Coagulation-flocculation: a potential application for mosquito Larval Source Management (LSM)

Acta Tropica ◽  
2021 ◽  
Vol 213 ◽  
pp. 105748
Author(s):  
Xin-Ran Li ◽  
Min-Sheng Huang ◽  
Pei-En Leng ◽  
Xin-Yu Lu ◽  
Bing Xiao
2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Salum A. Mapua ◽  
Marceline F. Finda ◽  
Ismail H. Nambunga ◽  
Betwel J. Msugupakulya ◽  
Kusirye Ukio ◽  
...  

Abstract Background Larval source management was historically one of the most effective malaria control methods but is now widely deprioritized in Africa, where insecticide-treated nets (ITNs) and indoor residual spraying (IRS) are preferred. However, in Tanzania, following initial successes in urban Dar-es-Salaam starting early-2000s, the government now encourages larviciding in both rural and urban councils nationwide to complement other efforts; and a biolarvicide production-plant has been established outside the commercial capital. This study investigated key obstacles and opportunities relevant to effective rollout of larviciding for malaria control, with a focus on the meso-endemic region of Morogoro, southern Tanzania. Methods Key-informants were interviewed to assess awareness and perceptions regarding larviciding among designated health officials (malaria focal persons, vector surveillance officers and ward health officers) in nine administrative councils (n = 27). Interviewer-administered questionnaires were used to assess awareness and perceptions of community members in selected areas regarding larviciding (n = 490). Thematic content analysis was done and descriptive statistics used to summarize the findings. Results A majority of malaria control officials had participated in larviciding at least once over the previous three years. A majority of community members had neutral perceptions towards positive aspects of larviciding, but overall support for larviciding was high, although several challenges were expressed, notably: (i) insufficient knowledge for identifying relevant aquatic habitats of malaria vectors and applying larvicides, (ii) inadequate monitoring of programme effectiveness, (iii) limited financing, and (iv) lack of personal protective equipment. Although the key-informants reported sensitizing local communities, most community members were still unaware of larviciding and its potential. Conclusions The larviciding programme was widely supported by both communities and malaria control officials, but there were gaps in technical knowledge, implementation and public engagement. To improve overall impact, it is important to: (i) intensify training efforts, particularly for identifying habitats of important vectors, (ii) adopt standard technical principles for applying larvicides or larval source management, (iii) improve financing for local implementation and (iv) improve public engagement to boost community awareness and participation. These lessons could also be valuable for other malaria endemic areas wishing to deploy larviciding for malaria control or elimination.


2021 ◽  
Author(s):  
Dumisani Mfipa ◽  
Mphatso Kamndaya ◽  
Kingsley Lungu

Abstract BackgroundLimited studies have compared determinants of household knowledge of split and grouped mosquito larval source management (LSM) methods. Thus, we compared determinants of household knowledge of split and grouped mosquito LSM methods for malaria control in Malawi. MethodsA cross-sectional study was conducted among 479 households in Nthache, Mwanza district, Malawi. Household knowledge of mosquito LSM methods; draining stagnant water, larviciding, clean environment and clearing grass/bushes were assessed by using a validated structured household questionnaire administered to an adult household member. Chi-square test was used to compare the distribution of household knowledge of each of the split and grouped mosquito LSM methods. Multivariable logistic regression was used to examine factors associated with household knowledge of each of the split and grouped mosquito LSM methods. ResultsHousehold knowledge of draining stagnant water was lower than high-level knowledge of grouped mosquito LSM methods (32.9% versus 83.5%, p=0.000). Household knowledge of clearing grass/bushes was lower than high-level knowledge of grouped mosquito LSM methods (8.2% versus 77.7%, p=0.000). Household knowledge of clean environment was lower than high-level knowledge of grouped mosquito LSM methods (21.8% versus 63.8%, p=0.000). No significant differences were observed between knowledge of larviciding and high-level knowledge of grouped mosquito LSM methods (4.1% versus 5.8%, p=0.421). Respondents without education had 57% less the odds of having knowledge of draining stagnant water than those with primary education (AOR=0.43, 95% CI 0.26-0.69). Those from iron-roofed households and the widowed had three and more than four times the odds of having knowledge of larviciding than those from grass-thatched households and the married (AOR=3.03, 95% CI 1.26-7.29 and AOR=4.73, 95% CI 1.34-16.73), respectively. ConclusionsExcept for larviciding, household knowledge of grouped mosquito LSM methods was significantly higher than split methods. Policy for integrated vector management should address determinants of split mosquito LSM methods to improve household knowledge.


2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Kimberley McLaughlin ◽  
Thomas R. Burkot ◽  
Jance Oscar ◽  
Nigel W. Beebe ◽  
Tanya L. Russell

Abstract Background In the Solomon Island, the dominant malaria vector, Anopheles farauti, is highly anthropophagic and increasingly exophilic and early biting. While long-lasting insecticide-treated nets remain effective against An. farauti, supplemental vector control strategies will be needed to achieve malaria elimination. Presently, the only World Health Organization recommended supplemental vector control strategy is larval source management (LSM). Effective targeted larval source management requires understanding the associations between abiotic, chemical and biological parameters of larval habitats with the presence or density of vector larvae. Methods Potential and actual An. farauti larval habitats were characterized for presence and density of larvae and associated abiotic, chemical and biological parameters. Results A third of all sampled potential habitats harboured An. farauti larvae with 80% of An. farauti positive habitats being in three habitat classifications (swamps/lagoons, transient pools and man-made holes). Large swamps were the most abundant positive habitats surveyed (43% of all An. farauti positive habitats). Habitats with An. farauti larvae were significantly associated with abiotic (pH, nitrate, ammonia and phosphate concentrations and elevated temperature) and biotic (predators) parameters. Conclusion Large swamps and lagoons are the largest and most abundant An. farauti habitats in the Solomon Islands. Positive habitats were more frequently associated with the presence of predators (vertebrates and invertebrates) and higher water temperatures. Cohabitation with predators is indicative of a complex habitat ecosystem and raises questions about the potential of biological control as an effective control strategy. Increased presence of An. farauti with higher water temperature suggests a potential explanation for the coastal distribution of this species which is not found inland at elevated altitudes where temperatures would be cooler.


2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Susan S Imbahale ◽  
Andrew Githeko ◽  
Wolfgang R Mukabana ◽  
Willem Takken

Author(s):  
Nina Berlin Rubin ◽  
Leonard E.G. Mboera ◽  
Adriane Lesser ◽  
Marie Lynn Miranda ◽  
Randall Kramer

Microbial larviciding can be an effective component of integrated vector management malaria control schemes, although it is not commonly implemented. Moreover, quality control and evaluation of intervention activities are essential to evaluate the potential of community-based larviciding interventions. We conducted a process evaluation of a larval source management intervention in rural Tanzania where local staff were employed to apply microbial larvicide to mosquito breeding habitats with the aim of long-term reductions in malaria transmission. We developed a logic model to guide the process evaluation and then established quantitative indicators to measure intervention success. Quantitative analysis of intervention reach, exposure, and fidelity was performed to assess larvicide application, and interviews with larviciding staff were reviewed to provide context to quantitative results. Results indicate that the intervention was successful in terms of reach, as staff applied microbial larvicide at 80% of identified mosquito breeding habitats. However, the dosage of larvicide applied was sufficient to ensure larval elimination at only 26% of sites, which does not meet the standard set for intervention fidelity. We propose that insufficient training and protocol adaptation, environment and resource issues, and human error contributed to low larvicide application rates. This demonstrates how several small, context-specific details in sum can result in meaningful differences between intervention blueprint and execution. These findings may serve the design of other larval source management interventions by demonstrating the value of additional training, supervision, and measurement and evaluation of protocol adherence.


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