___________ is the best method to attack the problem of parasites.
Prevention
The fauna (animal life) and flora (plant life) of entire regions have been changed in an attempt to disrupt the reproduction of _________ in some snails.
Schistosoma
cycle of Schistosomiasis
-Adult worms live and copulate in blood vessels of human gut; eggs migrate into digestive tract.
-Eggs are passed in feces.
-Ciliated larvae (miracidia) hatch in water and enter snail.
-Mother sporocyst encloses many developing daughter sporocysts.
-Daughter sporocyst encloses many developing larvae (cercariae).
-Larvae (cercariae) break out of daughter sporocysts, escape snail,and enter water.
-Larvae enters human system.
-Cycle continues.
Before the discovery of unicellular parasites c. 1880s onwards, ______ or ______ were the major focus of attention.
worms, helminths
Annual morbidity due to ascaris infections is estimated at _____ with a
mortality of __________.
1.5 B, 20,000
Intestinal hookworm cycle
1. Egg feces.
2. Rhabditiform larva hatches.
3. Development to filariform larva in environment.
1. Human drinks unfiltered water containing copepods with L3 larvae.
2. Larvae are released when copepods die. Larvae penetrate the host's stomach and intestinal wall. They mature and reproduce.
3. Fertilized female worm migrates to surface of skin, causes a blister, and discharges larvae.
4. L1 larvae released into water from emerging female worm. (Diagnostic Stage)
5. L1 larvae consumed by copepod.
6. Larvae undergoes two molts in the copepod and becomes L3 larvae. (Infective Stage)
7. Cycle continues.
The word "parasite" came from what Greek words?
para- near
sites- food
A living organism which for the purpose of procuring food & shelter take up their abode temporarily, on or within another living organism.
Parasite
_____________ is a type of symbiosis that may be defined as an interspecific association in which one species, the parasite, lives on or in a second species, the host, for a significant period of its life, exploiting the host, such as to obtain nourishment, shelter, and/or protection.
Parasitism
The one that benefits in parasitism
parasite
The one that is harmed in parasitism
host
Parasitic relationships may be ____________, _________, or ________.
temporary, facultative, obligatory
Parasitic relationship can be loose or mostly intimate, and for the parasite, it is usually _________.
obligatory
Parasites can be nonpathogenic. Give an example.
Entamoeba coli
Parasites can be definitely pathogenic and live at the expense of the host causing it harm. Give an example.
Entamoeba histolytica
In parasitism, there is always ________ and _______.
exploitation, harm
There are no known cases of species extinction traced to parasitism. True or False?
True
Multicellular parasites that are visible to the naked human eye, such as helminth parasites (parasitic worms, such as flukes, tapeworms, and roundworms, or nematodes).
Macroparasites
examples of macroparasites
-Ascaris lumbricoides
-Schistosoma-japonicum
-Taenia solium
Microparasites are small, generally, unicellular and invisible to the naked eye, such as _____________.
protozoan parasites
examples of microparasites
Entamoeba histolytica trophozoite
Giardia lamblia trophozoite
Balantidium coli trophozoite
A particular parasite can infect only a particular host, not any other. True or False?
True
As a parasite has to break through the different layers of defense mechanisms of the host in order to localize and thrive on the host, the parasite must be equipped with _______________.
specialized mechanisms
How can a parasite cause harm to the host?
1. depriving the host of digested food
2. erecting mechanical blockades of food, blood, lymph, and bile passages
3. causing tissue damages by rupture, enzymatic digestion, induction of autolysis, or secretion of toxins
This kind of parasite lives on the surface of the host.
Ectoparasite
examples of ectoparasite
ticks, lice, leeches, mites, fleas
Many endoparasites acquire hosts through ______________, as well as through consumption of __________.
entrance of the tissue, raw foods
This kind of parasite lives within the host.
Endoparasite
examples of endoparasite
roundworms and tapeworms in gut
What are the 4 kinds of parasites according to needs for a host?
-Obligatory Parasite
-Facultative Parasite
-Spurious Parasite
-Intermittent Parasite
kind of parasite which depends entirely on its host for its existence
Obligatory Parasite
Majority of parasites are ______________ and are totally dependent on the host for food, shelter, and/or protection; they cannot survive without the host.
obligatory parasites
kind of parasite capable of choosing either a free-living or a parasitic existence
Facultative Parasite
Examples:
S. stercoralis
Naegleria fowleri
a parasite of another animal which pass through the human body without further development or without causing any injury or damage
Spurious Parasite
kind of parasite which visit & leave its hosts at intervals like that during its feeding time; also known as temporary parasite; visit their host only for a short period of time
Intermittent Parasite
(e.g. leeches, bed bugs)
it is a protozoan organism which is able to live and multiply in moist fecal matter outside the body
Coprophilic parasite
is a parasite living inside a red blood cell, e.g. Plasmodium
Hematozoic parasite
is a parasite living inside the cell or tissue , e.g. Plasmodium, Isospora hominis
Cytozoic parasite
it is the parasite living in body cavities, e.g. Acanthocheilonema perstans
Coelozoic parasite
it is the parasite living inside the lumen of the intestines, e.g. Ascaris lumbricoides
Enterozoic parasite
parasite within a parasite; i.e. malaria in mosquitoes, tapeworm larvae in fleas
Hyperparasite or secondary parasite
Secondary parasite or hyperparasite is also referred to as _______________
hyperparasitoidism
an object that is mistaken for a parasite
Pseudoparasite
type of parasite which is never transmitted from man to man & which develops abnormally in man
Wandering or Abberant Parasite
these parasites have only one host, rest of the cycle being parasite spent outside the host
Monoxenous
these parasites have two or more hosts, usually belonging to parasite
widely separated taxonomic groups
Heteroxenous (aka digenetic parasite)
having female and male reproductive organs in different individuals; or
separate sexes
Dioecious
having female and male reproductive organs in same individual; hermaphroditic
Monoecious
transmits parasites from host to host
Vectors
(Vector) essential in life - cycle of parasite
Biological vector
(Vector) unessential in life - cycle of parasite
Mechanical Vector
(Vector) when the vector prefers human blood when it is available
Anthropophilic Vector
(Vector) when the vector prefers animal blood when it is available
Zoophilic Vector
literally means “diseases of animals”; now used to describe those diseases of animals, which are transmittable to humans
Zoonosis
the living organism that harbors the parasite
hosts
host in which parasite reaches sexual maturity & reproduces; is usually the main host. For digenetic parasites, it is the host for the adult stage and for the completion of sexual part of life cycle
Definitive or Final Host
(Type of Host) Some development in host, but does not reach sexual
maturity; often asexual stages; is a temporary environment, but one that is essential for the completion of a particular parasite's life cycle.
Such as host is found only in the case of digenetic parasites for the completion of larval stage, asexual reproduction, and for transmission to the definitive host.
Intermediate host/ Secondary host
an IH in which no development of the parasite occurs, although its presence may be required as an essential link in the completion of the parasite's life cycle
Paratenic host
The ______________ is a reservoir host of bubonic plague with the oriental rat fleas that infest them being a prime vector of the disease.
Roof rat (Rattus rattus)
Non-human animals that serve as sources of infection to humans.
It can harbor a pathogen indefinitely with no ill effects; are permissive host alternatives to definitive hosts, such that the infective stage can be passed from the host to the population of the definitive host.
Reservoir host
host that is readily infected by a particular parasite
Suscpetible host
is either a definitive, intermediate, or accidental host that allows the parasite to complete its life cycle in part or the whole
Permissive host
is a host organism other than true definitive host, which receives the parasite but the parasite finds itself in a dead end
