Ethiopia ICEMR

Malaria Epidemiology and Vector Biology of Invasive Anopheles stephensi Across Rural and Urban Landscapes in Ethiopia

Lead Institution: University of California, Irvine, USA

ICEMR website: https://www.icemreastafrica.org/

Research Areas

The overall goal of this project is to assess the impact of An. stephensi invasion of malaria epidemiology and transmission, develop surveillance tools and methods needed to track vector spread, and identify cost-effective vector control methods that can be adapted to settings of varying urbanicity in Ethiopia.

Anopheles stephensi is a major malaria vector species in South Asia. Since its first detection on the African continent in Djibouti in 2012, the distribution of this vector species has expanded to Ethiopia, Sudan, Somalia, Kenya, and Nigeria. The emergence and spread of An. stephensi in Africa pose serious challenges for malaria control and elimination in fast-growing urban Africa. An. stephensi biology has been well characterized in its native range, South Asia. However, the ecology, behavior, and population genetics of newly invasive An. stephensi in Africa are not well studied. An. stephensi invasion may cause a shift in the vectorial system and alter transmission dynamics. Knowledge gaps in the newly invasive vector’s biology and the effectiveness of available intervention methods have impeded An. stephensi control in Africa. Further, lack of sensitive surveillance methods for An. stephensi has also hindered efforts to effectively track An. stephensi population spread over time. This ICEMR aims to significantly advance knowledge of the ecology and behavior of newly invasive An. stephensi, develop new serology-based surveillance methods to assess human exposure to invasive An. stephensi, and provide important information on the cost-effectiveness of urban vector control methods.

In close collaboration with the Ethiopian Ministry of Health and the President’s Malaria Initiative, two interrelated research projects were conducted in four Ethiopian sites (urban center and surrounding areas) with contrasting An. stephensi abundance, malaria endemicities, and different urbanicity are conducted to:

· examine the entomological drivers of malaria transmission along the rural-urban continuum

· elucidate the extent of the spread of invasive An. stephensi

· evaluate serological biomarkers for An. stephensi exposure surveillance

· examine the impact of An. stephensi invasion on malaria risk

· evaluate the impact of larviciding on invasive An. stephensi and native malaria vectors and malaria transmission reduction.

The study designs of the Ethiopia ICEMR projects involve monitoring changes in land use, land cover, and new settlements over time, quantifying the incidence of uncomplicated and severe malaria, entomological surveillance of malaria vectors, and geospatial analysis to determine malaria risk heterogeneity and association with An. stephensi and native vector’s distribution. A variety of malaria surveillance methods, including passive case detection at health centers and hospitals, cross-sectional sampling, reactive case detection, and serological surveillance, will be used to assess malaria risks.

Entomological studies in each site include longitudinal entomological monitoring using various trapping methods, characterizing larval habitats, examination of population dynamics, and biting and resting behaviors of invasive An. stephensi and native malaria vectors across the rural to urban landscapes. Observational studies will be performed to assess the impact of ongoing microbial larviciding on malaria vectors and non-target organisms. Finally, peptide microarray technology will be used to identify biomarkers that can differentiate human exposure to An. stephensi from native vectors.

Study Sites

· Gambella

· Hawassa

· Semera

· Dire Dawa

Figure 1. Map showing the four study site locations of the Ethiopia ICEMR.

Staff

Principal Investigator: Guiyun Yan, Ph.D., University of California, Irvine, USA

Project Leads

• Delenasaw Yewhalaw, Ph.D., Jimma University, Ethiopia
• Ming Chieh Lee, Ph.D., University of California, Irvine, USA

Collaborating Institutions

• Case Western Reserve University, USA
• Jimma University, Ethiopia
• Hawassa University, Ethiopia
• Addis Ababa University, Ethiopia
• Dire Dawa University, Ethiopia
• Semera University, Ethiopia
• Ethiopian Public Health Institute
• Ethiopian Ministry of Health
• President’s Malaria Initiative (PMI)