Chapter 48 - Blood and Tissue Protozoa Flashcards
Plasmodium spp.
- what disease are they responsible for?
- what are the 5 species?
Malaria
- P. vivax (80% of infections)
- P. falciparum
- P. malariae
- P. ovale
- P. knowlesi
Plasmodium spp.
- what is the vector?
- female anopheline mosquito
Life Cycle of Plasmodium
- First 2 steps
- how does the illness enter the host?
- what organ is affected?
- Vector bites you, releasing sporozites into the puncture wound.
- Within an hour carried to the liver.
Life Cycle of Plasmodium
- What step is the Preerythrocye?
- describe the steps in this cycle.
Preerythrocye or primary exoerythrocytic cycle
- Divide (Schizogony)
- Schizont—Is a trophozoite with dividing nuclei
- Mature schizont—Contains merozoites that invade RBCs.
- Exoerythrocytic merozoites
- Merozoite—Is the young trophozoite
Life Cycle of Plasmodium: Erythrocytic Cycle
- Describe the two steps to this cycle.
- What part of the Plasmodium life cycle does this make up?
- Merozoites leave the liver and invade RBC and feed on hemoglobin
- mosquito then takes a blood meal of infected RBCs
- Last two steps
Life Cycle of Plasmodium:
- define schizont
- what is a mature schizont?
- what are gametocytes?
- Schizont—Is a trophozoite with dividing nuclei.
- Mature schizont—Contains merozoites that invade RBCs.
- Gametocytes—Includes mature male or female merozoites
Plasmodium vivax
- primary disease?
- where is the most common geographic location(s) for this disease?
- Causes benign tertian malaria.
- Is widely distributed in the tropics, subtropics, and temperate zones.
Plasmodium vivax
- what are the main morphologic characteristics of this disease organism?
- Infection of young cells
- Enlargement of RBCs (one to two times the normal size)
- Schüffner dots
- Delicate ring
- Very amoeboid trophozoites
- Schizont containing 12 to 24 merozoites
Plasmodium vivax
- can a patient relapse?
- what are paroxysms and how often to they occur?
- define hypnozoites.
- Relapses occur.
- Paroxysms are when the clinical signs manifest themselves in a patient.
- Paroxysms may cycle every 48 hours.
- Resting stages are called hypnozoites
Plasmodium vivax
- what triggers the paroxysms?
- Occur when the schizont releases the merozoites
Plasmodium vivax
- how often does the pathogen cycle through?
- what does that correspond with?
- Cycle 44-48 hrs.
- Corresponds with cycles of paroxysms
Plasmodium vivax
- what are the cell stages of the life cycle?
- Early trophozite – ring form
- Schuffner dots-in all except very early.
- Trophozoite ameboid
- Schizont with TWELVE -
TWENTY-FOUR merozoites - Macro and microgametes
Plasmodium ovale
- geographic range?
Geographic range is confined to central West Africa and some South Pacific islands
Plasmodium ovale
- how does this change the morphology of the cells it infects/what does it look like under a microscope?
- Infection of young cells
- Enlargement of RBCs with fimbriated edges (oval)
- Early appearance of Schüffner dots
Smaller ring than P. vivax - Schizont containing EIGHT merozoites
Plasmodium ovale
- relapses?
- paroxysm cycles?
- Relapses are possible but with spontaneous recovery.
- Paroxysms cycle every 48 hours
Plasmodium ovale
- describe the morphology of the infected erythrocytes
- size
- edges
- shape
- 1.25x enlarged
- fimbriated
- oval
Plasmodium ovale
- what do the trophs look like?
- describe the schizonts
- how many merozoites?
- color of pigment?
- pattern of schizonts?
- what shape are the gametocytes?
Trophs: compact
Schizonts:
- 6-14 merozoites
- dark pigment
- rosettes
- gametocytes are round-oval
Plasmodium malariae
- type of malaria caused?
- geographic distribution?
- Causes quartan malaria
- associated with nephrotic syndrome
- Is sporadically distributed
Plasmodium malariae
- infected RBC characteristics?
- Infection of older cells
- Normal-size RBCs
- No stippling
- Thick ring, large nucleus
- TROPHS that form “BANDS” across the cell
- Schizont containing 6 to 12 merozoites
Plasmodium malariae
- relapses?
- define recrudescence
- how frequent are the paroxysm cycles?
- No relapses occur, but recrudescence is recognized.
- a new outbreak after a period of abatement or inactivity
- every 72 hours
Plasmodium falciparum
- type of malaria caused?
- geographic distribution?
- Causes malignant tertian malaria.
- Is confined to tropical areas
Plasmodium falciparum
- characteristics of infected cells?
- Invasion of all stages of RBCs (heavy parasitemia)
- Comma-like red dots (Maurer dots)
- Multiple ring forms, some appliqué forms
- Crescent-shaped gametocytes
Plasmodium falciparum
- how often do fever cycles occur?
- relapses?
- Fever cycles every 36 to 48 hours.
- No relapses occur.
Plasmodium falciparum
- where does schizogony occur?
- what happens to the organs infected?
- Schizogony occurs in spleen, liver, and bone marrow.
- Vessels of organs become plugged, causing fatal complications (e.g., black water fever).
Plasmodium falciparum
- describe the rings in the infected RBCs
- trophs - how often seen in peripheral smears
- rings are double chromatin dots, accole then forms, which allows for multiple infections in the same cell
- trophs are compact and rarely seen in peripheral blood
Plasmodium falciparum
- Gametocytes
- two different forms?
- which is seen in peripheral blood?
- how many merozoites in a schizont?
- how often seen in peripheral blood?
- Gametocytes: mature form and immature form
- immature form rarely seen in peripheral blood
- 8-24 merozoites in a schizont
- rarely seen in peripheral blood
Plasmodium knowlesi
- geographic location?
- what is the best way to detect?
- Is associated with forested areas of Southeast Asia.
- Higher detection rate with PCR
Plasmodium knowlesi
- characteristics?
- what do the early stages resemble?
- what do the later stages resemble?
- stippling?
- chromatin?
- unique characteristic of the trophs?
- how many merozoites
- Early stages resemble P. falciparum and
- later/mature stages resemble P. malariae
- RBC’s are all sizes, no true stippling
- Multiple rings, with 2 to dots of chromatin
- Band forms with trophozytes
- Schizonts with 16 merozoites
Plasmodium knowlesi
- what is the gold standard for diagnosis?
- what type of specimen is preferred?
- how is it diagnosed in the field?
- Thick and thin blood films
- 200 and 300 oil immersion fields are examined
- Giemsa or Wright stain is acceptable.
- EDTA
- Rapid malaria tests are now available (dipstick, cartridge).
Plasmodium knowlesi
- why is it hard to detect with automated instruments?
- what non-smear test is used?
- Automated instruments are not designed to detect intracellular parasites.
- Polymerase chain reaction (PCR) with specific deoxyribonucleic acid (DNA) probes is used
Plasmodium knowlesi
- treatment
- drugs
- what phase is being treated?
- why is it so hard to treat?
- Schizonticides, gametocytocides, and sporonticides are directed against relapses.
- Chloroquine-resistant P. falciparum is present in most endemic areas.
Babesia spp.
- mode of transmission
- what other protozoa life cycle does it mimic?
- what is the main difference?
- Is transmitted by ticks. Genus Ixodes.
- Has a life cycle similar to Plasmodium
- no exoerythrocytic stage
Babesia spp.
- how do trophs reproduce?
- what makes the ring forms unique?
- what makes the chromatin unique?
- Trophs reproduce by binary fission.
- Ring forms are pleomorphic. Can be outside erythrocytes.
- Maltese cross tetrads may be present
Babesia spp.
- what disease does it mimic?
- how is it diagnosed?
- Similar clinically to malaria
- Diagnosis with thick and thin blood smears
Babesia vs. Plasmodium
- transmission
- hosts
- geographic locations
Babesia
- Is transmitted by ticks. Genus Ixodes.
- Infect wild and domestic animals
- Worldwide, US outbreaks around Cape Cod, LI, east coast Islands
Plasmodium
- Is transmitted by Anopheles mosquito
- Infects humans
- Tropics and subtropics, some temperate
Babesia vs. Plasmodium
- life cycle stages
- troph reproduction
- troph size
Babesia
- Has a lifecycle similar to Plasmodium spp., but no exoerythrocytic stage.
- Trophs reproduce by binary fission.
- Trophozoites are smaller than P. falciparum
Plasmodium
- Has an exo and endoerythrocytic stage.
- Troph reproduce by schizogony
Babesia vs. Plasmodium
- ring forms
- ring form location
- # of species
Babesia
- Ring forms are pleomorphic.
- Can be outside erythrocytes.
- Maltese cross tetrads may be present
- About 100 species
Plasmodium
- Inside the cell.
- Ringforms are uniform.
- 5 species
Babesia vs. Plasmodium
- symptoms
- diagnosis
Babesia & Plasmodium (same for both)
- Fever, chills, malaise, anemia, hepatosplenomegaly.
- Diagnosis with thick and thin blood smears
Trypanosoma spp.
- what type of protozoa are they?
- what is the common name for the diseases it causes?
- how many types/what names are the subgroups of the diseases?
Hemoflagellate protozoa
Trypanosomiasis
- African sleeping sickness
- East African
- West African
- Chagas’ disease
- American
- Trypanosoma cruzi
Trypanosoma spp.
- what are the three main features in an amastigote?
- nucmeus
- basal body
- kinetoplast
Trypanosoma spp.
- what are the two additional features that a mature trypomastigote possesses?
- an undulating membrane
- a flagellum
African sickness - East vs West:
- organism
- vector
- reservoir
East
- Trypanosoma brucei rhodesiense
- tsetse fly (morsitans)
- animals
West
- Trypanosoma brucei gambiense
- tsetse fly (palpalis)
- humans
African sickness - East vs West:
- illness time frame
- lymphadenopathy
East
- acute w/early CNS invasion, less than 9 months
- minimal
West
- chronic w/late CNS invasion, months to years
- prominent
African sickness - East vs West:
- parasitemia
- epidemiology
East
- high
- anthropozoonosis, game park
West
- low
- anthropozoonosis, rural populations
African sickness - East vs West:
- diagnostic stage
- recommended specimens
East and West (same for both)
- Trypomastigote
- chancre aspirate, lymph node aspirate, blood, CSF
African Trypanosomiasis
- what is a unique feature that makes this challenging to treat?
- Unique feature is that they can change the antigenic surface coat of the outer membrane.
American Trypanosomiasis (Chagas’ Disease): T. cruzi vs T. rangell
- vector
- reservoir
T. cruzi
- reduviid bug
- opossums, dogs, cats, wild rodents
T. rangell
- reduviid bug
- wild rodents
American Trypanosomiasis (Chagas’ Disease): T. cruzi vs T. rangell
- symptomatic?
- recommended specimens?
T. cruzi
- symptomatic, can be acute or chronic
- blood, lymph node, aspirate, chagoma
T. rangell
- asymptomatic
- blood
American Trypanosomiasis (Chagas’ Disease): T. cruzi vs T. rangell - diagnostic stage
T. cruzi
- blood:
- Trypomastigote
- tissue:
- amastigote
T. rangell
- blood:
- Trypomastigote
- tissue:
- none
Trypanosomiasis
- what are the three stages?
- Amastigotes
- Trypomastigotes
- Epimastigotes
Leishmania spp.
- Disease spectrum:
- Cutaneous lesions (flattened plaque or ulcer)
- Mucocutaneous infections
- Visceral involvement
Leishmania spp.
Two phases:
- Amastigote—Intracellular parasite in humans
- Promastigote—Form found in vector
Leishmania spp.
- what are some common hospital and in-the-field diagnostic tests?
- Exudate from the lesion is smeared and stained.
- A rapid dipstick test is also available for the detection of anti-Leishmania antibodies.
