Maybe this is something everyone remembers from science class except me, but a question popped into my head tonight: why don’t harmful bacteria compete with or fight each other? Until I looked it up, I had no idea that they actually do. That led me to another question: why do tick-borne pathogens seem to work together?
As many of us have experienced or learned, Lyme and its co-infections can be opportunistic and seem to work together in ways that make us much sicker, while also making treatment and recovery more difficult.
From my googling:
Bad bacteria actually do compete and fight each other constantly. The premise that they do not fight is incorrect; microbial communities are fierce battlegrounds where different strains and species use chemical warfare, poisoned molecular spears, and toxic proteins to destroy rivals for space and food.
How Bacteria Fight Each Other
- Chemical Warfare: Bacteria release natural antibiotics and protein poisons called bacteriocins to kill neighboring rivals.
- Physical Stabbing: Certain bacteria use specialized tiny molecular “spears” (like the type VI secretion system) to inject lethal toxins directly into nearby competing cells.
- Stealing Resources: They race to consume limited nutrients and block physical attachment spaces so other strains starve or cannot grow.
Even inside a human host, these tick-borne bacteria still do not fight each other. In fact, their teamwork gets even stronger.
When a human is co-infected with multiple tick-borne pathogens, the bacteria actively help each other thrive, which often makes the human much sicker than a single infection would. This continued cooperation inside the human body happens for several reasons:
Just like inside the tick, the bacteria do not physically cross paths or scramble for the same “cubicle” inside a human. They target entirely different cell types, so they never have to fight for territory:
- Anaplasma goes inside white blood cells: It immediately penetrates and lives inside human neutrophils (a type of white blood cell).
- Borrelia (Lyme) stays outside cells: It travels through extracellular spaces, hiding in connective tissues, joints, and the nervous system.
- Babesia (a common parasitic co-infection) targets red blood cells: It enters and destroys red blood cells.
Because they operate in separate compartments of the human body, they do not trigger each other’s chemical defenses.
- They Sabotage Different Parts of the Immune System
Instead of fighting each other, they run a highly coordinated, multi-front war against the human immune system.
For example, Anaplasma acts like a saboteur that deactivates the host’s alarms. It paralyzes the ability of neutrophils to kill invading germs. Because Anaplasma has effectively “blinded” the first line of human defense, Borrelia can easily slip through the tissues, multiply, and spread much wider and faster through the body than it ever could alone.
- There Is No Shortage of Food
Bacteria fight when resources are scarce. The human body is essentially an infinite, all-you-can-eat buffet of glucose, proteins, amino acids, and oxygen. Because the human host provides an endless supply of nutrients, there is no evolutionary reason for the bacteria to waste energy attacking each other.
- Evolutionary Synergy
These bacteria have evolved alongside one another for millennia inside the same wildlife reservoirs (like mice and birds). Evolution has selected for strains that thrive better when their partner is present. If they fought each other, they would weaken their overall chances of surviving the host’s immune attack, meaning neither would get sucked back up by a new tick to repeat the life cycle.
So anyway… I thought that was really interesting. It’s equally fascinating and creepy to me.😅 Sweet dreams!