart TM and Nova) using blood sample of symptomatic and asymptomatic health care seeking individual in a health care center in Ilorin. Capacities of the products were compared with the microscopy in the diagnosis of malaria.
Methods: A total of 122 blood samples were collected through venipuncture of post-cubical veins of the patients using a syringe. The blood samples collected from each patient were transferred to a clean prelabeled bottle containing ethylenediaminetetra acetic acid (EDTA). Two RDT products: CareStart TM Pf and Nova Pf/Pv were purchased for evaluation or comparison with microscopy.
Results: Overall, 122 health care seeking individuals were examined. The sensitivity and specificity forPlasmodium falciparum malaria were 47% and 82%, respectively for CareStartTM RDT while 52% and 83% were for Nova RDT respectively. There was no significant difference (p>0.05) in the sensitivity and specificity between the two RDTs. The positive and negative predictive values of the two test kits were not significantly different: CareStartTM (87% and 37%), Nova (90% and 36%). The Nova RDT however, performed better than the CarestartTM though with a close margin.
Conclusion: The two RDT products could be used as the first screening test for malaria diagnosis thereby improving on the current situation of treating patients for malaria without laboratory outcome to confirm clinical evaluation.