Protozoa

Classification of Protozoa

• based on 18s rRNA sequences

• 6 groups

  • parabasala

  • diplomonadida

  • euglenoza

  • alveolates

  • rhizaria

  • amoebozoa

Parabasala

• contain Golgi body

• lack mitochondria

• single nucleus

• ex:

  • trichonympha

  • trichomonas

Trichomonas Vaginalis

• parabasala

• sexually transmitted

• in GI system of men and women

• men asymptomatic

• women: abdominal and vaginosis pain, odorous discharge

• treatment: -zole drugs

• prevent: abstinence

Diplomonadida

• lack mitochondria

• 2 nuclei

• multiple flagella

• ex:

  • Giardia

Giardia Intestinalis

• Diplomonadida

• most common GI disease in US

• found in GI of animals and environment

• from asymptomatic to severe GI disease

• ingest cyst from contaminated water

• prevent: filtered water

Euglenozoa

• flagella with crystalline rod

• mitochondria w/ disk-shaped cristae

• ex:

  • euglenids

  • kinetoplastids

Euglenids

• euglenozoa

• photoautotrophic

• unicellular

• plants

Kinetoplastids

• kinetoplast: region of mitochondrial DNS

• pathogenic kinetoplastids:

  • trypanosoma

  • leishmania

Trypanosoma Cruzi

• cause Chagas’ disease

• central and south america

• reservoirs: opossums, armadillos

• transmitted via bug bite

• “kissing bug”

  • feed on lip blood vessel

• can symptomatic for years

• parasite-induces heart disease

Alveolates

• alveoli

• ex:

  • ciliates

  • apicomplexans

  • dinoflagellates

Ciliates

• alveolates

• use cilia for mvmt

• two nuclei

• chemoheterotrophs

• balatidium (only ciliate pathogenic to humans)

Apicomplexans

• alveolates

• chemoheterotroph

• complex organelles

• penetrate host cells

• plasmodium, cryptosporidium, toxoplasma → cause disease

Dinoflagellates

• alveolate

• unicellular

• algae

• freshwater and marine plankton

• two flagella

• bioluminescent

• some produce neurotoxins

Balantidium Coli

• ciliate (only one to cause disease in humans)

• found in animal GI tract

• food or water contaminated by feces w/ cysts

• asymptomatic in healthy adults

• bad for immunocompromised

  • pain, diarrhea → intestinal mucosa ulcer

• treatment: antibacterial

Plasmodium

• apicomplexan

• causes malaria

• 4-5 known species

• genetic traits incr. malaria resistance

• symptoms: (erythrocyte loss) fever, chills, fatigue

• p. falciparum: blackwater fever

• preventative medication

• use two drugs simultaneously

Toxoplasma

• apicomplexans

• most are asymptomatic

• fever, self-limiting

• caution w/ AIDs, pregnancy/fetuses

• prevent:uncooked meats, avoid cat litter if pregnant

Rhizaria

• amoebae

• threadlike pseudopods

• ex:

  • foraminifera

  • radiolaria

Foraminifera

• rhizaria, amoebae

• live on ocean floor

• most are fossil species

Radiolaria

• rhizaria, amoebae

• ornate shells of silica

• a part of marine plankton

Amoebozoa

• amoebae

• lobe-shaped pseudopods, no shells

• slime mold (plasmodial, cellular slime molds)

• some human pathogens:

  • nargleria

  • acanthamoeba

  • entamoeba

Acanthamoeba and Naegleria

• amoebozoa

• do not form aggregates

• rare and fatal brain infection

  • 97% fatality rate

  • death 1-18 days post infection

• inhabit natural/artificial water systems

• avoid washing contact lenses

• brain infection often diagnosed too late

• prevent: difficult, clean swimming pools

Acanthamoeba

• amoebozoa

• enter via cuts, inhalation

• amebic encephalitis: most common disease

  • symptoms: headache, neurological defects, death

Naegleria

• amoebozoa

• swimmers inhale contaminated water

• amebic meningoencephalitis

  • symptoms: hemorrhage, coma, death

Entamoeba

• amoebozoa

• asymptomatic in digestive tracts

• do not form aggregates

• no animal reservoir exists

• infection from contaminated water

• encystment occurs in small intestine

• causes amebiasis

  • luminal amebiasis

  • invasive amebic dysentery

  • invasive extra intestinal amebiasis

• treat: oral rehydration

• prevent: clean water

Luminal Amebiasis

• entamoeba

• asymptomatic in healthy individuals

Invasive Amebic Dysentery

• entamoeba

• severe diarrhea, appendicitis, intestine ulcer

• can be fatal

Invasive Extraintestinal Amebiasis

• entamoeba

• trophozoites in blood

• can be fatal