• Dr. Gladis Walter


Updated: Apr 17, 2020

One is a particle, the other is a cell.

They are both microorganisms, but they are very different in size and structure. When in contact with either virus or bacteria, you may develop symptoms later, like fever, vomit, shortness of breath, for instance. If this happens, you may think you have an infection and it’s when you may ask yourself: “Is this caused by a virus or bacteria?”

It’s important to know who is causing the infection, because the treatment that your doctor will prescribe won’t be same. Let’s have a look.

1. Virus

A virus has a size that is so small that some people even think it doesn’t exist. It may be a fruit of imagination.

In terms of structure, a virus is not a cell, but a combination of nucleic acid surrounded by a coat of protein called capsid. Nucleic acid and protein together form a complete virus particle, called virions. Depending on the type of virus, it will have preference for invading cells of specific tissues. For example, the influenza virus binds to receptors of the epithelial cells in the respiratory tract.

As virus are not cells, they depend on the host cells to replicate and survive. When it is transmitted to another person, the virus will start a new cycle of replication in another host. After a period of days, the virus won’t be able to survive, and if it doesn't find a new host, the cycle may be closed.

A recent study on the impact of mass gatherings,show how public events have been contributing to pandemics, that also applies to the spread of COVID-19. It also shows the importance of implementation of nonpharmaceutical interventions, like the quarantine - that we know as social distancing, to avoid the expansion of disease outbreaks, like we are living now on 2020.

2. Bacteria

Bacteria is a cell, is a microbe with a nuclear membrane. Because bacteria can transcribe and translate their own proteins, they can live in a host for a long time. They are very adaptable and live in a variety of environments like your home, your car. And your gut too. You may associate the presence of bacteria in your body with the development of disease, but this is not always true. With the advancement of science, we are learning that about 10,000 bacterial species live in our body. The disruption of this internal ecosystem may be associate with disease. Among these 10,000 bacteria some are pathogens, like Streptococcus pyogenes (strep throat) and Streptococcus pneumonia (pneumonia). A review on pandemic influenza a(H1N1)pdm09, compiled data published between 01/01/2009 and 05/07/2012, and was published this month.

The study shows that 1 in 4 cases of fatal infection by H1N1, the patient had a secondary bacterial infection with the prevalence of Streptococcus pneumoniae.

It means that a bacterial infection can also be a secondary cause of fatal outcomes during pandemic and this should be taken into consideration when developing strategies do treat patients affected by the COVID-19, in the 21st century.

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MacIntyre CR, Chughtai AA, Barnes M, Ridda I, Seale H, Toms R, Heywood A3. The role of pneumonia and secondary bacterial infection in fatal and serious outcomes of pandemic influenza a(H1N1)pdm09. BCM Infect Dis. 2018;18(1):637. PMID: 30526505

DeSalle, R. Perkins. Susan L. Welcome to the Microbiome: Getting to Know the Trillions of Bacteria and Other Microbes In, On, and Around You. Yale University Press Books, 2016. 264p.

Ebrahim SH, Memish ZA. COVID-19 and the role of mass gatherings. Travel Med Infect Dis. 2020 Mar 9:101- 617. [Epub ahead of print] PMID: 32165283

Honigsbaum M. The pandemic century: one hundred years of panic, hysteria, and hubris. 1st ed. New York: W. W. Norton Company, 2019. 450p

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