Issue Description The giardia organism inhabits the digestive
tract of a wide variety of domestic and wild animal species, as well
as humans. It is a common cause of gastroenteritis in humans,
infecting approximately 200 million people worldwide. Other Names Giardiasis, Beaver Fever
Transmission Giardiasis is passed via the fecal-oral route.
Primary routes are personal contact and contaminated water and food.
People who spend time in institutional or day-care environments are
more susceptible, as are travelers and those who consume improperly
treated water. It is a particular danger to people hiking or
backpacking in wilderness areas worldwide. Giardia is suspected to be
zoonotic (communicable between humans and lower animals). Major
reservoir hosts include beavers, dogs, cats, horses, humans, cattle
Symptoms Symptoms include loss of appetite, fever,
explosive diarrhea, hematuria (blood in urine), loose or watery stool,
stomach cramps, upset stomach, projectile vomiting (uncommon),
bloating, flatulence, and burping (often sulphurous). Symptoms
typically begin 1-2 weeks after infection and may wane and reappear
cyclically. Symptoms are caused by Giardia organisms coating the
inside of the small intestine and blocking nutrient absorption. Most
people are asymptomatic; only about a third of infected people exhibit
symptoms. Untreated, symptoms may last for six weeks or longer.
Symptomatic infections are well recognised as causing lactose
intolerance, which, while usually temporary, may become permanent.
Although hydrogen breath tests indicate poorer rates of carbohydrate
absorption in those asymptomatically infected, such tests are not
diagnostic of infection. It has been suggested that these observations
are explained by symptomatic giardia infection allowing for the
overgrowth of other bacteria. Some studies have shown that giardiasis
should be considered as a cause of Vitamin B12 deficiency, this a
result of the problems caused within the intestinal absorption system.
Treatment Drugs used to treat adults include
metronidazole, albendazole and quinacrine. Furazolidone and
nitazoxanide may be used in children. Treatment is not always
necessary, as the body can defeat the infection by itself.
The drug tinidazole can treat giardiasis in a single treatment of 2000
mg, instead of the longer treatment of the other medications listed.
The shorter duration of treatment may also cause less patient
distress. Tinidazole is now approved by the FDA and available to U.S.