Effect of Bendiocarb (Ficam^®80% WP) on Entomological Indices of Malaria Transmission by Indoor Residual Spraying in Burkina Faso, West Africa

Context: The vector control is essential in malaria prevention strategies in several endemic countries in Africa including Burkina Faso. The high transmission of malaria occurs during the period of high vector abundance (August to October) in Burkina Faso. Therefore, a vector control strategy based on the use of indoor residual spraying targeting this period should provide effective protection against malaria. This study aimed to evaluate the effect of bendiocarb applied in indoor residual spraying on entomological parameters of malaria transmission in a pyrethroid resistance area in southwestern, Burkina Faso. Methods: CDC light trap and early morning collections by pyrethrum spray catches were performed monthly to determine the change in entomological parameter within malaria vector in sprayed (Diebougou) and unsprayed sites (Dano). The female’s malaria vectors collected by both methods were used to determine their blood feeding pattern, biting and sporozoites rates as well as the malaria transmission risk estimated by entomological inoculation rate. Results: A total of 26,276 mosquitoes (13,555 anopheline and 12,721 other culicines) were collected using both CDC light trap (9158 mosquitoes) and PSC collection methods (17,118 mosquitoes) from June to December 2012. An. gambiae complex was the predominant species collected. An. gambiae was the predominant species collected (P = 0.0005), comprising 88% of the total collected and the most infected species. Malaria vectors densities were significantly lower in sprayed villages (n = 4303) compared with unsprayed villages (n = 12,569) during post-spraying period (P = 0.0012). In addition, mean human biting rate of An. gambiae s.l. and An. funestus s.l. were significantly lower in sprayed areas compared to unsprayed areas (P < 0.05). Overall, malaria vector transmission risk was significant four-fold lower in villages which received IRS (P = 0.0001) whatever the malaria vectors species (An. gambiae s.l. and An. An. funestus s.l.). Conclusions: The results showed that in the sprayed area (Diebougou), vector densities, human biting rates and malaria transmission risks were very lower than unsprayed areas (Dano). The findings also showed a change in vector behavior especially within An. funestus s.l. which became more zoophagic following IRS. The indoor residual spraying could be promoted as a control tool in areas where malaria transmission occurs during a given period of year.

Geographical Reconnaissance of Household in Northern Nigeria towards Optimizing Indoor Residual Spraying Method for Malaria Elimination

As a part of an effort to roll back malaria in Nigeria, exploring the use of geographically related tools triggered the use of modern approaches of knowing the spatial distribution of target populations to attain significant malaria elimination intervention. GIS tool was used for geographical reconnaissance (GR), providing demographic data on respondents’ household and spatial information on the distribution of households in the selected location. A cross-sectional study design was used to collect spatial data in the two locations, while a quantitative questionnaire was used to collect the household data. The analysis of field data indicated that 49,500 unique households were enumerated and thus included in the Indoor Residual Spraying to prevent malaria infection, covering 424 towns in the two Local Government Areas (LGAs). 383,301 persons were recorded during the GR exercise in Doma and Nassarawa Eggon LGAs out of which 79,339 were children of agesless than five years, with 13,526 pregnant women. Further data analysis revealed that the average number of persons per household in both LGAs was approximately eight. The spatial information from the GR provides a foundation for an updateable database for any future survey for developmental activities in Nigeria. The use of modern GR approach has proved to be accurate, reliable and more cost effective and less cumbersome than the traditional approach in the collection and geo-positioning of household data. Use of Garmin e-Trex GPS handheld instruments to collect household data in the designated areas removed the constraints of expensive Personal Digital Assistants and reduced errors of wrong location coordinates. Several African countries which did not use GR or applied the use of Geospatial tool appropriately had setbacks. The previous study in other countries showed limitations which was characterized by substantial inherent logistical and technical challenges culminating in missed targets. This setback was addressed in our study.

Effectiveness of indoor residual spraying on malaria control: a systematic review and meta-analysis

Background:Indoor residual spraying(IRS)is one of the key interventions recommended by World Health Organization in preventing malaria infection.We aimed to conduct a systematic review and meta-analysis of global studies about the impact of IRS on malaria control.Method:We searched PubMed,Web of Science,Embase,and Scopus for relevant studies published from database establishment to 31 December 2021.Random-effects models were used to perform meta-analysis and subgroup analysis to pool the odds ratio(OR)and 95%confidence interval(CI).Meta-regression was used to investigate potential factors of heterogeneity across studies.Results:Thirty-eight articles including 81 reports and 1,174,970 individuals were included in the meta-analysis.IRS was associated with lower rates of malaria infection(OR=0.35,95%CI:0.27-0.44).The significantly higher effectiveness was observed in IRS coverage≥80%than in IRS coverage<80%.Pyrethroids was identified to show the greatest performance in malaria control.In addition,higher effectiveness was associated with a lower gross domestic product as well as a higher coverage of IRS and bed net utilization.Conclusions:IRS could induce a positive effect on malaria infection globally.The high IRS coverage and the use of pyrethroids are key measures to reduce malaria infection.More efforts should focus on increasing IRS coverage,developing more effective new insecticides against malaria,and using multiple interventions comprehensively to achieve malaria control goals.

Insecticide resistance in phlebotomine sandflies in Southeast Asia with emphasis on the Indian subcontinent

Background:Visceral leishmaniasis,commonly known as kala-azar in India,is a global public health problem.In Southeast Asia,Bangladesh,Bhutan,India,Nepal,Sri Lanka and Thailand are endemic for visceral leishmaniasis.The role of sandflies as the vector of kala-azar was first confirmed in 1942 in India.Insecticide resistance in Phlebotomus argentipes Annandale and Brunetti,the vector of kala-azar in the Indian subcontinent,was first reported in 1987 in Bihar,India.This article provides a scoping review of the studies undertaken from 1959 to 2015 on insecticide resistance in P.argentipes and P.papatasi(Scopoli),the vectors of visceral and cutaneous leishmaniasis respectively,in Southeast Asia,mainly in Bangladesh,India,Nepal and Sri Lanka.Results:Studies undertaken in areas of Bihar and West Bengal in India where kala-azar is endemic have reported resistance of P.argentipes to DDT,while in non-endemic areas it has been reported to be susceptible.In areas of Nepal bordering India,there are indications of resistance to DDT;biochemical resistance has been reported in Sri Lanka.No laboratory studies have been undertaken in Bangladesh;however,the sandfly vector is reported to be still susceptible to pyrethroids in all kala-azar endemic areas in the aforementioned countries.Conclusions:Studies are needed to determine the resistance of sandfly vectors to all available classes of potential insecticides in kala-azar endemic areas.There is a need to assess the impact of indoor residual spraying with DDT and pyrethroids on the incidence of kala-azar in India where 54 districts remain endemic for the disease,strengthen entomological surveillance capacity,and develop and implement an insecticide management plan.Alpha-cypermethrin indoor residual spraying has been introduced in 33 kala-azar endemic districts in Bihar State of India in a pilot trial;the outcomes should be used to inform decisions on expanding coverage with alpha-cypermethrin in all remaining endemic districts to achieve the revised goal of elimination of visceral leishmaniasis by 2020.