Implementing a larviciding efficacy or effectiveness control intervention against malaria vectors: key parameters for success

Abstract

During the last decade, scale-up of vector control tools such as long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) contributed to the reduction of malaria morbidity and mortality across the continent. Because these first line interventions are now affected by many challenges such as insecticide resistance, change in vector feeding and biting behaviour, outdoor malaria transmission and adaptation of mosquito to polluted environments, the World Health Organization recommends the use of integrated control approaches to improve, control and elimination of malaria. Larviciding is one of these approaches which, if well implemented, could help control malaria in areas where this intervention is suitable. Unfortunately, important knowledge gaps remain in its successful application. The present review summarises key parameters that should be considered when implementing larviciding efficacy or effectiveness trials.

Opinions of key stakeholders on alternative interventions for malaria control and elimination in Tanzania

“…In Tanzania for example, housing improvement was linked to significant historical declines of malaria in Dar es Salaam [39], and was likely a major factor in more than 99% decline in malaria in Ifakara town, the main town in the area of our study [33] Larval source management Larval source management (LSM) refers to environmental manipulations to target mosquito larval habitats [13]. LSM can include the use of larvicides as well as environmental management methods [13,14,40]. In Tanzania, large-scale larviciding resulted in 21% reduction in malaria prevalence in Dar es Salaam between 2006 and 2008 [41].…”

“…Several complementary vector control interventions are currently being discussed as possible candidates to accelerate the malaria elimination efforts [12]. Examples include: (a) larval source management (LSM), including larviciding and environmental management [13,14], (b) topical repellents for personal protection [15,16], (c) mass drug administration with endectocides such as ivermectin [17,18], (d) use of mosquito modification techniques, either to suppress or replace vector populations [19,20], (e) outdoor targeting of male mosquitoes through insecticide-spraying of mosquito swarms [21][22][23], (f ) housing improvement measures such as better window screening and improved house designs [24][25][26], (g) spatial repellents able to protect multiple individuals over wide areas [27,28], (h) attractive toxic sugar baits targeting sugar-seeking mosquitoes [29,30], and (i) mosquito-killing fungal spores and toxins [31,32].…”

Geographically extensive larval surveys reveal an unexpected scarcity of primary vector mosquitoes in a region of persistent malaria transmission in western Zambia

“…Larviciding targets mosquitoes when they are con ned to aquatic habitats, irrespective of future adult feeding and resting behaviours; this not only avoids behavioural resistance, but also circumvents increasing resistance to insecticides used in ITNs and IRS, which is a global concern [8,64,74,78,79,80,81]. Modelling and other analyses suggest that larviciding is more effective if targeted [81,82,83,84], notwithstanding that it is untargeted, blanket applications of larval source management that have been historically successful (e.g.…”

Opinions of key stakeholders on alternative interventions for malaria control and elimination in Tanzania

“…Larval source management Larval source management (LSM) refers to environmental manipulations to target mosquito l environmental management methods (13,14,41). In Tanzania, large-scale larviciding resulted 2006 and 2008 (42).…”

“…Several complementary vector control interventions are currently being discussed as possible candidates to accelerate the malaria elimination efforts (12). Examples include: a) larval source management (LSM), including larviciding and environmental management (13,14), b) topical repellents for personal protection (15,16), c) mass drug administration with endectocides such as ivermectin (17,18), d) use of mosquito modification techniques, either to suppress or replace vector populations (19,20), e) outdoor targeting of male mosquitoes through insecticide-spraying of mosquito swarms (21)(22)(23), f) housing improvement measures such as better window screening and improved house designs (24-26), g) spatial repellents able to protect multiple individuals over wide areas (27,28), h) attractive toxic sugar baits targeting sugar-seeking mosquitoes (29,30) and i) mosquito-killing fungal spores and toxins (31,32).…”