Medical Parasitology

• Symbionts


  Organisms living together
• Symbiosis 


  Relationship of two or more organisms living together
• Types of Symbiosis

  • Mutualism
  • Commensalism
  • Parasitism
• Mutualism - both the host and organism benefit from one another
• Commensalism - one organism benefits and the other is not harmed.
• Parasitism - one organism (microbe) benefits at the expense of another (host)
• Parasite - living organism that takes nourishment and other needs through contact with another species
• Host - organism that supports parasite, and may later develop disease
• Parasitology - Is a branch of science that deals with the study of parasites
• Human parasitology - restricted to studying those parasites that are living in or on the body of human, their geographic distribution, the diseases caused by them, clinical picture and the response generated by human against them.
• Anthroponosis - parasitic infection is found in man alone
• Zooanthroponosis - parasitic infections mainly affect man; animals become infected in life cycle of parasite like in taeniasis
• Anthropozoonosis - parasitic infection is mainly in animal, may be acquired by man as in trichinosis, echinococcosis
• Types of Parasites by Location

  1. Ectoparasite 2.Endoparasites
• Ectoparasite - a parasitic organism that lives on the outer surface of its host, e.g. lice, ticks, mites etc.
• Endoparasites - parasites that live inside the body of their host e.g. Entamoeba histolytica
• Infestation - presence of ectoparasites
• Infection - presence of endoparasites
• Obligate Parasite - completely dependent on the host during a segment or all of its life cycle
• Facultative Parasite - exhibits both parasitic and non-parasitic modes of living
• • Accidental Parasite - parasite attacks an unnatural host and survives but may or may not complete life cycle
• Erratic Parasite - parasite that wanders into an organ in which it is not usually found
• Temporary Parasites - those that only visit the host from time to time for feeding
• Permanent Parasite - remains on the host for life
• Pseudoparasite - NOT a true parasite but mistaken as parasite
• Hyperparasite - parasite that parasitizes another parasite
• • Definitive Host - a host that harbors a parasite in the adult stage
• • Intermediate Host - harbors the larval stages of the parasite or an asexual cycle of development takes place
• Paratenic Host - a host that serves as a temporary refuge and vehicle for reaching an obligatory host, usually the definitive host
• Reservoir Host - a host that makes the parasite available for the transmission to another host and is usually not affected by the infection.
• 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
• • Autoinfection - Infected individual becomes his own direct source of infection
• Superinfection - Infected individual is further infected with same species leading to massive infection
• Female adult worms can be OVIPAROUS or LARVIPAROUS
• Strongyloides stercoralis - This is a parasitic (parthenogenetic) female recovered from a mucosal scraping of the small intestine of a dog.
• Vehicle - non-living entity
• Vector - living entity
• Biological Vector - transports pathogens plus plays a role in the life cycle of pathogen (Malaria inside mosquito)
• Mechanical Vector - organism that only transports a pathogen