Contagious or Not: A dissection of infectious disease

Figure 1 - Infectious Disease  Photo Credit: Dr. Shannon Hedtke (Evolutionary Biology, The University of Texas)
Figure 1 – Infectious Disease: Photo Credit – Dr. Shannon Hedtke (Evolutionary Biology 2011, The University of Texas)

I love Austin, TX, it’s an amazing place to call home.  Unfortunately, this past month it seems like microbes apparently share the same sentiment.  A new form of “keeping Austin weird”? — micro-organismic diversity. Infections seem to be running rampant, and practically everyone I know has been infected with some variation of virus, bacterium, or wandering DNA particle (manifesting in what we Austinites know intimately as allergies).  I’ve been astounded at the sheer diversity of these infections.  Just this past week five people tested positive for a highly pathogenic strain of Swine Flu at the place of my employment and many more of my friends have undiagnosed upper respiratory infections.  (see previous post on different forms of influenza:  http://meganjrutherford.com/2013/04/01/2-men-in-china-die-of-lesser-known-strain-of-bird-flu/ )

After two weeks of battling the fierce Austin allergens (mold and cedar), I was finally taken down by an unidentified microscopic visitor and soon banned from work thereafter because of fear that the unwelcomed microbe might spread.

I wasn’t too happy about being quarantined and the time I had spent studying microbiology led me to believe that I was not carrying a contagious pathogen [pathogen (Greek: πάθος pathos “suffering, passion” and γενής genēs “producer of”) — typically the term is used to mean an infectious agent — a microorganism, in the widest sense such as a virus, bacterium, prion, or fungus, that causes disease in its host (www.wikipedia.org)].

So I went to the doctor, surely a doctor could provide finite answers….  Wrong!  The physician performed a physical examination and then diagnosed me with “text-book” acute bronchitis based on the following symptoms:

  • Tenderness-to-the-touch in the throat and collar-bone region, due to infection of the trachea
  • Dry cough
  • Dark, thick mucus
  • Compromised breathing caused from inflamed and blocked airway passages (see image below)

    Figure 2 - Bronchitis Lung
    Figure 2 – Bronchitis Lung

He then wrote a prescription for the trusty Z-pak (street slang for Zythromax), a fast acting therapeutic antibiotic. Okay, awesome, so it’s confirmed that I have a bacterial infection since I need antibiotics to get better but what does that mean?  Can I go back to work or do I need to be quarantined?

Naturally, I tried to question the doctor further on the characteristics of a contagious bacterial infection but he quickly informed me that he was no doctor and that “he’s not smart enough to get paid the big bucks…”  *eye brow raised — sad face*  He was a physicians assistant (PA), not a doctor.  Ah, sweet ambiguity…

Upon arrival at the pharmacy, I questioned the pharmacist about chances that I might be contagious.  Again, I received the glazed over answer of “I believe so, but it depends… Didn’t you ask your doctor about that?”  I felt so bamboozled, why couldn’t any of these professionals tell me if I was a threat or not?

This post is dedicated to briefly classifying viruses, bacteria, and infections caused by microbes.   

Be a friend and keep your germs to yourself.
Be a friend and keep your germs to yourself.

Before getting into the gory details of infectious microorganisms, it’s important to understand that we have trillions of bacteria currently inhabiting our bodies.  The surfaces of the human body inside and out, for example the skin, mouth and the intestines, are covered in individual micro-organisms that don’t do us any harm. In fact they help to protect us from becoming infected with harmful microbes. They are known as the normal body flora.  Only about 1% of bacteria can invade our body and make us ill.  (Microbiology Online, 2014).

First things first: Influenza and how to differentiate it from the cold and allergies

Symptom Cold Flu Seasonal allergies
Cough Often (moderate) Often (severe) Sometimes
Diarrhea* Rarely Sometimes Never
Fatigue Sometimes Often Sometimes
Fever/chills Rarely Often Never
Headache Sometimes/Rarely Often Rarely/Never
Itchy eyes Rarely Rarely Often
Muscle/body aches Sometimes (minor) Often (severe) Rarely/Never
Runny/stuffy nose Often Often Sometimes
Sneezing Often Sometimes Often
Sore throat Often Sometimes Sometimes
Swelling of sinuses Often Rarely Never
Vomiting* Rarely Sometimes Never

http://www.healthline.com/health/cold-flu/contagious#1

The flu is a very scary threat to everyone.  It causes symptoms that come on hard and fast, and leave you feeling like you were hit by a truck.  Many complications can develop from the flu like pneumonia, bronchitis, sinus and ear infections.  Flu activity most commonly peaks in the US in January or February. However, seasonal flu activity can begin as early as October and continue to occur as late as May (CDC, 2013).  There are other viral and bacterial infections that share similar onset symptoms with the flu, which can make diagnosis complicated.  However, diagnostic instruments have now been developed that are able to rapidly test for the presence of the influenza virus and other infectious pathogens.  Recognizing the warning signs of different types of infections could prove to be very helpful.  Please see the tables below for side-by-side comparisons of 15 common infectious diseases.

Side-by-side comparison of 15 common infectious diseases

Table 3 - Contagious diseases:  Information gathered from: American Academy of Pediatrics; American Public Health Association; Centers for Disease Control and Prevention; Montana Department of Public Health and Human Services Communicable Disease Epidemiology Program; Wikipedia) Table Credit: Rutherford, MJ
Table 1 – Contagious disease: Information gathered from: American Academy of Pediatrics; American Public Health Association; Centers for Disease Control and Prevention; Montana Department of Public Health and Human Services Communicable Disease Epidemiology Program; Wikipedia) Table Credit: Rutherford, MJ

15 Common Infectious Diseases – Table PDF: 15 Contagious Diseases | Side-by-side

Table 2 - Contagious disease:  Information gathered from: American Academy of Pediatrics; American Public Health Association; Centers for Disease Control and Prevention; Montana Department of Public Health and Human Services Communicable Disease Epidemiology Program; Wikipedia) Table Credit: Rutherford, MJ
Table 2 – Contagious disease: Information gathered from: American Academy of Pediatrics; American Public Health Association; Centers for Disease Control and Prevention; Montana Department of Public Health and Human Services Communicable Disease Epidemiology Program; Wikipedia) Table Credit: Rutherford, MJ

15 Common Infectious Diseases – Table PDF: 15 Contagious Diseases | Side-by-side

Table 3 - Contagious disease:  Information gathered from: American Academy of Pediatrics; American Public Health Association; Centers for Disease Control and Prevention; Montana Department of Public Health and Human Services Communicable Disease Epidemiology Program; Wikipedia) Table Credit: Rutherford, MJ
Table 3 – Contagious disease: Information gathered from: American Academy of Pediatrics; American Public Health Association; Centers for Disease Control and Prevention; Montana Department of Public Health and Human Services Communicable Disease Epidemiology Program; Wikipedia) Table Credit: Rutherford, MJ

15 Common Infectious Diseases – Table PDF: 15 Contagious Diseases | Side-by-side

The Verdict: sweet ambiguity

There are multiple factors that come into play when trying to classify risks related to contagious disease, which may also contribute to the glazed over answers received from medical professionals.  As for my prognosis: acute bronchitis via bacterial infection, I guess that I’m “keeping Austin weird” since only about 5% of acute bronchitis cases are bacterial (treated with antibiotics).  Viruses cause about 90%-95% of cases of acute bronchitis in healthy adults. The most common viruses are rhinovirus, adenovirus, influenza A and B, and parainfluenza virus; bacteria are usually commensals (PubMed, 2008).

So based on this information, my immune system might have been weakened from trying to fight off the vast spectrum of viruses and allergens circulating throughout the city; and that’s when an opportunistic bacterium “carpe diemed” my bronchial tubes.  There are no reliable diagnostics or laboratory tests for the cause of acute bronchitis; the diagnosis is a clinical one.  Most likely I was not contagious, unless the strain of bacteria that I was carrying did not mesh well with someone else’s normal body flora.

The microbial world is alive and well in our bodies and our surroundings.  The events are cascading that lead to infection, but we depend on endogenous microorganisms for optimal health.  Trillions of bacteria are on our side (in our bodies), in the past 5 years many new findings have been made that will blow your mind on the importance of native flora to promote and protect the quality of our lives.  This will be the focus of the next post – more about the “Good Guys”.

Disclaimer:  I am not a medical doctor.  I have previously worked at a biotechnology company that develops molecular diagnostics to test for infectious disease.  The material in this post was compiled in an effort to inform and empower, but please consult a medical professional in the event of infection.

References:

http://www.aap.org/en-us/aap-store/clinical-publications/Pages/clinical-publications.aspx

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001969/

http://www.cdc.gov/outbreaks/index.html

http://www.cdc.gov/parvovirusb19/fifth-disease.html

http://www.dphhs.mt.gov/publichealth/cdepi/documents/CommunicableDiseaseResourceGuideForSchools.pdf

http://healthservices.unomaha.edu/selfcare.php?item=26

http://www.microbiologyonline.org.uk/about-microbiology/introducing-microbes/bacteria

http://www.aap.org/healthtopics/infectiousdiseases.cfm

http://www.apha.org/publications/bookstore/ccdmmobile.htm

http://www.webmd.com/a-to-z-guides/understanding-scarlet-fever-basics

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2278319/