Thursday, December 14

Basic Information About Parasitology

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Parasites like all animal species are classified by the binomial system of nomenclature.  Each has two (2) Latinized names, first the Genus and second, the species to which it belongs.


Parasitology is the area of biology which concerned with the phenomena of dependence of one living organism to another.

Clinical Parasitology:

This primarily concerns with the animal parasites of man, and their importance in human communities, as well as their medical significance.

Definition of Terms in Parasitology

Parasite: an organism which lives on or in the host.

Parasitism: an association in which one animal the host is injured through the activities of the other animal, the parasite.

Commensalisms: a relationship wherein the parasite derives benefit without injury to the host.

Symbolisis: permanent association of two organisms that cannot exist independently, protection and other advantages is being provided by each other.

Mutualism: the relationship which is beneficial to both the parasite and the host.

Infestation: a relationship of parasites to its host in a way that they are attached to the skin or the superficial tissue of the host’s body.

Exposure: the act or process of inculcation.

Infection:  connotes a take whereby the infective agent, the parasite become established in the host.

Pathogen: animal parasites that are harmful causing injuries or damage to the host.

Host: any organism which harbors the parasite.

Type of Host of Parasite:

  • Definitive / Final Host – harbors the adult or sexually nature parasite.

  • Intermediate Host – harbors part or all the stage of the parasite.

  • Obligate Host – specific species is required for each intermediate host.

  • Reservoir Host – animal that harbors a stage of the parasite but wherein no further development of the parasites takes place.

  • Pseudoparasites – artifacts mistaken for a parasite.

Types of Parasites according to the mode of living:

  • Ectoparasite – parasite that lives on the outside of the body of the host.

  • Endoparasite – parasite that lives within the body of the host.

  • Facultative parasite – parasite that which is able to live both to a free and parasitic existence.

  • Obligate parasite – parasite that is completely dependent upon the host for its existence throughout its life.

  • Incidental parasite – parasite that establishes itself in the host in which it does not ordinarily live.

  • Occasional or periodic parasite – parasite that seeks its host intermittently to obtain nourishment.

  • Temporary parasite – parasite which is free living during part of its existence wherein its stages has different hosts up to its adult stage.

  • Permanent Parasite – parasite which remains on or in the body of the host fro early life to maturity.

  • Coprozoic or Spurous Parasite – parasite that are passed thru the alimentary tract without infecting the host, at times recovered in the living or dead stage from human excreta.

  • Saprophytes – parasite that live in organic substances in state of decomposition.

Distribution of Disease:

  • Endemic – there is a steady, moderate level of disease in a human population.

  • Hyper-endemic – there is a high prevalence of the disease in the human population.

  • Epidemic – there is a sudden rise in the incidence or/and outbreak of high intensity of the disease in the human population.

  • Sporadic – the disease in the human population appears only occasionally in or at most few number of a community.

Sources of exposure/infection/infestation:

  1. Dirty, polluted and contaminated soil and water.

  2. Contaminated foods containing the immature infective stage of parasite.

  3. Blood sucking insects.

  4. Domestic or wild animals harboring the parasite.

  5. Another person, his clothing, immediate environment which he has contaminated.

  6. One’s self.

Portal of Entry of the parasite:

  1. By mouth

  2. Skin penetration

  3. Inhalation of eggs

  4. Transplacental infection

  5. Sexual intercourse

Pathogenesis of Parasite to the host:

  1. Traumatic or physical damage

  2. Lytic necrosis

  3. Stimulation of host-tissue reactions

  4. Toxic and allergic phenomena

  5. Secondary invasion by bacteria

Diagnosis for parasite:

  1. Clinical: through examination of a physician.

  2. Laboratory: through an examination of medical technologists.

Treatment for parasite:

  1. Chemotherapy

  2. Surgical intervention

Prevention of parasite:

  1. Detection and accurate diagnosis and evaluation of the clinical importance of the disease in the patient.

  2. Sufficient medicine and adequate treatment of the patient.

  3. Search for and treatment of other cases in the patient’s family.

  4. Determination if possible of the source of infection, reporting into health officials.

  5. Advice to patient and is family on how they can avoid further exposure.

  6. Education of patient’s in ways of utilizing and strengthening local health departments.

  7. Support and cooperation in community preventive measures.


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