Parasites

Question 1

Protozoa Overview

Answer 1

Unicellular Eukaryotes

NEED A LIQUID ENVIRONMENT

Live in VACUOLES –> water balance and food assimilation

Many modes of movement

Question 2

AMEBIASIS is primarily caused by?

Answer 2

ENTAMOEBA HISTOLYTICA

Question 3

Amebiasis

Answer 3

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

Question 4

GIARDIASIS

Answer 4

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

Question 5

CRYPTOSPORIDOSES

Answer 5

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

Question 6

LEISHMANIA

Answer 6

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)

Question 7

TRYPANOSOMIASIS

Answer 7

Trypanosome Cruzi (look like C’s on peripheral smear)

Transmitted by BLOOD-SUCKING TRIATOMINE INSECTS

MEXICO and CENTRAL/SOUTH AMERICA

Question 8

What does Trypanosomiasis cause?

Answer 8

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

Question 9

AFRICAN TRYPANOSOMIASIS

Answer 9

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!

Question 10

Malaria overview

Answer 10

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

Question 11

What stage is responsible for RELAPSING malaria?

Answer 11

HYPNOZOITE STAGE! Not all of the organisms have this

Question 12

Clinical Manifestations of Malaria

Answer 12

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

Question 13

P. Falciparum

Answer 13

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

Question 14

P. Vivax and P. Ovale

Answer 14

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)

Question 15

P. Malariae

Answer 15

Relatively benign form

Can be there for many years (20-30)

QUARTAN MALARIA –> every 72 hours/3 days = FEVER

Question 16

Treatment for Malaria

Answer 16

Not sure if we need to know

P. Falciparum is RESISTANT to Chloroquine; so we use QUININE/DOXYCYCLINE

P. Vivax/P. Ovale –> CHLOROQUINE; PRIMAQUINE to prevent relapse!!!!

Question 17

BABESIOSIS

Answer 17

B. Microti

Can be acquired in US! NEW ENGLAND (CAPE COD), California, Washington

IXODES SCAPULARIS TICK –> 20% are co-infected with LYME (which is Borellia burgdorferi)

ELDERLY, SPLENECTOMIZED, IMMUNOCOMPROMISED

Fever, Myalgias, Headache, Hemolytic Anemia, Thrombocytopenia, Elevated LFTs –> similar to malaria

CAPE COD*

Question 18

Ascaris Lumbricoides

Answer 18

Nearly 1/4 of the WORLD is infected

Transmission via ingestion of parasitic EGGS –> hatched in the small intestine -> larvae penetrate GI –> larvae migrate to lungs, penetrate alveoli –> mature into adults –> worms produce 200.000 eggs/day

WARM, HUMID, TROPICAL CLIMATES –> resource poor countries; children who play on contaminated soil –> Eggs VIABLE FOR SIX YEARS

Large burdens of WORMS in the GI tract/STOOL –> worms can get in the bile and pancreatic ducts and cause OBSTRUCTIVE symptoms –> can migrate through LUNGS and cause PNEUMONIA

Question 19

TRICHURIS TRICHURIA

Answer 19

TRICHURIASIS
800 million worldwide

Impoverished children in the urban tropics, subtropics –> adult worms infect the CECUM and ASCENDING colon; DO NOT involve lungs

Question 20

HOOKWORM

Answer 20

Infection occurs in TROPICAL and SUBTROPICAL regions

Important cause of IRON DEFICIENCY ANEMIA

Walking BAREFOOT!!!! Exposure to infected soil, resource poor countries

LARVAE penetrate the skin –> pass to lungs and alveoli –> go to trachea/GI –> couched up!!!

GROUND ITCH –> rash at the site of penetration (foot), Eosinophilic pneuomonitis with worm passage; abdominal pain, anorexia, diarrhea, eosinophilia, Fe DEFICIENCY ANEMIA (they literally suck blood from the intestinal walls)

Question 21

STRONGYLOIDAISIS

Answer 21

Walking barefoot! Seen in the US – APPALACHIA, SOUTHEAST US

Clinically associated with ESOPINOPHILIC PNEUMONIA

Auto-infection – can live in humans INDEFINITELY; keeps RE-NFECTING the peri-anal skin; can be asymptomatic

ACUTE infection –> Rash at the site, eosinophilic pneumonia, peripheral eosinophilia, abdominal pain/diarrhea, larva currens

HYPERINFECTION –> Associated with STEROIDS, use of TNF-ALPHA inhibitors, heme malignancies, DM, infection with HTLV-1, immunosuppressive therapy

Larvae can penetrate bowel and DISSEMINATE INTO CSF

Associated with POLYMICROBIAL GRAM NEGATIVE SEPSIS –> gram negatives can seed the CNS –> GRAM NEGATIVE MENINGITIS

Question 22

ENTEROBIASIS

Answer 22

Enterobus vermicularis –> PINWORMS

Most common among CHILDREN, INSTITUTIONALIZED PATIENTS, HOUSEHOLDS

Adult worms live in the CECUM/APPENDIX –> migrate to PERI-ANAL REGION at night and lay eggs –> can re-infect with ingestion of eggs

PERI-ANAL PRURITIS –> SCOTCH TAPE TEST

Question 23

DIPHYLLOBOTHRIUM LATUM

Answer 23

FISH tape worm –> MUST HAVE FISH EXPOSURE*

Ingestion of UNCOOKED FRESH WATER FISH –> Smoked fish, Gefilte Fish, Cerviche/Salmon

Fish contain the LARVAL CYSTS which develop into adult tapeworms in humans

Endemic –> Lake and Delta areas of Siberia, Europe, Scandanavia, Baltics, N. America, Japan, Chile

CLINICAL –> Can grow to 25 METERS in length!!!! Often asymptomatic; B12 DEFICIENCY (tapeworm competes for B12 in the intestine) –> MEGALOBLASTIC ANEMIA, Peripheral neuropathy

Question 24

TAENIA SAGINATA

Answer 24

Transmission by eating UNDERCOOKED BEEF that contains larval cysts

Endemic in CATTLE BREEDING AREAS –> Central Asia, Near East, Central and East Africa

OFTEN ASYMPTOMATIC; Occasional abdominal pain

Question 25

TAENIA SOLIUM

Answer 25

PORK! PORK! PORK! Ingestion of raw/undercooked PORK Ingestion of the EGGS --> egg become larva which goes to the MUSCLE and CNS TISSUE Mexico, Central America, South America, Africa, Southeast Asia, Phillipines ***CYSTICERCOSIS*** MASSIVE CYSTS in the CNS, SEIZURES, ABNORMAL MRI, IMMIGRANTS*******

Question 26

ECHINOCOCCUS

Answer 26

Exposure to FOOD PRODUCTS infected with echinococcal eggs Transmitted by INFECTED DOMESTIC DOGS in LIVESTOCK AREAS Africa, Middle East, Southern Europe, Latina America, SOUTHWESTERN US GIGANTIC LIVER CYSTS!!!!!!!!! FEVER, ABDOMINAL PAIN, LARGE CYSTS, EOSINOPHILIA

Question 27

FILARIASIS

Answer 27

Vector borne -- DENSE EXPOSURE to MOSQUITOES Endemic in SUB-SAHARAN AFRICA, SE ASIA Clinical --> RECURRENT FEVERS with INFLAMMATION of the LYMPHATICS Fever and SWELLING OF THE LEG, ARM, MALE GENITALS Chronic Lymphedema and DISFIGUREMENT ELEPHANTIASIS EOSINOPHILIA Tropical Pulmonary

Question 28

LOIASIS

Answer 28

LOA LOA EYE WORM --> Worms can migrate through the EYE (may actually report seeing a worm in their eye); Also HAND SWELLING Recurrent, intermittent swelling of the FACE, EXTREMITIES --> worms migrate through the SKIN Deer flu, horse fly, mango fly

Question 29

TRICHINELLOSIS

Answer 29

Ingestion of UNDERCOOKED MEAT/GAME PRODUCTS PORK, BOAR, DEER, POLAR BEAR, WALRUS... Fever, diarrhea, severe myalgias/myositis, facial and peri-orbital edema, peripheral eosinophilia

Question 30

SCHISTOSOMA

Answer 30

Exposure to WATER, need a SNAIL INTERMEDIATE (not in the US) Schistosoma DERMATITIS --> occurs when cercaria PENETRATE THE SKIN; pruritic, maculopapular rash; Swimmer's itch ACUTE Schistosoma --> Fevers, Chills, Malaise, Abd pain, diarrhea, lymphadenopathy, hepatosplenomegaly, cough, pulmonary infiltrates, eosinophilia CHRONIC --> intestinal, portal HTN with splenomegaly, Cystitis with hematuria, NEURO INVOLVEMENT (CNS, Transverse myelitis) Schistosoma MANSONI = GI symptoms, PORTAL HTN ****Schistosoma HEMATOBIUM --> Can lead to KIDNEY FAILURE due to inflammation induced obstruction --> Can get SCC of the BLADDER!!!!!!

Question 31

PARAGONIMASIS

Answer 31

LUNG fluke ASIA Caused by consumption of FRESHWATER CRUSTACEANS (crayfish, crabs) Infection occurs when the TREMATODES are INGESTED and CROSS THROUGH DUODENUM/PERITONEUM --> then migrate across the diaphragm to cause lung disease Clinical --> VERY SIMILAR TO TB!!! Presents with COUGH with SIGNIFICANT BLOODY SPUTUM (hemoptysis) and CAVITATIONS in the lungs May have CNS lesions!!! Eosinophilia