Trichenella Spiralis Flashcards
Also known as the
Trichina Worm”, “Pork Worm”
Is it zoonotic?
Yes
MALE T.S
Measures 1.4-1.6 mm in length by 40-60 micra in transverse diameter.
______is found at the caudal end which is evertible during coitus.
It is guarded by___ conspicuous conical papillae which clasp the female during copulation.
Spicule is____.
Posterior end of the worm is_____ ventrad
Cloaca
2
absent
curved
FEMALE T.S
- About 3-4 mm long and 60-80 micra in width.
-____ opens at the anterior fifth of the body.
- Has a single_____ which contains larvae.
Vulva
uterus
Encysted larvae of T.S
measures 100 by 6 micra when extruded by the female worm
• provided with a_____-like burrowing tip at its tapering anterior end
• in the____ muscles, the larva grows to about 0.8-1mm and becomes encrusted along the axis of the muscle fibers
spear
striated
Phasmid or Aphasmid T.S
Aphasmid
Hosts of TS
Definitive = Humans & pigs, rats, dogs, bears, foxes walruses and other omnivore and carnivore (swines)
Final host = Humans & pigs, rats, dogs, bears, foxes walruses and other omnivore and carnivore (swines)
Intermediate = Humans & pigs, rats, dogs, bears, foxes walruses and other omnivore and carnivore (swines)
Humans are considered = ________
accidental hosts
Habitat TS
Small intestine, Tissue
MOT TS
Ingestion/consumption of raw or undercooked meat of infected animals
Infective stage TS
Encysted larva
Diagnostic stage TS
Encysted larva
Treatment TS
Albendazole
Menendazole
Diseases of TS
- Trichinosis
- Trichiniasis
- Trichinelliasis
Diagnosis of TS
- Muscle Biopsy
- Bentonite Flocculation Test
German investigators proved that raw or insufficiently cooked meat like____ causes human trichinellosis
pork
Most important cause of trichinellosis in humans
Most adapted to pigs
Trichinella spiralis
Second most common species affecting humans
Most widely distributed species among wild animals; can also infect pigs
Trichinella britovi
Infects primarily wild carnivores in the frigid zones
Trichinella nativa
Trichenella spiralis is most adapted to
Pigs
Trichenella britovi is widely distributed to
Wild animals
Trichenella nativa infects primarily
wild carnivores
Other species affecting humans:
T. murrelli
T. nelsoni
T. papuae
T. zimbabwemsis
T. pseudospiralis
How does it give birth?
Viviparous
Larviparous
Infection is maintained in _____ cycle
pig-to-pig
pig-to-rat-to-pig cycle
EPIDEMIOLOGY
Cosmopolitan infection
____country worldwide
10,000 cases/year
0.2% resulting to mortality
55
_____parasitic nematode to humans
______-like
_____in color
Smallest
Thread
Ivory white
Male
Single_____ near the posterior end of the body, joined by genital tube in the mid-body, extends back to the cloaca
_____spicule
______: evertible and equipped by__ conspicuous conical papillae (claspers) which clasp the female during copulation
testis
No
Cloaca; 2
Female
____than the male
Single ovary, oviduct, seminal receptable, coiled uterus, vagina, and vulva
____for copulation located at the anterior fifth, ventral side
Bigger
Vulva
LARVA
Anterior end: spear-like for burrowing
______ similar with adult
Reproductive organ not fully developed already possible to identify the___
Digestive tract
sex
the only intracellular parasitic nematode
Trichinella spiralis
Capsule =____ capsule
______= where the larva gets its nourishment
______= made up of stichocytes, which is like the esophagus of the parasite
collagen
Nurse cell
Stichosome
What type of hosts are humans
definitive
Final
Intermediate
Encysted larvae are released once exposed to_____&____(EXCYSTATION)
gastric acid and pepsin
Newly released larvae invade the small intestine mucosa and undergo___ molting
develop to become adult (2 days)
4
Adult male and female worms copulate ____days post infection
After 1 week: female gives birth larvae (LARVIPAROUS)
5-7
ENCYSTATION in the_____
Start of encystation:__ weeks
Complete encapsulation:___ wks
Life span of encysted larva: ____ yrs
striated muscles
3
4-5
5-40
Life span of adult worm:
4 weeks
Both diagnostic stage, and infective stage
Encysted Larvae
Corresponds to stage of incubation and intestinal invasion
Enteric Phase
Corresponds to stage of larval migration and muscle invasion
Invasion Phase
Corresponds to stage of encystment and encapsulation
convalescent Phase
Diarrhea, constipation, vomiting, abdominal cramps, malaise, nausea
ENTERIC PHASE
Migrating larvae - immunological, pathological, and metabolic reactions
Marked Eosinophilia
increase histamine
Histamine, serotonin, bradykinin, and prostaglandin → increase vascular permeability → tissue edema
INVASION PHASE
Cardiac manifestations:
heart failure, Pericardial pain, tachycardia, ECG abnormalities
Pericardial effusion
Neurological manifestations:
(stroke)
Meningitis, meningoencephalitis
Heavy Infection: ocular disturbances, diplegia, deafness, seizure, and coma
Abatement of symptoms
Full recovery: self limited
Protean neurologic signs from brain damage may persist
CONVALESCENT PHASE
DEFINITIVE DIAGNOSIS
Demonstration of encysted larva through muscle biopsy like the grastrocnemius muscle
DEMONSTRATION OF LARVAE IN THE BLOOD
Venous blood
Knott concentration technique
Membrane filtration technique
screening test
confirmatory test
Low reactivity, not a favored test
Primarily used to diagnose trichinellosis infection
ELISA (enzyme-linked immunoassay)
Western Blot
Bentonite Flocculation Test
SUPPORTIVE TREATMENT
– to address pain (i.e., muscle pain)
– to address fever
: control hypersensitivity reactions to larvae
Analgesics
Anti-pyretics
Steroids
