Parasites Flashcards
Protozoa Overview
Unicellular Eukaryotes
NEED A LIQUID ENVIRONMENT
Live in VACUOLES –> water balance and food assimilation
Many modes of movement
AMEBIASIS is primarily caused by?
ENTAMOEBA HISTOLYTICA
Amebiasis
E. Histolytica
Fecal oral transmission, oral/anal sex (MSM)
HALLMARK –> Dense nucleolar ring with central chromatin dye*
Clinical –> More in CHILDREN, PREGGOS, IMMUNOCOMPROMISED
Asymptomatic intraluminal infection –> 80% are asymptomatic E. Histo cyst passengers; 4-10% DEVELOP INVASIVE DISEASE…
Diarrhea with mucous and BLOOD (dysentery)
ABDOMINAL CRAMPING
TOXIC MEGACOLON
AMEBOMA (inflammatory mass in the colon)
AMEBIC LIVER DISEASE –> FEVER, N/V, RUQ pain, Abnormal LFTs, R lobe of liver, Abscess
Thoracic Amebiasis –> 10% of patients with amebic liver disease, spreads transdiaphragmatically
Cerebral Abscess possible!
Treat with METRONIDAZOLE
GIARDIASIS
Giardia lamblia
Most commonly identified intestinal parasite in the US
Oral ingestion of cysts (CONTAMINATED WATER); exposure to recreational/fresh WATER (lakes!); Untreated well water; Sexual transmission (MSM); Day Care centers
RISK factors –> common variable immunoglobulin deficiency (IgA); REDUCED ACIDITY (PPI, Gastrectomies)
Clinical –> Asymptomatic cyst passage (1/3), Acute self-limited diarrhea (1/3), Chronic diarrhea with malabsorption (1/3)
Features –> DIARRHEA (FATTY), ABDOMINAL CRAMPS, BLOATING, FLATULENCE, WEIGHT LOSS
CRYPTOSPORIDOSES
C. Parvum
Needs an ACID-FAST STAIN for diagnosis!
Contaminated water
Ileocecal region for normal individuals, widespread GI for immunocompromised
RESISTS disinfection, so there can be large water-borne outbreaks –> well water, runoff, urban outbreaks, recreational water, person-person spread
Self-limiting watery diarrhea, abdominal cramps, N/V, fever in normal patients
MUCH bigger problem in immunocompromised –> Childhood diarrhea in developing countries; AIDS –> CD4 < 50 get SEVERE CHRONIC DIARRHEA, WEIGHT LOSS, MALABSORPTION, ELECTROLYTE WASTING
Extra-intestinal disease –> cholangiopathy (biliary obstruction, RUQ pain), pancreatitis, pneumonitis
LEISHMANIA
Leishmania donovani
VISCERAL Leishmaniasis –> Kala-Azar –> India, Nepal, Bangladesh, Sudan, Brazil –> SPIKING, PROLONGED FEVERS; Weight loss; HEPATOSPENOMEGALY, PANCYTOPENIA, HYPERGAMMAGLOBULINEMIA
Severe disease in AIDS, transplant patients, malnourished patients
CUTANEOUS Leishmaniasis –> MIDDLE EAST –> > 2000 cases in veterans; NON-HEALING ULCER with ROLLD UP EDGES on an INDURATED BORDER
MUCOSAL Leishmaniasis –> TROPICAL RAINFORESTS of S. America –> Erosive lesions in the mucosal areas around the mouth and ears
TRANSMISSION via the SANDFLY* –> taken up by MACROPHAGES (amastigotes)
TRYPANOSOMIASIS
Trypanosome Cruzi (look like C’s on peripheral smear)
Transmitted by BLOOD-SUCKING TRIATOMINE INSECTS
MEXICO and CENTRAL/SOUTH AMERICA
What does Trypanosomiasis cause?
CHAGAS DISEASE
Acute –> often bits mucosal areas –> palpebral fissue of the eyes (Periorbital edema with lymphadenopathy = ROMANA’S SIGN); Fever, edema, lymphadenopathy, hepatosplenomegaly; myocarditis; meningioencephalitis
CHRONIC –> CARDIOMYOPATHY -_> one of the more COMMON causes of CHF in South America!!!
Mega-colon, mega-esophagus
AFRICAN TRYPANOSOMIASIS
Trypanosomiasis brucei complex
TSETSE FLIES!!!! Only in the RAIN FOREST and SAVANNAHS OF AFRICA –> Exposure to GAME PARKS
Also known as SLEEPING SICKNESS
Bite occurs –> chancre/ulcer/nodule –> disseminates to STAGE ONE –> hemolymphatic stage –> lymphadenopathy, hepatosplenomegaly, fevers
WINTERBOTTOM’S SIGN = POSTERIOR CERVICAL LYMPHADENOPATHY
STAGE TWO –> meningoencephalitic stage –> headache, altered mental status, somnolence, ataxia, coma –> DEATH!
Malaria overview
Incredibly important
300,000,000 annually; 900,000 deaths; 80% children in Sub Saharan Africa; HUGE public health problem
Most severe? PLASMODIUM FALCIPARUM!!!!
Transmission through the ANOPHELINE MOSQUITO!!! Spores go to blood –> liver/hepatocytes first
What stage is responsible for RELAPSING malaria?
HYPNOZOITE STAGE! Not all of the organisms have this
Clinical Manifestations of Malaria
FEVER –> for returning travelers with fever, MALARIA until proven otherwise
Chills/Rigors Headache Diarrhea Jaundice Tertian (fever every other day) or Quartan (every 3rd day) possible
Hemolytic anemia, thrombocytopenia, abnormal LFTs
P. Falciparum
BY FAR DEADLIEST, rapid progression
Invades ALL LEVELS OF RBCs –> alters surface so they become “sticky” and sequester in the vital organs!!!
PERSISTENT FEVERS
LACKS the hypnozoite stage, so NO RELAPSE
Histo –> BANANA GAMETOCYTE on smear, RING FORMS in RBCs
Complications –> Multiple target organs –> CEREBRAL MALARIA = COMA, Lactic Acidosis, Hypoglycemia, ARDS, Acute kidney injury/black water fever
P. Vivax and P. Ovale
TERTIAN MALARIA –> Fever every other day
Only TROPICAL Africa
HYPNOZOITE PHASE! Can RELAPSE!
No target organs, so less severe than P. falciparum
All of the cells infected are BIGGER (they infect RETICULOCYTES/immature RBCs which are big)
P. Malariae
Relatively benign form
Can be there for many years (20-30)
QUARTAN MALARIA –> every 72 hours/3 days = FEVER