Condition: A diarrheal illness resulting from parasitic infection
Infectious Agent: Giardia intestinalis, a protozoan parasite
Signs and Symptoms: Symptoms can range from aysmptomatic to a variety of gastrointestinal complaints including diarrhea, abdominal cramping, bloating, fatigue, flatulence and nausea. Diarrhea is classically foul smelling and greasy. Symptoms generally present 1-2 weeks after exposure and are generally self limiting after 2-4 weeks.
Diagnosis: Giardia cysts or trophs are not always seen in the stool of infected patients. Examining up to three stool samples over several days can increase investigative power.
Transmission: Ingestion of fecally contaminated food or water including water swallowed while swimming; contact with fecally contaminated surfaces such as diaper changes, caring for an infected person or sexual contact.
Treatment: Metronidazole, tinidazole, nitazoxanide and furazolidone are drugs known to have efficacy against Giardia. Because of the difficulty of definitive diagnosis, empiric treatment can be started in patients with appropriate symptoms and history.
Prevention: Travelers should follow strict food and water precautions. There is no vaccine or role for preventative antibiotics.
Epidemiology: Found worldwide, the risk of Giardia infection increases with duration of travel. Roughly 31 of 1,000 travelers seeking medical care are diagnosed with giardia. This is most commonly seen in travelers from South Asia, Middle East and South America although it has been in seen in travelers from all regions of the world. Long-term travelers (>6 months) have a much higher incidence than shorter-term travelers. In Nepal, Giardia is found in 10% of stool samples from patients with complaints of diarrhea.