Nematodes- infective eggs

Question 1

What is the distribution of Trichuris species?

Answer 1

worldwide, but especially in tropical areas with poor sanitation, esp in children

Question 2

Is Trichuris an old parasite?

Answer 2

yes, petrified eggs have been found in prehistoric humans

Question 3

What is the name of the human whipworm specie?

Answer 3

Trichuris trichiura

Question 4

What are the species names for cat, pig, mouse, and dog whipworm?

Answer 4

Trichuris campanula, Trichuris suis, Trichuris muris, Trichuris vulpis

Question 5

What are some distinguishing features of whipworm species?

Answer 5

has a narrow anterior end and a wider posterior end

females are always larger than the males

Question 6

Under what conditions will whipworm eggs embryonate?

Answer 6

must be in external environment: high humidity, sandy soil and 20-30 degrees celcius

Question 7

Describe the whipworm egg morphology

Answer 7

barrel-shaped, unembryonated, has bipolar plugs, a smooth shell

Question 8

Where does the first stage larva hatch from the egg?

Answer 8

in the host small intestine and migrate to colon

Question 9

Where do adult whipworms inhabit?

Answer 9

in the cecum and ascending colon, with anterior portions threaded through mucosal layer

Question 10

What is the life span of adult whipworms?

Answer 10

1 year

Question 11

What is the pathology of whipworm infection?

Answer 11

frequently asymptomatic
heavy infections in children can cause abdominal pain, diarrhea and rectal prolapse (caused by weakened ligaments holding rectum), sometimes growth retardation

Question 12

How can a whipworm infection be diagnosed?

Answer 12

microscopic identification of eggs in feces

Question 13

Which drugs can be used to treat whipworm infections?

Answer 13

mebendazole and albendazole

Question 14

What is the distribution of Enterobius vermicularis (pinworm)?

Answer 14

broadest geographic range. most common in temperate regions of Western Europe and North America (rare in the tropics)

Question 15

How are pinworm eggs spread?

Answer 15

oral-fecal route

Question 16

What are the hosts of pinworm?

Answer 16

humans are the only known natural host, no reservoirs

Question 17

Describe the adult pinworm morphology

Answer 17

small, white, threadlike bodies, females are bigger.

females have a long, pin-shaped posterior

Question 18

Where do the adult pinworms reside?

Answer 18

in the cecum. gravid females migrate at night to lay eggs

Question 19

Describe the pinworm egg morphology

Answer 19

flattened asymmetrically on one side, ovoid in shape, embryonate in 6h. viable for 20 days in moist environments

Question 20

What is retro-infection of pinworms?

Answer 20

When the larvae hatch on the anus and crawl back up the intestinal tract to the cecum to mature into adults

Question 21

What is the pathology of pinworms?

Answer 21

usually asymptomatic.
females and eggs may cause irritation of butt hole region.
female migration at night may lead to discomfort and scratching, aiding in the spread of eggs

Question 22

How can pinworm infection be diagnosed?

Answer 22

scotch tape test: cellulose tape is applied to anal area

anal swabs: has adhesive material

Question 23

How are pinworm infections treated?

Answer 23

primarily mebendazole, but also albendazole

Question 24

What is the largest and most common intestinal nematode?

Answer 24

Ascaris lumbricoides (human roundworm)

Question 25

What is the distribution of Ascaris lumbricoides?

Answer 25

worldwide, but mostly in Africa, in the countryside. eggs can remain viable for years in moist environments

Question 26

How are people common infected with Ascaris lumbricoides?

Answer 26

using feces to fertilize soil, children playing in soil

Question 27

What are the hosts of Ascaris lumbricoides?

Answer 27

humans are the only definitive host

Question 28

Describe the morphology of the adult roundworms

Answer 28

adults are the largest nematodes to infect humans
females larger than males
male posterior end is curved due to spicules
three lips at anterior end, lined with miniscule teeth

Question 29

Describe the roundworm egg morphology

Answer 29

unembryonated when passed in the feces, become embryonated in soil, eggs are the infectious stage. thick, rough outer shell

Question 30

Which path do the larva follow in the body?

Answer 30

hatch, burrow in the intestine, through intestinal mucose to blood, reach the lungs and migrate up the respiratory tract so that they can be swallowed. mature into adults in the small intestine

Question 31

What is the pathology of ascariasis from adult worms?

Answer 31

light infection is usually asymptomatic, but can lead to vague abdominal pains
heavy worm burden results in malnutrition
wandering adults can cause blockages resulting in intestinal obstruction, appendicitis, biliary ascariasis, perforation of intestine, pancreatitis, etc

Question 32

What is the pathology of ascariasis from larvae?

Answer 32

larvae can penetrate alveoli, causing plasma to enter them and cause an inflammatory reaction. leads to pneumonia-like symptoms such as low fever, cough, blood in sputum, asthma

Question 33

How is ascariasis diagnosed?

Answer 33

identify egg in feces

Question 34

Which drugs are used to treat roundworm infections?

Answer 34

albendazole in combination with mebendazole. ivermectin can be used alternatively.
this treats adults. no treatment for larvae

Question 35

What is the distribution and host of Baylisascaris procyonis?

Answer 35

it is a raccoon roundworm that does not develop in humans but can cause problems.
common throughout North America

Question 36

What is the pathology of Baylisascaris procyonis?

Answer 36

migration of large larvae through many tissues, including liver, heart, lungs, brain, eyes causes visceral larval migrans or ocular larval migrans symptoms.
symptoms are severe because the larvae are large and move a lot

Question 37

How can Baylisascaris procyonis infection be diagnosed and treated in humans?

Answer 37

rare infection, not often diagnosed. serological test and identification of larvae (biopsy or autopsy).
no drugs are completely effective