Infectious Disease in Cities

Ways Cities Can Control the Spread of Infectious Viruses

The recent COVID-19 pandemic is unlike anything that the world has seen in modern times. We have witnessed the devastating effects it has had on cities with the largest and densest populations. Urbanization has helped to create breeding grounds for diseases. Unfortunately, outbreaks of viruses like COVID-19 spread more rapidly within these dense populations, affecting hundreds of thousands of people.

One of the main concepts that the COVID-19 pandemic has demonstrated to planners and epidemiologists is that the future of city planning must take the potential to spread infectious disease into consideration. When utilized effectively, planning can help to reduce the spread of disease and support public health. In order to prevent major outbreaks of future diseases and minimize their spread, city planning must shift from a focus on urbanization to other types and tools of planning. Spatial planning, transportation planning, and strategic planning can all be used to shape future regions, communities and cities into healthier spaces in which we can live, work and play.

Here, we will examine pandemics and other infectious diseases and look at how urbanization can be a major contributor to their spread. We will also study ways in which today’s city planners can minimize the effects of, or even prevent, future pandemics from occurring through effective planning.

How Urbanization and Overpopulation Contributes to the Spread of Infectious Diseases

Urbanization is defined as the process by which cities grow. An increasing percentage of the world’s population is moving into the city to live. Today, more than half of the world’s population – over 4 billion people, or 55 percent of the total population of the globe – live in urban areas. Compare that with the fact that, in 1800, less than 10 percent of the world’s population resided in urban areas. Rates of urbanization have been increasing worldwide.  By 2050, it is projected that 70 percent of humans around the world will live in cities. These numbers are expected to increase as incomes increase and as employment patterns shift away from agriculture.

Author and economist George Morris defined overpopulation in 1973 as the state of the population “when there are more people than can live on the earth in comfort, happiness, and health and still leave the world a fit place for future generations.” Overpopulation is not just determined by the number of people living in an area. The sufficiency of the resources that are available to support that population are the true test of whether an area is overpopulated or not.

Population density, or the number of people per unit of geographical area, is a better determination of whether an urban area is considered to be “overpopulated.” It has been shown that urbanization and population density can contribute to the spread of disease. If urban centers grow too rapidly, with poor planning and insufficient capacity to meet the needs of the growing population, sanitation and waste removal becomes a challenge and infectious diseases can spread like wildfire.

Take, for example, the Spanish influenza pandemic of 1918-19. Over 50 million people worldwide are believed to have died during that pandemic, and death rates were highest in urban areas. As the influenza vaccine was not yet developed, public health officials learned that one of the best ways to reduce infection and death rates was to minimize points of contact between infected and non-infected people. These interventions are believed to have lowered the death rates by 50 percent. When such measures were relaxed in urban areas, however, the infection and death rates would climb once again.

Sanitation and water, other facets of urbanization, relate to the spread of disease as well. About one-third of the world’s population does not have access to clean water. Forty percent lacks access to sanitation facilities to safely dispose of human waste. Fecal matter in water leads to infectious diseases such as cholera and typhoid, particularly in urban areas. In areas where pit latrines are constructed close to wells, infectious disease has broken out in greater numbers. Many of the regions lacking water and proper sanitation facilities are in urban areas or areas with dense population.

In the future, city planners must keep in mind the rapid spread of infectious disease within these urban areas and learn from past mistakes.  Urban planners will be instrumental in creating cities and urban centers that can help to minimize, not maximize, the spread of such diseases.

How Urban Planning Can Reduce the Spread of Infectious Viruses

Urban planning is one solution to helping to reduce the spread of infectious viruses, particularly in population-dense urban areas. Different urban planning professions are responsible for handling different aspects of urbanization. Future spatial and GIS planners will help to determine the future of space and land use. Transportation planners can create more effective and efficient public transportation methods and build roads to areas outside of cities, based upon spatial and GIS planners’ analysis of space. Each planning profession must work in tandem with the others to collectively reduce the spread of infectious viruses.

Spatial Planning

Spatial planners are instrumental to helping to curb the spread of infectious diseases in metropolitan areas and other regions. Landscape architect Ian McHarg argued in the mid-20th century for using ecological systems as a basis for planning. In his 1969 book, Design with Nature, McHarg addressed health in a chapter about Philadelphia, detailing the impact of the physical environment on health outcomes within the city. He noted that landscape architects could integrate the sciences, arts and planning through suitability analysis, which pre-dated the development of geographic information systems (GIS). Likewise, today’s land use and GIS/spatial planners must work with public health officials to understand where diseases exist within an area and to better manipulate the physical environment to prevent their spread.

Deforestation is one example of a land use problem that can encourage the spread of infectious disease. It is believed that deforestation contributed to the spread of Ebola Virus Disease (EVD) beginning in March 2014 in the Democratic Republic of the Congo. EVD is spread through bodily fluids, which are often transmitted during the hunting process. As forests disappear, animals which can spread deadly disease come out of the forests and humans go deeper into the forests that remain in order to hunt. Eliminating the physical barrier of the forest that separates humans from animals potentially caused humans to inadvertently expose themselves to contact with animals who were infected.

Deforestation can also allow for new transportation infrastructure to connect previously unconnected cities, thereby allowing infectious disease to spread to them rapidly. In this example, hunters in the DRC could kill and sell infected meat, which is then transported to cities through new transportation infrastructure, spreading the disease to these areas.

While spatial and land use planning can be beneficial for connecting cities for trade, it can also cause infectious disease to spread more rapidly than it would otherwise. However, transportation planning can also be used to connect areas with health care in cities that they could not otherwise access. It is a delicate balance that spatial and GIS planners must achieve, working with transportation planners and other types of planners.

Transform Transportation

Transportation systems, especially passenger transportation systems, can play a major role as a vector in carrying infectious diseases. This is easily seen in the early spread of COVID-19. The COVID-19 virus spread rapidly around the world as a result of the prominence of international air travel. In the early phase of a pandemic (generally the first 10 days), transportation systems are most likely to spread outbreaks globally.

The transportation sector has two major roles during the outbreak of an infectious disease: one, to control the spread of infection; and two, to assess the impact of reduced outdoor activities on the transportation sector. Transportation planners can help to curb the spread of infectious viruses if they plan transportation systems in strategic ways. Transit systems may be shut down to reduce the spread of infectious disease, but if a transit infrastructure is key to getting goods and services to the public, other measures must be taken. Separating its operators from passengers, reducing the passenger load, and requiring things like masks and social distancing can help to curb the spread of disease in those instances. It is also important to note that passenger density in public transit systems will likely decline during a pandemic as commuter demand is decreased, but masking and social distancing should also be encouraged on mass transit.

Roads and highways on which individual vehicles travel are generally thought of as safe forms transportation during a pandemic. Deliveries must continue during a pandemic, and risks that occur during loading, unloading and refueling can be mitigated with proper masking and distancing techniques.

Transportation planners must work with pandemic planners and public health officials to identify priority lanes for cargo during the pandemic. They must work with government officials to train the transportation workforce in safe techniques that will allow them to continue working.

Strategic Planning

Strategic planners work on planning an area with a specific city model in mind. Strategic urban planning involves citizens in policy decisions. Learning lessons from the COVID-19 pandemic will help strategic planners to change how they shape urban spaces in the future. Infectious disease does not only spread in cities and urban areas, as COVID-19 has shown us. As Michelle Acuto, professor of global urban politics at the University of Melbourne, notes, “COVID-19 is really a story of peri-urban and rural-to-urban connections, in places that are often not on the global map.” Non-global cities, peri-urban areas and tertiary cities all felt the spread of this infectious disease. This is likely to be the disease pattern seen with future infectious viruses.

Acuto notes that rethinking and re-planning density management is one key for long-term survival in a pandemic world. Essential services must be decentralized. Changes in the built environment are necessary to plan for containment of infectious diseases. Spreading cities over areas instead of densifying them also presents challenges with climate change and sustainability, another reason why strategic planners must work with other planners like sustainability planners in making these changes.

Utilizing digital infrastructure is another way that strategic planners can prepare for the impact of future pandemics. Digital resources can tell public health officials who is sick within a certain region, city or neighborhood, and they can subsequently plan decisions based upon that information. The fields of modern civil engineering and urban planning were born from developments of sanitation in the mid-19th century that came as a response to the spread of cholera and malaria in cities. Digital infrastructure that is now being used as a result of COVID-19 might be similar to the function of sanitation back then, changing, or at least adding to, the entire discipline of civil engineering and urban planning.

Future Urban, Regional and Community Planning

Who knows if we would even be discussing controlling the spread of infectious diseases through urban planning if the COVID-19 pandemic hadn’t occurred? But it did, and we are now faced with the tasks of planning a better environment in order to mitigate the spread of future viruses. The World Health Organization (WHO) and United Nations-Habitat (UN-Habitat) have produced a book, Integrating Health in Urban and Territorial Planning, to help future urban, regional and community planners in their endeavors. As they note, infectious diseases thrive in overcrowded urban areas and areas with limited to no access to clean water and sanitation facilities. Only one out of ten cities meet worldwide standards for healthy air.

“If the purpose of urban planning is not for human health, then what is it for?” asks Dr. Maria Neira, WHO Director, Department of Environment, Climate Change and Health. She adds that urban areas have historically been planned to meet adequate standards of living and working, to sustain economic growth, to foster social development, for environmental sustainability, and for improved connectivity. She argues that planners must also focus on the future physical and mental health and well-being of citizens when planning urban, regional, and community areas.

As mentioned earlier, over half of the population of the world live in cities, and by 2050, that percentage will rise to 70 percent. But at least 75 percent of the infrastructure that will be needed by that time has yet to be built. This might seem frightening, but is, in fact, an opportunity for planners to “get it right” and meet the planning challenges that occurrences such as the COVID-19 pandemic have brought to light. They can now build transformative urban areas that have a better link to land use, space and human health.

Equity in planning areas becomes even more important, as there are vast differences in health opportunities and outcomes across urban areas worldwide. Public health, public policy and urban planning must both target equitable outcomes and access to essential services for everyone.