Parasitology lecture

Question 1

Each animal can be a host of many parasites; thus?

Answer 1

There are many parasitic organisms on earth

Question 2

It has been estimated that more than 50% of all living plants and animals are?

Answer 2

parasitic at some stage during their life cycle

Question 3

In this course we will concentrate on 3 major groups of parasites

Answer 3

1. Protozoa- flagellates, amebas, malarial organisms
2. Helminths - parasitic worms such as the flukes, tapeworms, and roundworms
3. Arthropods - insects and arachnids that are ectoparasites and carriers (vectors) of diseases

Question 4

Why do we study parasites?

Answer 4

• Parasites provide unique examples of biological phenomena not found in free-living organisms
• Parasites provide unique examples of biological phenomena not found in free-living organisms.
* Medical Importance
* Veterinary Importance
* Economic Importance

Question 5

______ are hosts to many species of parasites

Answer 5

Humans are hosts to many species of parasites

Question 6

Medical Importance of Parasites

Answer 6

• Humans are hosts to many species of parasites.

* Many of these parasites are causative agents of major public health problems of the world.

Question 7

Examples of Medical Importance in the World

Answer 7

• The life expectancy of an Egyptian is in the mid-40’s due to Schistosomes.
• 15 million children in the world will die this year from a combination of malnutrition and parasites.
• Over 1 million African children will die this year from the effects of malaria.
• Many cases of plague, transmitted by fleas, still occur throughout the world.
• We in the comfort of the U.S. are not immune from parasites.

Question 8

Common parasitic diseases in the U.S. include

Answer 8

1) Pinworms
2) Giardiasis
3) Dog roundworms
4) Ticks

Question 9

Importation of Parasites from Tropics to the U.S.

Answer 9

Movement of persons from all areas of the world have introduced parasitic diseases into the U.S
– Numerous cases of malaria are brought back by vacationers from the tropics.
– Service personnel are often employed in areas endemic with many parasites.
– Many immigrants have brought their parasites with them.

Question 10

Veterinary Importance of Parasites

Answer 10

• In Africa, cattle cannot be raised in an area equal to that of the U.S. due to trypanosomes.
• A poultry farmer can be wiped out by coccidia.
• Cattle, pigs, and sheep infected with parasites fail to gain weight and may not reproduce.
• Dogs may become infected with heartworm and die if untreated.
• Cats are infected by many species of protozoans and helminths.

Question 11

Parasites are primarily divided in 2 major groups

Answer 11

– Protozoa

– Helmints

Question 12

Protozoa are? (specific types)

Answer 12

– Sarcodina (Amoeba)
– Sporozoa (Sporozoans)
– Mastigophora (flagellates)
– Cilliata (Ciliates)

Question 13

Helmints are (specific types)

Answer 13

– Platyhelmints (flatworms)
• Cestoda (Tapeworms)
• Trematoda (Flukes)
– Nemathelmints (Roundworms)

Question 14

Protozoans

Answer 14

– Trophozoite: Motile, feeding and reproducing
form
– Cyst: Non motile, non metabolizing and non reproducing form surrounded by thick wall.

Question 15

Helmints are

Answer 15

– Egg
– Larva
– Adult

Question 16

Definitive Host is?

Answer 16

One in which the sexual cycle takes place or the adults are present.

Question 17

Intermediate Host is?

Answer 17

Asexual cycle takes place or the larva is present.

Question 18

Protozoa features

Answer 18

– Microscopic unicellular organisms
– Lack photosynthetic capability
– Usually motile
– Reproduce by asexual fission

Question 19

Protozoan habitats

Answer 19

– Majority are free-living
• Found in marine, fresh water and terrestrial habitats
– Essential decomposers
– Require large amounts of moisture
– Important part of food chain
• Protozoa eat bacteria and serve as food for larger species
• Help maintain ecological balance in soil
• Important in sewage disposal
– Results in decrease of sewage solids

Question 20

Structure of protozoa

Answer 20

– Cell wall: Lack cell wall
– Shape determined by material beneath plasma
membrane
– Cell structures:
• Have membrane bound nucleus and organelles
• lack photosynthetic chloroplasts
• Have specialized structures for movement– Cilia, flagella or pseudopodia
• Protozoa grouped by mode of locomotion