Infectious Diseases

War, What is it Good for? Spreading Infectious Diseases, It Turns Out

Author Kimberly Hazel , 29-Sep-2022

When it comes to wartime, there is one undeniable thing – things spread—News, rumors, people, and diseases all travel at an unprecedented pace. 


Infectious diseases have played a role in some of the most significant wars in history. Some historians and infectious disease specialists refer to infectious diseases as the “third army” of any war. Poor living conditions, increased stress levels, and close quarters all contribute to the spread of disease


Many historians believe infectious diseases have played a role in civilizations’ fall and empires’ rise and fall. For example, the bubonic plague is thought to have contributed to the fall of the Roman Empire. The Plague of Justinian, which killed millions of people in the 6th century, is thought to have weakened the Byzantine Empire and made it easier for Muslim armies to conquer Constantinople.

Which War Was Worse When it Comes to Infectious Diseases?


Major disease outbreaks have often been linked to wars throughout history. One of the most infamous examples is the Black Death, which killed an estimated 25 million people in Europe during the 14th century. The disease is thought to have been spread by fleas living on rats brought into Europe by ships carrying soldiers returning from the Crimean War. It is thought to have contributed to the end of feudalism.

This isn’t the only time that infectious diseases influenced the course of history during war, however.


The Peloponnesian War


The Peloponnesian War is another example, as it saw the spread of typhus. This war was fought between Athens and Sparta from 431-404 BCE and involved nearly the entire Greek world at its height. In 430 BCE, Athens was struck by a plague that would kill an estimated 75,000 people, or one-third of the city’s population. The plague continued to ravage Athens for another two years before finally subsiding. 

While the plague’s exact cause is unknown, it is believed to have been brought to Athens by Spartan soldiers who were infected with typhus. This theory is supported by the fact that most of the deaths from the plague occurred in crowded areas like prisons and army barracks, where sanitation was poor. Regardless of its cause, the Plague of Athens was one of antiquity’s deadliest disease outbreaks.


The American Civil War


The American Civil War (1861-1865) is widely considered to be the deadliest conflict in American history, with over 600,000 soldiers killed in action. But what is less well-known is that infectious diseases actually claimed more lives than combat wounds during the war. In all, historians believe that approximately two-thirds of all deaths during the Civil War were due to infections contracted while in service.

It is even said that one in four soldiers died from infectious diseases such as typhoid fever and dysentery. Both sides used battlefield hospitals to care for wounded soldiers during the conflict. However, these hospitals were often overcrowded and unsanitary, which facilitated the spread of disease. The Civil War was also fought mainly in the southern states, where mosquitoes and pests were more prevalent. This provided ideal conditions for the spread of malaria and yellow fever.


The Napoleonic Wars


The Napoleonic Wars were also a trying time for many reasons – not the least of which was the spread of disease. The most common diseases during the war were cholera, typhus, and dysentery. These diseases spread quickly due to the unsanitary conditions of many battlefields and camps. These wars saw a similar rate of disease-related deaths, with around 25% of fatalities attributed to infectious diseases

Poor sanitation meant soldiers often consumed contaminated food and water, and diseases could quickly spread through close quarters such as crowded barracks. In addition, wounds were often left untreated, providing an entry point for infection. And because medical knowledge was limited at this time, there was no practical way to treat them.


The World Wars


Infectious diseases also impacted the First World War. During World War I, an estimated 200,000 soldiers from each country directly involved in the war died from infectious diseases. While advances in medicine meant fewer soldiers died from infections than in previous wars, the close quarters and poor living conditions still resulted in the spread of disease. One notable example is the 1918 flu pandemic, which killed millions of people worldwide, including many soldiers. 

The use of chemical weapons in World War I also had a devastating effect on soldiers’ health. Mustard gas and other chemicals damaged soldiers’ respiratory systems, making them susceptible to pneumonia and other respiratory infections.


Modern Wars


The Iraq War saw a significant cholera outbreak. Interestingly, the 2003 invasion of Iraq also led to a rise in cases of hepatitis A. Also, the 2014 outbreak of Ebola in West Africa has been linked to the outbreak of civil war in that region. 

As these examples show, wars often provide the perfect conditions for spreading disease. Consequently, it is unsurprising that many significant epidemics have been linked to wars throughout history, even in recent history.


What Diseases are Most Commonly Spread During War?


Several diseases are commonly spread during wartimes. Here are some of the most common diseases spread during wars:

  • Cholera: a waterborne bacterial infection that causes severe diarrhea and dehydration.
  • Dysentery: an intestinal infection caused by bacteria or parasites. It causes severe diarrhea and can be fatal if untreated. 
  • Malaria: a mosquito-borne parasitic infection that causes fever, chills, and flu-like symptoms. 
  • Pneumonia: a serious lung infection caused by bacteria, viruses, or fungi.  Symptoms include coughing, chest pain, shortness of breath, rapid breathing, and sweating.
  • Tuberculosis: a bacterial infection that affects the lungs and can lead to death if left untreated. Symptoms include coughing blood, weakness, weight loss, fever, and night sweats. 
  • Typhoid Fever: an illness caused by a bacteria called Salmonella typhi with Symptoms that include high fever, fatigue, headache, stomach pain, and loss of appetite.
  • Dengue Fever: a virus that causes high fever, headache, pain behind the eyes, muscle and joint pain, rash, and bleeding gums.


All of these diseases can be deadly if not treated properly. They can all lead to severe complications, such as dehydration, sepsis, and organ failure. While treatments are available for these diseases are often in short supply during wartime. While some of the most common diseases spread during the war, others can also be transmitted through contaminated food and water.


What Makes Diseases Spread During War?


When armies march into battle, they bring more than just weapons and ammunition. They also carry diseases. There are several reasons why diseases spread during wartime, like close quarters, poor sanitation, and more. 

One of the most important factors is the increased mobility of people during the conflict. Soldiers and refugees often travel long distances, coming into contact with new populations and exposing them to new diseases. In addition, war often leads to crammed living conditions, which provide ideal breeding grounds for disease-carrying insects. 

The chaos of battle also makes it difficult for sick soldiers to get the medical care they need. As a result, the disease can quickly spread through an entire army, leading to devastating losses on and off the battlefield. Lack of hygiene is also a significant factor. This can spread bacterial and viral infections, especially when wounds are inundated with contaminated water. 

Finally, weakened immune systems make people more susceptible to illnesses. Stress, malnutrition, and lack of sleep affect the body’s ability to fight disease, making it more likely that an infection will take hold.

In sum, war is a perfect storm for the spread of disease. By understanding how and why diseases spread during the conflict, we can be better prepared to prevent outbreaks in the future.


How Can We Stop the Spread During Wartime?


While infectious diseases will always pose a threat during wartime, we can minimize the risk of them spreading by taking simple precautions.

One of the most important is to ensure that soldiers are healthy and have access to adequate medical care. Therefore, soldiers should be vaccinated against common infections such as influenza

Access to medical care is essential, but we cannot forget the critical role that hygiene and access to sanitation play in disease spread. Ensuring access to clean water and sanitation facilities can be very helpful in preventing disease spread. 

Soldiers having basic hygiene and sanitation training can also help prevent diseases from spreading in close quarters. Speaking of close quarters, we should make every effort to improve living conditions for soldiers, such as providing proper ventilation and nutrition.

Even following these precautions, diseases will likely continue to spread during wartime and peacetime. This is why GIDEON exists. It protects societies by providing reliable, timely epidemiological data. This, in turn, can help communities and governments combat infectious diseases.

Kimberly Hazel

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