Protozoa

The Protozoa section provides High Yield Information needed for USMLE, COMLEX, Medical School, Residency, and as a practicing Physician.

Table Of Contents
1 Babesia
2 Cryptosporidium
3 Entamoeba Histolytica
4 Giardia Lamblia
5 Leishmaniasis
6 Naegleria Fowleri
7 Plasmodium species
8 Toxoplasma Gondii
9 Trichomonas Vaginalis
10 Trypanosoma Brucei
11 Trypanosoma cruzi

Babesia

  • Features:
    • Protozoa of blood
  • Causes:
    • – Babesiosis
    • – Severe cases: malarial symptoms and death
    • – Babesiosis causes blood related symptoms:
      • – Hemolytic anemia
      • – Hemoglobinuria
      • – All resulting to jaundice
  • Transmission:
    • – Ixodes tick
  • Clinical presentation:
    • – Hemolytic anemia–> jaundice
    • – fever and sweating: irregular cycling fevers
  • At risk:
    • sickle cell disease
  • Diagnosis:
    • – Blood smear: thick
  • Treatment:
    • – Atovaquone
    • – Macrolide: Azithromycin

 

Cryptosporidium

Entamoeba Histolytica

  • Features:
    • Protozoa of intestinal tract
  • Causes:
    • Amoebiasis
  • Classic presentation:
    • bloody diarrhea
  • Transmission:
    • – ingested cyst from contaminated water, men having sex with men
  • Clinical presentation:
    • – Right lobe of liver most affected with amoebic liver abscess
    • – Anchovy paste pus
    • – Right upper quadrant pain
    • – Enlarged and tender liver
    • – Intestinal amoebiasis
    • ulceration along colon
    • flask shaped ulcers
    • invasive–> dysentery
  • Diagnosis:
    • stool ova and parasite test
    • ELIZA
    • colonoscopy and sigmoidoscopy
  • Treatment:
    • – DOC: Metronidazole

Giardia Lamblia

  • Features:
    • Protozoa of intestinal tract
    • Associated with campers and hikers
  • Transmission:
    • endemic area of giardia and drink unfiltered water
  • Clinical manifestation:
    • – Bloating
    • – Flatulence
    • – Foul smelling diarrhea
    • – Steatorrhea
    • – Weight loss
    • – Malabsorption
    • – Trophozoite attach but doesn’t invade intestinal wall
  • Diagnostic:
    • – Trophozoite in stool
    • – ELIZA stool antigen test
  • Treatment:
    • Metronidazole

Leishmaniasis

  • Features:
    • Protozoa of the blood
  • 2 species:
    • L braziliensis:
      • cutaneous or mucocutaneous leishmaniasis
      • – Host: vertebrates/humans
      • – Vector: sandfly
      • – Causes: cutaneous leishmaniasis: disfiguring ulcers
    • L donovani:
      • – Endemic in Mediterranean, Middle East, and Africa
      • – Causes: Visceral leishmaniasis: Black fever/kala-azar pigmentation- 100% fatal if left untreated
  • Treatment:
    • – Stibugluconate: Cutaneous leishmaniasis/L braziliensis
    • – Amphotericin B: Visceral leishmaniasis/L donovani

Naegleria Fowleri

  • Features:
    • Protozoa of CNS
    • Amoeba
    • Associated with freshwater
    • High mortality rate
    • Enters through cribiform plate
  • Clinical presentation:
    • – Primary amoebic meningoencephalitis: nuchal rigidity, fever, altered mental status rapidly fatal disease with poor prognosis
    • – Associated with water sports
  • Diagnosis:
    • Lumbar puncture
  • Treatment:
    • – Amphotericin B

Plasmodium species

  • Features:
    • Protozoa of the blood
    • 4 species:
      • – P. malariae: quartan fever cycle 72 hours
      • – P. vivax: tertian fever cycle 48 hours. treated with P ovale, produces dormant hypnozoites in liver
      • – P ovale: tertian fever cycle 48 hours. P vivax and P ovale treated as one, produces dormant hypnozoites in liver
      • – P falciparum: Irregular fever pattern. most severe malarial illness. Neurologic symptoms: cerebral malaria
    • Sickle cell disease: protective against P falciparum
    • Endemic in Africa
  • Transmission:
    • anopheles mosquito
  • Classical presentation:
    • Fever and headache, anemia and splenomegaly
  • Diagnosis:
    • Blood smear: Giemsa stain
  • Treatment:
    • – Mefloquine: strongest drug, less likely to produce resistance. Used for prophylaxis for travelers
    • – Chloroquine: not widely used due to malarial resistance
    • – Primaquine: check G6PD deficiency before administering
    • – Artemisins and atovaquone proguanil: treatment for severe cases of malaria by P falciparum

Toxoplasma Gondii

  • Features:
    • Protozoa of CNS
    • Intracellular parasitic protozoa that infect warm blooded animals
  • Populations at risk:
    • – Pregnant
    • – Immunocompromised
  • Transmission:
    • – Consumption of raw/undercooked meat containing cyst
    • – Ingestion of water or vegetables contaminated
    • – Transplacental transmission in utero (TORCH)
    • – Immunocompromised
  • Causes:
    • – Flu like symptoms in immunocompetent
    • – Toxoplasma encephalitis- brain abscesses – ring enhancing lesions
    • – Congenital toxoplasmosis: chorioretinitis, hydrocephalus, intracranial calcifications, deafness
  • Diagnosis:
    • Serology and biopsy
  • Treatment:
    • – Sulfadiazine and Pyrimethamine
  • Prophylaxis:
    • for HIV patients <100 CD4 count and IgG positive for toxoplasmosis:
    • – TMP-SMX

Trichomonas Vaginalis

  • Features:
    • Protozoa of female reproductive system
    • STD
  • Causes:
    • vaginitis and cervicitis
  • Clinical presentation:
    • – Burning
    • – Itching
    • – Malodorous yellow-green discharge
    • – Strawberry cervix
    • – Presentation similar to garderella, candida, chlamydia and neisseria
  • Diagnosis:
    • – Wet mount: motile trophozoites
    • -pH > 4.5
  • Treatment:
    • – Treat both partners (pt and male partner)
    • – Metronidazole
  • Differential:
    • – Gardnerella vaginalis:
      • gram variable bacterium associated bacterial vaginosis: clue cells

Trypanosoma Brucei

  • Features:
    • Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense
    • AFRICAN SLEEPING SICKNESS
    • Motile
    • Endemic to western and southeastern Africa
  • Transmission:
    • bite from tsetse fly
  • Clinical Presentation:
    • – Recurrent and undulating fevers
  • Diagnosis:
    • typomastigotes seen on blood smear: test blood, CNS and lymph nodes
  • Treatment:
    • – Melarsoprol for CNS
    • – Suramin for peripheral blood

Trypanosoma cruzi

  • Features:
    • Protozoa of the blood
    • Parasitic protozoan
  • Causes:
    • Chaga’s disease
    • Endemic to South and Central America
  • Transmission:
    • Reduviid bug “kissing bug” bites around mouth. bug deposits feces and patient scratches
  • Clinical presentation:
    • – Acute: asymptomatic or localized inflammation around biting site
    • – Chronic: 10-20 years after inoculation–> dangerous symptoms
    • – Megacolon: constipation and acute abdomen due to perforation
    • – Dilated cardiomyopathy: common cause of death
    • – Megaesophagus
  • Diagnosis:
    • – Blood smear
    • – Serology
  • Treatment:
    • – Acute: Nifurtimox
    • – No known treatment for Chaga’s