Survivorship Of Anopheles gambiae In Relation To Malaria Transmission In Ilorin, Nigeria

For the first time in Africa, an entomological study went beyond the conventional practice of determining parity and survival rates of field-collected adult anopheline mosquitoes but also related these variables to duration of Plasmodium sporogony and estimated the expectation of infective life. Blood-seeking female mosquitoes were collected in Ilorin, Nigeria, from January 2005 to December 2006, and dissected for ovarian tracheations following WHO recommended techniques. The results indicated an annual mean parous rate of 70.92%, and significantly higher parous rates in the rainy than dry season, which also had very low densities. Mean probability of daily survival of the mosquitoes was 0.80, with annual mean life expectancy of 12.24 days. The probability of surviving the sporogonic cycle was low (< 0.4) but the expectation of infective life was long, especially in the rainy season (mean = 8.31 days). The epidemiological implications of these results were discussed. The An. gambiae population in Ilorin is dominated by older mosquitoes with high survival rates thus, suggesting a high vector potential for the species in the area. These information on the survival rates of An. gambiae in relation to malaria transmission would enhance the development of a more focused and informed vector control interventions

Design and methods for a quasi-experimental pilot study to evaluate the impact of dual active ingredient insecticide-treated nets on malaria burden in five regions in sub-Saharan Africa

Background:Vector control tools have contributed significantly to a reduction in malaria burden since 2000, primar‑ily through insecticidal‑treated bed nets (ITNs) and indoor residual spraying. In the face of increasing insecticide resist‑ance in key malaria vector species, global progress in malaria control has stalled. Innovative tools, such as dual active ingredient (dual‑AI) ITNs that are effective at killing insecticide‑resistant mosquitoes have recently been introduced. However, large‑scale uptake has been slow for several reasons, including higher costs and limited evidence on their incremental effectiveness and cost‑effectiveness. The present report describes the design of several observational studies aimed to determine the effectiveness and cost‑effectiveness of dual‑AI ITNs, compared to standard pyre‑throid‑only ITNs, at reducing malaria transmission across a variety of transmission settings.Methods:Observational pilot studies are ongoing in Burkina Faso, Mozambique, Nigeria, and Rwanda, leveraging dual‑AI ITN rollouts nested within the 2019 and 2020 mass distribution campaigns in each country. Enhanced surveil‑lance occurring in select study districts include annual cross‑sectional surveys during peak transmission seasons, monthly entomological surveillance, passive case detection using routine health facility surveillance systems, and studies on human behaviour and ITN use patterns. Data will compare changes in malaria transmission and disease burden in districts receiving dual‑AI ITNs to similar districts receiving standard pyrethroid‑only ITNs over three years. The costs of net distribution will be calculated using the provider perspective including financial and economic costs, and a cost‑effectiveness analysis will assess incremental cost‑effectiveness ratios for Interceptor® G2, Royal Guard®, and piperonyl butoxide ITNs in comparison to standard pyrethroid‑only ITNs, based on incidence rate ratios calcu‑lated from routine data.Conclusions:Evidence of the effectiveness and cost‑effectiveness of the dual‑AI ITNs from these pilot studies will complement evidence from two contemporary cluster randomized control trials, one in Benin and one in Tanzania, to provide key information to malaria control programmes, policymakers, and donors to help guide decision‑making and planning for local malaria control and elimination strategies. Understanding the breadth of contexts where these dual‑AI ITNs are most effective and collecting robust information on factors influencing comparative effectiveness could improve uptake and availability and help maximize their impact

The lipid profile of the pallid emperor moth Cirina forda Westwood (Lepidoptera: Saturniidae) caterpillar

The phospholipid, cholesterol and triglyceride levels, as well as, the fatty acid profile of the caterpillar of Cirina forda , a pallid emperor moth, known for its popularity as a food insect in Nigeria, were elucidated and compared with other popular sources of lipids. C. forda had 554.96mg/100g, 201.01mg/100g and 244.03mg/100g of phospholipid, cholesterol and triglyceride, respectively. It proved to be a rich source of unsaturates, surpassing other popular lipid sources as a source of polyunsaturates. It is rich in fatty acids such as Linolenic acid (33.84%), Linoleic acid (7.81%) and Oleic acid (12.93%). The possible nutritional implications of the consumption of C. forda caterpillar on the human nervous system are highlighted

Surveillance and insecticide susceptibility status of Culicine mosquitoes in selected communities utilizing long-lasting insecticidal nets in Kwara state, Nigeria

Vector control programs in Nigeria are mostly targeted towards reducing the burden ofmalaria with less emphasis placed on other debilitating vector borne diseases such asdengue, yellow fever and filariasis. This study assessed the indoor resting densities andinsecticide susceptibility status of Culex and Aedes mosquitoes in selected communitiesutilizing long-lasting insecticidal nets (LLIN) in Kwara State, Nigeria. Pyrethrum spraycollections of indoor resting Aedes and Culex mosquitoes were conducted in threecommunities while adults of both mosquito species reared from larval collections wereexposed to pyrethroid, organochlorine, and carbamate insecticides following WHOprocedure. Results showed that the higher indoor resting densities of Culexquinquefasciatus (2.5 – 3.4) collected were not significantly (p&gt;0.05) different from theAedes aegypti (0.3 – 1.3) in all the communities. Carbamate resistance (≤ 81 % postexposure mortalities) was observed in both Culex (Ilota and Amoyo) and Aedespopulations (Gaa-Bolorunduro). Aedes in Gaa-Bolorunduro and Ilota were fullysusceptible (100 % mortality) to permethrin and DDT while the Culex population showeddifferential susceptibility (64 – 100%) to pyrethroid and organochlorine insecticidestested. These findings show focal insecticide resistance requiring specific intervention ineach community based on the evidence provided by this study. Pyrethroid resistancestatus of the Culex quinquefasciatus in these areas may result in access of the vectors tonet occupants leading to lower LLIN utilization rates among users. Environmentalmanagement strategy in addition to the use of effective insecticide will be most probablefor management of vector borne diseases in these localities.Keywords: Insecticide resistance, Aedes aegypti, Culex quinquefasciatus, LLIN, Dengue, LymphaticFilariasis, Kwara State, Nigeri

Spatial distribution and ecological niche modeling of geographical spread of Anopheles gambiae complex in Nigeria using real time data

Abstract 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