How does trichinosis work in pregnancy?

January 10, 2005 6:24 AM

If a pregnant mother had trichinosis, would she inevitably pass it on to her child? If her child were born and went untreated, would the child survive? How long might it survive, and with what symptoms?
posted by Shane to Health & Fitness (10 answers total)

Trichinosis is causes by the parasite Trichinella spiralis. It is an interesting organism because the larvae changes the genetic coding of its host's muscle cells. Once a juvenile form of the worm enters a muscle cell it changes the muscle cell into a nurse cell. The nurse cell no longer functions as a muscle cell and its sole purpose now is to harbor the parasite. The parasite is even able to make its host grow blood vessels around the nurse cell for nourishing the parasite. This is the infective form of the parasite, larvae in host tissue.

Anyway the parasite can only be transmitted by eating infected muscle cells ie. under cooked meat. The juveniles in the muscle cells are incapable of further developement and reproduction until the reach digestive fluids.

I have never read anything about Trichinosis being congenital. If it is possible the chances are incredibly small. I would assume the mother would have to be initially infected durring her pregnancy and somehow the parasite would enter the fetus muscle tissue. If the mother already had the parasite before pregnancy it would not be possible.
posted by Recockulous at 8:05 AM on January 10, 2005

Are you sure you mean trichinosis and not trichomonas?
posted by Recockulous at 8:09 AM on January 10, 2005

Response by poster: Fascinating answer, Recockulous. Thanks. I didn't realize the extent to which the little buggers "use" their host.

No, I mean trichinosis. Don't the worms reproduce, though, and the eggs or larvae enter the bloodstream of the host (and thus the bloodstream of a child in utero)?
posted by Shane at 8:20 AM on January 10, 2005

The adult worms die after they reproduce but the larvae can live for years in muscle tissue. The larvae are responsible for most of the pathogenesis and is also the diagnostic stage.

So it depends on when the mother is infected for the first time and how often she is exposed to the parasite, how often she consumes raw/undercooked meat.

If exposure to the parasite only happened once and was a rare event and the disease is diagnosed before pregnancy, chances are that the larvae has already spread and is settled outside of the blood stream.

I am not sure how interested you are in the subject or for what reason you ask this but if you are really interested I can email you professor who would probably love to answer your question and could do so more accurately.
posted by Recockulous at 8:50 AM on January 10, 2005

Response by poster: ...chances are that the larvae has already spread and is settled outside of the blood stream.

Right. So, if she contracted trichinosis while pregnant, and the infected meat contained larvae, or the adult worms laid eggs before becoming "settled" in the muscle tissue, then the unborn infant might become infected...

I am not sure how interested you are in the subject or for what reason you ask this but if you are really interested I can email you professor...

I'd probably be wasting your prof's time, as I'm just interested out of curiosity sparked by a TV show plot, and I'm not otherwise much of a biology student.

Anyway, Thanks!
posted by Shane at 8:59 AM on January 10, 2005

Yes.

From PubMed:
[Trichinellosis= Trichinosis, BTW]

Parasite. 2001 Jun;8(2 Suppl):S180-2.

Congenital trichinellosis? Case report.

Dubinsky P, Boor A, Kincekova J, Tomasovicova O, Reiterova K, Bielik P.

Parasitological Institute of the Slovak Academy of Sciences, Hlinkova 3, 040 01 Kosice, Slovak Republic. [e-mail]

A large trichinellosis outbreak in the Slovak Republic caused by the species Trichinella britovi and affecting 336 people also affected a pregnant woman. The mother was infected in the 10th week of pregnancy and was treated with mebendazole. On her own request abortion was performed in the 22nd week of pregnancy. Medium IgM and high IgG anti-Trichinella antibody titres were found. The placenta, body cavities liquid, tissues and organs of the foetus contained 0.02-30 larvae per gram of tissue, measuring 0.68 +/- 0.05-1.17 +/- 0.07 mm, with blurred inner structure. Immunocytochemical examination identified Trichinella larvae that infected the foetus in the early stage of development.

Did you get the idea from that episode of House?
posted by availablelight at 10:47 AM on January 10, 2005

Maternal/fetal medicine is way far from my field of expertise, but I would venture to say that the parasite is far too large to cross the placenta. The placenta is designed for efficient gas exchange, but the two blood supplies are separated from one another, thereby preventing an immune crisis.

I don't recall whether trichinosis is confined to skeletal muscle or not, but if it's not, I suppose one could get an infection of the uterine myometrium while pregnant. And this could result in a very risky pregnancy if we suppose that infection might increase the risk of uterine rupture. Which would be bad.
posted by drpynchon at 10:47 AM on January 10, 2005

On reviewing your question, I should have qualified my reponse with, "Yes, it's POSSIBLE to pass along trich. in at least some cases." :)
posted by availablelight at 10:49 AM on January 10, 2005

Response by poster: A large trichinellosis outbreak in the Slovak Republic caused by the species Trichinella britovi and affecting 336 people also affected a pregnant woman. The mother was infected in the 10th week of pregnancy and was treated with mebendazole. On her own request abortion was performed in the 22nd week of pregnancy.

Whoa. The fetus must have been in bad shape. Of course I'm assuming she didn't abort for other reasons. I guess untreated trichinosis in adults usually results in death eventually...

I guess the main conclusion is still that the pregnant woman would have to contract trichinosis while pregnant, not sometime before.

Did you get the idea from that episode of House?

That's mostly what set me to thinking about it. Weird show, eh? Intelligent and oddly compelling. And thus I doubt if it'll last long. Maybe it will show up on Trio Channel's Brilliant But Cancelled. (In this case I still won't see it because goddammed DirecTV cancelled Trio, probably because of the new Xtian Right activity/homophobia in the U.S. and Trio's once-weekly "OUTzone," loosely gay-themed programming, on Saturday nights. No more Johnny Staccato or Parking Lot, etc., for me.)
posted by Shane at 12:36 PM on January 10, 2005

Bleah, nasty.

Cestodes are my least favorite part of medicine. Cestodes infesting the eyeball have a special place in my catalog of overly nasty things I wish never to hear about. But transplacental cestodes are nearly as bad.
posted by ikkyu2 at 4:41 PM on January 10, 2005