Chemical composition and larvicidal activity of essential oil of Lippia kituiensis against larvae of Rhipicephalus appendiculatus

This study evaluated the larvicidal activity of essential oil of Lippia kituiensis leaves against larvae of Rhipicephalus appendiculatus. The oil was obtained by hydro-distillation of fresh leaves and analysed using Gas Chromatography-Mass Spectrometry (GC-MS). Analysis showed that sesquiterpenes were dominant (56.57%), followed by monoterpenes (36.36%), diterpenes (2.59%) and others (5.19%). Major sesquiterpenes were germacrene D, β-bourbonene, gamma cadinene and 2-isopropyl-5-methyl-9-methylene-bicycle (4.4.0)dec-1-ene. Major monoterpenes were (1S, 4S)-(-)-camphor, trans-sabinene hydrate, gamma-terpinene, dl-limonene, alpha-terpinolene, l-Phellandrene, beta-Myrcene, sabinene, camphene, alpha-pinene, 4-terpineol, 4-methyl-1-(1-methylethyl)-3-cyclohexen-1-ol, 14.29 borneol (=endo-borneol), camphore, and neo-alloocimene. At 6, 12, 24, and 48 hrs after larval treatment, the oil showed activity against R. appendiculatus larvae with LC50in mg/ml of 3.26(3.14-3.38), 3.21(3.08-3.32), 3.15(3.03-3.26), 3.09(2.97-3.20) while LC90in mg/ml were 4.15 (3.95-4.45), 4.03 (3.85-4.30), 3.94 (3.77-4.19), 3.86 (3.69-4.09) respectively. Results of one way ANOVA (Analysis of Variance) showed there was no significant difference in activity of the oil against the larvae, between 6, 12, 24 and 48 hrs in all the concentrations used P = 0.97, 95% confidence. The findings indicatedthat essential oil of L. kituiensis possessed larvicidal properties and can be used to control tick larvae.Keywords: Rhipicephalus appendiculatus; essential oils; acaricidal activity, ticks

Verbal autopsy as a tool for identifying children dying of sickle cell disease : a validation study conducted in Kilifi district, Kenya

Background: Sickle cell disease (SCD) is common in many parts of sub-Saharan Africa (SSA), where it is associated with high early mortality. In the absence of newborn screening, most deaths among children with SCD go unrecognized and unrecorded. As a result, SCD does not receive the attention it deserves as a leading cause of death among children in SSA. In the current study, we explored the potential utility of verbal autopsy (VA) as a tool for attributing underlying cause of death (COD) in children to SCD. Methods: We used the 2007 WHO Sample Vital Registration with Verbal Autopsy (SAWY) VA tool to determine COD among child residents of the Kilifi Health and Demographic Surveillance System (KHDSS), Kenya, who died between January 2008 and April 2011. VAs were coded both by physician review (physician coded verbal autopsy, PCVA) using COD categories based on the WHO International Classification of Diseases 10(th) Edition (ICD-10) and by using the InterVA-4 probabilistic model after extracting data according to the 2012 WHO VA standard. Both of these methods were validated against one of two gold standards: hospital ICD-10 physician-assigned COD for children who died in Kilifi District Hospital (KDH) and, where available, laboratory confirmed SCD status for those who died in the community. Results: Overall, 6% and 5% of deaths were attributed to SCD on the basis of PCVA and the InterVA-4 model, respectively. Of the total deaths, 22% occurred in hospital, where the agreement coefficient (AC(1)) for SCD between PCVA and hospital physician diagnosis was 95.5%, and agreement between InterVA-4 and hospital physician diagnosis was 96.9%. Confirmatory laboratory evidence of SCD status was available for 15% of deaths, in which the AC(1) against PCVA was 87.5%. Conclusions: Other recent studies and provisional data from this study, outlining the importance of SCD as a cause of death in children in many parts of the developing world, contributed to the inclusion of specific SCD questions in the 2012 version of the WHO VA instruments, and a specific code for SCD has now been included in the WHO and InterVA-4 COD listings. With these modifications, VA may provide a useful approach to quantifying the contribution of SCD to childhood mortality in rural African communities. Further studies will be needed to evaluate the generalizability of our findings beyond our local context