The topic is highly useful for MBBS students. Trichinella is a neamtode, The disease is called as Trichinellosis/Trichinosis. This topic will be explaining about Morphology of Trichinella, mode of transmission, life cycle ,clinical features, lab diagnosis, treatment and its prevention.

1. DR ARUNA RANI BEHERA
MD MICROBIOLOGY

2. A/K/A-Trichina worm
Trichos – hair, ella – diminutive, spiralis – coiled
Smallest nematode
First observed in muscles of the patient by James
Paget.
Common parasite of pig, Zoonotic disease
Geographical distribution: Europe & USA
Habitat: Adult – mucosa of small intestine, Larvae -
Striated muscles

3. Morphology:
Males:
 Measures 1.4 – 1.6 X 0.04 mm
 Tail end Contains pair of pear shaped
clasping conical papillae(Claspers), Short
lived
Females:
 Measures 3 – 4 X 0.06 mm
 Viviparous, 1st stage of larvae released into
intestine.
 Life span: very short
Larvae:
 Infective larvae measures: 80 X 8 µm
 Encysted larvae present only in the striated
skeletal muscles, measures 1mm X 36 um.
 It is tightly coiled inside the cyst.

4. Life cycle:
 One host (Man, pig or rat)
 Man is dead end host.
 Pig is the optimum host
 Man acquires infection by ingestion of raw or
inadequately cooked pork containing the viable
encysted larvae.

6. Pathogenesis:
 Trichinellosis or Trichinosis
 Asymptomatic to acute fatal illness.
Clinical features:
Stage of intestinal invasion:
 Gastrointestinal disturbances – malaise,
nausea, vomiting, diarrhoea & abdominal pain.

7. Stage of muscle invasion (larval migration):
 Fever, myalgia, periorbital edema, weakness of
effected muscles & Allergic manifestations
Stage of encystation:
 Occurs in striated muscles, all symptoms subside &
larvae calcify..
 Calcified larvae can be seen grossly in exposed
muscles.
 Muscular pain

9. Lab Diagnosis:
Parasitological:
 Demonstration of larva in the muscle from biopsy.
 Detection of adult worms & larvae in diarrhoeic
stool(occasionally positive).
Serological:
 Bentonite flocculation test, Latex agglutination, ELISA
Skin test: Bachman antigen – 0.1 ml (1 in 1000 dilution)
intradermal injection of larval antigen – causes erythematous
wheal in positive cases within 15 – 20 min.
Radiology: X-Ray,
Eosinophilia (20 – 95 %)

10. Treatment:
 Thiobendazole, Mebendazole(100mg TID for 3days)
Prevention :
 Proper cooking of pork or freezing at – 20o C.
 Avoid the practice of feeding pigs with raw garbage
 Inspection of slaughtered pigs.