[DISCUSSION] MODULE 3 UNIT 3 Flashcards
The phylum Nematoda is divided into classes based on the presence or absence of “(?)’, which are caudal chemoreceptors.
phasmids
The two (2) classes were earlier called Aphasmidia and Phasmidia, but now have been renamed as (?), respectively.
Adenophorea and Secernentea
This module unit will deal with the phasmid nematodes belonging to the class Secernentea.
Medically important phasmids include (?)
Ascaris lumbricoides, Enterobius vermicularis, hookworm species, and Strongyloides stercoralis.
The specific name of Ascaris lumbricoides has been derived from its resemblance with earthworm ([?], meaning earthworm in Latin).
lumbricus
Two species of hookworms are human parasites:
(1)Ancylostoma duodenale
2) Necator americanus
(Greek ankylos-hooked, stoma-mouth)
Ancylostoma duodenale
(?) whose name literally means the “American murderer” (Latin necator-murderer)
Necator americanus
o identified in specimens obtained from Texas, USA, it is believed that it actually originated in Africa
Necator americanus
Small cylidrical worms were observed in diarrheic stool of some French soldiers repatriated from Cochin-China (referring to Vietnam), thus, earliest cases were decribed as Cochin-China diarrhea.
These were named Strongyloides stercoralis (strongylus- round, eidosresembling, stercoralis-fecal).
Common Name: Giant intestinal roundworm
A. Ascaris lumbricoides
1
(?) live in the lumen of the small intestine.The female worm produces both fertilized and unfertilized eggs which are passed out in faeces.
Adult worms
2
A female may produce approximately (?) eggs per day
200,000
3
In the (?), the fertilized egg embryonates. Larvae develop to third stage within fertile eggs after 2 to 3 weeks in moist, warm, shaded soil
soil
4
Humans become infected by ingestion of the ?
embryonated eggs
5
the (?) hatch
larvae
6
the (?) invade the intestinal mucosa, and are carried via the portal, then systemic circulation on to the heart, then into the lungs
larvae
7
The (1) break out of the capillaries into the alveoli. The (2) mature further in the lungs (10 to 14 days), after a (3), penetrate the alveolar walls, ascend the bronchial tree to the throat, and are swallowed
- larvae
- larvae (L4s)
- molt
They develop into (1) in the small intestine, where they worms maintain their position due to their body muscle tone, spanning the lumen,
and exerting pressure against the walls of the small intestine.
Between 2 and 3 months are required from ingestion of the (2) to oviposition by the adult female.
(3) can live 1 to 2 years.
- adult worms
- Infective eggs
- Adult worms
Clinical manifestations of ascariasis are caused by the pulmonary migratory phase of (?) in the small intestine and the wandering adult worms.
the larvae, the adult worms
The (?) causes allergic reaction.
larval migration
The initial exposure to (?) during the lung migration phase is usually asymptomatic, except when the larval load is heavy.
larvae
One may experience symptoms referable to respiratory system such as ?
asthmatic respiration, cough with bronchial rales and chest pain.
These symptoms may be due to the (?) and massive destruction of the lung parenchyma as the larvae break through the capillaries on their way to the alveolar sacs,
petechial hemorrhages
In massive infection, the hemorrhage may give rise to ?.
Ascaris pneumonitis