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What is a flood? -

A flood is defined as an overflow of water that submerges land that is usually dry. And that's a mild description. Some of the worst natural disasters in recent years have involved flooding on a colossal scale. 

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A destructive force of nature -

Extensive flooding is of significant concern in agriculture, civil engineering, and public health.

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Catastrophic for infrastructure -

Flooding can devastate infrastructure—buildings, transportation routes, energy systems, and utilities. 

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A natural disaster -

Food sources, fresh water supply, and sanitation systems are often seriously affected. 

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High casualty rate -

These risk factors are considerable, and the casualty rate speaks for itself. At least 12,000 people—30% more than in 2022—lost their lives due to floods, wildfires, cyclones, storms, and landslides globally in 2023, according to a recent analysis from Save the Children.

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The risk of disease -

And like all natural disasters, a catastrophic flood brings with it the risk of infectious diseases. 

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Contaminated water -

An immediate consequence of a severe flood is water contamination by human or animal feces, or the carcasses of drowned animals and indeed, human corpses. 

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Vectors of misery -

Stagnant water can quickly attract mosquitoes, flies, and other vectors of contagious illnesses. 

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Desperate times -

Crowded emergency living conditions and/or loss of access to healthcare resources only serve to exacerbate an already desperate situation. 

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Upsetting the environment -

Flooding disrupts the environment's natural equilibrium and frequently creates a habitat that is conducive to the growth of infections and their carriers, notes the National Center for Biotechnology Information (NCBI). The chances, though, for infectious disease to spread after a flood event vary considerably. 

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Risk factors -

Specific risks depend on factors related to the affected population, the surroundings, and, to a degree, the transmissible diseases already present in the area.

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Threat to vulnerable communities -

What is certain is that the greatest threat to human life is posed by endemic infectious illnesses that harm displaced and vulnerable communities.

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No fresh water -

A disrupted fresh water supply and ineffective sanitation system increases the risk of diarrheal diseases most commonly caused by the vibrio cholera bacterium. 

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Waterborne diseases -

In fact, waterborne diseases such as cholera, typhoid, hepatitis A, hepatitis E, and diarrheal disorders, to mention a few, thrive in such unhealthy conditions. 

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Global risk -

A post-flood landscape provides ideal vector-borne conditions. Depending on the region of the globe, survivors run the risk of contracting a wide range of life-threatening diseases, including malaria, yellow fever, West Nile disease, dengue, Chikungunya, and Zika.

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Not safe to drink -

A lack of safe drinking water means that food preparation and personal hygiene such as hand cleaning is difficult if not impossible, facilitating human fecal-oral transmission. 

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Respiratory problems -

According to NCBI, infections of the respiratory tract are typically one of the leading causes of morbidity and mortality among flood survivors. 

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Breathing difficulties -

Potential illnesses and disorders range from mild viral upper respiratory infections, pertussis (whooping cough), and influenza to more serious maladies such as pneumonia, tuberculosis, and chronic obstructive pulmonary disease.  

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No shelter from danger -

Sheltering in crowded conditions can result in the transmission of respiratory tract conditions as much as losing shelter and being exposed to flood waters and rain. 

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Other medical problems -

Direct contact with contaminated water can result in disorders of the skin and the eyes. Besides wound infections, typical illnesses include dermatitis and conjunctivitis. 

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Water hazard -

Wading through floodwater or mud increases the risk of contracting or exacerbating a skin condition. Quite often though, this is the only option for many in getting around. 

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Controlling vermin -

Leptospirosis is a disease caused by bacteria that affects people and animals. It's spread in the urine of infected animals. In a flood scenario, exposure can occur through rat urine contaminating water, particularly if rodent populations expand with increased access to garbage or crops following floods.  

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Braving the damage -

Rescue teams working in flood zones are not immune to disease, or to the dangers posed by damaged infrastructure. Injuries are common, with the risk of tetanus or bacterial wound infection being particularly high. 

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The psychological impact -

Navigating such a devastated landscape while extracting the injured and the dead can have a lasting psychological impact on those charged with helping in the cleanup following a natural disaster. A major flood is no exception. 

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Managing the dead -

In fact, management of the dead is one of the most difficult aspects of disaster response. The process has profound and long-lasting consequences for rescue workers. 

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Overcoming grief and stress -

As with survivors, members of relief and emergency services are also subjected to adverse psychological effects such as anxiety, depression, and post-traumatic stress disorder. 

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A lingering uncertainty -

And while media coverage of the immediate aftermath of a natural disaster is common, potential infectious exposures in a flood-affected area may persist for weeks, long after the photographers and TV crews have left.  

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Living with the consequences -

In countries with fewer resources, post-flood areas may remain without assistance for months despite the pleas of the hungry and homeless. 

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Natural calamities in the industrialized world -

Recent floods in Europe and the United States demonstrate that even the most industrialized nations are vulnerable to natural calamities.

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Global flood risk -

Underlying this fact is the January 2024 report published by the United Nations Office for Disaster Risk Reduction that revealed that during 2023 nearly every region of the world was inundated with floods.

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Long-term impact -

But it's in poorer nations, places like Pakistan and Bangladesh, where people impacted by a flooding event are at significantly increased risk of dying—including from heart and lung problems—even after the floodwaters have receded. 

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Global warming and climate change -

Meanwhile, global warming is already intensifying extreme rainfall more than climate models suggested, according to the Potsdam Institute of Climate Impact Research.

Sources: (Washington State Department of Health) (Save the Children) (NCBI) (International Committee of the Red Cross) 

See also: The worst floods in history

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