pathogens shaping history

yersinia pestis

• gram-negative bacteria

• caused the bubonic (caused buboes, swollen lymph nodes ~50% mortality rate) and pneumonic plague

• when sepsis goes into the blood and travels to the lungs, you get the pneumonic plague: 90-100% mortality rate

• treatable in less than 24 hrs since first symptoms

• F1 toxin makes fleas less hungry

• transmission through rodents, prairie dogs, rodent fleas and human respiratory aerosol (pneumonic)

• treatable via antibiotics and vaccine (but limited value)

yersinia pestis is a zoonotic pathogen affectin rodents and wild dogs

• when the rodent is infected, the fleas will be infected as well and because they are super hungry, they will turn to humans for their food source instead, as the rodents would be dead

epizootics

• animal equivalent of an epidemic

phytophthora infestans

• causes potato blight/ late blight

• symptoms:white mycelium growth over surface of leaves and tubers (potatoes)

• classification: spore-forming, oomycete (water mold)

• virulence: approaching 100% of crops

• transmission/reservoir: very stable spore structures

• treatment: fungicides and copper sulfate (can cause issues with heavy metal toxicity)

how did potato blight occur?

• potatoes originated from Peru, which were brought over by spanish and british sailors in the late 1500s, but they only brought back a few species

• pathogens share similar geographic distribution with their hosts and usually co-evolve with them

• the blight was not a problem in Peru as there was a large variety however, if the monoculture is susceptible to blight, then the potatoes will be infected, and the soil will be full of spores

influenza virus

• causes influenza

• symptoms: fever, chills, cough, chest pain, soar throat, muscle pain

• virulence: 0.01-50% depending on the strain

• major virulence facots: changes in the H and N proteins can be linked to virulence

• classification: negative ssRNA

• reservoir/transmission: human reservoir/ respiratory droplets and can also infect other animals

• treatments: antiviral drugs and vaccines (varied efficacy)

how does genetic diversity in influenza form?

• re-assortment of genetic material generates new influenza particles

• influenza has 8 vital chromosomes