DD- HUMAN PARASITES Flashcards Preview

BL/DD USMLE and Basics > DD- HUMAN PARASITES > Flashcards

Flashcards in DD- HUMAN PARASITES Deck (33):
1

an organism which lives upon or within another living organism at whose expense it obtains some advantage

a parasite

2

helminths are

worms

3

arthropods are

insects

4

definitive host

species in which the parasite undergoes sexual replication

5

intermediate hosts

species in which asexual replication

6

Tropism

ability to infect specific tissues

7

helminths that cause parasitic diseases

1. Roundworms/Nematodes
2. Flatworms/Trematodes/Flukes
3. Tapeworms/Cestodes

8

Schistosomiasis

disease caused by parasitic worms of the Schistosoma type. It may infect the urinary tract or intestines.

9

Schistosomiasis is transmitted to humans by exposure to contaminated

fresh water

10

Schistosomes are

trematodes/flatworms.

11

______ is the most important parasitic disease

Malaria

12

Infected mosquitos bite humans and inject
_____ into the blood.

sporozoites

13

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)

14

_____ are released into the blood, infect erythrocytes, and undergo additional asexual replication

merozoites

15

symptoms of malaria are primarily associated with the rupture of______and release of merozoites

infected erythrocytes

16

involves granulamatous and fibrotic changes in the liver or in the bladde

chronic stage of schistosomiasis

17

A ______is an organism which lives upon or within another living organism at whose expense it obtains some advantage

parasite

18

parasitology is concerned with pathogenic protozoa (unicellular eukaryotes) and pathogenic metazoa (multicellular eukaryotes), including ______

worms and insects.

19

Many parasites of humans have complex life cycles that require

one or more additional hosts

20

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

21

The ability of parasites to infect specific tissues (_________) is often essential for their life cycles.

tropism

22

Many parasites have mechanisms to avoid immune responses

encapsulation
intraluminal location
immunosuppression
acquisition of host antigens

23

Major Groups of Human Parasites- worms

Roundworms
Flatworms (Flukes)
Tapeworms

24

Major Groups of Human Parasites- Protozoa

Amebas
Flagellates
Ciliates
Sporozoa
Microsporidia

25

Schistosomiasis Phases are Associated with

Cercarial invasion
Worm maturation and onset of oviposition
Host responses to eggs in tissues

26

dermatitis (“swimmers itch”) at 2-3 days after skin invasion (also with avian Schistosomes)

Cercarial invasion

27

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

28

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

29

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

30

Acquired Immunity against Malaria

___________ prevents high-level disease but does not eradicate infection (premunition).

Acquired immunity

31

Acquired Immunity against Malaria


Asymptomatic parasitemia is common among adults and older children in areas with _________________

stable and intense transmission

32

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:

33

Genetic Diseases that Increase Resistance to Death from Falciparum Malaria

Sickle cell disease
Ovalocytosis
Glucose-6-phosphate deficiency
Thalassemia