Cryptosporidium cannot be killed by routine boiling. Another parasite resistant to such boiling is __________.


a. Giardia
b. Trypanosoma
c. Toxoplasma
d. Plasmodium

Verified step by step guidance

1. Understand the context: The question asks about parasites that are resistant to routine boiling, similar to Cryptosporidium, which is known for its hardy oocysts that survive standard boiling times.
2. Recall characteristics of each parasite: Giardia is a protozoan parasite causing giardiasis, but its cysts are generally killed by boiling. Trypanosoma causes diseases like sleeping sickness and is transmitted by insect vectors, not typically resistant to boiling in water. Toxoplasma gondii forms tissue cysts that are resistant to some environmental conditions but are usually killed by proper cooking or boiling. Plasmodium causes malaria and is transmitted by mosquitoes, not typically associated with resistance to boiling.
3. Focus on the parasite known for forming environmentally resistant cysts or oocysts similar to Cryptosporidium, which can survive routine boiling.
4. Identify Giardia as the parasite that forms cysts resistant to some environmental stresses, including routine boiling, making it the correct answer.
5. Summarize: The parasite resistant to routine boiling, like Cryptosporidium, is Giardia.

Key Concepts

Heat Resistance of Parasite Cysts and Oocysts

Some parasites produce cysts or oocysts that are highly resistant to environmental stresses, including routine boiling. These structures protect the parasite's infectious form, allowing survival in harsh conditions and complicating water treatment and food safety.

Cryptosporidium and Giardia as Waterborne Parasites

Cryptosporidium and Giardia are common waterborne parasites that cause gastrointestinal illness. Both produce resistant forms (oocysts for Cryptosporidium and cysts for Giardia) that can survive standard boiling, making them significant public health concerns in contaminated water.

Differences Among Parasite Types and Their Resistance

Parasites like Trypanosoma, Toxoplasma, and Plasmodium differ in life cycle and transmission; they generally do not form heat-resistant cysts or oocysts. Understanding these differences helps identify which parasites can survive routine boiling and pose risks in waterborne transmission.