A Tale of Two Pathogens

and a note of love on this tough day

Today is a weird day. I don’t quite know what to say or do. There is a lot that is unknown and a lot of unknowns to worry about.

I have struggled lately with feeling like our efforts are worthless. I know this is not true and many, myself included, have discussed how feeling hopeless and assuming nothing will change leads to inaction and then that assumption becoming true.

It is sometimes easier said than done though. Some days it's normal for us to want to quit. It is why it is critical to remember we are in a marathon not a sprint.

So I won’t stop educating on science online. But some days I will take breaks. I also am trying to assemble resources and ideas to involve all of you in science education efforts in your own communities because we need you. Scientists and educators cannot do this alone. We all have our own sphere of influence and we can all make a difference. Stay tuned, it just takes me time as I am doing this in my spare time. In the meanwhile I am sending you love, you aren’t alone. We will face today and the tomorrow’s together.

Today felt appropriate to try something different, so stick with me. I am going to try to use a story to illustrate a concept I keep mentioning a lot - that infection with one pathogen doesn’t help you fight other, different pathogens.

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A Tale of Two Pathogens

The view from the real Beech Mountain in Acadia National Park. Photo by me from one of my many hikes up its summit,

Margaret is solo hiking up a beautiful mountain in Acadia known as Beech Mountain. She is about halfway up the mountain when she notices someone ahead of her has fallen and needs help getting up. She rushes up and extends a hand to help them. They chat for a bit and Margaret notices the person is sneezing a lot. She finishes her hike and forgets all about her encounter with the sick person.

A few days later she starts to get a runny nose, cough and a fever. She goes to urgent care where she is told she has RSV. Eventually she gets better. But then a few days later she develops chills, body aches and a fever. She returns to the doctor where they tell her she now has influenza A. What the heck? Why didn’t the first infection help prevent the second? Shouldn’t her immune system be stronger now? (hint: that isn’t how this works).

When Margaret helped the sick person on the mountain she was exposed to RSV. The virus was able to escape the immune system's first line of defense - the barrier system. This is composed of skin and mucous membranes. Their job is to prevent the pathogens from entering you in the first place but they don’t always work. Once inside the next defense is the innate immune system. This system is composed of cells that can detect a foreign invader, but cannot learn to recognize it if they encounter them again. Think of them like Dory from Finding Nemo - they can’t form memories.

Sometimes, the innate immune system can stop an infection from progressing, but sometimes this isn’t enough. When this happens the adaptive immune system is turned on. This is composed of B cells, T cells and antibodies that learn to recognize each unique pathogen it encounters and helps eliminate it. After Margaret recovered from RSV these adaptive immune cells can form memory that would protect her for a while (how long is unclear, estimated around 2 months).

However Margaret was still susceptible to flu A a few days later because it's caused by a different virus. So the immune system cells that recognize RSV won’t recognize and prevent or help with flu A infection.

Think of it like meeting one stranger named Sharon in the grocery store - you’re not suddenly going to recognize a different stranger named Ron the next time you visit the same store. BUT if you see Sharon again a day later you may still remember her because it has been a short time. Fast forward to a year from now and you likely wouldn’t recognize Sharon again either from that one short encounter.

The same is true for your immune system. It can recognize things you’ve encountered but can lose that memory over time. That memory won’t help with something it hasn’t seen (met) before.

Why am I telling you this story?

Well it is because there is a common rumor still circulating that getting sick with one pathogen will make your immune system stronger and better able to fight other pathogens. But that isn’t how this system works, as this story hopefully illustrates.

Infection with one pathogen helps your immune system recognize that one pathogen for varying amounts of time going forward - this can help prevent an infection again or reduce severity (time this lasts varies), but it doesn’t help with unrelated pathogens.

Now, remember a pathogen is a microbe that makes you sick. Not all microbes are pathogens. Many form parts of our microbiome and are important for our health. This is why getting out in nature, avoiding overuse of antibiotics, playing with animals and dirt etc can be helpful.

I have covered some of the complexities of this in an earlier post linked here. But I thought it was worth trying a different method of illustrating this concept. Let me know what you think! Should I do this more or less?

From the teacher’s house

• I start my journey towards Tanzania on Weds! I fly to NY where I am for a bit before flying the rest of the way with Anni! I am excited and hoping we all stay healthy. I have been masking everywhere to avoid as many germs that could ruin this trip as possible. I could be Margaret here as I have had a string of illness recently that have been frustrating.

• Last week I co-taught a genetics course with a coworker and it was so fun. We taught undergraduates key genetic techniques - including CRISPR. Which is a tool to edit DNA.

Reading:

• I finished The Posionwood Bible and loved it!

• I am currently reading The Girl Who Saved the King of Sweden by Jonas Jonasson and so far I am enjoying it. I loved his book The 100-Year Old Man Who Climbed Out a Window and Disappeared.

MLK Jr. Quotes

Have I ever mentioned I am obsessed with quotes and poetry? Today is Martin Luther King Jr day so here are a few of my favorites from him that seem particularly important moving forward.

"Out of the mountain of despair, a stone of hope"

“Darkness cannot drive out darkness, only light can do that. Hate cannot drive out hate, only love can do that.”

“The ultimate measure of a man is not where he stands in moments of comfort and convenience, but where he stands at times of challenge and controversy.”

Let’s do what we can friends, one day at a time <3

xoxo,

Liz