This reply is in reference to treatment of giardia in a women in the
beginning of her thrid trimester.

Giardiasis is a fairly common parasite endemic in St. Petersburg (Leningrad)
Russia as well as various places around the US.  The drug of choice for
treatment of this parasite is metronidazole. The length of treatment in
giardiasis is usually around 7 days, not a month.  It is a class B agent.  It
has been used in pregnant women in  the 2nd and 3rd trimester for the
treatment of giardiasis and in the treatment of Crohn's disease. If this were
my patient, I would not hesitate to treat her with this drug.  I'd probably
put her on metronidazole 250-500mg three times a day for 5-7 days and then
repeat the stool tests to see if the giardiasis was eradicated. While no drug
is perfectly safe, I think the risk to the mother and fetus from this
particular drug are FAR LESS than the risks of an untreated parasite for
three months.  (Not to mention the risk of spread of this infection to her
other family members.) Furthermore, the drugs used to suppress vomiting (the
suggestion of her doctor) are probably at least class B drugs as well!  I
think your friend needs to obtain a second opinion either from a Board
Certified Infectious Disease specialist or a Board Certified
Gastroenterologist as soon as possible.

Peter Salomon,MD, FACG
Board Certified Gastroenterologist

P.S.
Please feel free to post this.