Introduction to Parasites

Question 1

State what is meant by the term ‘parasite’.

Answer 1

A symbiont that gains benefit in terms of nutrients/food at the expense of its host

Question 2

The parasitic disease that causes the most deaths globally is

Answer 2

Malaria

Question 3

State the 3 groups of parasites.

Answer 3

• Protozoa
• Helminth
• Arthropods

Question 4

Describe the features of protozoa parasites.

Answer 4

• Microscopic, one-celled organisms (unicellular)
• Free living OR parasitic
• Multiply in human host

Question 5

Protozoa that live in a human’s intestine are transmitted via

Answer 5

Fecal-oral route

Question 6

Protozoa that live in the blood or tissue of humans are transmitted via

Answer 6

Arthropod vectors

Question 7

The disease malaria is caused by what type of parasite?

Answer 7

Protozoa

Question 8

State the symptoms of malaria.

Answer 8

Fever, chills and flu-like illness

Question 9

In malaria, sporozoites that are injected under the skin by a mosquito travel

Answer 9

Through the blood (and enter the liver).

Question 10

Once sporozoites mature and re-enter circulation, they’re known as

Answer 10

Meroziotes

Question 11

Describe the features of plasmodium falciparum

Answer 11

• Ring stage with double chromatin dots

- Crescent-shaped gametocytes

Question 12

State the 3 examples of helminths

Answer 12

• Cestodes (tapeworms)
• Nematodes (roundworms)
• Trematodes (flatworms)

Question 13

Describe the features of helminth parasites

Answer 13

• Long and thin worms

- Contain ova

Question 14

State 3 examples of arthropods

Answer 14

• Lice
• Ticks
• Mites

Question 15

Explain fully the pathology of malaria.

Answer 15

• Involves plasmodium parasite and mosquito vector
• Sporozoites are injected under the skin by the mosquito
• Sporozoites travel through the blood and into the liver - - They re-enter circulation and mature to become meroziotes
• Meroziotes invade and destroy red blood cells, using them to multiply
• Sexual forms are taken up by the mosquito vector

Question 16

How do you prevent malaria?

Answer 16

• Insecticide treated mosquito nets (ITN’s)

- Prophylaxis

Question 17

Describe Amoebic Dysentery

Answer 17

Protozal Infection → Entamoeba histolytica

Symptoms include:

• Diarrhoea with blood/pus
• Liver abscess
• Intestinal and extra intestinal infections

Microscopy: Cysts in formed stool

Question 18

Describe Leishmaniasis

Answer 18

Protozoal infection → multiple types of Leishmania species.

Sandfly bite is the vector

Symtoms include:

• Skin or mucosal ulceration
• Fever
• Weight loss
• Hepatosplenomegaly

Question 19

How do you detect leishmaniasis?

Answer 19

Diagnosis by histology of biopsy material

Question 20

Describe the features of Enterobiasis (pinworm) including how to diagnose.

Answer 20

• It is a helminth nematode
• Typically found in children
• 1cm, threadlike
• Diagnosis: Ova can be seen on microscopy

Question 21

State the features of Ascaris Lumbricoides.

Answer 21

• Nematode Helminth

- Largest nematode in the human intestine

Question 22

State the symptoms caused by Ascarias Lumbricoides.

Answer 22

• Often asymptomatic
• Transient pulmonary symptoms (Loeffler’s syndrome)
• Mass of worms may obstruct small intestine or common bile duct

Question 23

Describe the pathology of Ascarias Lumbricoides.

Answer 23

• Ingested eggs hatch in the intestine
• Larvae carried by circulation to lungs
• Adult worms develop in and inhabit small intestine

Question 24

State how to detect Ascarias Lumbricoides.

Answer 24

Ova seen in the faeces by microscopy