PARA 410 Lecture Notes - Lecture 13: Trichuris Trichiura, Pinworm Infection, Necator Americanus
12 Jun 2018
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Parasitology – lecture 13 (February 5th, 2018)
Slide 1
Slide 2
juveniles // adults
Slide 3 – Trichinella spiralis – Historical notes
- Owen, in 1835, described for the first time Trichinella
- Virchow described the life cycle (1850-70)
- Raillet named this non-segmented nematode Trichinella spiralis
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Slide 4 – Trichinella spiralis – an unusual nematode
- World largest intracellular parasite
- The smallest worms amongst the nematodes
- Trichinella, with its worldwide distribution, is one of the most widespread and clinically important nematode
in the world
- Puerto Rico and Australia are free of Trichinella
- The same individual serves as both definitive and intermediate host
- Although nematodes are usually host-specific, T. spiralis is not host-specific
Slide 5 – Comparative size of adult nematodes
- First row:
o Necator americanus ♀♂
o Ancylostoma duodenale ♀♂
- Second row:
o Enterobius vermicularis ♀ (pinworm)
o Trichinella spiralis ♀♂
- Third row:
o Trichuris trichiura ♀♂
Slide 6 – Trichinells spiralis – worms
Female (3mm x 36µm) // male (1.5 mm x 36µm) // New born larvae (L1) (80µm x 7 µm) // new born larvae entering
muscle
Slide 7 – Trichinells spiralis – life cycle
- During its life cycle, Trichinella larvae undergo 4 molts over a period
of 30 hours, developing into adults
- NB: only 1 host (IH and DH is the same individual
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Slide 7 cont’d – Trichinella spiralis – life cycle
1. Larvae are ingested in raw or undercooked meats.
Larvae are released from nurse cells in stomach
2. Larvae enter the small intestine. Adults mature and
live in small intestine
3. Female sheds newborn larvae that enter lymph or
blood
4. Newborn larvae are carried throughout bloodstream →
pathology – heart failure, CNS damage. Newborn
larvae enters skeletal muscle cell
5. Larvae matures in muscle. Nurse cell-larvae complex
formed
6. Normal (red) and calcified Nurse cell-larvae
complexes
Slide 8 – Trichinella spiralis – life cycle
Domestic cycle
- They are all zoonoses with humans becoming infected
incidentally (i.e. eating raw or undercooked meat,
pork) and not playing a role in the life cycle
- You can have the animals infecting themselves
Sylvatic cycle
- Temperate zome
- Tropic zone
- Arctic zone
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Document Summary
Slide 3 trichinella spiralis historical notes. Owen, in 1835, described for the first time trichinella. Raillet named this non-segmented nematode trichinella spiralis. Slide 4 trichinella spiralis an unusual nematode. Trichinella, with its worldwide distribution, is one of the most widespread and clinically important nematode in the world. Puerto rico and australia are free of trichinella. The same individual serves as both definitive and intermediate host. Although nematodes are usually host-specific, t. spiralis is not host-specific. Slide 5 comparative size of adult nematodes. First row: necator americanus , ancylostoma duodenale . Second row: enterobius vermicularis (pinworm, trichinella spiralis . Female (3mm x 36 m) // male (1. 5 mm x 36 m) // new born larvae (l1) (80 m x 7 m) // new born larvae entering muscle. Slide 7 trichinells spiralis life cycle. During its life cycle, trichinella larvae undergo 4 molts over a period of 30 hours, developing into adults.
