Genetic analysis of molecular markers is critical in tracking the emergence and/or spread of artemisinin resistant parasites. Clinical isolates collected in western Kenya pre- and post- introduction of artemisinin combination therapies (ACTs) were genotyped at SNP positions in regions of strong selection signatures on chromosome 13 and 14, as described in Southeast Asia (SEA). Twenty five SNPs were genotyped using Sequenom MassArray and pfmdr1 gene copy number by real-time PCR. Parasite clearance half-life and in vitro drug sensitivity testing were performed using standard methods. One hundred twenty nine isolates were successfully analyzed. Fifteen SNPs were present in pre-ACTs isolates and six in post-ACTs. None of the SNPs showed association with parasite clearance half-life. Post-ACTs parasites had significantly higher pfmdr1 copy number compared to pre-ACTs. Seven of eight parasites with multiple pfmdr1 were post-ACTs. When in vitro IC50s were compared for parasites with single vs. multiple gene copies, only amodiaquine and piperaquine reached statistical significance. Data showed SNPs on chromosome 13 and 14 had different frequency and trend in western Kenya parasites compared SEA. Increase in pfmdr1 gene copy is consistent with recent studies in African parasites. Data suggests genetic signature of artemisinin resistance in Africa might be different from SEA.

Euclea divinorum, a fast establishing, unpalatable, and fire resistant bush is considered an invasive species in some parts of its range. In Ol Pejeta Conservancy (OPC), Kenya, E. divinorum bushes cover ˜27% of the total area (˜9470 ha.) and has been expanding in coverage and encroaching into A. drepanolobium woodlands, a key woody habitat for the endangered black rhino. Between 2006 and 2010, we assessed the spatial distribution, annual rates of spread and recruitment of E. divinorum in OPC. We used data from satellite imagery and belt transects laid at the transition between E. divinorum habitat and other habitats. Density of E. divinorum seedlings increased by 27% annually over five years, with more seedlings establishing in grassland habitat (56.6%) than in A. drepanolobium woodland (43.4%). Within the infection frontier, the number of seedlings was high at the ecotone and reduced predictably with an increase in distance into the infection zone. Increase in rainfall facilitated recruitment and survival of E. divinorum seedlings and also reduced damage on trees and seedlings by mega‐herbivores, especially elephants. This study confirms the encroachment of E. divinorum bushland into other habitats. This has been accelerated by burning and damage to A. drepanolobium habitat thus opening it up to encroachment by E. divinorum.

BACKGROUND Assessing the infectious reservoir is critical in malaria control and elimination strategies. We conducted a longitudinal epidemiological study in a high malaria burden region in Kenya to characterize transmission in an asymptomatic population. METHODS 488 study participants encompassing all ages in 120 households within 30 clusters were followed for one year with monthly sampling. Malaria was diagnosed by microscopy and molecular methods. Transmission potential in gametocytemic participants were assessed using direct skin and/or membrane mosquito feeding assays, then treated with artemether-lumefantrine. Study variables were assessed using mixed-effects generalized linear models. RESULTS Asexual and sexual parasite data was collected from 3,792 participant visits, with 903 linked with feeding assays. Univariate analysis revealed that 6-11-year old age-group were at higher risk of harboring asexual and sexual infections than the less than 6-year-old (Odds Ratio [OR] 1.68, p < 0.001 and OR 1.81, p < 0.001), respectively. Participants with submicroscopic parasitemia were at a lower risk of gametocytemia compared to microscopic (OR 0.04, p < 0.001), but they transmitted at a significantly higher rate (OR 2.00, p = 0.002). A large proportion of the study population was continuously infected (despite treatment) with asexual (71.7%, 291/406) or sexual (37.4%, 152/406) parasites. 89.4% (365/408) of feeding assays conducted in individuals who failed treatment the previous month resulted in transmissions. CONCLUSION Individuals with asymptomatic infection sustain the transmission cycle, with the 6-11-year old age-group serving as an important reservoir. The high rates of artemether-lumefantrine treatment failures suggest surveillance programs using molecular methods need to be expanded for accurate monitoring and evaluation of treatment outcomes.