Protective efficacy of menthol propylene glycol carbonate compared to N, N-diethyl-methylbenzamide against mosquito bites in Northern Tanzania

Abstract

BackgroundThe reduction of malaria parasite transmission by preventing human-vector contact is critical in lowering disease transmission and its outcomes. This underscores the need for effective and long lasting arthropod/insect repellents. Despite the reduction in malaria transmission and outcomes in Tanzania, personal protection against mosquito bites is still not well investigated. This study sought to determine the efficacy of menthol propylene glycol carbonate (MR08), Ocimum suave as compared to the gold standard repellent N, N-diethyl-methylbenzamide (DEET), either as a single dose or in combination (blend), both in the laboratory and in the field against Anopheles gambiae s.l and Culex quinquefasciatus.MethodsIn the laboratory evaluations, repellents were applied on one arm while the other arm of the same individual was treated with a base cream. Each arm was separately exposed in cages with unfed female mosquitoes. Repellents were evaluated either as a single dose or as a blend. Efficacy of each repellent was determined by the number of mosquitoes that landed and fed on treated arms as compared to the control or among them. In the field, evaluations were performed by human landing catches at hourly intervals from 18:00 hr to 01:00 hr.ResultsA total of 2,442 mosquitoes were collected during field evaluations, of which 2,376 (97.30%) were An. gambiae s.l while 66 (2.70%) were Cx. quinquefaciatus. MR08 and DEET had comparatively similar protective efficacy ranging from 92% to 100 for both single compound and blends. These findings indicate that MR08 has a similar protective efficacy as DEET for personal protection outside bed nets when used singly and in blends. Because of the personal protection provided by MR08, DEET and blends as topical applicants in laboratory and field situations, these findings suggest that, these repellents could be used efficiently in the community to complement existing tools. Overall, Cx. quinquefasciatus were significantly prevented from blood feeding compared to An. gambiae s.l.ConclusionThe incorporation of these topical repellents for protection against insect bites can be of additional value in the absence or presence of IRS and ITNs coverage. However, a combination of both the physical (bed nets) and the repellent should be used in an integrated manner for maximum protection, especially before going to bed. Additional research is needed to develop repellents with longer duration of protection.

Biting patterns and seasonality of anopheles gambiae sensu lato and anopheles funestus mosquitoes in Kamuli District, Uganda

“…Malaria vector feeding and resting behaviours are likely to have changed to maximize available feeding opportunities [27]. In the present study, outdoor biting densities of An.…”

Toxicity of essential oil from Indian borage on the larvae of the African malaria vector mosquito, Anopheles gambiae

“…Targeting the mosquito larval stage by using non synthetic or alternative larvicides can be of significant impact as larvae cannot move from breeding sites [5]. In recent years, searching for new mosquito control agents from natural sources such as essential oil has gained recognition among researchers in countries with a renowned biodiversity and large numbers of plants/essential oils have been reported to possess larvicidal and repellent activity [6-8]. …”

Insecticide Resistance in East Africa — History, Distribution and Drawbacks on Malaria Vectors and Disease Control

“…More innovative vector control strategies including control of resistant vector populations in the sub-region are use of entomopathogenic fungi [35,36], larval source management [7] and vector trapping [37][38][39]. Plant-based derivatives have also been used in vector control in Uganda [40], Tanzania [41][42][43], Kenya [44,45] and Ethiopia [46][47][48].…”

“…In monitoring and management of resistance, the use of two or more tools or combinations of interventions simultaneously is an option in insecticide resistance management. The use of tools targeting adults such as LLINs and implementation of IRS or vise versa or combined with larviciding or larval source reduction is shown to have effects on vector control in Kenya [26,124], Tanzania [43,79,113], Uganda [125] and Ethiopia [126].…”