INTRODUCTION TO PARASITOLOGY (2) Flashcards
Biological relationships (host- parasite relationship)
symbiosis
commensalism
parasitism
-both host and parasite are dependent upon each other
-none of them suffers any harm from association
symbiosis
-only parasite derives benefit from the association without causing any injury to the host
-capable of living an independent life also
commensalism
-the parasite derives benefits and the host is always harmed due to the association
-the parasite cannot live an independent life
parasitism
types of host
definitive or final host
intermediate host
paratenic host
reservoir host
types of vector
biological vector
mechanical or phoretic vector
are harmful and frequently cause mechanical injury to their host
pathogens
harbors a particular pathogen without manifesting any signs and symptoms
Carrier
process of inoculating an infective agent
Exposure
connotes the establishment of the infective agent in the host.
Infection
period between infection and evidence of symptoms.
Incubation period
period between infection or acquisition of the parasite and evidence or demonstration of infection.
Pre-patent period
Results when an infected individual becomes his own direct source of infection.
Autoinfection
Happens when the already infected individual is further infected with the same species leading to massive infection with the parasite.
Superinfection (hyperinfection)
source of infection
contaminated soil and water
food
vectors
carrier
self
refers to a vector, which not only assists in the transfer of parasites but the parasites undergo development or multiplication in their body as well.
biological vectors
refers to a vector, which assists in the transfer of parasitic form between hosts but is not essential in the life cycle of the parasite.
mechanical vectors
modes of infection
oral transmission
skin transmission
vector transmission
direct transmission
vertical transmission
latrogenic transmission
• The most common method of transmission is through oral
route by contaminated food, water, soiled fingers, or fomites.
• Many intestinal parasites enter the body in this manner;
the infective stages being cysts, embryonated eggs, or
larval forms.
• Infection with E. histolytica and other intestinal protozoa
occurs when the infective cysts are swallowed.
oral transmission
• Entry through skin is another important mode of
transmission.
• Hookworm infection is acquired, when the larvae enter
the skin of persons walking barefooted on contaminated
soil.
• Schistosomiasis is acquired when the cercarial larvae in
water penetrate the skin
Skin transmission
• Many parasitic diseases are transmitted by insect
• A vector could be a biological vector or a mechanical
vector.bite,
Vector transmission
malaria is transmitted by bite of
female Anopheles
mosquito
• Parasitic infection may be transmitted by person-to person contact in some cases
Direct transmission
• Mother to fetus transmission may take place in malaria and toxoplasmosis.
Vertical transmission
