Exam 4 Nematodes

Question 1

Explain how nematodes differ anatomically in comparison to cestodes

Answer 1

Cestodes have no digestive tract are acelomate and have no body cavity.
Nematodes are coelmate, have a false body cavity and digestive tract

Question 2

Some nematodes are ovoviviparous and parthenogenetic- explain?

Answer 2

• unfertilized eggs inside the female hatch inside her and are brown alive
• female can produce eggs that can develop without fertilization- haploid eggs

Question 3

What external morphological characters distinguish male vs female nematodes

Answer 3

Female is usually larger than the male

Question 4

What worm species may be associated with intestinal blockage under certain conditions?

Answer 4

Ascaris lumbricoides can cause intestinal blockage

Question 5

How is Necator distinguished from Ancylostoma?

Answer 5

The mouth parts
Ancylostoma has vampire like teeth
Necator has a smoother opening with plate like discs

Question 6

What ecological conditions are detrimental to hookworm larvae?

Answer 6

Optimal soil conditions are required

Question 7

What is an auto infection? What nematodes species can lead to an auto infection?

Answer 7

Reinfect host without leaving the body

Strongyloidiasis stercoralis

Question 8

What are some ways that trichnosis can be prevented?

Answer 8

Cool meat to safe temperatures
Clean meat grinders after each use
Do not allow pigs or wild animals to eat undercooked meat, scraps or carcasses

Question 9

Explain how the nematode body cavity functions as a hydrostatic skeleton?

Answer 9

H

Question 10

What is a stichosome and what nematode is this characteristic to?

Answer 10

Long glandular esophagus

Trichuris trichiura

Question 11

What species of nematode is an intercellular parasite? Explain

Answer 11

H

Question 12

By what pathway is the kidney worm passed to the definitive host?

Answer 12

Eating undercooked paratenic hosts

Question 13

Explain the difference between homogonic vs. heterogenous life cycle in Strongyloides?

Answer 13

Homo- parasite

Hetero- free living in the soil, both male and female can alter to parasitic of soil conditions are not adequate

Question 14

How is Trichinella spiralis passed to pig hosts?

Answer 14

By scavenging

Question 15

How is strongyloidiasis diagnosed in humans?

Answer 15

Blood test

Question 16

How do humans get infected with hookworm disease? Explain the route of infection in humans or how the worm completes its life cycle in humans?

Answer 16

H

Question 17

How are male and female Ascaris worms distinguished?

Answer 17

N

Question 18

Explain how humans acquire an infection of ascariasis? How does the work complete its life cycle in humans?

Answer 18

B

Question 19

Explain the difference between cutaneous larval migrans and visceral larval migrans? What parasite species are implicated in both?

Answer 19

H

Question 20

How is it young puppies may be heavily infected with Toxocara canis without ever having eaten any intermediate hosts?

Answer 20

The worms can transverse across the placental barrier and the puppies will be born infected

Question 21

How is it that raccoons get infected with the parasite Bayliascaris?

Answer 21

B

Question 22

What is the pathway that humans get infected with pinworm? Why is the infection so potentially contagious?

Answer 22

H

Question 23

What bacteria is often associated with filarial worm infections

Answer 23

H

Question 24

How are filarial worms transmitted to the definitive hosts?

Answer 24

H

Question 25

What characters identify the larval stage of Wuchereria bancrofti?

Answer 25

H

Question 26

Explain the effects of Bancroftian filariasis in humans?

Answer 26

H

Question 27

What is meant by periodicity and subperiodicity in Wuchereria infections?

Answer 27

Periodicity- comes out at night

Sub- comes out in the day

Question 28

What are the effects of onchocerciasis in humans? How is the infection acquired?

Answer 28

Onchocerciasis or River Blindness
Hanging groin
The Black fly vector bites you and the L3 larvae that are in the mouthparts of the fly gain access to the body through the bite

Question 29

Why is the mode of feeding in the vector of onchocerciasis so important in the parasite being able to complete its life cycle

Answer 29

H

Question 30

What is the distribution of Onchocerca volvulus?

Answer 30

Mainly central Africa

Question 31

What was the strategy of the World Health Organization in its Onchocerciasis control efforts?

Answer 31

Aerial larval sprays targeting the black fly larva
Ivermectin to infected individuals
Was ended because of cost

Question 32

Explain the life cycle of Dirofilaria in the definitive host?

Answer 32

• Mosquito takes a blood meal infected with the microfilaria
• Microfilaria penetrate the mosquitos midgut and and migrate to m tubules
• L1 larvae
• L3 Larvae
• migrate to mosquitos proboscis
• mosquito takes a blood meal and the parasite enters the blood stream through the bite
• adults in pulmonary arteries

Question 33

Explain how humans acquire an infection of dracunculiasis?

Answer 33

Contaminated drinking water

Question 34

What is spirocercosis in dogs and what is the cause?

Answer 34

Esophageal cancer

Spirocerca lupi will form nodules in the dogs esophagus and they will eventually become cancerous

Question 35

By what methods are the following parasites or diseases diagnosed in humans:
Enterobius vermicularis

Answer 35

Pinworm

Scotch tape method

Question 36

By what methods are the following parasites or diseases diagnosed in humans:
Ascaris lumbricoides

Answer 36

Fecal smear

Eggs are in the fecal matter

Question 37

By what methods are the following parasites or diseases diagnosed in humans:
Trichnosis

Answer 37

Biopsy of body

Question 38

What parasitic infliction causes rectal prolapses in children?

Answer 38

Trichuris trichiura