Parasitology

Question 1

Parasite kingdoms

Answer 1

Protozoa- unicellular

Metazoa- multicellular

Question 2

Local transmission

Answer 2

When a traveler picks up an infection in an endemic area, and then returns to a non-endemic area, but is still able to spread the infection because the vector responsible is there.

Question 3

What defines the geographic range of a parasite?

Answer 3

The presence/absence of a vector.

Question 4

Protozoa

Answer 4

Microscopic, unicellular
Free living or parasitic
Multiply in humans

Question 5

Helminths

Answer 5

Worms
Large, multicellular
Almost all are parasitic

Question 6

Intermediate host

Answer 6

Where parasite develops

Only multiplies asexually here

Question 7

Definitive host

Answer 7

Matures the parasite
Multiples sexually
Normally humans

Question 8

Intermediate host of Paragoniumus westermani

Answer 8

snails and crustaceans

Question 9

Intermediate host of Fasciola spp.

Answer 9

snails and plants

Question 10

Intermediate host of Tania solium

Answer 10

pigs

Question 11

Intermediate host of Trypanosoma cruzi

Answer 11

Triatomine bug

Question 12

Prepotent period

Answer 12

Where the parasite has infected a host but is undergoing developmental changes and has not yet caused any damage for sxs to be observed

Question 13

Pathogenic mechanisms of parasitic infections

Answer 13

1- Toxic products
2- Mechanical tissue damage
3- Immunopathology- HS rxns, AI rxns, metaplastic changes
Severity linked to repeated exposures

Question 14

Stain used for Babesia spp.

Answer 14

Giemsa stain

Question 15

Nocturnal periodicity

Answer 15

Periodic migration of microfilariae between peripheral blood and lung capillaries

Influences sampling time

Question 16

Ultrasound useful for detecting:

Answer 16

Echinococcosis
Cysticercosis
Onchocerciasis
Lymphatic filariasis

Gives information about:
Abscess/cyst/space-occupying lesion
#, size and location

Question 17

4 major groups of protozoa

Answer 17

1- Sarcodina (amoeba)
2- Mastigophora (flagellates)
3- Ciliophora (ciliates)
4- Sporozoa (non-motile adult stage)

Question 18

Examples of relevant GI Sporozoa

Answer 18

Cryptoisospora belli
Cyclospora cayetanium

Both are apicomplexa (coccidian protozoa)

Question 19

Examples of GI Mastigophora

Answer 19

Giardia intestinalis

Question 20

Examples of GI Sarcodina

Answer 20

Entamoeba histolytica

Question 21

Example of GI Ciliophora

Answer 21

Balantidium coli

It’s the ONLY human pathogenic ciliate.

Question 22

Example of sporozoa

Answer 22

Plasmodium

Question 23

Physiology and Repro of protozoa

Answer 23

get nutrients from pino- or phagocytosis
Respiration: facultative anaerobic
Survival form: cyst. If not cyst then must have person-person transmission or a vector.
Reproduction: binary fission
    Some exceptions (plasmodium)

Question 24

Trohphozoite

Answer 24

Motile feeding stage
Normally found in the tissues
Larger than cyst.

Question 25

Cyst

Answer 25

Non-motile, resistant Multinucleated, smaller T. vaginalis has NO cyst form

Question 26

Metazoa

Answer 26

Have life functions in tissue and organ systems (unlike protozoa which are in a cell) Nemathelminthes (roundworms) Platyhelminthes (flatworms)

Question 27

Ascariasis

Answer 27

Mostly asx Lungs (larvae): asthma or pneumonia-like cough, SOB and wheezing Intestines (adult worms): diarrhea or bloody stools. N/V abd. pain. Severe infections: malnutrition and wt. loss

Question 28

Most common cause of DALYs

Answer 28

Soil-transmitted helminths. Hookworms are #1 of those

Question 29

Lymphatic filariasis

Answer 29

Cause hydrocele in men Lymphedema in women Common in Africa, Asia, Americas, Pacific. Most are in SEA

Question 30

Physiology and Repro of Metazoa

Answer 30

Nutrients from active ingestion of tissue and fluid from hot, or passive absorption. No multiplication/replication of adult form in humans. Produce large # of eggs per day

Question 31

Infective forms of nematodes

Answer 31

Egg Filariform larvae 3rd stage larvae

Question 32

Infective forms of Trematodes

Answer 32

Cercaria | Metacercaria

Question 33

Infective forms of cestodes

Answer 33

Cysticercus Proglottid Embryonate egg Cystericeroid

Question 34

Polyparasitism/Co-infection

Answer 34

Infection of multiple parasites at one time. Increases morbidity of other infectious diseases (TB and HIV)

Question 35

Roundworms

Answer 35

aka Nematodes Most common transmission: ingestion of eggs or larvae Adult stages in GIT, blood, lymph or subcut tissues. Adults or larvae can cause disease

Question 36

Flatworms

Answer 36

aka platyhelminths | Includes Trematodes and cestodes

Question 37

Trematodes

Answer 37

``` aka flukes Flattened 2 anterior suckers Hermaphroditic Diagenetic- sex and asex development ```

Question 38

Life cycle of trematode

Answer 38

``` Eggs are excreted into feces Hatch in water--> form miracidia Enter intermediate host Develop sporocysts Enter definitive host Hatch into cercariae ```

Question 39

Miracidia

Answer 39

ciliated, first-stage larva of a trematode, emerges from the egg Penetrates the intermediate host

Question 40

Cercariae

Answer 40

free-swimming trematode | In definitive host

Question 41

Cestodes

Answer 41

aka tapeworms Flattened, but not flukes. More mature and developed the further away from the head. The mature parts contain the eggs that are released into the environment and cause infection. No digestive system. Absorb nutrients across their surface

Question 42

Life cycle of cestodes

Answer 42

aka tapeworms Adult form found in intestine of mammalian carnivores (definitive host). Some spp. have same intermediate and definitive host. Eggs are ingested--> develop into larvae --> enter circulation and encyst --> intermed. host consumed by definitive --> encysted form released into intestine, develops into adult.

Question 43

Control strategies for trypanosomiasis

Answer 43

Insecticide treated nets