Muscle parasites

Question 1

Discuss how we get the trichinella parasite and what it does

Answer 1

We get it from pork

Larva forms cyst in muscle, and if heavy, can show intestinal pathologies of crypt hyperplasia, villous atrophy, and goblet cell hyperplasia causing diarrhea and intestinal discomfort

Question 2

How long do Trichinella hang around?

Answer 2

These guys turn from larvae to adult in 30 - 40 hours, mate and produce larvae in less than 5 days, and live until T cell response evicts them in about a month

Question 3

Movement of trichinella in the body

Answer 3

1. Larvae deposited onto mucosa, enter villous lymphatics and migrate to capillaries
2. Leave capillaries in striated muscle, penetrate the cells
3. Coil in a spiral and modify the myosyncitium to become a nurse cell

Question 4

Discuss the nurse cell pathophysiology related to trichinella

Answer 4

The larva secretes nuclear regulatory factors that alter the way the myocyte behaves.

Increased host nuclear division followed by mitochondrial damage and loss of muscle proteins by 8 days.

Targets collagen types 4 and 6 and causes the host cell to make VEGF to get more blood supply to help this guy move around.

Question 5

Key clinical features to cue you in to Trichinella

Answer 5

Fever and gastroenteritis are a given

Circumorbital edema and myositis (2-3 weeks later)

Hemorrhages sublingual, retinal, and subconjunctival, as well as splinter hemorrhaging of the nails

Rarely: Dyspnea, encephalopathy, cardiac failure

Question 6

Lab findings for Trichinella

Answer 6

Eosinophilia, larvae in muscle biopsies, and trichinella-specific antibody response

Question 7

How do we treat trichinella?

Answer 7

Corticosteroids may be life saving but they permit a longer adult infection.

Give azoles and fluid support.