Aedes-borne Diseases and Sustainable Development Goal 11

By: Steve Lindsay, Professor, Durham University, Durham, UK

Recent outbreaks of Zika, yellow fever, chikungunya, and dengue continue to attract considerable global attention. The viruses that cause these diseases are all transmitted by one of the world’s most efficient arthropod vectors, the mosquito Aedes aegypti. After centuries of global spread, this mosquito is now present in nearly every tropical and sub-tropical region and poses an unprecedented threat to urban health worldwide. All four of the diseases listed above are caused by viruses that spilt over from forest transmission cycles involving non-human primates to urban transmission cycles. There is concern that other viruses could do the same and therefore it is therefore reasonable to ask, what other viruses, and the diseases that they cause, will be next?[1]

The Aedes aegypti mosquito is one species that can spread Zika, yellow fever, chikungunya, and dengue. [Photo by Graham Snodgrass/ U.S. Army Public Health Command]

It is pertinent to ask why Aedes-borne diseases are thriving in urban environments in tropical and sub-tropical regions.

Rapid population growth in low and middle income countries has led to uncontrolled urbanization, which is often accompanied by high population density, poor housing conditions, lack of basic services such as water, sanitation and refuse collection, and environmental deterioration.

Development of cheap plastics and rubber has allowed Ae. aegypti to flourish in small bodies of water found in discarded plastic containers, plant pots, gutters and tires. A lack of piped water or insecure water supply means that communities often store water in their homes in containers which provide habitats for Aedes mosquitoes.

In the absence of any specific treatments for Aedes-borne viral diseases, a partially protective dengue vaccine and a short supply of yellow fever vaccine, vector control is the most viable approach to controlling these diseases. The World Health Organization recommends a two-stage approach for Aedes control: 1) control of immature and adult mosquitoes by removing larval development sources and/or the use of larvicides and biocontrol and 2) a long-term commitment to improving the built environment in ways that reduce mosquito populations and their contact with human hosts. [2]

Larvae of Aedes aegypti, the mosquito that transmits dengue. [Photo: Gabriel Jabur / Agency Brasilia]

Sustainable control of Aedes-borne diseases in urban environments requires a proactive, integrated and multisectoral approach. Alongside implementation of vector control by public health authorities and community behavior change campaigns to reduce mosquito populations breeding near to homes, engagement of the non-health sector is critical. For example, provision of solid waste management, recycling of plastics and tires, reliable piped water supplies, and design and delivery of better housing are all key long-term steps towards reducing vector populations, biting on humans and the diseases that they cause.

Learn more about Sustainable Development Goal 11 (UNDP Photo)

This is closely aligned to Sustainable Development Goal (SDG) 11: ‘making cities and communities… safe, resilient and sustainable’ which calls for governments and partners to “ensure access for all to adequate, safe and affordable housing and basic services and upgrade slums”. We call for those working for the laudable goal of SDG 11 in tropical and sub-tropical cities and towns to recognize the impact of vector-borne diseases and work with control experts to build resilient settlements where the risk of Aedes-borne disease is greatly reduced or eliminated. Creating tropical and sub-tropical communities that are undesirable to Ae. aegypti should be a priority for safe, resilient and sustainable modern cities.


About the Author: Professor Steve Lindsay is a public health entomologist with an interest in the development and testing of vector control tools. He has over 30 years’ experience of working in developing countries and has written over 190 scientific publications.

Editor’s Note: The views and opinions expressed in this article are those of the author and do not necessarily reflect the official position or policy of the U.S. government.

References:

[1] Weaver SC, Barrett ADT. Transmission cycles, host range, evolution and emergence of arboviral disease. Nature Reviews Microbiology 2004;2:789–801.

[2] WHO. Global strategy for dengue prevention and control 2012–2020. Geneva: WHO; 2012.