Chapter 23

What diseases are caused by amoeboid (pseudopodia) protozoa?

• Amebiasis

• Brain infection

What diseases are caused by ciliated (cilia) protozoa?

• Balantidiosis

What diseases are caused by flagellated (flagella) protozoa?

• Giardiasis

• Trichomoniasis

• Trypanosomiasis

• Leishmaniasis

What diseases are caused by apicomplexan (non-moving) protozoa?

• Malaria

• Toxoplasmosis

• Cryptosporidiosis

• Isosporosis

• Cyclosporiasis

What is a trophozoite?

• Vegetative, asexual cell division form of protozoan

• Occurs in moist environment + plentiful nutrients

What is a cyst?

• Dormant, resistant, infectious form of protozoan

• Occurs in dry environment + lacking nutrients

What is Naegleria fowleri?

• Common free-living protozoan that causes fatal infection of brain

• Found in warm bodies of freshwater

• Enters through nasal passages

What is Acanthamoeba spp.?

• Common free-living protozoan that causes fatal infection of brain

• Found in warm bodies of freshwater

• Enters through broken skin

What is Entamoeba histolytica?

• Pathogenic amoeba that disrupts gastrointestinal tract

• Found in untreated sewage for crop fertilization

• Enters through cyst ingestion

What is Giardia intestinalis?

• Pathogenic, flagellated protozoan that damages epithelial cells of intestines

• Found in feces of

  • Beavers, cattle, coyotes, cats, humans

• Enters through cyst ingestion

What is Balantidium coli?

• Pathogenic, ciliated protozoan that erodes intestinal mucosa

• Found in feces of

  • Pigs, sheep, cattle, horses, primates

• Enters through cyst ingestion

What is Trypanosoma brucei?

• Pathogenic, flagellated protozoan that causes African sleeping sickness + affects the central nervous system

• Found in salivary glands of tsetse flies in Africa

• Enters through bite

What is Trypanosoma cruzi?

• Pathogenic, flagellated protozoan that causes Chagas disease + targets heart muscle/large intestine

• Found in feces of reduviid bugs (kissing bugs) in Latin America

• Enters through bite near eyes/mouth + defecates

What is Plasmodium spp.?

• Pathogenic, apicomplexan protozoan that causes malaria

• Found in female Anopheles mosquito

• Enters through bite + injected sporozoites

What is schizogony?

• Process of multiple fission where

  • Nucleus divides several times

  • Cytoplasm subdivides for each new nucleus

What are merozoites?

Motile, infective stage of apicomplexan parasite that comes from liver/red blood cell undergoing multiple fission

What are sporozoites?

• Minute elongated bodies generated by oocyst multiple division

• Infectious form of malarial parasite harbored in salivary gland of mosquito + inoculated during feeding

What are ring trophozoites?

Converted merozoites + red blood cells that grow + undergo multiple divisions to produce a schizont

What are macro/microgametocytes?

• Specialized gametes differentiated from merozoites

  • Macrogametes (female)

  • Microgametes (male)

What can be done to treat malaria?

• Using bed nets treated with insecticides, screens, repellents

• Remaining indoors at night

• Using quinine drugs

• Artemisinin-based combination therapy (ACT)

What is metronidazole?

• Drug used to treat against amebiasis

• Targets anaerobic protozoa

What is an axostyle?

• Sheet of microtubules involved in movement/support

• Found in trichomonads (mastigophorans)

What is a scolex?

Anterior end of tapeworm characterized by hooks and/or suckers for attachment to host

What is a proglottid?

Egg-generating segment of tapeworm that contains male + female organs

What is a strobila?

Long ribbon found in tapeworm composed of individual body segments (proglottids)

What is an intermediate host?

Organism where larval development of parasite occurs

What is a definitive host (final host)?

Organism where parasite develops into adult/sexually mature stage

What are nematodes (roundworms)?

• Free-living soil + freshwater helminths

• Around 200 parasitic

  • 50 to humans

• “Headless”

What are trematodes (flukes)?

• Parasitic helminths containing mouth at anterior end

• Has systems for

  • Digestion

  • Excrement

  • Neuromuscular

  • Reproduction

What are cestodes (tapeworms)?

• Parasitic helminths with hooks/suckers to absorb nutrients

• Has no mouth

What diseases can mosquitos transmit?

• Malaria

• West Nile fever

• Zika virus

What diseases can fleas transmit?

• Bubonic plague

What diseases can biting flies transmit?

• African sleeping sickness

What diseases can biting bugs transmit?

• Chagas disease

What diseases can hard ticks transmit?

• Lyme disease

• Rocky Mountain spotted fever

What is cycle A of helminth life cycle?

1. Worm develops in intestine

2. Egg released w/ feces → environment

3. Eggs are ingest by new host + hatch in intestine

Helminths that follow

• Ascaris

• Trichuris

What is cycle B of helminth life cycle?

1. Worms mature in intestine

2. Eggs released w/ feces → environment

3. Larvae hatch + develop in environment

4. Infection through skin penetration by larvae

Helminths that follow

• Hookworms

What is cycle C of helminth life cycle?

1. Adult helminth matures in human intestine

2. Eggs released → environment

3. Eggs eaten by grazing animals (intermediate host)

4. Larval forms encyst in tissue

5. Humans (definitive host) eat animal flesh = infected

Helminths that follow

• Taenia

What is cycle D of helminth life cycle?

1. Eggs are released from human

2. Humans (definitive host) are infected through ingestion/direct penetration by larval phase

Helminths that follow

• Opisthorchis

• Schistosoma

What are filarial nematodes?

• Thin, filamentous nematodes spread by arthropods

• Causes chronic, deforming diseases

What is filariasis?

• Disease spread by mosquitos

• Causes elephantiasis

  • Swelling of scrotum/legs

  • Caused by inflammation + blockage of lymphatic channels

What is schistosomiasis?

• Infection by blood fluke (schistosomes)

• Contracted by contact with contaminated water in rivers + streams

• Symptoms

  • Fever, chills, diarrhea, cough

What is miracidium?

• Ciliated first life-stage larva of trematode (blood fluke)

• Infects corresponding intermediate host snails

What is cercaria?

• Free-swimming larva of trematode (blood fluke)

• Emerges from snail host + penetrates human skin

• Causes schistosomiasis

What diseases/microbes can Anopheles mosquitoes carry?

• Malaria/Apicomplexan protozoan

• Filariasis/Nematode

What diseases/microbes can Culex mosquitoes carry?

• Filariasis/Nematode

• Dengue fever/Arbovirus

• West Nile fever/Arbovirus

What diseases/microbes can Aedes mosquitoes carry?

• Yellow fever/Arbovirus

• Zika virus/Arbovirus