M4: Topic 3: Disease Transmission

• Q. Define reservoirs 


  Sites which infectious agents remain viable and where it occurs ie. living organisms
• define zoonosis 


  any disease that primary infect animals
• List the soruce of diease

  1. infectious individual 2. Reservoir 3. Carriers and 4. Non-living agents
• compare the different transmission types

  1. contact (direct and indirect and droplets) 2. vehicle ( water, air and food) 3. vector (moving object, mechanical and biological)
• list the different contact transmission

  1. direct host-host 2. indirect host-host
• direct host- host 


  infected and transimt disease directly to susceptible host without assistance of intermediate ie. cold, flu, STI
• indirect host to host


  Involves a vector /living/formite (non-living) ie. plague
• explain tuberculous

  • by mycobacterium turber
• Explain tuberculosis

  • By mycobacterium tuber <- non-spore forming gram +ve
  • wacky cell wall <— hard to treat with antibiotics
  • tranismitted through airborne agents
  • bacteria enfluged by macrophage and increase slowly
• explain diphtheria

  • by corynbacterium dip <— non-sporting gram +ve
  • air-borne
  • produces powerplex exotoxin <— AB —> tissue death
  • B receptors attaches to cell memrbane = release toxin and blocks mRNA
• explore plague

  • by versinia pet is
  • in rodents
  • lipoproteins
  • capsule
  • exotoxin
  • murine exotoxin
• list the common sources of infection

  1. food safety
  2. water
  3. industrial products
  4. hospitals
• list the 2 types of food products

  1. poisoning: microbial toxins
  2. infection: ingestion of pathogen
• explain food spoilage

  • changes to appearance, smell, and taste are unacceptable
• lis the chemical composition of food to susceptibility to spoilage

  1. perishable: high moisture
  2. semipersihable: fresh fruit and vegetable
  3. nonperoshible - low moisture
• food intoxication

  • didease = from ingestion of food with micro toxins
• food infection 


  from ingestion of pathogen contaminated food by growth of pathogen in host
• explain widespread disease outbreak

  • cluster = by micro in foods
  • heat-stable entertoxins
  • super antigen = increase T cell response = inflammation
• Staphylococcal virulence factors

  1. Structural
  2. enzyme
  3. exotoxin
• what are the 2 types found in food posining

  1. perfrigens
  2. boutlism
• perfrigens

  • increase nuMyer of ingested (10^8)
  • 6-24 hrs
  • exotoxins and heat liable
  • meat and fish
  • rapid cooling prevents growth
• boutlism

  • exotoxin
  • affected autonomic nerves
  • destoryed at 80 degrees and 10 minutes
• salmonellosis

  • GI illness
  • large number 10^5
  • form: enetrolist
  • onset 12-72 hrs
  • resolves 2-5 days
  • invades phaogYates and grows as intracellular pathogen
  • fever, cramp and dia
• e.coli

  • non-pathogen
  • entertoxins - shiga
  • bloody d and kidney failure
• campylobacter

  • trans to human via contaminated food
• liesterosis

  1. in dairy
  2. 2 types
• l. monocytogens 


  bacteria and meningitis
• l.monocyogens

  • intracellular pathogen <— uptake by phagocytes