Evaluation of Lambda-Cyhalothrin Persistence on Different Indoor Surfaces in a Malaria Epidemic-Prone Area in Kenya

Mulambalah, Chrispinus Siteti; Siamba, D. N.; Ngeiywa, Moses; Vulule, John

doi:10.3923/rjbsci.2010.258.263

Cited by 12 publications

(10 citation statements)

References 8 publications

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“…The lower mortality rates observed on treated mud wall could also be due to less bioavailability of the insecticides on the sprayed surfaces. Studies from different countries such as Tanzania and Vietnam also found that the material of walls affected the durability of insecticides sprayed on the wall [ 16 , 50 – 53 ], a factor should be considered when choosing the insecticides for indoor residual spraying as many rural areas in tropical Africa are shifting from building mud walled houses to modern cemented houses. For example, studies in Tanzania with ICON 10 CS recorded 100 % mortality of An.…”

Section: Discussionmentioning

confidence: 99%

“…Mosquito resistance to insecticide, which reduces the efficacy of LLINs, has been intensively studied across Africa, and resistance has been detected in all major African malaria vectors and resistance to multiple classes of insecticides is not uncommon [ 4 – 15 ]. However, insecticides may lose their effectiveness due to chemical degradation over time and bioavailability of the insecticide on the sprayed surface which may be affected by the porosity of the sprayed surface [ 16 ]. Reduced effectiveness of ITN/LLIN and IRS control programs can contribute to an upsurge of malaria incidence [ 17 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

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Insecticidal decay effects of long-lasting insecticide nets and indoor residual spraying on Anopheles gambiae and Anopheles arabiensis in Western Kenya

et al. 2015

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BackgroundIndoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) are the first-line tools for malaria prevention and control in Africa. Vector resistance to insecticides has been extensively studied, however the insecticidal effects of the nets and sprayed walls on pyrethroid resistant mosquitoes has not been studied thoroughly. We evaluated the bioefficacy of LLINs of different ages and lambda-cyhalothrin (ICON 10cs) on the sprayed mud walls for a period of time on malaria vector survivorship.MethodsWHO tube bioassay was performed using diagnostic doses of lambda-cyhalothrin (0.05 %), permethrin (0.75 %) and deltamethrin (0.05 %). Cone bioassays were conducted on netting materials from 0 to 3 years old long-lasting insecticide-impregnated nets. Wall bioassays were performed monthly on mud slabs sprayed with lambdacyhalothrin over a period of seven months. All bioassays used An. gambiae mosquitoes collected from the field and the laboratory susceptible reference Kisumu strain. Concentration of the insecticides on the netting materials was examined using the gas chromatography method. Mosquitoes were identified to species level using PCR and genotyped for the kdr gene mutation frequencies.ResultsWHO bioassays results showed that populations from five sites were highly resistant to the pyrethroids (mortalities ranged from 52.5 to 75.3 %), and two sites were moderately resistant to these insecticides (80.4 – 87.2 %). Homozygote kdr mutations of L1014S ranged from 73 to 88 % in An. gambiae s.s. dominant populations whereas L1014S mutation frequencies were relatively low (7–31 %) in An. arabiensis dominant populations. There was a significant decrease (P < 0.05) in mosquito mortality with time after the spray with both lambda-cyhalothrin (75 % mortality after six months) and with the age of LLINs (60 % mortality after 24 month). Field collected mosquitoes were able to survive exposure to both IRS and LLINs even with newly sprayed walls (86.6–93.5 % mortality) and new LLINs (77.5–85.0 % mortality), Wild mosquitoes collected from the field had significantly lower mortality rates to LLINs (59.6–85.0 %) than laboratory reared susceptible strain (100 %). Insecticide concentration decreased significantly from 0.14 μg/ml in the new nets to 0.077 μg/ml in nets older than 18 months (P < 0.05).ConclusionThis study confirms that insecticide decay and developing levels of resistance have a negative contribution to reduced efficacy of ITN and IRS in western Kenya. These factors contribute to decreased efficacy of pyrethroid insectides in ongoing malaria control programs. In order to mitigate against the impact of insecticide resistance and decay it is important to follow the WHO policy to provide the residents with new LLINs every three years of use while maintaining a high level of LLINs coverage and usage. There is also need for urgent development and deployment of non-pyrethroid based vector control tools.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Insecticidal decay effects of long-lasting insecticide nets and indoor residual spraying on Anopheles gambiae and Anopheles arabiensis in Western Kenya

et al. 2015

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“…The residual efficacy and persistence of insecticide are known to be affected by several factors that include, but are not limited to, the nature of the sprayed surfaces (mud, wood, cement, thatched, etc.) [ 17 – 21 ], pH of the sprayed substrates [ 22 ], physicochemical properties of the sprayed insecticide (vapor pressure and volatility) [ 23 ], availability of degrading bacteria [ 20 ], insecticide formulation [wettable powder (WP), capsule suspension (CS), emulsifiable concentrate (EC), suspension concentrate (SC) or wettable granules (WG)] [ 7 , 24 , 25 ], the amount of insecticide deposited on sprayed surfaces [ 26 ], and temperature and humidity [ 19 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

Multi-country assessment of residual bio-efficacy of insecticides used for indoor residual spraying in malaria control on different surface types: results from program monitoring in 17 PMI/USAID-supported IRS countries

et al. 2018

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BackgroundIndoor residual spraying (IRS) is the application of insecticide to the interior walls of household structures that often serve as resting sites for mosquito vectors of malaria. Human exposure to malaria vectors is reduced when IRS involves proper application of pre-determined concentrations of the active ingredient specific to the insecticide formulation of choice. The impact of IRS can be affected by the dosage of insecticide, spray coverage, vector behavior, vector susceptibility to insecticides, and the residual efficacy of the insecticide applied. This report compiles data on the residual efficacy of insecticides used in IRS campaigns implemented by the United States President’s Malaria Initiative (PMI)/United States Agency for International Development (USAID) in 17 African countries and compares observed length of efficacy to ranges proposed in World Health Organization (WHO) guidelines. Additionally, this study provides initial analysis on variation of mosquito mortality depending on the surface material of sprayed structures, country spray program, year of implementation, source of tested mosquitoes, and type of insecticide.MethodsResidual efficacy of the insecticides used for PMI/USAID-supported IRS campaigns was measured in Benin, Burkina Faso, Ethiopia, Ghana, Kenya, Liberia, Madagascar, Malawi, Mali, Mozambique, Nigeria, Rwanda, Senegal, Tanzania, Uganda, Zambia and Zimbabwe. The WHO cone bioassay tests were used to assess the mortality rate of mosquitoes exposed to insecticide-treated mud, wood, cement, and other commonly used housing materials. Baseline tests were performed within weeks of IRS application and follow-up tests were continued until the mortality of exposed mosquitoes dropped below 80% or the program monitoring period ended. Residual efficacy in months was then evaluated with respect to WHO guidelines that provide suggested ranges of residual efficacy for insecticide formulations recommended for use in IRS. Where the data allowed, direct comparisons of mosquito mortality rates were then made to determine any significant differences when comparing insecticide formulation, country, year, surface type, and the source of the mosquitoes used in testing.ResultsThe residual efficacy of alpha-cypermethrin ranged from 4 to 10 months (average = 6.4 months), with no reported incidents of underperformance when compared to the efficacy range provided in WHO guidelines. Deltamethrin residual efficacy results reported a range of 1 to 10 months (average = 4.9 months), with two instances of underperformance. The residual efficacy of bendiocarb ranged from 2 weeks to 7 months (average = 2.8 months) and failed to achieve proposed minimum efficacy on 14 occasions. Lastly, long-lasting pirimiphos-methyl efficacy ranged from 2 months to 9 months (average = 5.3 months), but reported 13 incidents of underperformance.ConclusionsMuch of the data used to determine application rate and expected efficacy of insecticides approved for use in IRS programs are collected in controlled laboratory or pilot fiel...

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“…A good residual spraying should be long lasting on a given surface, such that any mosquito coming in contact will get a lethal dose and die. Therefore, the transmission of malaria is interrupted [3]. The insecticide toxicity should also remain high over a sufficiently long period to prevent the need for frequent re-application, which is costly and time-consuming.…”

Section: Introductionmentioning

confidence: 99%

Impact of Indoor Residual-Sprayed Deltamethrin on Different Surfaces in a Malaria Endemic Area in Balai Ringin, Sarawak

Raza¹,

Zamree²,

Ali³

et al. 2014

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Malaria control programme utilizing indoor residual spraying of chemical insecticide is only effective if a high coverage of targeted area is achieved. The effectiveness of the residual spraying, on the other hand, relies on the efficacy and residual activity of the insecticides applied, which to a certain extent are influenced by the nature of the sprayed surfaces. The bioefficacy of indoor residual-sprayed deltamethrin wettable granule (WG) formulation for the control of malaria was compared with the current dose of deltamethrin wettable powder (WP) in malaria endemic areas in Balai Ringin, Sarawak. Doses of 20 mg/m 2 WP (control), 20 mg/m 2 WG, 30 mg/m 2 WG and 40 mg/m 2 WG were sprayed separately on different surfaces namely, wooden, rough-bamboo, smooth-bamboo and brick surfaces. Residual activity of WP and WG formulations was tested against lab-bred Anopheles maculatus using WHO standard procedure. Deltamethrin at 30 mg/m 2 WG exhibited the highest sustainable level of effectiveness against An. maculatus (An. maculatus mortality was between 95%-100%) up to week 60 post-spraying when sprayed on smoothbamboo surface. These results indicated that 30 mg/m 2 WG could be an ideal concentration for controlling malaria vector effectively up to 15 months of which long-lasting residual spraying was envisaged. The usual two spraying cycles per year with 20 mg/m 2 deltamethrin WP could be replaced with 30 mg/m 2 deltamethrin WG since the long residual activity was achieved by employing a single spraying only.

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Evaluation of Lambda-Cyhalothrin Persistence on Different Indoor Surfaces in a Malaria Epidemic-Prone Area in Kenya

Cited by 12 publications

References 8 publications

Insecticidal decay effects of long-lasting insecticide nets and indoor residual spraying on Anopheles gambiae and Anopheles arabiensis in Western Kenya

Insecticidal decay effects of long-lasting insecticide nets and indoor residual spraying on Anopheles gambiae and Anopheles arabiensis in Western Kenya

Multi-country assessment of residual bio-efficacy of insecticides used for indoor residual spraying in malaria control on different surface types: results from program monitoring in 17 PMI/USAID-supported IRS countries

Impact of Indoor Residual-Sprayed Deltamethrin on Different Surfaces in a Malaria Endemic Area in Balai Ringin, Sarawak

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