Comprehensive Microorganisms and Parasites: Fungi, Protists, Helminths, and Diseases

Fungi

Eukaryotic, cell walls made of chitin, non-photosynthetic, decomposers (saprophytic), reproduce sexually or asexually via spores. Can be unicellular (yeasts) or multicellular (molds).

Examples of Fungi

Candida albicans (yeast infections), Aspergillus (respiratory infections)

Algae

Eukaryotic, photosynthetic, contain chlorophyll, mostly aquatic, produce oxygen, rarely pathogenic (except through toxins).

Examples of Algae

Spirogyra, Diatoms, Dinoflagellates (red tides)

Protists (Protozoa)

Unicellular, eukaryotic, lack cell wall, heterotrophic, motile (via flagella, cilia, or pseudopodia), some form cysts.

Examples of Protists

Amoeba proteus, Paramecium, Plasmodium

Helminths (Parasitic Worms)

Multicellular eukaryotic animals, have organ systems, complex life cycles (egg → larva → adult), often require hosts.

Examples of Helminths

Ascaris lumbricoides, Schistosoma mansoni

Sarcodina / Amoeboids

Protozoans classified by pseudopodia (false feet) movement.

Examples of Sarcodina

Entamoeba histolytica (amoebic dysentery), Naegleria fowleri (brain infection)

Mastigophora / Flagellates

Protozoans classified by flagella movement.

Examples of Mastigophora

Giardia lamblia (giardiasis), Trypanosoma brucei (African sleeping sickness)

Ciliophora / Ciliates

Protozoans classified by cilia movement.

Examples of Ciliophora

Balantidium coli (balantidiasis), Paramecium (non-pathogenic)

Apicomplexa

Protozoans that are nonmotile (sporozoans).

Examples of Apicomplexa

Plasmodium spp. (malaria), Toxoplasma gondii (toxoplasmosis), Cryptosporidium

Nematodes (Roundworms)

Cylindrical, complete digestive system, separate sexes.

Examples of Nematodes

Ascaris lumbricoides, Enterobius vermicularis (pinworm), Trichinella spiralis

Platyhelminths (Flatworms)

Flattened, no complete digestive system.

Cestodes (Tapeworms)

Long, segmented, absorb nutrients through skin, have scolex (head) and proglottids.

Examples of Cestodes

Taenia saginata (beef tapeworm), Taenia solium (pork tapeworm)

Trematodes (Flukes)

Leaf-shaped, have suckers, hermaphroditic, complex life cycles with snail hosts.

Examples of Trematodes

Schistosoma mansoni

Amoebic dysentery

Disease caused by Entamoeba histolytica, characterized by bloody diarrhea.

Giardiasis

Disease caused by Giardia lamblia, characterized by greasy stools.

Malaria

Disease caused by Plasmodium vivax / P. falciparum, transmitted by Anopheles mosquito.

Trichinosis

Disease caused by Trichinella spiralis, associated with undercooked pork.

Cryptosporidiosis

Disease caused by Cryptosporidium parvum, characterized by diarrhea from contaminated water.

Toxoplasmosis

Disease caused by Toxoplasma gondii, associated with cat feces or undercooked meat.

Schistosomiasis

Disease caused by Schistosoma mansoni, leading to liver damage and blood fluke.

Trichomoniasis

Disease caused by Trichomonas vaginalis, characterized as an STD (urogenital infection).

Trophozoite

Active, feeding, motile stage of a protozoan

Cyst

Dormant, protective stage allowing survival in harsh conditions

Definitive host

Host where the parasite reaches maturity and reproduces sexually

Intermediate host

Host where the parasite undergoes development but not sexual reproduction

Scolex

Head of a tapeworm, used for attachment

Proglottids

Body segments of tapeworms containing reproductive organs

Vector

Organism that transmits pathogens between hosts

Flagella

Whip-like tails for movement

Cilia

Short hair-like structures for movement

Pseudopodia

Extensions of cytoplasm used for movement and feeding

Mechanical vector

Physically carries pathogen without infection inside the vector

Biological vector

Pathogen develops or multiplies inside the vector before transmission

Systemic infection

Affects internal organs or bloodstream

Superficial infection

Limited to skin, hair, or nails

Infection

Invasion by microorganisms (bacteria, fungi, protozoa) inside the body

Infestation

Presence of larger parasites (worms, lice, mites) living on or in host

Ectoparasites

Live on body surface

Endoparasites

Live inside the host body

Pinworm infection

Infection caused by Enterobius vermicularis