Parasites 1

Question 1

Parasitism

Answer 1

Association between populations of two species, in which the smaller (parasite) is physiologically dependent on the larger (host); the parasite has: A higher reproductive potential than the host AND the potential of HARMING the host.* Parasites that harm the host aren’t always the most successful… Don’t kill the ones feeding you!

Question 2

Ectoparasite vs Endoparasite

Answer 2

Ectoparasite - Live on your surface. Ex. Crab lice. Pubic lice can also cling on eyelashes and eyebrows… to thick and coarse hair!

Endoparasite - Live in your body! In tissues or in digestive tract, etc! Ex. Round worm!

Question 3

Host… Intermediate vs Definitive

Answer 3

Host (carries parasite): Two kinds…

• Intermediate…. carries larva.. the immature parasite! (although hard to tell if a single celled organism is hard to tell…), or supports Asexual multiplication. Ex. Cow is intermediate host for beef tapeworm… just sits there! Not an adult tapeworm that is replicating!
• Definitive: Carries Adults parasite, and supports sexual multiplication! Ex. we are definitive host for beef tapeworm! They replicate in us!!

Question 4

Vectors… Mechanical vs Biological

Answer 4

Vectors: Has to be invertebrate (ex. mosquito, flies, etc. but also another…). 2 types of vectors:

• Mechanical… invertebrate that actually carries the parasite from one host to another, but no development or multiplication of parasite while in the vector!
• Biological… vector where parasite can either multiply or undergo developmental changes! Easy to get rid of disease in this… jsut get rid of vector and you get rid of parasite! Not so in mechanical vectors….

Question 5

Single Host parasites… Direct vs Indirect

Answer 5

Single Host Parasites: Transmission determined by viability. Basically causes infection in host. This distribution is DETERMINED BY HYGIENE AND SANITATION

• Direct: ex. through sexual contact. Called the vegetative form. Can’t live in harsh conditions!
• Indirect Life Cycle: Better, more complicated way to spread to different hosts. But they use a “trojan horse” strategy! Larva surrounded by egg shell or cyst wall.. They when put in environment… can survive and wait out for quite a while until another host comes by and takes up the “trojan horse”.

Question 6

Multiple Host Parasites

Answer 6

Transmission requires more than 1 host… Distribution determined by second host’s ecological niche.
- ex. Liver fluke… adult reproduces in body, these eggs to grow need to be taken up by snail… which then needs to be eaten by a fish to grow more… then to reproduce that fish needs to be eaten by the human!

Question 7

Parasites Classification

Answer 7

1. Protozoa…
   - Unicellular… nucleus, cytoplasm
   - Locomotion.. flagella, pseudopodia
   - Multiplication: asexual and sexual reproduction (cysts)
2. Helminths (worms)
   - Multicellular organisms
   - Specialized, differentiated organs
   - Sexual reproduction (eggs)

Question 8

Effects of Parasites on Host

Answer 8

• Often kills those who are weak.. example 5 year old in africa who doesn’t eat much food… parasite kills child. Not enough food to feed both!

Question 9

Acquired Immunity with parasites

Answer 9

Acquired Immunity: Not very much of this in Parasites… reinfection is practically the same as first infection… which is different form Virus and bacteria!

Question 10

Eosinophilia and parasites

Answer 10

Defined as >500 cells/mm. It really ins’t specific for parasitic diseases!!!!!! Don’t just zero in on parasites.. could be allergy, neoplasm, or connective tissue disorders. Produced in helminth infections only.