Dr. Abdallah Samy (Ain Shams University, Cairo): mapping the global potential distributions of two a
Dr. Abdallah Samy is a researcher based in the Entomology Department of the Ain Shams University, Cairo, Egypt. Dr. Samy's research addresses several questions at the interface of ecology, epidemiology, public health, and global health, and his lab are keen to pursue interdisciplinary and multi-faceted approaches to research questions. In recent work, Dr. Samy and colleagues have focused on arboviruses and mosquito-borne diseases, in the aim of developing disease forecast (in particular dengue), understanding the major drivers of disease spread, and identifying the possible shifts at disease risk in response to global warming in future.
In this Infectious Thoughts interview, Dr. Samy speaks more specifically about recent work on modelling the global distribution of the vectors of arboviral diseases under changing climate, what can be learned from this to improve global public health strategies for dengue control for the forthcoming decades, and which knowledge gaps remain to be addressed given complex climatic change.
Your recent work has focused on mapping the current and predicted global distribution of two vectors of arboviral diseases, the mosquitoes Aedes aegypti and Ae. albopictus - why did you choose to look closely at these particular species? What are the public health priorities of improving the understanding of their distribution?
It is important to work on these mosquito species to identify areas at risk of arbovirus transmission. Aedes aegypti and Ae. albopictus transmit dengue, chikungunya, and zika virus. The arboviruses have become growing public health threats across the world. Their outbreaks are now recognized just a few kilometers from your setting and cause major outbreaks in several parts of the world. We still remember the deadly zika outbreak approached anxiety at Brazil and Florida where availability of vector occurrence data are necessary to assist in identifying the major areas at risk, particularly if these deadly diseases spread rapidly to other continents. In late 2017, Egypt experienced a dengue outbreak that strikes the Red Sea Coast of Egypt where vector data were sparse. So, the availability of our updated maps should have public health implications to ongoing disease outbreaks and identify possible future shifts of these two competent vectors and diseases they transmit.
Your models are looking at scenarios up to 2070 - given this long-term view, how can your predictions help governments and local authorities improve their preparedness for potential disease outbreaks?
Our models identified possible shifts in the distributions of Ae. aegypti and Ae. albopictus across many parts of the world. Governments and local authorities should identify their priorities for surveillance and control programs to improve the preparedness for possible disease outbreaks possibly occur by further expansions of both vector species anticipated by our study. The spread of both vectors will remain a major health problem that leads to rapid spread of major arboviral outbreaks (e.g. dengue, zika, and chikungunya). It possibly drives the emergence of more threats including other arbovirus outbreaks like Mayaro that may raise another case for WHO emergency. Finally, vector control programs should be implemented regularly to protect the possible invasions of these vectors to new habitats and prevent their spread across several parts of the world. These programs may include coordination between countries for better preparedness, for example, the successful mission implemented by the Medilabsecure that include surveillance, monitoring, and control of disease vectors in 19 countries across the Balkan and Middle East countries. These regional efforts should track the spread of these vectors considering the nature of their response to climatic changes that we introduced.
Do you have any specific advice for the global improvement of advocacy, control, treatment and management of arboviral diseases? Are there technologies, partnerships or vector control solutions which you feel urgently need to be improved or developed?
Yes, the major advice is to improve surveillance and monitoring systems, insecticide resistance monitoring and management, vector control capacity and capability, community participation, and cross-sectoral coordination as per WHO guidelines, particularly via integrated vector management on regional levels for optimal use of available resources for vector and disease control programs. We can see that enhancing these activities may be achieved via collaboration between different sectors in the region (e.g. Medilabsecure project).
Are you specifically looking for certain partnerships and collaboration, whether they be in research, funding or mapping?
Yes, further collaborations and funding will contribute directly to develop further detailed analyses that cover different aspects of mapping vectors and vector-borne diseases in the region and across the world. We previously developed several collaborations in different parts of the world and work with many experts across many parts of the world. So, we are confident that further funding of our work should provide further details for the development of our infrastructure, mapping efforts, and increase our team members and place the better uses of our available toolkits. We worked on several projects that provided assistance in many public health threats across the world (e.g. mapping zika virus). All our partnerships and collaborations along with the availability of funding should allow building new facilities for vector and disease mapping at Ain Shams University campus, Cairo, Egypt to present a key regional center in the Middle East and Africa.
What are the main trends for current distribution of these vectors? What are the main climatic variables which you have considered and how will this affect their future distribution?
Aedes aegypti and Ae. albopictus occurred mainly in the tropics and subtropics; however, the two species have different distributional potential in temperate Europe and North America. Aedes albopictus expands further to include most of Europe and USA till it strikes southern Canada. Aedes aegypti has a limited distribution instead in these regions. These distributional patterns raised several important points regarding the interspecific competitions between the two species, the point that we respect a bit and we think it should be considered by future research. We used 15 bioclimatic variables available from the WorldClim archive; these variables are based on temperature and precipitation which were identified as a major limiting factor for the distributions of both species. We observed that the potential distributions of both species increase as the temperature elevate with industrial activities and global warming events.
What were the advantages of your model, using a ecological niche modeling approach?
Our models have several advantages; 1) the models provided the most updated and detailed maps of the current and future distributions of Ae. aegypti and Ae. albopictus, 2) they used robust methodologies, 3) our models were the first to look more closely for the distributional patterns of both species in the Middle East, North Africa, Spanish islands, Red sea coasts, and several other regions across the world, 4) our models added another dimension of novelty by using the most updated version of climatic scenarios rather than using the previous future climatic models, 5) model validation using independent records from the WHO Eastern Mediterranean region, 6) all our models came with uncertainty estimates, and finally 7) our study assessed the niche overlap between these two potential vectors. However, all of these advantages marked our work, but we still see several other gaps that we are working on it in our ongoing and future projects.
How would you like to expand this work in future?
We are working to explore many analyses in my lab. These analyses will include further improvements of methodologies, development of mapping efforts for other vectors and other diseases, including several key arboviruses. Now, my lab collaborates with other laboratories across the world to expand our work to include more diverse projects to our priorities agenda. The latter include parts of North Africa and the Middle East where data are sparse and information are limited, so, we are working on a very active collaboration in the region and several projects will come very soon. We build also our capacity and infrastructure to host several training programs along with other colleagues from the region and from other continents.
For more information please contact Dr. Abdallah Samy at samy@sci.asu.edu.eg
