Protozoan Flashcards
Unicellular eukaryote with the ability to form cyst
Protozoa
Protozoal stage that is dormant and highly resistant to environmental stress. Typically causes disease in the mode of infection.
Cyst stage
Protozoal stage that is active, reproductive, and feeding. It is the form that typically causes disease in humans.
Trophozoite stage
Protozoan most commonly transmitted by the ingestion of amebic cysts from fecally contaminated food or water.
Amebiasis (Entamoeba histolytica)
How do most infections of Entamoeba histolytica present?
Asymptomatically
Where does Entamoeba histolytica usually spread in the body and cause destruction?
Gastrointestinal System
Entamoeba histolytica has a 2 - 4 week incubation period in the gastrointestinal system, after that it causes what symptoms?
Bloody diarrhea
Abdominal Pain
Colitis
Fever
What might Intestinal Amebiasis progress to?
Necrotizing Colitis
- mucosal sloughing
- severe hemorrhage
Amebiasis can become severe and spread outside of the intestines. Where is it most likely to spread to?
Liver
Once Entamoeba histolytica spreads to the liver, what may develop?
Amebic Liver Abscess
- fever
- RUQ pain
- hepatomegaly
- high fever
(more commonly only one abscess)
What is the preferred diagnostic method for Intestinal amebiasis?
Stool PCR
How is Entamoeba liver abscess typically identified?
Ultrasound
CT
MRI
What is the treatment for Entamoeba histolytica?
Metronidazole or Tinidazole + Luminal agent
A needle aspiration of a large hepatic abscess caused by Entamoeba histolytica is required when the abscess reaches what size?
Over 5 - 10cm
Free living ameba with a flagellate form that is thermophilic and found in: soil, fresh and polluted warm lake water, domestic water supplies, swimming pools, thermal water, and sewers.
Naegleria fowleri
Aspiration of contaminated water or soil containing Naegleria flowleri causes what?
Primary Amebic Meningoencephalitis (PAM)
- Rapidly fatal
What is the most common protozoan parasite infection in the United States?
Giardia Lamblia
What age group is most commonly infected with Giardia Lamblia?
Young Children
How is Giardia Lamblia most commonly transmitted?
Contaminated water from remote streams, surface wells, or lakes.
(Backpacker’s Diarrhea)
What percentage of people develop symptoms when infected with Giardia Lamblia?
25 - 50%
What are the symptoms of Giardia Lamblia infection?
Profuse Watery Diarrhea
Greasy, Frothy, Foul Smelling Stools (Steatorrhea)
- can last days or weeks
What is the preferred diagnostic method for Giardia Lamblia?
PCR Stool Assay
What is the drug of choice for Giardia Lamblia?
Metronidazole or Tinidazole
Paramomycin (pregnancy)
An infection caused by the Plasmodium species.
Malaria
What single cell parasite is spread via the mosquito and is responsible for nearly all severe Malaria infections?
Plasmodium falciparum
- via the female Anopheles mosquito
What types of cells does the Plasmodium species infect and destroy?
Red Blood Cells
Liver Cells
Where is Malaria most common in the world?
Tropics
Sub-Saharan Africa
What are the two main phases of the Plasmodium parasite?
Human Phase (asexual)
Mosquito Phase (sexual)
What are the 5 steps of progression of Plasmodium via the Human Phase?
- Mosquito Bite and Sporozoite Injection
- Liver Stage (Exoerythrocytic Cycle)
- Dormant Hypnozoite Stage - Release of Merozoites
- Blood Stage (Erythrocytic Cycle)
- Trophozoite Stage
- Schizont Stage - Gametocyte Formation
Malaria Infected RBC Stages
- Early Trophozoite - ring form
- Late Trophozoite - growing ring form
- Further Trophozoite growth. Digestion of HGB.
- leaves behind Hemozoin (Schizont) - Rupture
What is the hallmark symptom of Malaria?
Cyclical Fever
- P. vivax and P. ovale = 48 hours
- P. malariae = 72 hours
- P. falciparum = variable (malignant tertian fever)
What are the physical findings of uncomplicated Malaria?
Anemia
Jaundice
Hepatomegaly
Splenomegaly
Severe Malaria is primarily caused by what species of Plasmodium?
P. falciparum
How does P. falciparum cause so much destruction inside the body?
Generates a sticky protein that coats the surface of red blood cells
Many of the clinical findings of P. falciparum are a result of the parasitized red blood cells adhering to the endothelial cells lining small blood vessels (cytoadherence) which causes what?
Small Infarcts
Capillary Leakage
Organ Dysfunction
What are two severe complications caused by P. falciparum?
Cerebral Malaria (AMS, Delirium, Seizures, Coma)
Blackwater Fever (severe hemolysis + hemoglobinuria + renal failure)
What is the mainstay of diagnosis for Malaria?
Giemsa-stained blood smears
What is a drawback to using a rapid antigen test for Plasmodium?
False negative for P. falciparum
How is Malaria caused by P. malariae treated?
Chloroquine
How is Malaria caused by P. vivax or P. ovale treated?
Chloroquine + Primaquine
(check for G6PD deficiency first)
How is uncomplicated Malaria by caused P. falciparum treated?
Artemisinin-based combination therapies (ACTs)
How is severe Malaria treated?
Artesunate (IV or IM)
How many vaccines are available for the prevention of Malaria that are approved by the World Health Organization (WHO)
2
Obligate intracellular protozoan found worldwide in humans, mammals, and birds. Cats are the definitive host.
Toxoplasmosis gondii
Toxoplasmosis infection that is usually asymptomatic in immunocompetent patients. May develop a Mono-like illness with fever, and non-tender lymphadenopathy.
Primary Toxoplasmosis
Toxoplasmosis infection that is the result of maternal infection in a non-immune woman during pregnancy.
Congenital Toxoplasmosis
What is the paradox of Congenital Toxoplasmosis?
More likely to be contracted during 3rd Trimester
Decreased severity the later the course of pregnancy
What is the Congenital Triad of Toxoplasmosis?
Chorioretinitis
Hydrocephalus
Intracranial Calcifications
What type of rash is seen with Congenital Toxoplasmosis?
Blue Muffin Rash
- Thrombotic Thrombocytopenia Purpura
An inflammatory condition affecting the retina and the choroid in the eyes. Most common late presentation of congenital toxoplasmosis. Symptoms will typically improve with treatment but visual defects may persist. Rarely, can progress to glaucoma or blindness.
Retinochoroiditis (ocular toxoplasmosis)
What is the most common problem seen in Toxoplasmosis in AIDS patients?
Encephalitis with Multiple Necrotizing Brain Lesions
Diagnostic test that is typically used for Toxoplasmosis?
Serologic testing for IgM or IgG
What drugs are used to treat Toxoplasmosis?
Pyrimethamine + Sulfadiazine and Folinic Acid
What drug is used to treat Toxoplasmosis in a pregnant patient during the first trimester?
Spiramycin
One of the most commonly sexually transmitted diseases. Caused by a protozoa and many patients are asymptomatic.
Trichomonas vaginalis
What are the symptoms of Trichomonas in a male?
Non-gonococcal Urethritis
Minimal Discharge
What are the symptoms of Trichomonas in a female?
Vaginitis with Copious Frothy and Foul Discharge
- itching
- dysuria
- dyspareunia
- abdominal pain
How can you diagnose Trichomonas?
Wet Mount (motile organism)
Antigen and Nucleic Acid Amplification Assay
What are the treatments for Trichomonas
Metronidazole
Tinidazole
