Protozoa Flashcards
What are the four organisms that cause malaria?
1) Plasmodium falciparum- causes severe malaria
2) Plasmodium vivvax
3) Plasmodium ovale
4) Plasmodium malariae
What is important to know about Plasmodium falciparum?
1) It causes the most severe malaria with symptoms of renal failure, cerebral symptoms, pulmonary edema, and severe anemia
2) Greater virulence
Why does Plasmodium falciparum cause a more severe pneumonia? (4 total)
1) It can infect rbcs of any age
2) Produces PfEMP1 protein that binds to rbc ligands (CD 36, ICAM-1)
3) Stimulates the production of cytokines, NO, and expression of PfEMP1 receptors
4) Antigenic variation of PfEMP1
How does Plasmodium vivax enter rbcs?
Duffy blood antigen
What are some presenting symptoms of a pt. with malaria due to P. falciparum?
1) Splenomegally (eventually leading to fibrosis)
2) Liver enlargement
3) Presence of parasite within macrophages in various tissue (bone marrow, liver, spleen)
4) Malignant cerebral malaria
5) Fever (due to increase in cytokines)
6) Hypoxic lesions in heart and other areas (NO production and adherence of rbcs to vessel wall)
What organism has the diagnostic Maltese cross appearance within rbcs?
Babesia
What are causes of Host Resistance to Plasmodium?
1) Inherited alterations (HbS, HbC, absence of duffy antigen)
2) Increased immune response over prolonged exposure
Protozoan that causes vaginitis; causes amine odor “fishy smell”
Trichomonas vaginalis
Treatment for Trichomonas
Metronidazole
Describe the life cycle of Plasmodium
1) sporozite is transferred from female mosquito to human host
2) sporozite is carried to the live and infects hepatocyte
3) in hepatocyte sporozite divides into a merozite
4) liver cell bursts releasing merozites
5) merozites invade rbcs
6) merozites in the rbcs develop into throphozite
7) throphozite divides into many merozites
8) merozites burst from rbcs
When do fevers, chills, and anemia manifest in the life cycle of plasmodium?
When merozites burst from rbcs
What is the most severe species of plasmodium?
P. Falciparum
What is a major complication of P. falciparum?
1) P. Falciparum causes knobs on rbcs which results in them sticking to venule/capillary walls
2) May result in occlusion or hemorrhage in the vascular urge of the brain, kidneys and lungs
What is the treatment for malaria (plasmodium infx.)?
Chloroquine
Non-flagellated Protozoa within macrophages; flagellated outside of macrophages
Leishmania donovani
Protozoan transferred by sand fly; once engulfed by macrophage it divides and destroys the cell; eventually leads to damage of liver, spleen, and bone marrow; also weakens immune system; causes hyperpigmented skin lesions and massive hepatosplenomegally
Leishmania donovani
Cause of watery diarrhea; fecal oral transmission of oocysts release; found in immunocompromised
Cryptosporidium parvum
What is the life cycle of Cryptosporidium?
1) Ingestion of oocyst
2) Oocyst release sporozoites
3) Sporozoites differentiate trophozoites and attach to the intestinal microvilli
Bloody diarrhea by protozoan
Entamoeba histolytica
Steatorrhea by protozoan
Giardia lamblia
Wattery diarrhea by protozoan
Cryptosporidium parvum
Treatment for Giardia lamblia
Metronidazole
Trophozoite that attaches to duodenal wall via suction disks (no invasion); presence of csyts or trophozoites in stool
Giardia lamblia
Protozoan that ingests RBCs; fecal oral tranmission; bloody diarrhea
Entamoeba histolytica
Flagellated protozoan in blood, nonflagellated in cardiac muscle; transferred via bug bite and enters blood via host scratching; transfered via Reduviid bug
Trypanosoma cruzi
What are complications of T. cruzi infection?
1) Congestive heart failure
2) Dilated cardiomyopathy
3) Cardiac arrhythmias
4) Megacolon
5) Dysphagia
What is a positive Romana’s sign? What protozoan causes this?
1) Soft tissue and lymphoid swelling around the eyes
2) T. cruzi
Causes of Sleeping sickness? What is the cause?
1) Trypanosoma Brucei
2) Changes surface coat antigenic variation to evade immune response and infect the CNS
Cause of West African Sleeping Sickness? East African Sleeping Sickness?
1) West = T. b. gambiense
2) East = T. b. rhodesiense
Crescent shaped trophozoite within macrophages; generally infection is associated with immunocompromised pt.; acquired by ingestion of under cooked meat or cat feces
Toxoplasma gondii
What protozoan is ingested as a cyst and in the intestines becomes its invasive form; penetrates intestinal wall and is phagocytized and spreads throughout the body; results in the formation of cyts
Toxoplasma gondii
What happens to an asymptomatic cyst formed by Toxoplasma gondii when pt. becomes immunocompromised?
1) Cysts rupture and release invasive form
2) Results in encephalitis, chorioretinitis
3) If in pregnancy can causes congenital toxoplasmosis
Most common cause of encephalitis in HIV pt?
Toxoplasma gondii
HIV pt alarmed by persistent watery diarrhea. Pt. visited a farm before diarrhea started. Positive acid fast stain for oocysts.
Cryptosporidium parvum
Baby with hydrocephalus, intracranial clacifications, and chorioretinitis. What should you think?
Toxoplasmosis infection
Treatment for Toxoplasmosis
Pyrimethamine and Sulfadizaine
HIV pt. with ring enhancing lesions on MRI for head
Toxoplasmosis
Pt. just got back from Africa and has had fever, chills, and sweating that occur every 48 hours
P. vivax or ovale
Plasmodium that establish a latent hepatic infection in the form of hypnozoites
P. vivax or ovale
Flask shaped ulcer
Entamoeba histolytica
What is the classic triad for toxoplasmosis
1) Chorioretinitis
2) Hydrocephalus
3) Intracranial calcifications
Rapidly fatal meningoencephalitits
Naegleria fowleria
Enlarged lymph nodes, recurring fever, somnolence, and coma
African Sleeping sickness
What plasmodium has a 72hr cycle?
Plasmodium malariae
Treatment for malaria
1) Chlorquine -blocks heme polymerase
When do you use primaquine for malaria treatment? Quinidine?
1) Primaquine for hypnozoites of vivax/ovale
2) Quinidine for life threatening
Fever, hemolytic anemia; presence of a Maltese cross; common in Northeastern US
Babesia
