Trichinella spiralis

Trichinella spiralis

Common name: Trichina worm- The Pork worm Trichinella spiralis means spira, how this coils up in its host. diseases: Trichinosis, Trichiniasis, is a zoonotic disease. it is passed between humans and

animals. Habitat: females in mucosa of small intestinal The same animal acts as final and intermediated host is most common in Europe, North America, and Asia, Infective stage: contaminated meat (muscle) containing encyst

larvae  (pig) Diagnostic stage: larvae encysted in muscle (human) Can be fatal if large numbers of cysts form in the heart muscle.

The sperm fertilizes the egg, but the female doesn’t release the eggs until they have hatched within her uterus, which is usually within the fifth or sixth day of infection.

Female worms can produce approximately 1500 newborn larvae (immature L1) during a life span (4-16 weeks), before expulsion by the host immune system.

Viviparous: Expel active larvae

Oviparous: Eggs laid in 1-cell stage or early cleavage stage.

Ovoviviparous: Eggs laid containing embryo orlarva (L1). Some hatch out prior to passage in feces.

Viviparous: Expel active larvae  

Morphology:Anterior end: slender with small non papilated mouth.

Male:1.5mm posterior end ventrally curved with 2 copulatory appendages

Female: 3.5mm single ovary Posterior end bluntly rounded

LARVAE

Measures 80-120 um by 5.6 u at birthAnd grows but little until it has entered A muscle fiber, size 900 um

developed.

Female worms deposit larvae into: The mucosa of small intestine Directly into the lymphatics Blood stream. The larvae carried to all parts of body, but the larvae developing only in striated

muscle.

Epidemiology The disease among humans, rats, and pigs Rats and pigs feeding on garbage that includes infected pork waste, become infected in turn Dead or dying infected rats are themselves eaten by pigs Raw or poorly cooked pork (sausage) harboring infective larvae then becomes the vehicle for human infections Trichinellosis is a cosmopolitan disease that occurs most commonly in Europe and the US

Pathogenesis:

1--Penetration of the adult females into mucosaThe first symptoms appear between 1- 2 days after ingestion. The worms migrating in the intestinal epithelium Inflammation of duodenal and jejunal mucosa: This causes: inflammation, nausea, vomiting, sweating, and diarrhea.

2- The migrating larvae Ten days after infection the larvae will penetrated

the muscle fibers, carried to all parts of body, This causes

muscular pain, difficulty breathing

Per orbital edema and conjunctivitis heart (myocarditis), lungs (pneumonitis), brain (encephalitis). Can be fatal if large numbers of cysts form in the heart

muscle. heart failure or respiratory or kidney malfunction

Diagnosis :

Muscle biopsy at the encystment stage blood test for eosinophilia increased levels of creatine phosphokinase

CPK, Serology test Immunoassays, such as ELISA At the diarrheal stage, adult and larvae may

be found in feces

 Treatment

Anti-inflammatory drugs. When infected, it is also suggested that you get a lot of rest to help give your body time to recover.

Mebendazole is the drug of choice.