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Other Pathogens: Fungi, Protozoans, Parasitic Worms, and Prions

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Other Pathogens

Overview

In addition to bacteria and viruses, several other types of pathogens can cause infectious diseases in humans. These include fungi, protozoans, parasitic worms, and prions. Understanding these pathogens is important for protecting against infectious diseases and maintaining personal health.

Types of Pathogens

Pathogen

Infectious Diseases

Transmission

Treatment

Fungi

  • Candidiasis: Caused by growth of Candida albicans (yeast), affecting mouth, vagina, skin.

  • Ringworm: Skin infection.

  • Athlete's foot: Skin infection.

  • Skin-to-skin contact

  • Contact with contaminated surfaces

Antifungal medicines

Protozoans

  • Malaria: Causes fever, sweats, chills.

  • Giardiasis: Abdominal pain, diarrhea.

  • Contaminated water

  • Insect bites (e.g., mosquitoes)

Antiprotozoal medicines

Parasitic Worms

  • Hookworm infection: Anemia, abdominal pain.

  • Tapeworm infection: Digestive symptoms.

  • Contaminated food

  • Contaminated soil

Antiparasitic medicines

Prions

  • Creutzfeldt-Jakob disease: Neurodegenerative disease (rare).

  • Mad cow disease: Affects cattle, can be transmitted to humans.

  • Contaminated food (especially nervous tissue)

No cure

Key Terms and Definitions

  • Pathogen: Any organism or agent that causes disease.

  • Fungi: Eukaryotic organisms, including yeasts and molds, that can infect skin, nails, and mucous membranes.

  • Protozoans: Single-celled eukaryotes, often transmitted by water or insects.

  • Parasitic Worms: Multicellular organisms (helminths) that live in the host's body, often in the intestines.

  • Prions: Infectious proteins that cause neurodegenerative diseases.

Examples and Applications

  • Malaria is caused by protozoans of the genus Plasmodium, transmitted by mosquito bites. Symptoms include fever, chills, and anemia.

  • Ringworm is a fungal infection of the skin, often appearing as a circular rash.

  • Hookworm infection occurs when larvae in contaminated soil penetrate the skin, leading to anemia and digestive symptoms.

  • Creutzfeldt-Jakob disease is a rare, fatal brain disorder caused by prions.

Matching Pathogens to Diseases (Practice)

  • Parasitic worms: Hookworm infection

  • Protozoans: Malaria

  • Prions: Mad cow disease

  • Fungi: Ringworm infection

Sample Question

Case Study: Camila has just returned from a trip to Southeast Asia. A week later she is experiencing fever, severe headache, and abdominal pain. Lab analysis shows single-celled organisms inside erythrocytes (red blood cells). Which type of pathogen is most likely responsible for these symptoms?

  • Correct answer: Protozoans

Prevention and Treatment

  • Practice good hygiene and avoid contact with contaminated surfaces to prevent fungal infections.

  • Use insect repellent and mosquito nets to prevent protozoan diseases like malaria.

  • Cook food thoroughly and avoid contact with contaminated soil to prevent parasitic worm infections.

  • There is currently no cure for prion diseases; prevention is key.

*Additional info: Prion diseases are extremely rare but always fatal. Antifungal, antiprotozoal, and antiparasitic medications are available for most other pathogen types. Proper sanitation and food safety are important preventive measures.*

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