Viral Infections Vs Bacterial Infections [What’s The Difference?]

We’re living in unprecedented times, with schools and businesses closing, along with mandatory quarantines, due to the global coronavirus pandemic. Because of this, I thought I’d write a post on the differences between viral infections vs bacterial infections. Viruses are much smaller than bacteria, the majority cause disease, including cancer, and their survival is dependent on a host. In contrast, most bacteria are harmless, and are ubiquitous in the environment, they’re in the water, air, and soil, and can even be found on plants and animals. Here are more facts about viruses and bacteria.

Viral Infections Vs Bacterial Infections

Viruses Can’t Live Without A Host

Viruses are able to reproduce by attaching to cells. They do this because they can’t survive without a host. Once they attach themselves to cells, they use cellular components to reprogram those cells to produce new viruses. This reproduction causes cells to explode and die. Viruses are able to turn healthy cells into malignant ones.

In fact, there are several oncoviruses that have been linked to cancer, including:

  • Human papillomaviurs virus (HPV): cervical, vaginal, throat, and anal cancers
  • Epstein-Barr virus (EBV): stomach cancer, Burkitt lymphoma, and certain types of non-Hodgkin’s and Hodgkin’s lymphoma
  • Human herpes virus 8 (HHV-8): Kaposi sarcoma (in people with compromised immunity)
  • Hepatitis B virus (HBV): liver cancer
  • Hepatitis C virus (HCV): liver cancer and non-Hodgkin’s lymphoma
  • Human T-cell leukemia virus (HTLV-1): T-cell leukemia and lymphoma in adults
  • Human immunodeficiency virus (HIV): increases cancer risk by reducing immune function

Antibiotics Don’t Work For Viral Infections

The reason antibiotics don’t work to kick colds or the flu is because these conditions are caused by a virus rather than a bacterium. Most sore throats and coughs are viral in nature, however strep throat and whooping cough are bacterial infections, and can thus be treated with antibiotics. Both viruses and bacteria can cause fevers.

Vaccines are used to prevent viral infections, which is why researchers worldwide are furiously trying to develop a vaccine for the coronavirus. Antiviral medications are used in some cases to prevent viral reproduction or to increase immune function. Since viruses must run their course before symptoms abate, symptom-relief is the primary course of action for viral infections. If you’ve experienced any type of infection caused by a virus, you know this to be true.

Chronic Viral Infections Can Turn Into Bacterial Infections

Chronic viral infections can turn into bacterial infections. This is because viruses compromise immunity and damage tissue, providing the perfect environment for bacteria to grow. Viral infections last anywhere from seven to 10 days. If your symptoms worsen or change after this time period, get checked by your health care provider to make sure your symptoms are not associated with a bacterial infection.

Certain populations are at increased risk of developing secondary bacterial infections, such as the elderly, those with underlying health conditions, and people with asthma. It’s not uncommon for an older person to be admitted to the hospital for a viral infection, only to end up needing treatment for pneumonia. The most significant period of susceptibility to bacterial infections is not when the virus initially takes hold, but rather during the time period when it should be clearing.

Both Infections Spread In Similar Ways

Although, viruses and bacteria differ in many aspects, the infections they cause are spread in similar ways. Sneezing, coughing, contact with people who are infected or contaminated surfaces are common modes of transmission. Also, contact with livestock, pets, or fleas and ticks, as is the case with Lyme disease, a vector-borne disease caused by the bacterium Borrelia burgdorferi.

Viral Infections Vs Bacterial Infections - Virus

Viruses And Bacteria Can Both Be Contagious

Both viral and bacterial infections can be contagious. The degree of contagion depends on how the infection is transmitted and how long the person with the infection is contagious, not whether the disease is viral or bacterial.

Measles is the most contagious airborne virus. A person with the disease can potentially infect up to 18 people. Ebola, another viral disease, can be transmitted to two susceptible people if they come into contact with an infected person’s bodily fluids.

Whooping cough, another airborne illness, is the most contagious bacterial infection, with the potential to infect up to 17 people who are susceptible. Compare this with diphtheria, a bacterial infection spread via droplets in the air, which has the potential to infect only a handful of people.

H. pylori is a common stomach bacterium that is highly contagious and can be passed via saliva. It’s not atypical that an entire family can become infected just from one infected member. Not all infections are contagious. Some, like Rocky Mountain spotted fever can be spread through tick bites or acquired through eating contaminated food, as is the case with botulism. Other infections caused by bacteria, including tetanus, can gain entrance into the body through a wound.

RO Values

R0 stands for “R naught,” a mathematical term that designates how contagious a disease is. It’s also called the reproduction number because it denotes a disease’s ability to reproduce. Infections reproduce by spreading to increasingly more and more people.  If a disease has an R0 less than 1, it will eventually decline and die out.

This is because each infected person only has the capability of infecting less than one other person. Diseases with an R0 value equal to 1 will not lead to pandemics because each person that is infected will only cause one new infection. Diseases with R naughts over 1 can cause pandemics due to the spread of the disease, with each infected person causing more than one new infection.

To give you some perspective on how contagious COVID-19 is, measles has an R0 of 12-18, ebola an Rbetween 1.5-2.5, and SARS-CoV-2  an R0 of 2.2. Keep in mind, R naught values apply only to populations where no one has had the disease or been vaccinated, along with an inability to contain the spread of the disease. The reproduction number is only one factor, however. For instance, taking into account the R naught values of both the measles and ebola, you can see that measles is significantly more contagious, yet more people died of ebola.

Examples Of Viral Infections Vs Bacterial Infections

Viruses and bacteria both cause varying degrees of infection, ranging from mild to deadly. Treatment is dependent on whether the infection is caused by a virus or bacterium. This can be difficult to determine at times because both types of infections can manifest similar symptoms. Blood, urine, and stool samples are used to identify the specific type of pathogen.

Bacterial infections are treated with antibiotics, which can be lifesaving, because they either halt the spread of the bacteria or kill it altogether. You never want to use antibiotics for viral infections: firstly, they won’t be effective, and secondly, they increase the risk of antibiotic resistance, which is a growing health concern. Antibiotics should only be given when absolutely necessary.

Some diseases, like meningitis, diarrhea, and pneumonia can be caused by either a virus or bacterium. Following is a list of diseases caused by either viruses or bacteria:

  • HIV: viral
  • H1N1 swine flu: viral
  • Polio: viral
  • Ebola: viral
  • MERS-CoV: viral
  • Herpes: viral
  • Warts: viral
  • Chicken pox: viral
  • UTIs: bacterial
  • Cellulitis: bacterial
  • Eye infections: bacterial
  • Food poisoning: bacterial
  • Sexually transmitted diseases: bacterial
  • Typhoid: bacterial
  • Cholera: bacterial
  • C. Diff: bacterial

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Viruses Are Smaller Than Bacteria

Viruses are microscopic organisms that are significantly smaller than bacteria, and can only be seen using a microscope. If you took the smallest bacterium (which is also microscopic) and compared it to the largest virus, the virus would be smaller. Viruses are composed of genetic material, including DNA or RNA, surrounded by a protein coating.

Bacteria are single-celled microbes, called prokaryotes, that have no nucleus. They are typically a few micrometers in length and exist in communities. Fresh water and soil are teeming with millions of bacteria, which are thought to be the first organisms to appear on planet earth.

Bacteria can be both infectious or beneficial. For example, fermentation is caused by bacteria transforming carbohydrates into lactic acid. The following fact underscores the importance of bacteria: the human body contains up to 10 times more bacterial cells than it does human ones. We live symbiotically together with these organisms.

The beneficial bacteria that make up a large percentage of the microbiome are vital for healthy immune function, digestion, detoxification, and vitamin synthesis. The skin itself is a diverse ecosystem that hosts more than 500 bacterial species.

Bacterium Live Outside The Cell / Viruses Are Intracellular

Unlike bacteria, viruses are not cells, and can only replicate intracellularly. They’re not capable of metabolizing independently, but need a host, such as an animal or human, to replicate. Once attached to a host, viruses cause infections by multiplying.

Bacteria does not need a host to survive, and can thrive inside or outside of the body. Bacteria are complex cells that are either rod, spiral, or spherical-shaped. They can live in all kinds of environments, including extreme cold or heat. There are trillions of bacterial strains, most do not pose a threat to humans, although some can be life-threatening.

The Coronavirus Is A Mutated Virus

COVID-19 is caused by a virus believed to be carried by bats. Last November, the virus mutated and evolved into SARS-CoV-2, the viral strain responsible for the pandemic we’re now experiencing. Bats, carry dozens if not more, coronavirus strains that are part of their natural microbiome. These strains live symbiotically with the bats without causing harm.

Two mutations in the coronavirus resulted in what is now COVID-19. As these viruses reproduce, they go through genetic changes. These mutations enable the viruses to be transferred to humans or to other animals. The first mutation altered the spike-like structures that protrude from the virus, allowing it to attach to the ACE2 proteins that line the respiratory tract. Knowledge of the molecular structure of the ACE protein will be an instrumental factor in the development of a coronavirus vaccine.

The second critical mutation enabled the virus, which uses furin proteins, to tightly bind to cells in the throat and lungs by slicing through other proteins. While these mutations may have taken place in bats, either could have occurred in an asymptomatic, infected person who had a previous strain of the virus. However, it is hypothesized that the mutation likely took place in an intermediate host.

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Key Points

Infections occur when pathogenic organisms enter the body. Viruses and bacteria both cause infections, but aren’t the only culprits. Fungus, protozoans, and parasites also cause disease.

Infections can range in severity from making you feel tired and run-down to full-fledged epidemics, as is the case with the coronavirus.

How infections are treated depends on the nature of the organism that is causing it. Fortunately, we have vaccines and antibiotics for some of the most deadly viral and bacterial infections.

Were you aware of the differences between viruses and bacteria? Let me know in the comments:)





(1) WebMD: How do viruses differ from bacteria?

(2) MD Anderson Center: 7 viruses that cause cancer

(3) LiveScience: What Are Viruses?

(4) NCBI: How Infection Works

(5) healthline: Why the Gut Microbiome Is Crucial For Your Health

(6) NCBI: The skin microbiome

(7) WebMD: Bacterial and Viral Infections

(8) CDC: Lyme Disease

(9) NAUTILUS: How Genetic Mutations Turned the Coronavirus Deadly

(10) LiveScience: Coronavirus ‘spike’ protein just mapped, leading way to vaccine

(11) Viruses

(12) healthdirect: Difference between bacterial and viral infection

(13) MedicalNewsToday: Everything you need to know about infections

(14) healthline: Are Bacterial Infections Contagious?

(15) Mayo Clinic: Bacterial vs. viral infections: How do they differ?

(16) healthline: What Is R0?: Gauging Contagious Infections

(17) NCBI: Features, Evaluation and Treatment Coronavirus (COVID-19)

(18) Scientific American: Understanding the Measles Outbreak with this One Weird Number


Disclaimer: This article is strictly for informational purposes only and is not intended to be medical advice. Please be diligent and always do your own research in regard to any material I present on this site. I claim no responsibility for any distress, whether it be physical or emotional, that may occur as a result of the information you obtain from my blog. 


8 thoughts on “Viral Infections Vs Bacterial Infections [What’s The Difference?]”

  1. Could there be anything more topical and relevant today than to really understand the difference between infections, notably viruses and bacteria? I doubt it. Your description is really clear about the differences. The video link on the importance and how to clean hands is also a really important reinforcement of this key public health message.

    I fully understand that antibiotics do not work for viruses.  However, do you think the excessive use of antibiotics has weakened our immune systems to such as extent that our bodies are actually more vulnerable today to new bacteria and viruses? I would be interested in your views and look forward to your reply.

    • Hi Trevor,

      Thanks for reading my article. I felt that the topic was timely considering what we’re all facing. The pandemic has become a personal issue for every single person on this planet. I’m glad you found the video helpful. 

      Yes, it’s unfortunate that antibiotics don’t treat viruses they same way they do bacteria. So many lives could have been spared. I do believe that antibiotics, handed out unjudiciously, have incurred damage in terms of weakening immune function and have contributed to the growing concern of antibiotic resistance. 

      This makes them less effective when they are truly needed. Antibiotics are lifesaving but should only be used. when absolutely needed for bacterial infections. Thank you for sharing your thoughts:)

  2. These are interesting times as we’re all being asked to make huge sacrifices to fight the COVID-19 novel coronavirus. It’s helpful to know as much as possible about the threat we’re facing so that we can use the most effective measures to fight it. We’re lucky to live in a time where we have access to so much critical information that can help us to contain the pandemic. 

    • Hi Aly,

      I agree, these are unprecedented times for sure. My heart goes out to all the workers on the front lines. Their sacrifice is much appreciated. It must be so trying both for them and their families. 

      Yes, information is power, the more we understand, the more equipped we are to fight. We are so blessed to have daily access to the internet. It’s a lifeline, particularly in these trying times. Thanks so much for reading my post:)

  3. Hi,

    Thanks for this timely and accurate article. An interesting matter, especially with this pandemic we are facing. It’s unfortunate that viruses can’t be treated with antibiotics. Although, vitamin C is antiviral and has been used in China and is being used in the US too to help fight the Coronavirus, intravenous vitamin C, along with conventional protocols help people in the recovery process. Particularly to survive pneumonia.

    Viruses are winning the war against humans. So far. 

    Stay safe,



    • Hi Isabella,

      Thanks for reading my post. Yes, I agree, the information is quite timely. It would be miraculous if antibiotics could be used for viral infections. Can you imagine the difference that would make? 

      I just made a batch of liposomal vitamin C, and am dosing continually with it. I’m confident that we will get through this pandemic, although I’m extremely heartbroken over everyone who has died and for their families. It’s tragic. Thanks for taking the time to leave a comment:)

  4. In the current situation and conditions we are living in right now, this article is a good outlook for those of us who have little or no knowledge as to the amount of different infections that are out there. Some I have never heard of.

    I find this information to be useful in terms of being aware of some things to look out for and to be mindful of. I found the video helpful. It illustrated such a calmness. I think it will help people in a great way that will most definitely break the panic levels down to minimum as it did for me. Just knowing that soap can actually kill these viruses and it doesn’t have to be anti-bacterial soap either.

    The video, to be specific, is of great help for some like myself who dread these sanitizing gels that totally dries out my skin. Therefore, I can now go back to using soap to wash my hands. Thank you for this info, you have given me some new insights to be mindful of. And nice touch with the video as well.

    • Hi Stephen,

      Thanks for reading my article on infections. The ways in which bacteria and viruses function is fascinating to me, especially in light of the pandemic. I’m glad you found the video interesting. Hand sanitizer dries my hands out too. I’d much rather use soap and water when possible. I appreciate your comment:)


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