The field of research is expanding on the interconnectedness of our immune system with our gut flora and we know that 70% of a person’s immune system resides in the wall of the colon. Our immune system begins developing the day we are born, it’s a temporary passive immunity which is passed from mother to baby occurring when the mother’s bacteria reaches the colon and stimulates the immune cells within the walls. Therefore, if our gut is comprised then so is our immunity.
The gut is also where most parasites make their home and if the conditions are favourable, they lay eggs, multiply and latch on to the gut lining. This inhabitation can cause symptoms relating to gastrointestinal disorders. In the Journal Parasite Immunology, Dr. Kamal, explains that parasitic activity often weakens the immune system’s ability to effectively respond to vaccines and medication because such worms induce an immune response that is less responsive than normal to the antigens.
Parasites have the ability in some cases to take over the mind and the will of their host, take for example the neurological parasite toxoplasma gondi tachyzoite, once this protozoan parasite makes its journey into the brain, it can dramatically alter the behaviour of the host, not just in cats and rats but also in controlling the brains of their human hosts. T- gondi tachyzoites can also hibernate for a long time within humans without any symptoms until its ready to leash out and strike. Research has estimated that around 30% of the population, possibly more than two billion of us are carrying the T- gondii tachyzoites in our brains at this present moment.
Parasites can be like magicians, altering the host’s brain chemistry to their advantage, take for example Dicrocoelium dendriticum, this Lancet liver fluke parasite directs the ants navigational skills against its free will into climbing to the top of a blade of grass where the ant waits in position to meet its deadly fate, to be eaten by an animal grazing on the grass. The parasite is then transferred into the grazing animal which houses the parasites eggs, the cycle continues…
Parasites that attacks certain species of crab eats up all the non- essential soft tissue inside of it and leaves the basics that allow locomotion, key muscles and optic nerve functions. The parasite is then able to take over the partially hollowed crab and use it like a puppet. Rabies is caused by a parasite and it produces a certain type of madness that will cause an infected host whether mammal or human, to bite or cause bloodshed with another mammal thereby allowing an opening of transmission for the parasite. Another example is infected rats with T-gondi tachyzoites, they become sexually aroused by the smell of cats, instead of being afraid they become fearless and run right into the cat’s domain where they are killed. This exchange releases the parasite into the cat which allows the egg laying cycle to start all over again.
Studies have shown that the mental condition Schizophrenia jumped sharply at the beginning of the 20th century, when pets and domestic cat ownership became common. There are variety of parasites that have a taste for the brain and we now understand that neurological parasites can do serious damage, sometimes leaving hosts with compulsions, insanity and death.
The Journal Proceedings of the Royal Society published that in areas with high T- gondii tachyzoite infection rates, these parasites could collectively alter the behavioural patterns of entire cultures, researchers have found Infected parents have a 30 percent rate of passing the parasite on to their children. There’s also some concern that the parasite may slows reaction times putting people at double risk of having traffic accidents, and a study in Jama Psychiatry found links between T- gondii tachyzoite and women’s risk of self-harm, such as self-mutilation.
Could Schizophrenia and other mental health issues be related to parasitic influence
of control of the human mind? What then can parasitic brain control mean for human behaviour, compulsions and reactions?
This topic is too broad to elaborate on here and deserves its own dedicated blog article that will be written.
All successful microbial pathogens are accomplished evaders, altering the host’s immune defences and responses. The evolution of immune responses by microbes is thought to have occurred in step with evolution of the vertebrate immune system, involving the central nervous system, which is interconnected with the cerebral cortex, thalamus, brainstem, and associated with a variety of functions: motor control, cognition, emotions, and learning.
Parasites have evolved to manipulate the hosts immune cell recognition, activation and regulation by employing a wide range of discrete mechanisms. Some parasites even manage to feed on the host’s immune response, for example, Leishmania parasites are spread by the bite of infected sand flies and uses host cytokines (signalling immune-modulating agents) as personal growth factors or tapeworms using the hosts antibodies as nutrients.
Parasites are dependent on immunological evasion mechanisms; this is a direct consequence that these organisms must live for prolonged periods within the host tissues during their life cycle. At a minimum the duration must be long enough for the organisms to replicate and develop fully into the life span cycle, allowing them to multiply for future successful transmissions or takeovers, leaving an heir to the throne so to speak.
Immune evasion is initiated by the parasite and the host is always the responding party. Parasites evade host immunity by employing both “passive” and “active” strategies. Passive evasion includes the altered display of MAMPs (microbe associated molecular patterns) to avoid activation of the hosts innate immune cell pattern recognition receptors, as well as the classic antigen variation in which the display of the molecule to which the antibody attaches itself is altered to avoid recognition by B and T lymphocytes immune system guards and killer cells. Many successful parasites and pathogens exhibit antigenic variation to avoid immune elimination during infection.
Active evasion of immune response refers to alterations in post-receptors signalling pathways, therefore the physiological responses to the neurotransmitter-receptor interaction is confused or scrambled with wrong information. Another method is the innate and adaptive immune system is prevented from generating a sufficient response and quick action to the sound of the invader alarm and to the receptor detection stimuli. Parasites also uses shielding techniques of camouflage protection and can lay dormant until the immune troops pass by.
⦁ Virulence is the severity or harmfulness of a disease and immune evasion is often the missing link to the proliferation of conditions. The main mission of the parasite is to live to maturity, and they use the host’s immune defence system for its own benefit, some of their survival tactics include:
⦁ Reducing the host’s level of resources and depleting, nutrients, enzymes, extracting iron from the body, in some cases iron is mobilised from host cells by parasite-induced tissue destruction. The aim is to weaken the body systems.
⦁ DNA switching or hiding gene sequences from the host, also referred to as anti -genetic variation, this is a means to escape and avoid the host’s immunity detection.
⦁ Using suppressing cellular mechanisms to dumb down the host’s natural immunity reactions. Putting the immune system into a slumber sleep mode.
⦁ Enabling immune evasion via shielding and master of disguising technique by using the properties of the VSG coat (VSG- stands for variant surface glycoprotein).
⦁ Using the host’s cell molecules to act as decoy receptors and thus impeding the immune response.
⦁ Manipulating the host’s own receptors into becoming dangerous virus receptors. Virus receptors sits on the host’s cell surface and is recognised by the virus as a gateway entry into the cell.
⦁ Altering the hosts mind and behavioural patterns to benefit their needs
The parasite face consequences should immune evasion fail. The parasite will lose its home and future prospects while the host may still have a chance to survive, and gain well-being. The game is definitely on for the parasites and it will pull out all the tricks to continue using the host as their home, life-dinner, servant and bodyguard. Parasites should not be underestimated, they’re out to win and are generally ahead in the co-evolutionary race for the control over the host’s immune system.
Parasitology may sound like an obscure branch of biology, but it is central to the evolution of life and understanding that there are highly evolved species of parasites and the relationship with its hosts is an energetic one. The human interface with the microbial world has largely been considered through the restrictive angle of finding symptoms that match a disease, but major progression has been made in the area of neurological, nervous system, and behavioural parasitic manipulation mechanisms with investigations still ongoing.
Despite all the awe amazing tactics parasites uses among its host, its all for the same purpose – what every parasite wants is a rich host with rich deposits of energy, like warn blooded mammals, which attract female mosquitoes that will use them to fertilise their eggs and complete her life cycle. They just want a good home.