PASASIT

• PARASITOLOGY - Study of organisms that live on and obtain their nutrients from another organism
• Parasites - a pathogen that simultaneously injures and derives sustenance from its host.
• MEDICAL PARASITOLOGY - concerned primarily with parasites of humans and their medical significance, importance in human communities.
• SYMBIOSIS - the association of two living organisms, each of a different species
• COMMENSALISM - association of two different species of organisms that are beneficial to one and neutral to the other.
• MUTUALISM - association of two different species of organisms that are beneficial to both.
• PARASITISM - association of two different species of organisms that are beneficial to one at the other's expense.
• PATHOGENIC - a parasite that has demonstrated the ability to cause disease.
• OBLIGATORY PARASITE - a parasite that cannot survive outside of a host.

  • Most parasites are obligate or obligatory.
  • Example: tapeworm (depends on the existence of the host because they need the host to complete their life cycle)
  • You need to harbor the larval stage of a parasite to get infected.
• FACULTATIVE PARASITE - a parasite that is capable of existing independently of a host

  • Example: Acanthamoeba (only transmitted through the eyes MOT
• ENDOPARASITE - a parasite living inside the body of a host.

  • Infection
  • Example: worms and amoeba
• ECTOPARASITE - a parasite living outside the body of a host.

  • Infestation
  • Example: lice/ flea and ticks
• ERRATIC PARASITE - a parasite found in an organ that is not in its usual habitat.

  • Example: Ascaris becomes erratic when it goes to the lungs.
  • They are found in the large intestine.
• ACCIDENTAL PARASITE/ INDICENTAL PARASITE - a parasite that establishes itself in a host where it does not ordinarily live.

  • Example: Hymenolepis nana (dwarf tapeworm) only infect canine animals (develop form – worm), it becomes an accidental parasite when it infects humans (cyst form – grows larger).
• PERMANENT PARASITE - a parasite that remains on or in the body of the host for its entire life
• TEMPORARY PARASITE - a parasite that lives on the host only for a short period of time.
• SPURIOUS PARASITE - a parasite that is a free-living organism that passes through the digestive tract without infecting the host.
• ACCIDENTAL HOST - host other than the normal one that is harboring a parasite.
• DEFINITIVE HOST/ FINAL HOST - host in which the adult sexual phase of parasite development occurs.
• INTERMEDIATE HOST - host in which the larval asexual phase of parasite development occurs.

  • Cattle and pig: tapeworm (Taenia species)
  • Snails: Schistosoma
• Schistosoma - 2 intermediate hosts are needed for the parasite to have a complete life cycle.
• RESERVOIR HOST - host harboring parasites that are parasitic to humans.

  • Allowing the lifecycle to continue but when it reaches human there will be an infection.
  • Example: rats, cats, and pigs (reservoirs of Balantidium coli) until it infects humans.
• TRANSPORT HOST - host responsible for transferring a parasite for one location to another
• CARRIER - parasite-harboring host that is not exhibiting any clinical symptoms but can infect others.
• • PARATENIC HOST - host in which the parasite does not develop further to later stages.
• EXPOSURE - the process of inoculating an infective agent.
• INFECTION - connotes the establishment of the infective agent in the host.
• INCUBATION PERIOD - the period between infection and evidence of symptoms
• PRE-PATENT PERIOD - the period between infection or acquisition of the parasite and evidence of demonstration of infection
• AUTOINFECTION - when an infected individual becomes his own direct source of infection

  • Example: E. vermicularis (pin worm (shape of the egg)/ social worm (easily spread)) - Hand to mouth transmission
• SUPERINFECTION/ HYPERINFECTION - happens when the already infected individual is further infected with the same species leading to massive infection with the parasite

  • Example: Trichuris trichiura – rectal prolapse (the rectum goes out)
• SOIL

  • Where the eggs of Ascaris, T. trichiura, S. stercoralis, and hookworms develop
  • Night soil: human defecate is used as the fertilizer for farming.
  • This is how hosts harbor ascaris eggs
• ARTHROPODS - most common for mosquitos is malaria or filarial parasites.
• DIRECT TRANSMISSION - contact with an infected person or animal; does not need an intermediate object or host.
• DIRECT TRANSMISSION

  1. Droplet spread – no parasite.
  2. Sexual intercourse – ping pong disease (Trichomonas vaginalis)
  3. Kissing – Gingivalis (mouth) not pathogenic
  4. Holding hands – Enterobius (social worm)
  5. Transplacental – mother to fetus; common: malaria, T. gondii, T. cruzi
• INDIRECT TRANSMISSION – involves an intermediate object.
• Most common source of parasitic infection is CONTAMINATION.

  • Contaminated food and water
  • Portal of entry: mouth
• INDIRECT TRANSMISSION

  • Foodborne (larval stage) - T. solium, T. saginata, and D. latum
• INDIRECT TRANSMISSION

  • Contaminated water (cysts stage) - E. histolytica and G. lamblia
• INDIRECT TRANSMISSION

  • Raw or improperly cooked freshwater fish (larvae) - Clonorchis, Opistorchis and Haplorchis