Parasites

Question 1

What is a parasite?

Answer 1

An organism that lives in or on a host and derives it nutrients at the expense of its host

Question 2

How are parasites classified?

Answer 2

By cellular structure and life cycle

Question 3

What is a vector?

Answer 3

An organism which acts as an intermediate host for a parasite. The vector transmits the parasite to the next host.

Question 4

What is the classification of parasites?

Answer 4

• Protozoa i.e. malaria and amoeba
• Helminths (worms) i.e. roundworms, tapeworms, flatworms
• Ectoparasites i.e. lice, ticks, mites

Question 5

What are protozoa parasites?

Answer 5

-Microscopic, single-celled organisms which can be free living or parasitic in nature.
They are able to multiply in humans

Question 6

How are protozoa transmitted?

Answer 6

• Protozoa that live in a humans intestine: faecal-oral route.
• Protozoa that live in the blood or tissue of human: insect vector

Question 7

Example of a protozoa parasite- Malaria?

Answer 7

-Malaria which is a mosquito-borne disease caused by a Plasmodium parasite.
-Causes the most deaths amongst all parasitic diseases.
-present throughout the tropics and subtropics.
It is preventable and recognition and appropriate treatment saves lives.
However, the complex life cycle of the parasite makes eradication very challenging.

Question 8

Example of a protozoa parasite- Amoeba?

Answer 8

-Amoebic dysentery causes bloody diarrhoea. Microscopy- cysts in formed stool.
FAECAL-ORAL ROUTE of transmission.

Question 9

What can parasites lead to?

Answer 9

Causes infection in a variety of body systems and can cause complications such as abscesses if it is left untreated.

Question 10

What are helminths parasites?

Answer 10

• Roundworms (nematodes),
• Tapeworms (cestodes),
• Flatworms (trematodes)

Question 11

How are most helminths parasites transmitted?

Answer 11

Also By faecal-oral route, but some use an intermediary host/vector

Question 12

What can nematodes/roundworms cause?

Answer 12

• Causes Enterobiasis/pinworm
• You are eating the worms, causes anal itch.

-Also causes Ascaris. The nematode can grow up to 35 cm long and causes failure to thrive in children. Severe complications can arise as a result of bowel obstruction.

Question 13

What can tapeworms/cestodes cause?

Answer 13

Taenia saginata- beef

Taenia solium- pork

Question 14

What can Tania solium cause?

Answer 14

In pork.

-Pork tapeworm cysts can from outside of the gut and causes problems especially in the brain

Question 15

What is the intermediate host for Cestodes/tapeworms?

Answer 15

Larval cysts ingested i.e. eating raw or uncooked meat

Question 16

What is the definitive host for cestodes/tapeworms?

Answer 16

Human

Question 17

What is the most common flatworm/trematode?

How is it transmitted?

Answer 17

Schistosomiasis.

This is transmitted by contact with freshwater where the snail intermediary host is present.

Question 18

What can trematodes/flatworms cause?

Where does it occur?

Answer 18

Liver failure and bladder cancer if it is left untreated

Resource poor settings i.e. the tropics

Question 19

What are ectoparasites?

Answer 19

• They live outside of the body i.e. ticks and body lice
• Most are insects or arachnids
• Many are vectors of infection