Synergistic mosquito-repellent activity of Curcuma longa, Pogostemon heyneanus and Zanthoxylum limonella essential oils

Mosquito repellents play an important role in preventing man-mosquito contact. In the present study, we evaluated the synergistic mosquito-repellent activity of Curcuma longa, Pogostemon heyneonus and Zanthoxylum Iimonella essential oils. The mosquito repellent efficacies of three essential oils were evaluated separately and in combination under laboratory and field conditions. N,N-Diethylphenylacetamide [DEPA] and dimethylphthalate [DMP] were used for comparison of the protection time of the mixture of essential oils. At an optimum concentration of 20%, the essential oils of C. longa, Z. Iimonella and P. heyneanus provided complete protection times [CRTs] of 96.2, 91.4 and 123.4min, respectively, against Aedes albopictus mosquitoes in the laboratory. The 1:1:2 mixture of the essential oils provided 329.4 and 391.0min of CPT in the laboratory and field trials, respectively. The percent increases in CPTs for the essential oil mixture were 30 for DMP and 55 for N,N-diethylphenylacetamide [DEPA]. The synergistic repellent activity of the essential oils used in the present study might be useful for developing safer alternatives to synthetic repellents for personal protection against mosquitoes

Culminating anti-malaria efforts at long lasting insecticidal net?

Long-lasting insecticidal nets [LLINs] are a primary method in malaria control efforts. However, a decline in the biological efficacy and physical integrity over a period of comparatively lesser time than claimed, waning of naturally acquired immunity among regular users and misuse of LLINs are serious concerns. The literature for the current review was searched in PubMed, SCOPUS Database and Google using combined search strings of related key-words. Literature with sufficient data and information on the current subject was selected to reach a valid conclusion. The World Health Organization [WHO] has emphasized that LLINs should be considered a public good for people inhabiting malaria endemic settings. LLINs exhibited a cumulative effect on the vector density and may force anthropophilic mosquito vectors to find alternative animal hosts for blood meal. However, the physical integrity and biological activity of LLINs declines faster than the anticipated time due to different operational conditions and the spread of insecticide resistance. LLINs have been successful in reducing malaria incidences by either reducing or not allowing human exposure to the vector mosquitoes, but at the same time, LLINs debilitate the natural protective immunity against malaria parasite. Misuse of LLINs for deviant purposes is common and is a serious environmental concern, as people believe that traditional methods of prevention against malaria that have enabled them to survive through a long time are effective and sufficient. Moreover, people are often ill-informed regarding the toxic effects of LLINs. Specific criteria for determining the serviceable life and guidelines on the safe washing and disposal of LLINs need to be developed, kept well-informed and closely monitored. Malaria case management, environment management and community awareness to reduce the misuse of LLINs are crucial. Focused research on developing effective anti-malarial drugs, vaccines and new insecticides to reduce resistance is imperative to tackle malaria in the future

Chemotherapy and drug resistance status of malaria parasite in northeast India

India reports the highest number of malaria cases in Southeast Asia, of which Plasmodium falciparum contribute more than half of the cases every year. North eastern states of India contribute only 3.96% of country's population but account for >10% of total reported malaria cases, 11% of Plasmodium falciparum cases and 20% of malaria related deaths annually. In India, chloroquine resistance was reported for the first time from northeast region and since then chloroquine treatment failure is being reported from many parts of the region. Increased chloroquine treatment failure has led to change of the drug policy to artemisinin combination therapy as first line of malaria treatment in the region. However, replacing chloroquine to artemisinin combination therapy has not shown significant difference in the overall malaria incidence in the region. The present review addresses the current malaria situation of northeastern region of India in the light of antimalarials drug resistance.

Field evaluation of repellency of a polyherbal essential oil against blackflies and its dermal toxicity using rat model

In the present study we have evaluated the repellent activity of mixture of Curcuma longa, Zanthoxylum limonella and Pogostemon heyneanus essential oils in 1:1:2 ratio at 5%, 10% and 20% concentration against blackflies in northeastern India. Initially the essential oil mixture tested here has been found effective against Aedes albopictus mosquitoes. The average protection recorded in 20% concentration (170.56±4.0; 95% CI = 162.09-179.02) was higher as compared to other two concentrations (F = 90.2; p<0.0001; df = 53). Percentage repellency and repellency index was found to be higher in 20% concentration (p<0.017). No appreciable clinical and behavioral signs were observed in the acute dermal toxicity using rat model. No changes were observed in biochemical profiles of treatment group animals. Similarly, no prominent lesions were observed in vital organs of treatment in both the sexes. The study concludes that tested repellent is safe for use and has multi-insects repellent property.