Acaricidal activity of the essential oils from Citrus hystrix (Rutaceae) and Cymbopogon citratus (Poaceae) on the cattle tick Rhipicephalus (Boophilus) microplus larvae (Acari: Ixodidae)

@# Rhipicephalus (Boophilus) microplus serves as an important ectoparasite of livestock and a vector of several pathogens resulting in diseases, subsequently affecting the agricultural field as well as the economy. The extensive use of synthetic acaricides is known to cause resistance over time and therefore a much safer, effective and environmentally friendly alternative to overcome tick infestation should be implemented. Larval immersion tests (LIT) were done to evaluate the effects of Citrus hystrix (Family: Rutaceae) and Cymbopogon citratus (Family: Poaceae) essential oils (EOs) for their individual and combined (1:1) acaricidal activity against the cattle tick. Results showed that LC50 and LC90 values in 24 and 48 hours for Cit. hystrix EO were 11.98% and 24.84%, and 10.95% and 21.71% respectively. LC50 and LC90 values for Cym. citratus EO were 1.21% and 6.28%, and 1.05% and 6.12% respectively. The mixture of EOs from two plants in 1:1 ratio (Cit. hystrix 50%: Cym. citratus 50%) was found to exhibit antagonistic effect (synergistic factor < 1). The 24 hours and 48 hours LC50 and LC90 values for combined EOs were 1.52% and 2.84%, and 1.50% and 2.76% respectively. Individual and combined essential oils were subjected to qualitative analysis using gas chromatography-mass spectrometry (GC-MS) to screen the chemical components present in EOs. Our results showed that the combination of Cit. hystrix and Cym. citratus at 1:1 ratio resulted in an antagonistic effect and the use of Cym. citratus alone is more toxic to R. (B.) microplus, making it a better alternative to chemical based acaricide.

Seroprevalence of toxoplasmosis among migrant workers from different Asian countries working in Malaysia.

A serologic study of Toxoplasma antibodies among 501 foreign migrant workers in Malaysia was conducted in a plantation and detention camp. The highest prevalence rate of 46.2% was among Nepalese workers. Statistical analysis indicated the IgG positivity rate among local residents was significantly higher than the migrants studied (p < 0.05). The IgM positivity rate showed no significant difference between the two groups (p > 0.05). No significant difference in the prevalence rate was noted between the migrants and the local workers when grouped by agricultural and non-agricultural occupations (p > 0.05). The continuous introduction of these infections may influence the epidemiology and further compromise efforts in control and prevention. It is therefore important to monitor of non-notifiable diseases.