Introduction to Parasites

Question 1

Parasites

Answer 1

Organsims that live in or on another organism (its host) and benefits by deriving nutrients at the others expense, does not necessarily cause disease

Question 2

Mutuallsm

Answer 2

An association in which both species benefit from the interaction

Question 3

Parastism

Answer 3

An association in which the parasite derives benefit and the host gents nothing in return but always suffers some injury

Question 4

Commensalism

Answer 4

An association in which the parasite only benefits without causing harm to the host

Question 5

3 classes of host

Answer 5

Definitive host
Intermediat host
Paratenic host

Question 6

Definitive host

Answer 6

Harbous the adult stage of hte parasite or where the parasite undergoes sexual reproduction

Question 7

Intermediate host

Answer 7

harbours the larval or asexual stages of the parasite. Some parasites have 2 intermediate hosts in their lifecycle

Question 8

Paratenic host

Answer 8

Host where the parasite remains viable without further development

Question 9

2 types of parasites

Answer 9

Protozoa

Helminths

Question 10

Microparasites

Answer 10

Protozoa

Question 11

Macroparasites

Answer 11

Helminths

Question 12

6 examples of microparasites

Answer 12

Cryptosporidium
P.Falciparum-malaria
T.cruzi trypomastigole
Trypanosoma cruzi
Entamoeba
Giardia Lamblia

Question 13

5 groups of helminth

Answer 13

Cestodes
Trematodes
Intestinal nematode
Tissue nematode

Question 14

Example of a cestode

Answer 14

Taenia sp

Question 15

Example of a trematode

Answer 15

Schistosomiasis

Question 16

Example of an intestinal nematode

Answer 16

Ascaris lumbricoides

Question 17

Example of a tissue nematode

Answer 17

Wucheria bancrofti

Question 18

Direct life cycle

Answer 18

Only 1 definitive host

Question 19

Simple indirect life cycle

Answer 19

2 hosts- intermediate and direct

Question 20

Complex indirect life cycle

Answer 20

More than 1 intermediate host

Question 21

Name the type of life cycle:

bird>poo>sourbug>bird

Answer 21

Simple indirect cycle

Question 22

Name the type of life cycle:

bird>poo>amphipod>amphibian>fish>bird

Answer 22

Complex indirect

Question 23

Name the type of life cycle:

Bird>poo>bird

Answer 23

Direct

Question 24

Describe the parasite ascariasis

Answer 24

Macroparasite. Intestinal nematode. Ascaris lumbricoidis.

Question 25

Who is most commonly affected by ascariasis?

Answer 25

3-8yrs. Areas of poor hygeine

Question 26

Describe the life cycle of ascariasis

Answer 26

Direct life cycle: eggs in human intestine, shed into environment in faeces. Eating contaminated food/water. eggs pass into intestine. Migrate to portal circulation to alveoli to lungs

Question 27

2 clinical phases of ascariasis

Answer 27

Lung migration | Intestinal Phase

Question 28

Describe the lung migration phase of Ascariasis

Answer 28

Loeffler's syndrome- dry cough, dyspnoea, wheeze, haemoptysis, eosinophilic pneumonitis

Question 29

Describe the intestinal phase of ascariasis

Answer 29

Malnutrition, migration into hepatobiliary tree and pancreas, intestinal obstruction, worm burden

Question 30

Treatment for ascariasis

Answer 30

Albendazole-prevents glucose absorption by worm-detaches and passes out in faeces

Question 31

Control for ascariasis

Answer 31

WHO 'Action against worms'- improve sanitation, education and deworming in communities

Question 32

Describe the parasite schistosomaisis

Answer 32

Macroparasite. Helminth. Bilharzia disease

Question 33

What is the intermediate host for schistosomiasis?

Answer 33

Snails

Question 34

A parasite that causes chronic diseasse resulting in bladder cancer and liver cirrhosis

Answer 34

Schistosomiasis

Question 35

4 clinical features of schistosomiasis

Answer 35

Swimmer's itch Katagoma fever Urinary-bladder fibrosis and dysfuction, squamous cell CA in bladder Hepatic-portal hypertension and liver cirrhosis

Question 36

Treatment for schistosomiasis

Answer 36

Praziquantel

Question 37

Control of schistosomiasis

Answer 37

Chemical treatment to kill snail intermediate hsots. Avoidanance of snail infected waters, education and imrpoved sanitation

Question 38

Describe the parasite causing Hydatid disease

Answer 38

Macroparasite-cestode. Echinococcus sp.

Question 39

Usual host for hydatid disease

Answer 39

Human is accidental host- usualy hosts are sheep and dogs.

Question 40

Describe the life cycle for hydatid disease

Answer 40

Complex, indirect life cycle. Worm in dog's intestine, eggs in faeces, Humans infected if eat contaminated food. Migrate to liver and lungs from hyatid cyst

Question 41

Where do hyatid cysts commonly develop?

Answer 41

70% liver | 20% lungs

Question 42

Control of hydatid disease

Answer 42

regularly worm dogs. Hand ygein. Safe disposal of animal carcasses

Question 43

Describe the protozoa that carries malaria

Answer 43

``` Protozoa-sporozoan. 4 species of plasmodium: P.flaciparium p.vivax p.ovale p.malariae ```

Question 44

Which type of plasmodium most commonly causes malaria?

Answer 44

P. falciparum

Question 45

Describe the transmission of malaria

Answer 45

Vector transmission-anopheles mosquito. Mosquito is infected. Injects parasite into human whilst feeding. Sporozoites enter liver and infect hepatocytes-replication. Hepatocytes rupture.

Question 46

Describe the 2 phases of the lifecycle of malaria

Answer 46

Asexual phase: self replicating. Infect other RBCs which rupture following replication. Sexual reproduction: another mosquito takes a meal fertilises eggs and spreads to others

Question 47

Clinical presentation of malaria

Answer 47

Parasites rupture RBCs, block capillaries and cause an inflammatory response. evers/rigor, cerebral malaria (confusion, headache, coma), renal failure, hypogycaemia, circulatory collapse, anaemia, bleeding and DIC

Question 48

Returning traveller + fever

Answer 48

Malaria unless proven otherwise

Question 49

Control for malaria

Answer 49

Insecticide spraying in homes, breeding pools. Nets, chemoprophylaxis

Question 50

Clinical presentation of malaria

Answer 50

Watery diarrhoea after approx 7 days. Bloating, cramps, fever, nausea, vomiting. Usually self limiting (up to 2 wks)

Question 51

Causative organism of cryptosporidiosis

Answer 51

Cryptosporidium parvium and hominis- sporazoa.

Question 52

Describe the life cycle of cryptosporidiosis

Answer 52

Direct life cycle- humans pass oocytes in stools, contaminate water ingested. Animal reservoir (cattle, sheep, goats)

Question 53

Clinical presentation of cryptosporidiosis

Answer 53

watery diarrhoea after approx 7 days. Bloating, cramps, fever, nausia, vomiting. Usually self limiting (up to 2 wks)

Question 54

Who are most at risk to cryptosporidium

Answer 54

Regular swimmers (immune to chlorine). Childcare, healthcare, animal workders

Question 55

Diagnosis of cryptosporidium

Answer 55

Faeces sample: acid fast staining

Question 56

Treatment of cryptosporidiosis

Answer 56

Paromycin (kills parasite) Nitazoxanide (broad spectrum antiparasite) Oetreatide (reduces cramps and frequency)

Question 57

Commonly used anti-protozoal treatment

Answer 57

Metronidazole Pentamidine Nitazoxamide Pyrimethamine

Question 58

Commonly used anti helminth

Answer 58

Albendazole Mebendazole Ivermectin Praziquantel