PARA LEC

• Symbionts: organisms living together
• Symbiosis: association/relationship of two or more organisms living together
• Mutualism: Biological relationship between two or more organisms when both the host and organism benefit from one another
• Commensalism: One organism benefits but there is NO beneficial or harmful effect to the host
• Parasitism: One species (microbe) benefits at the expense at the other
• Parasitology: is a branch of science that deals with the study of parasites
• Medical parasitology or Human parasitology: is restricted to studying those parasites that are living in or on the body of humans, their geographic distribution, the diseases caused by them, clinical picture, and the response generated by humans against them.
• Anthroponosis: parasitic infection is found in man alone (humans only)
• Zooanthroponosis: parasitic infections mainly affect man; animals become infected in life cycle of parasite line in taeniasis (taenia saginata or taenia solium)
• Anthropozoonosis: parasitic infection is mainly in animal, may be acquired by man as in trichinosis, echinococcosis (echinococcus granulosus)
• Intermittent or Temporary Parasites ○ those that only visit the host from time to time for feeding - Ex: Mosquito - pregnant female mosquito will not forever attach and live on the human host, it just visits the host during feeding ● Permanent Parasite ○ remains on the host for life - Ex: Trypanosomes, Wuchereria, Filaria ● Spurious or Coprozoic Parasite ○ organisms that have been swallowed and passed through the alimentary tract (GIT
• Pseudoparasite: Terms used to mean an artifact but mistaken as parasite (NOT a true parasite).
• Examples of pseudoparasites include thread, seeds, pollen, and air bubbles.
• Black arrows in the image represent Football-shaped Trichuris trichiura eggs.
• Red arrows in the image represent air bubbles, which are pseudoparasites.
• A fruit thorn can also be considered a pseudoparasite.
• Hyperparasite: Parasite that parasitizes another parasite.
• Female ixodes angustus tick is a parasite to humans, while the male tick is a hyperparasite as it parasitizes the female tick.
• Definitive Host: A host that harbors a parasite in the adult stage or where the parasite undergoes a sexual reproduction.
• Humans are definitive hosts in taeniasis.
• Intermediate Host: Harbors the larval stages of the parasite or an asexual cycle of development takes place.
• Pigs are intermediate hosts in T. solium, while cattle are intermediate hosts in T. saginata.
• In some cases, larval development is completed in TWO different intermediate hosts referred to as First Intermediate Host and Second Intermediate Host.
• Diphyllobothrium latum is a hermaphrodite, meaning the mature proglottid of the adult parasite contains both testes and ovaries.
• Sexual reproduction happens in the human body, making humans the definitive host.
• Copepod is the 1st intermediate host.
• Small fish is the 2nd intermediate host.
• Big fish is a paratenic host.
• Paratenic host is a host that serves as a temporary refuge and vehicle for reaching an obligatory host, usually the definitive host, and is NOT necessary for the completion of the parasite's life cycle.
• There is NO development of the parasite inside the paratenic host.
• Wild boar is an example of a paratenic host in Paragonimus westermani.
• Reservoir host is a host that makes the parasite available for the transmission to another host and is usually not affected by the infection.
• The unending source of parasite is represented by reservoir hosts.
• Natural host is a host that is naturally infected with certain species of parasite.
• Accidental host is a host that is under normal circumstances not infected with the parasite.
• Humans are accidental hosts in Echinococcus granulosus.
• Direct Life Cycle

  ○ AKA Monoxenous life cycle

  ○ parasite does NOT REQUIRE an intermediate

  host to complete its life cycle

  ● Indirect Life Cycle

  ○ AKA Heteroxenous life cycle

  ○ parasite REQUIRES an intermediate host to

  complete its life cycle