DD- HUMAN PARASITES Flashcards
an organism which lives upon or within another living organism at whose expense it obtains some advantage
a parasite
helminths are
worms
arthropods are
insects
definitive host
species in which the parasite undergoes sexual replication
intermediate hosts
species in which asexual replication
Tropism
ability to infect specific tissues
helminths that cause parasitic diseases
- Roundworms/Nematodes
- Flatworms/Trematodes/Flukes
- Tapeworms/Cestodes
Schistosomiasis
disease caused by parasitic worms of the Schistosoma type. It may infect the urinary tract or intestines.
Schistosomiasis is transmitted to humans by exposure to contaminated
fresh water
Schistosomes are
trematodes/flatworms.
______ is the most important parasitic disease
Malaria
Infected mosquitos bite humans and inject
_____ into the blood.
sporozoites
a serum-sickness like illness that occurs 4-8 weeks after skin invasion, coincident with worm maturation and onset of oviposition, and often accompanied by lymphadenopathy and hepatosplenomegaly
acute phase of schistosomiasis (also called Katayama fever)
_____ are released into the blood, infect erythrocytes, and undergo additional asexual replication
merozoites
symptoms of malaria are primarily associated with the rupture of______and release of merozoites
infected erythrocytes
involves granulamatous and fibrotic changes in the liver or in the bladde
chronic stage of schistosomiasis
A ______is an organism which lives upon or within another living organism at whose expense it obtains some advantage
parasite
parasitology is concerned with pathogenic protozoa (unicellular eukaryotes) and pathogenic metazoa (multicellular eukaryotes), including ______
worms and insects.
Many parasites of humans have complex life cycles that require
one or more additional hosts
The definitive host is the species in which sexual reproduction occurs. Hosts in which sexual reproduction does not occur are called inter- mediate hosts. Not all parasites replicate_______
sexually
The ability of parasites to infect specific tissues (_________) is often essential for their life cycles.
tropism
Many parasites have mechanisms to avoid immune responses
encapsulation
intraluminal location
immunosuppression
acquisition of host antigens
Major Groups of Human Parasites- worms
Roundworms
Flatworms (Flukes)
Tapeworms
Major Groups of Human Parasites- Protozoa
Amebas Flagellates Ciliates Sporozoa Microsporidia
Schistosomiasis Phases are Associated with
Cercarial invasion
Worm maturation and onset of oviposition
Host responses to eggs in tissues
dermatitis (“swimmers itch”) at 2-3 days after skin invasion (also with avian Schistosomes)
Cercarial invasion
in Falciparum Malaria, Infected erythrocytes containing mature asexual forms of P. falciparum stick to small blood vessels (_______).
They also stick to each other (_______) and to uninfected erythrocytes (__________), thereby enhancing sequestration
- sequestration
- agglutination
- rosetting
Because of sequestration, only ring forms (immature) and sexual forms of P. falciparum are found in circulating erythrocytes.
Sequestration of infected erythrocytes interferes with the host’s____________________
microcirculation and metabolism
Acute Schistosomiasis (a.k.a. Katayama fever) - a serum sickness-like illness with lymphadenopathy and hepatosplenomegaly at 4-8 weeks after skin invasion
Worm maturation and onset of oviposition
Acquired Immunity against Malaria
___________ prevents high-level disease but does not eradicate infection (premunition).
Acquired immunity
Acquired Immunity against Malaria
Asymptomatic parasitemia is common among adults and older children in areas with _________________
stable and intense transmission
Chronic granulomas and fibrotic changes in liver (from S. mansoni, S. japonicum, S. mekongi, or S. intercalatum) or in bladder (from S. hematobium)
Host responses to eggs in tissues:
Genetic Diseases that Increase Resistance to Death from Falciparum Malaria
Sickle cell disease
Ovalocytosis
Glucose-6-phosphate deficiency
Thalassemia
