Lecture 17: Everyday life Flashcards
Can pathogens control their hosts?
Give examples
Yes
The parasitic hairworm attaches itself to grasshoppers. It gains resources from the grasshopper and then it alters its brain and causes the grasshopper to drown itself. This allows the worm to swim away and find a new host.
The guinea worm makes your foot feel hot, 1 year after it enters the body, so you put it in water, allowing the worm to leave and find a new host.
Snail zombies, attracting birds to eat them
Fungus that causes bugs to climb to the top of a plant where they die. Spores release from the body and climb down to the floor in the surrounding area to infect more.
Caterpillars can be made to defend wasp eggs
Parisitoid wasps can make cockroach zombies that are eaten from the inside out.
Describe rabies
It’s a parasite that controls its host. It multiplies in the limbic system and paralyses oesophageal muscles. It doesn’t psychologically effect bats but it causes hydrophobia in humans.
Describe toxoplasma gondii
It can affect almost all mammals. It’s present in 1/3 of the human population and felines are the definitive host. Rodents are the intermediate host. It’s dangerous to pregnant women and has pervasive effects on humans. There are sex differences though. If it ends up in farm yard animals, they stay there for life and then we ingest them. It doubles the risk of car accidents as it slows your reaction time and abnormal fear response. It makes men more jealous, slow, emotionally unstable, disregard rules and more suspicious. It makes women have more self esteem, more intelligence and makes them seem more attractive. However, it makes them both more anxious. People with schizophrenia have more antibodies against this illness, this occurs with mumps and rubella also.
Can STIs manipulate behaviour?
They might increase libido. Spanish fly is an aphrodisiac and also makes the sufferer itch. Neurosyphilis, if untreated, can cause an infection of the brain and/or spinal cord. This can make the sufferer hallucinate or confuse things, for example one man mistook his wife for a hat. Natasha K had untreated syphilis which was dormant for many years but when she was 88, it made her feel young, vibrant, flirty and frisky. She called it Cupid’s disease. It doesn’t cause any harm so she didn’t get it treated. People advertise their sexual attractiveness via creativity so STIs might enhance this, this was found with Miguel O who became much more creative after he got an STI.
Discuss pathogen influences on culture
The antimicrobial hypothesis states that pathogens have an influence on food norms and taboos and that meat is more likely to be tabooed than other norms. Also it believes that cultures have evolved to use spices that help combat food born illness. There has been studies on the Aka tribe that could answer questions as to why we evolved to be reinforced by some drugs. For example, nicotine is an antihelminth so it protects you against the worm. Parasites can be considered as good as they have helped our evolution and caused the development of allergies which can be advantageous. Lawrence created Helminth therapy as it treats immune disorders.
Discuss bacteria in the microbiome
We have gut bacteria that have adapted to the local diet, This was compared against children from Italy and other cultures. In meat eating populations, there was more protein digesting microbes and Africans had more carbohydrate digesting microbes. They also produce more vitamin K. European microbiomes are more refined. Japanese people have zobellia which is gut bacteria that digests seaweed, they had different enzymes as well, compared to north americans. If mice are supplemented with certain gut bacteria, then they exhibit less anxiety. This was also found with women who ate fermented yoghurt as it reduced the brain activity associated with anxiety.
Discuss probiotics and prebiotics
Probiotics are living microbes that you can ingest via pills or food, they only live in the gut for a few days, companies don’t advertise this, they just list the bacteria it contains.
Prebiotics are substances we can’t digest but they promote good bacteria in the gut
Can microbes control eating behaviour?
Yes, gut bacteria manipulate reward pathways and produce toxins that alter your mood, they also alter taste receptors and they hijack the main neurotransmitter between the gut and the brain, this is the vagus nerve.
What are the benefits of fecal transplants?
The gut bacteria in the faeces can help gastrointestinal problems, like irritable bowel syndrome, and can help problems like metabolism and multiple sclerosis.
