Causal Agents
Balantidium coli, a large ciliated protozoan parasite.
Cysts are the parasite stage responsible for transmission of balantidiasis The number 1. The host most often acquires the cyst through ingestion of contaminated food or water The number 2. Following ingestion, excystation occurs in the small intestine, and the trophozoites colonize the large intestine The number 3. The trophozoites reside in the lumen of the large intestine of humans and animals, where they replicate by binary fission, during which conjugation may occur The number 4. Trophozoites undergo encystation to produce infective cysts The number 5. Some trophozoites invade the wall of the colon and multiply. Some return to the lumen and disintegrate. Mature cysts are passed with feces. The number 1
Geographic Distribution
Worldwide. Because pigs are an animal reservoir, human infections occur more frequently in areas where pigs are raised. Other potential animal reservoirs include rodents and nonhuman primates.
Clinical Presentation
Most cases are asymptomatic. Clinical manifestations, when present, include persistent diarrhea, occasionally dysentery, abdominal pain, and weight loss. Symptoms can be severe in debilitated persons.
Causal AgentsBalantidium coli, a large ciliated protozoan parasite.Cysts are the parasite stage responsible for transmission of balantidiasis The number 1. The host most often acquires the cyst through ingestion of contaminated food or water The number 2. Following ingestion, excystation occurs in the small intestine, and the trophozoites colonize the large intestine The number 3. The trophozoites reside in the lumen of the large intestine of humans and animals, where they replicate by binary fission, during which conjugation may occur The number 4. Trophozoites undergo encystation to produce infective cysts The number 5. Some trophozoites invade the wall of the colon and multiply. Some return to the lumen and disintegrate. Mature cysts are passed with feces. The number 1Geographic DistributionWorldwide. Because pigs are an animal reservoir, human infections occur more frequently in areas where pigs are raised. Other potential animal reservoirs include rodents and nonhuman primates.Clinical PresentationMost cases are asymptomatic. Clinical manifestations, when present, include persistent diarrhea, occasionally dysentery, abdominal pain, and weight loss. Symptoms can be severe in debilitated persons.
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