Infectious Disease (Block 6): Helminths (Trematodes & Cestodes)

Front 1

name the most common parasitic infection in the world. what is its pathogenesis?

Back 1

Ascaris - transmitted by ingestion of eggs in contaminated soil, migrates to lungs (via veins), swallowed back down to the lumen of the small intestine to lay eggs

Front 2

clinical presentation of ascaris

Back 2

- most commonly infects children, often asymptomatic
- intestinal obstruction with WORM BALL
- Loeffler's syndrome: wheezing/coughing + eosinophilia due to larvae migration thru lungs
- cholangitis and pancreatitis (due to worms wandering into various ducts

Front 3

Dx and Tx of ascaris

Back 3

dx: eggs/adult worms in stool

tx: mebendazole, ALBENDAZOLE, ivermectin

Front 4

within the helminths, there are 3 main groups. name them!

Back 4

Cestodes - aka. tapeworms
Nematodes - aka. roundworms
Trematodes - aka. flukes

Front 5

there are 3 types of flukes (aka. trematodes), depending on where they go. what are they?

Back 5

- blood flukes (shistosomes)
- liver flukes (fasciola, clonorchis, opisthorchis)
- lung flukes (paragonimus)

Front 6

all flukes can be treated with _____, except for ______. This exception needs to be treated with _____ instead.

Back 6

praziquantel; Fasciola; triclabendazole

Front 7

Schistosomes are ____ flukes. name the intermediate host.

how do they infect humans?

Back 7

- blood
- Snails! They infect humans by the cercariae leaving snails and penetrate human skin during contact with fresh water.

Front 8

what 3 venous places do the schisotosome adults migrate to?

Back 8

- inferior mesenteric vein (S. mansoni)
- superior mesenteric vein (S. japonicum)
- venous plexus around bladder (S. hematobium)

Front 9

what clinical manifestations are caused by the 3 types of schistosomes?

Back 9

1. S. mansoni (Africa/Middle East) --> acute schistosomiasis (Katayama Fever--> hypersentivity to egg-assoc antigens; causes hepatosplenomegaly + EOSINOPHILIA) & chronic schistosomiasis (hepatosplenic dz)

2. S. japonicum (E. Asia) --> chronic schistosomiasis (hepatosplenic dz)

3. S. hematobium (Africa/Middle East) --> acute schistosomiasis & chronic schistosomiasis (urinary complications)

Front 10

upon penetration of skin by cercariae, all schistosomes cause what condition?

Back 10

schistosome (cercarial) dermatitis
- pruritic (itchy), maculopapular rash
- due to skin penetration by cercariae

Front 11

dx and tx of schistosomes

Back 11

dx: history of fresh water exposure
- microscopic examination of eggs in feces/urine
-serology

Tx: praziquantel

Front 12

there are 3 kinds of liver flukes. cercariae exit snails and then go to 2 different places. classify the 2 groups and tell me which specific trematodes are in which group.

Back 12

HUMAN INGESTS CONTAMINATED AQUATIC PLANTS (IE. WATER CRESS)
- fasciola hepatica

HUMAN INGESTS CONTAMINATED RAW/UNDERCOOKED FISH
- clonorchis
- opisthorchis

Front 13

name the clinical manifestations of fasciola (dont' forget, there's 2 phases)

Back 13

acute phase:
- hepatomegaly + eosinophilia

chronic phase:
- cholangitis (due to biliary involvement)

Front 14

what are the dx and tx for fasciola?

Back 14

dx: serology for acute phase
- eggs in stool

tx: triclabendazole (nitazoxamide in the US)

Front 15

clinical manifestations, dx and tx of clonorchis/opisthorchis

Back 15

-eosinophilia, RUQ pain w/ jaundice, pancreatitis, cholangitis, cholangiocarcinoma

dx: eggs in stool
tx: praziquantel ("praise the quantum scientists")

Front 16

name fluke that infects the lungs. how do humans get it? and what does it show up as?

Back 16

Paragonimus

- humans get it through ingestion of raw/undercooked crabs & crayfish
- you get a TB-like dz (cough/hemoptysis)

Front 17

dx and tx of paragonimus

Back 17

dx: eggs in stool
tx: praziquantel

Front 18

there are 2 main branches for cestodes (tapeworms). name them. which one is milder in clinical manifestations?

Back 18

1. tapeworms with intermediate host.
2. tapeworms without intermeidate host, they eat the eggs (larvae) directly!

the first group is milder (often asymptomatic or with minor abdominal symptoms).

Front 19

within the branch of cestodes (tapeworms) that have intermediate hosts, what are the 5 groups that humans can ingest? name the appropriate organism associated with them.

Back 19

pig (T. solium)
cow (T. saginata)
fish (D. latum)
dog fleas (D. canis)
human stool containing eggs (H. nana)

"Peanut Butter For Dinner Stinks!"

Front 20

what is unique about H. nana (dwar tapeworm)? what population does it occur in mostly?

Back 20

-can spread person-to-person...so nurseries and day cares are sites of transmission (therefore transmission through INGESTION isn't necessary)
-occurs especially in children

Front 21

which tapeworm with an intermediate host can compete for absorption of vit B12 causing B12 deficiency?

Back 21

D. latum (fish)

Front 22

do cestodes with intermediate hosts produce eosinophilia? how do you dx and tx them?

Back 22

- no eosinophilia!!
Dx: eggs can be identified in stool, but need repeated exams bc the proglottids are shed intermittently

Tx: praziquantel

Front 23

which cestode can also cause cysticercosis? how do you get it?

Back 23

T. solium
- get it through direct ingestion of the EGGS!!!

Front 24

what are the 2 species that are under the category of cestodes (tapeworms) that you get through eating egg directly?

Back 24

- T. solium (cysticercosis) --> affects brain and muscle
- echinococcus

Front 25

pts with cysticercosis (T. solium) usually harbor cysts for years before any onset of symptoms. what is the most common symptom and what kind of pt is typical?

Back 25

-neurocysticercosis is most common condition

-"hispanic immigrant (peru/bolivia) with new adult-onset seizures"

Front 26

dx and tx of cysticercosis (T. solium)

Back 26

dx:
- neuroimaging studies with CT/MRI (see "ring-enhancing lesions")
- confirm with serology

tx: symptomatic therapy with anticonvulsants (for seizures)
-may use anti-parasitic tx (praziquantel) for multiple cysticerci or if in ventricles/basilar cisterns, but NOT on calcifications

Front 27

tell me about echinococcus: name the definitive host and the 2 intermediate hosts. run through the transmission of echinococcus...

Back 27

definitive host: dogs
2 intermediate hosts: sheep (S. America/Middle East) & rodents (Alaska, arctic, C. Europe)

dog feces eaten by intermediate hosts --> dogs re-eat the dead intermediate hosts and poop out parasites --> humans ingest contaminated dog feces

Front 28

which echinococcus is found in sheep-raising areas like S. America and the middle east?

which echinococcus is endemic in Alaska, arctic regions and C. Europe?

name the dz they cause

Back 28

- E. granulosus (CYSTIC hydatid dz: slowly expanding mass lesion in liver > lungs)

- E. multilocularis (ALVEOLAR hydatid dz: expanding infiltrative process in liver)

Front 29

dx and tx of echinococcus

Back 29

dx: clinical suspicion, radiographic procedures (ultrasound, CT)
- serologic tests to CONFIRM

tx: PAIR + albendazole therapy