DNP 830 Module 2 An Emerging Infection Expanding Its Range Example

A Mosquito That Moved to the City: The Epidemiology and Global Expansion of Dengue

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Doctor of Nursing Practice Program, Aspen University

DNP 830: Global Population Health

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A Mosquito That Moved to the City: The Epidemiology and Global Expansion of Dengue

Dengue is a viral infection transmitted mainly by the Aedes aegypti mosquito. Most people infected never feel ill or have only fever and aches, but some progress to severe dengue with plasma leakage, bleeding and shock. Once confined largely to a few tropical regions, dengue has become one of the fastest-growing infectious diseases in the world, and local transmission now occurs in places that rarely saw it before, including parts of southern Europe and the United States. This paper describes the burden and distribution of dengue, the factors driving its expansion, projections of future spread, and the implications for nursing and public health in newly affected areas.

Burden and Distribution

Estimating dengue's burden is difficult because most infections are mild or unreported. Mapping every available record of dengue occurrence and linking the map to cohort studies and population data, one group of modelers estimated that there were 390 million infections in 2010, of which 96 million produced apparent illness, and found that risk was influenced strongly by rainfall, temperature and urbanization (Bhatt et al., 2013). Transmission is concentrated in Asia, which carries most of the burden, and in Latin America, Africa and the Pacific. Case reports have risen sharply in recent years, with record numbers reported in several regions, although some of the increase reflects better surveillance.

Why Dengue Is Expanding

The expansion of dengue is closely tied to the ecology of its vector. Aedes aegypti adapted to live alongside humans, breeding in containers such as water storage jars, discarded tires and flower pots, and feeding on people during the day. A review of the global expansion of dengue argued that this adaptation to a niche created by human settlement, together with growing tropical megacities, trade and travel, allowed the mosquito to become a highly efficient vector and dengue to become entrenched in urban areas worldwide, with 100 million to 400 million new infections a year (Brady & Hay, 2020).

Several forces reinforce one another. Rapid, unplanned urbanization creates dense populations and abundant breeding sites where piped water and waste collection are inadequate. Air travel moves infected people between endemic and non-endemic areas within days, seeding outbreaks. Climate change extends the range of temperatures suitable for the mosquito and for viral replication within it. And the circulation of four dengue virus serotypes means that people can be infected more than once, with second infections carrying a higher risk of severe disease.

Projections

Modeling suggests the range will continue to grow. Using an extensive database of case locations and projections of climate, population and socioeconomic change, one study estimated that dengue already affects more than half the world's population and projected further expansion of environmental suitability and population at risk to 2050 and 2080, driven by climate change and urbanization, with the spread of Aedes vectors considered explicitly for the first time (Messina et al., 2019). Projections carry uncertainty, since they depend on assumptions about emissions, development and control efforts, but they point consistently toward more people living where dengue can be transmitted.

For planners, the practical message is to prepare surveillance and clinical capacity before transmission becomes established.

Implications for Nursing and Public Health

In places where dengue is new, clinicians may not recognize it. Nurses in emergency departments, urgent care and primary care need to ask about travel and local exposure in patients with fever, headache, eye pain, muscle and joint pain and rash, and to know the warning signs of severe dengue, including abdominal pain, persistent vomiting, bleeding, lethargy and a rising hematocrit with falling platelets, which typically appear as the fever subsides. Management relies on careful fluid therapy and monitoring, and nonsteroidal anti-inflammatory drugs should be avoided because of bleeding risk.

Public health nurses have roles in surveillance, reporting suspected cases so that vector control can respond around cases, and in community education on removing standing water and preventing bites. Where local transmission occurs, they help coordinate household investigations and communicate risk without causing panic. Vaccines exist but have specific eligibility conditions, including prior infection for some products, which nurses must understand to counsel patients accurately.

Equity Dimensions

Dengue's burden falls unevenly. Within cities, transmission is often highest in informal settlements where water is stored in containers because piped supply is intermittent, where waste collection is irregular and where housing lacks screens. Residents of these areas also have less access to timely care, which matters because survival in severe dengue depends on careful monitoring and fluid management. Travelers from wealthy countries who acquire dengue abroad usually recover with good care at home, while severe disease and death concentrate among children and adults in low-resource settings. Global responses that focus only on vaccines and vector control without addressing water, sanitation and health services will leave these inequities in place.

For nurses in high-income countries, the equity lens also applies locally. Where local transmission begins, migrant farmworkers, people experiencing homelessness and residents of substandard housing may face the greatest exposure and the least access to care and information, so outreach must reach them in their languages and settings.

Limits of Current Control

Traditional vector control, insecticide spraying and container removal, has struggled to stop dengue in large cities, partly because breeding sites are numerous and partly because of insecticide resistance. Newer approaches, including releasing mosquitoes carrying bacteria that reduce viral transmission, show promise in some settings but require sustained community engagement and investment. Control therefore depends as much on urban planning, water and waste services, and community participation as on health services.

Conclusion

Dengue has expanded from limited tropical regions to affect more than half the world's population, driven by a mosquito adapted to cities, rapid urbanization, travel and a warming climate. Burden estimates of hundreds of millions of infections a year and projections of further spread make dengue a global and increasingly local concern. Nurses in newly affected areas must recognize dengue and its warning signs, report cases promptly and help communities reduce breeding sites, while recognizing that lasting control depends on broader urban and environmental change.

References

Bhatt, S., Gething, P. W., Brady, O. J., Messina, J. P., Farlow, A. W., Moyes, C. L., Drake, J. M., Brownstein, J. S., Hoen, A. G., Sankoh, O., Myers, M. F., George, D. B., Jaenisch, T., Wint, G. R. W., Simmons, C. P., Scott, T. W., Farrar, J. J., & Hay, S. I. (2013). The global distribution and burden of dengue. Nature, 496(7446), 504-507. https://doi.org/10.1038/nature12060

Brady, O. J., & Hay, S. I. (2020). The global expansion of dengue: How Aedes aegypti mosquitoes enabled the first pandemic arbovirus. Annual Review of Entomology, 65, 191-208. https://doi.org/10.1146/annurev-ento-011019-024918

Messina, J. P., Brady, O. J., Golding, N., Kraemer, M. U. G., Wint, G. R. W., Ray, S. E., Pigott, D. M., Shearer, F. M., Johnson, K., Earl, L., Marczak, L. B., Shirude, S., Davis Weaver, N., Gilbert, M., Velayudhan, R., Jones, P., Jaenisch, T., Scott, T. W., Reiner, R. C., & Hay, S. I. (2019). The current and future global distribution and population at risk of dengue. Nature Microbiology, 4(9), 1508-1515. https://doi.org/10.1038/s41564-019-0476-8