Giardia
July, 1999
Hello Dr. Silverio,
I am inquiring to see if you know of a vaccine that has just been
developed or is available for Giardia. On our whippet list there
was mention of such a new vaccine.
Thank You,
Lee & Brenda Muirhead
Dauntae Boxers & Whippets Reg.
Giardia is a microscopic organism known as a protozoa, and is
found all over the world. The species Giardia Lamblia has been
known to infect people, dogs, cats and livestock. The most recent
study on prevalence rates found that, in some U.S. cities, as
much as 13% of the dog population is carrying this parasite.
While in the intestinal tract of its host, the organism forms
cysts which are passed in the stool. These cysts can survive in a
cool, moist environment for months. Clean, clear water is the
ideal environment for their longevity. The disease, Giardiasis,
is contracted by ingestion of the cysts from an environment
contaminated by an infected animal’s feces. Clinical signs,
if they occur, may show up in as short as 5-7 days, but infection
may not be detectable in a stool sample for several weeks. Signs
usually include diarrhea, poor appetite and weight loss.
Diagnosis can frequently be accomplished by detecting the
organism or its cysts in a stool sample. Sometimes this is
difficult, due to the fact that they are not excreted in every
stool produced during the disease, even when a severe diarrhea is
present. Also, the typical sugar flotation solution used to
identify most intestinal worms can distort Giardia, and other
tests need to be employed for positive identification. The most
sensitive test is an ELISA test which detects a specific protein
that is more reliably found in every stool produced during the
disease. This test can either be run in the veterinarian’s
office or sent to a referral laboratory. Drugs that may be used
to treat the infection include metronidazole (Flagyl),
albendazole (Valbazen), and fenbendazole (Panacur). None are 100%
effective. Frequent use of these drugs may be leading to
development of resistance.
Good sanitation practices are important to prevent recurrence.
For dogs that have repeated access to an area that may be a
source of Giardia, the new vaccine produced by Fort Dodge Animal
Health may be very useful. This is a brand new product, and still
needs to be studied, but the research that has been done so far
indicates both effectiveness and safety. As part of these
studies, healthy dogs were divided into 2 groups. One group was
vaccinated and one was not. All were then infected with Giardia.
All of the unvaccinated dogs developed diarrhea, and none of the
vaccinated dogs did. After 35 days, the organism was detected in
all of the unvaccinated dogs and in none of the vaccinated ones.
I would not hesitate to use the vaccine in a situation where
Giardia is a known risk.