Introduction to Parasitology

Parasitology

An area of biology that is concerned with the study of living organisms that depend on other living organisms for the purpose of procuring nourishment and securing protection.

Medical Parasitology

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

Parasitism

Any reciprocal association in which a species depends upon another for its existence.

Commensalism

One partner is benefited and other is unaffected.

Symbiosis

A permanent association of two organisms that cannot exist independently.

Mutualism

Type of relationship between the host and a symbiont, where both organisms benefit and no one is harmed.

Parasite

An organism that lives on or in other organisms from which it obtains nutrients to live and causes harm in the process.

Endoparasite

those that live within the body of the host.

Ectoparasite

those that live outside the body of the host.

Free Living Parasites

Refers to non-parasitic stages of active existence which live independent on the host.

Pathogenic

a parasite which causes injury to the host by its mechanical, traumatic or toxic activities.

Non-pathogenic

a parasite derives benefits from the host without causing any considerable damage or harm.

Obligate

A parasite that cannot exist without a host.

Facultative

capable of leading both a free and parasitic existing which can live as an opportunistic parasite.

Temporary

a free-living during part of its existence and seeks its host intermittently to obtain nourishment. It visits the host for a short period.

Permanent

remains in the body of the host from early life to maturity

Spurious or Coprozoic

a foreign species that has passed through the alimentary tract without infecting the host.

Accidental or Incidental

One that establishes itself in a host in which it does not ordinarily lives.

Aberrant Parasites

Parasites which infect a host where they cannot develop further.

Host

An organism which harbors the parasite.

Final or Definitive Host

Harbors the adult or sexual stages of the parasites

Intermediate Host

Harbors part or all of the larval or sexual stages of the parasites

Reservoir Host

Animals that harbors the same species of parasites as man.

Paratenic Host

Animal that harbors the parasite in an arrested state of development;

Vector

Host that transmits parasite to man.

Biological Vectors

Essential in the life cycle.

Mechanical or Phoretic Vectors

Not essential in the life cycle.

Parasite Reservoir (PR)

The biotope where the parasite lives.

Definitive Host

where lives the sexual stage of the parasite, producing large amounts of larvae or eggs, that serves as the PR.

Intracellular Parasites

These parasites try to escape any immunological reactions mounted by the host by hiding themselves inside the host cells where the immune system cannot reach them.

Extracellular Parasites

Some parasites cover their cell surface with host serum proteins to avoid recognition by the immune system of the host.

Schistosoma

worms that cover themselves with host serum albumin

Rodent

trypanosomes that cover themselves with ablastin

Infection

the presence of endoparasite in a host.

Infestation

the presence of ectoparasite in a host.

Clinical Diagnosis

based on the recognition of the characteristics signs and symptoms of certain parasitic disease.

Laboratory Diagnosis

final diagnosis and proper methods of treatment require the identification of the parasite in the laboratory.

Epidemiology

It is the body of knowledge that concerns disease in human populations or communities rather than in individuals.

Endemic

When a disease in human population maintains a relatively steady moderate level.

Hyperendemic

If the prevalence of a disease in a community is high

Epidemic

If there is a sharp rise in the incidence or an outbreak of considerable intensity occurs. It typically results from introduction of an agent or a new strain into a community that is essentially non-immune.

Sporadic

If it appears only occasionally in one or at most few members of a community.

Pandemic

the disease covers extensive areas of the world

Eradication

Permanent reduction to zero of the worldwide incidence of infection caused by a specific agent.

Elimination

Reduction to zero of the incidence of a specified disease in a defined geographic area as a result of deliberate efforts.