Vector-Borne Disease Epidemiology and Vector Biology
Dr. Yan's lab members:
Dr. Guofa Zhou, Associate Scientist
Dr. Daibin Zhong, Associate Scientist
Dr. Ming-Chieh (Alex) Lee, Assistant Scientist
Dr. Solomon Kibret, Postdoc fellow
Dr. Elizabeth Hemming, Postdoc fellow
Dr. Chloe Wang, Postdoc fellow
Dr. Randy David, Postdoc fellow
Lauren Bradley, PhD student
Grace Choi, Project coordinator
Dr. Eugene Li, Visiting Scholar
Ecology of African Highland Malaria
Malaria is a major public health problem in sub-Saharan Africa. The East African highlands (1,500m above sea level) were either free of malaria or had very low incidences; however, since late 1980s malaria epidemics have frequently occurred in some highland areas. We examine the mechanisms leading to the resurgence of malaria in African high-elevation areas, including climate, land use, topography and antimalarial drug resistance in the Plasmodium parasites. We found that deforestation and swamp reclamation affect microclimatic and nutritional conditions of larval habitats, increase the survivorship of malaria vectors at larval and adult stages, shorten the development time of malaria parasites, and significantly increase mosquito vectorial capacity. We are developing models to predict the spread of malaria infections in an epidemic, and evaluating new malaria vector control methods for outdoor transmission control.
Molecular Epidemiology of vivax Malaria in Ethiopia
Vivax malaria is the most geographically widespread human malaria, causing tremendous suffering and major negative effects on economic productivity. African blacks or people with African ancestry, are thought to be protected from Plasmodium vivax infection because their lack of Duffy antigen expression on the surface of the erythrocytes renders P. vivax unable to invade the erythrocytes. However, recent studies challenge this conventional wisdom, raising the possibility that that some lineages of P. vivax may have evolved to use receptors other than Duffy for erythrocyte invasion. However, the epidemiological significance of vivax infection in Duffy-negative individuals is unknown. Furthermore, there is no information on the evolutionary history and infection diversity of P. vivax in Duffy-negative individuals. We are examining the molecular epidemiology and population genetics of P. vivax in endemic southwestern Ethiopia. Specifically we determined the prevalence of asymptomatic infections and the incidence of symptomatic malaria due to P. vivax in Duffy-negative and Duffy-positive individuals and are examining the role of mutations in PvDBP gene and gene copy numbers in vivax infections in Duffy-negative people.
Population Biology of African Malaria Vectors
We are interested in 1) larval population regulation of Anopheles gambiae and An. funestus mosquito, 2) outdoor malaria transmission, and 3) pyrethroid resistance. Previously, we have determined green algae are important food source for anopheline larvae. We are currently determining the species composition of green algae in larval habitats and identifying the gut contents of mosquito larvae using the pyrosequencing technique. Using bioassays we determine the nutritional values of algae and bacteria to mosquito larvae and adults. We are also interested in the potential tradeoffs between larval nutritional status and adult survivorship, blood feeding and vectorial capacity. We are examining physiology, ecology and genetics of desiccation resistance, and age-grading molecular marker development for An. gambiae.
Li, J, Wang, X, Zhang, G, Githure, JI, Yan, G, & James, AA (2013). Genome-block expression-assisted association studies discover malaria resistance genes in Anopheles gambiae. PNAS USA 110(51), 20675-20680.
Chang, X, Zhong, D, Fang, Q, Hartsel, J, Zhou, G, Shi, L, Fang, F, Zhu, C and Yan, G (2014). Multiple resistances and complex mechanisms of Anopheles sinensis mosquito: a major obstacle to mosquito-borne diseases control and elimination in China. PLoS Negl Trop Dis. 8(5):e2889.
Zhu, G, Zhong, D, Cao, J, Zhou, H, Li, J, Liu, Y, Bai, L, Xu, S, Wang, MH, Zhou, G, Chang, X, Gao, Q and Yan, G (2014). Transcriptome profiling of pyrethroid resistant and susceptible mosquitoes in the malaria vector, Anopheles sinensis. BMC Genomics 15:448.
Wanjala, CL, Mbugi, JP, Ototo, E, Gesuge, M, Afrane, YA, Atieli, HE, Zhou, G, Githeko, AK and Yan, G (2015). Pyrethroid and DDT Resistance and Organophosphate Susceptibility among Anopheles spp. Mosquitoes, Western Kenya. Emerg Infect Dis 21:2178-81.
Neafsey, DE, Waterhouse, RM, Abai, MR, Aganezov, SS, Alekseyev, MA, Allen, JE, Amon, J, Arca, B, Arensburger, P, Artemov, G, Assour, LA, Basseri, H, Berlin, A, Birren, BW, Blandin, SA, Brockman, AI, Burkot, T………. Yan, G,……. Zwiebel, LJ and Besansky, NJ (2015). Mosquito genomics. Highly evolvable malaria vectors: the genomes of 16 Anopheles mosquitoes. Science 347(6217):1258522.
Chen, XG, Jiang X, Gu J, Xu M, Wu Y, Deng Y, Zhang C, Bonizzoni M, Dermauw W, Vontas J, Armbruster P, Huang X, Yang Y, Zhang H, He W, Peng H, Liu Y, Wu K, Chen J, Lirakis M, Topalis P, Van Leeuwen T, Hall AB, Jiang X, Thorpe C, Mueller RL, Sun C, Waterhouse RM, Yan G, Tu ZJ, Fang X and James AA (2015). Genome sequence of the Asian Tiger mosquito, Aedes albopictus, reveals insights into its biology, genetics, and evolution. PNAS USA 112(44):E5907-E5915.
Gunalan, K, E Lo, JB Hostetler, D Yewhalaw, J Mu, DE Neafsey, G Yan and LH Miller (2016). "The role of Plasmodium vivax Duffy binding protein 1 in invasion of Duffy null Africans." PNAS USA 113(22):6271-6.
Funded by NIH: