MICROPARA - PARASITES

• Parasitology 


  area of biology that deals with the phenomenon of dependence of one organism on another living organism. The study deals with the relationship between parasites and their host.
• Medical Parasitology 


  – deals with the human parasites and the diseases they cause
• Veterinary Parasitology


  deals with the animal parasites
• Structural Parasitology


  studies the structures of proteins from parasites
• Quantitative Parasitology


  involves the quantitative study of parasitism in a host population
• Parasite Ecology 


  studies the ecological impact of parasites
• Symbiosis 


  – a relationship where unlike organisms exist together.
• Commensalism 


  a form of symbiotic relationship in which two species live together and one species benefits from the other without harming or benefiting the other.
• Mutualism


  a symbiotic relationship in which two organisms mutually benefit from each other.
• Parasitism


  a form of symbiotic relationship where one party or symbiont (e.i., parasites) benefits to the detriment of the other party (host)
• Important Elements of Parasitism

  Host and Parasite
• Host


  are organisms that harbor the parasite and provide nourishment to them.
• Parasites


  are organisms that usually depend on the host for survival and growth.
• 4 types of Hosts

  1. Definitive Hosts 2. Intermediate Hosts 3. Reservoir Hosts 4. Paratenic Hosts
• Definitive Hosts


  – hosts that harbor the adult stage of the parasite or where the sexual stage of the life cycle of the parasite occurs
• Intermediate Hosts 


  – those that harbor the larval stage of the parasite or where the sexual phase of the life cycle of the parasite occurs.
• Reservoir Hosts 


  – are vertebrate host that harbor the parasite and may act as additional source of infection in man.
• Paratenic Hosts


  hosts that serve as a means of transport for the parasite so that the infective stage of a certain parasite may reach its final host
• Ectoparasites


  parasites that live outside the body of the host.
• Endoparasites


  parasites that live inside the host’s body.
• Facultative parasites


  parasites that can live independently of the host
• Obligate parasites


  – parasites that must live inside the host. Most of the parasites that infect humans belong to this classification
• Permanent parasites


  – remains in the host from early life to maturity (e.i. Plasmodium)
• Intermittent parasites


  simply visits the host during feeding time (e.i. non-pathogenic parasites
• Incidental parasites


  – parasites that occur in an unusual host (e.i. dog tapeworm in humans)
• Infestation


  Invasion of the body by ectoparasites is called?
• Infection


  Invasion of the body by endoparasites is called? ___ and is the result of the entry where parasites multiply within the host.
• Transitory parasites


  – parasites whose larvae develops in a host while the adult is free-living (e.i. dog tapeworm – Echinococcus granulosus)
• Erratic parasites


  – parasites that are seen in an unusual organ, different from what it ordinarily affects.
• SOURCES OF EXPOSURE TO INFECTION OR INFESTATION

  1. Contaminated soil or water (most common) 2. Food containing the parasite’s infective stage 3. A blood-sucking insect 4. A domestic or wild animals harboring the para 5. Contaminated clothing, beddings, or immediate environment the person has infected 6. Auto-infection
• MODES OF TRANSMISSION

  1. Oral-fecal route 2. Skin penetration 3. Insect bites 4. Eggs inhalation 5. Transplacental or congenital infections 6. Trans-mammary infection 7. Sexual intercourse
• PORTAL EXITS OF PARASITES (BY ORGAN)

  1. Anus. 2. Ureter. 3. Lungs. 4. Vagina.
• PORTAL EXITS OF PARASITES (BY MEANS OF)

  1. feces 2. urine 3. phlegm 4. Vaginal discharges
• PATHOGENESIS OF PARASITES

  1. Trauma or physical damage 2. Lytic necrosis 3. Stimulation of host tissue reaction 4. Toxic & allergic phenomena (immunopathology) 5. Opening of pathways for entry of other pathogens into the tissues
• source of infection 


  parasite comes in contact with soil or water and other intermediate host
• mode of transmission 


  parasite comes in contact with human
• infective stage 


  parasite enters & establishes residence in or on human
• pathogenic stage 


  parasite multiples and competes w/ humans for nutrional needs
• diagnostic stage 


  parasite emerges from human
• CLASSIFICATION OF MEDICALLY IMPORTANT PARASITES (two types of parasites)

  PROTOZOA & HELMINTHS