Why Is It Important To Find ‘Patient Zero’ In An Epidemic?

You’ve heard of Ebola, right? Ebola virus disease (EVD) is a severe, often fatal illness found in humans. The first massive EVD outbreak occurred in villages of Central African rainforests back in 2014. Before the epidemic was controlled, it had claimed the lives of more than 11,000 people.

Ebola virus epidemic in west africa

2014 Ebola virus epidemic in West Africa. (Photo Credit : Mikael Häggström / Wikimedia Commons)

Whenever such an outbreak is identified, one of the first things that the concerned government and medical authorities do is to find ‘patient zero’, i.e., the first patient to have contracted the disease.

In the Ebola outbreak of 2014 in Western Africa, “patient zero” was found to be a toddler – a 2-year-old boy named Emile Ouamouno, who lived in a rainforest village in southern Guinea. According to the researchers of The New England Journal of Medicine, this little boy was the first person to contract the Ebola virus in the outbreak of 2014.

But why is it important to identify patient zero? What good does it do?

As it turns out, it does a lot!

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What is Patient zero

It’s interesting to note that the provocative term ‘patient zero’ is actually the result of some researcher’s arbitrary scribble. It’s believed that a researcher’s scrawling of the letter ‘O’ was misinterpreted as a zero in reference to an HIV patient in the early 1980s. Since then, the term ‘patient zero’ has become widely used by everyone.

In reference to an outbreak of a disease, epidemic or pandemic, the term ‘patient zero’ commonly refers to the first case of the disease. In other words, the first person whom the disease attacked. Determining the identity of the first victim of a disease paves the way for control and prevention of a more serious epidemic.

Patient zero

It’s very important to determine the identity of patient zero to curb the spread of a disease. (Photo Credit : Fcleetus / Wikimedia Commons)

Needless to say, finding patient zero requires meticulous and arduous detective work. Healthcare workers and medical researchers have to go from case to case in order to establish where the disease made its first appearance.

Containment of the epidemic

Once you’ve established the identity of patient zero, you can then map all the places they visited (during their illness) and who they have been in physical contact with. Basically, it helps to determine how a particular disease is spread among the masses. Is it airborne, does it live in the environment or only within hosts? Can it survive outside the host? If yes, then for how long?

When you have that information, it becomes easier to guide efforts in the direction of containment of the epidemic and keep it from spreading further.

Simplified 2014 ebola virus epidemic situation map, simplified

Simplified 2014 ebola virus epidemic situation map, simplified. (Photo Credit : ZeLonewolf / Wikimedia Commons)


This is another important aspect of dealing with an epidemic. After you’ve identified patient zero for a particular epidemic, you can look at their lives, i.e., what they did, what their daily life was like, what they ate, what environment they lived in and what animals they came in contact with. You can then identify likely candidates for animal hosts and go into the wild to collect those animals and investigate if they actually have the particular virus.

If an animal has the virus, then you can warn the public – “We have identified that xxxxxxx is how you can contract this disease, so stay away from xxxxxxx.”

In addition to that, studying outbreaks that cross species barriers can give us an idea about what those diseases could do in the future, which helps us to be prepared in case another outbreak occurs.

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About the Author

Ashish is a Science graduate (Bachelor of Science) from Punjabi University (India). He spearheads the content and editorial wing of ScienceABC and manages its official Youtube channel. He’s a Harry Potter fan and tries, in vain, to use spells and charms (Accio! [insert object name]) in real life to get things done. He totally gets why JRR Tolkien would create, from scratch, a language spoken by elves, and tries to bring the same passion in everything he does. A big admirer of Richard Feynman and Nikola Tesla, he obsesses over how thoroughly science dictates every aspect of life… in this universe, at least.

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