Ambler parasites

Question 1

Entamoeba histolytica

Answer 1

10% of the population of world infected
do not confuse with Entamoeba coli (E.coli as well!) but usually not pathogenic
cyst is ingested (#>1000) and infective stage
can cause intestinal symptoms with diarrhea or become invasive with liver abscess
anchovy paste on aspiration and right lobe liver
tx is metronidazole

Question 2

Blastocystis hominis

Answer 2

found in asymptomatic healthy people and people with diarrhea so debated pathogen
watery diarrhea, pain, perianal pruritus and excessive flatulence.
can try metronidazole or sulfa/TMP

Question 3

Cryptosporidiosis

Answer 3

important cause of traveler’s diarrhea from infected water source.

Cryptosporidium parvum – almost all human cases and also guinea pigs.

short term cholera-like diarrheal illness in healthy

chronic for months in immunocompromised
can see respiratory disease in AIDS

Tx: not great. get immune system up. otherwise paramomycin

Question 4

Cyclospora

Answer 4

ingestion from contaminated water/food.
outbreak near Chicago in 1990’s from Guatemalan raspberries
self limited. Even in HIV, if CD4 up then resolution.
Tx: if necessary sulfa/TMP

Question 5

Isospora

Answer 5

contaminated water/food.
Self limited in healthy otherwise months to years (record 26 yrs) and mainly in HIV/AIDS
Tx: sulfa/TMP

Question 6

suspect a -spora? try this test

Answer 6

acid-fast

Question 7

Primary Amebic Meningoencephalitis (PAM)

Answer 7

free living organisms so direct invasion from contact. Usually up nose through cribiform plate.

Naegleria fowleri most talked about. also Balamuthia mandrillaris and Acanthamoeba sp.
129/132 in US died
Tx. Ampho-B but now miltefosine is in investigation.

Question 8

Toxoplasmosis

Answer 8

Epidemiology- 22.5% people in US are infected over age 12.
worldwide distribution.
can infect almost all warm blooded animals but felines are main shedder of infective ooztyes.
domestic cats 16-80% seroprevalence in US.

Question 9

Toxoplasmosis - Clinical (acute and chronic)

Answer 9

Acute form
most asymptomatic but if not;
immunocompentent (CD4>100)
Head/Neck lymphadenopathy over generalized
can mimic lymphoma or mononucleosis like illness
Immunocompromised-more severe
(meningo)encephalitis, pneumonitis, myocarditis, pericarditis, hepatitis, coombs-neg hemolytic anemia or polymyositis

Chronic form
cysts any organ but primarily brain, heart and skeletal muscle.
chorioretinitis more common with congenital but can happen rarely in adults.

Question 10

toxoplasmosis- congenital

Answer 10

Congenital
1/1000 births in US. 1/200 pregnancies
late pregnancy transmission greatest but early infection more devastating (1st/2nd trimester)
70% infected neonates asymptomatic at birth but develop ocular or degrees of mental retardation later in life.
symptomatic shows hydrocephalus, microcephaly, microophthalmia, mental retardation, failure to thrive, seizures, hepatosplenomegaly, pneumonitis, fever, rash, thrombocytopenia, chorioretinitis and blindness.

Question 11

Toxoplasmosis - HIV

Answer 11

CD4 less than 100
CNS, brain lesions common
slowly evolving dementia without LOC in conjunction to pathologic effect of HIV.
Pneumonitis is 2nd most common complication
(also seen in kidney transplants)
looks like Pneumocystis but more rapid

Question 12

Toxoplasma gondii

Answer 12

eating undercooked meat esp pork, lamb, venison
cats and litter boxes
TORCH
Ring enhancement CT

Tx: sulfa/tmp or clindamycin with pyrimethamine
hint. we also use sulfa/tmp for prophylaxis in CD4 less than 100.

Question 13

Lymphatic Filariasis

Answer 13

Think bad Lymphedema patient.
most common is W. bancrofti. also Brugia sp and Loa Loa

Tx: DEC (dietheylcarbamazine) except for onchocerciasis where it is ivermectin.

Question 14

Onchocerca volvulus

Answer 14

transmitted by black fly
‘river blindness’
Tx: Ivermectin

Question 15

Dirofilaria immitis

Answer 15

dog/coyote heartworm
human not normal host but can happen in pulm arteries causing lesion.
tx surgical for granuloma or no tx

Question 16

Dracunculiasis

Answer 16

not sure if will be important as major eradication effort has been underway
“Guinea Worm”, “fiery serpent worm”
tx is daily turning of a stick

Question 17

Toxocariasis

Answer 17

“Visceral Larva Migrans” – although Ascaris, Strongyloides, Trichinella and filaria do migrate; this mainly applies to Toxocara sp.
T. canis (dog), cati (cat)
Visceral 2-3yo , Ocular and neural forms 3-40yo
Baylisascaris procyonis (from raccoon poop)
VLM mainly benign but more significant systemic
TX: symptomatic to reduce inflammation but can try DEC

Question 18

Enterobiasis

Answer 18

Enterobius vermicularis “pinworm”; scotch tape….
40 million infected in US
5-10yo children
many asymptomatic but ‘perianal pruritis’ in kids is the clinical case. can cause intestinal symptoms with high worm burden

TX: albendazole x1 and repeat in 2 weeks.

Question 19

Trichuriaisis

Answer 19

Trichuris trichiura “whipworm”
poor hygeine, all ages
most asymptomatic but loose stool with mucus+/- blood and at night. Rectal prolapse with heavy burden
TX: mebendazole or albendazole x 3 days.

Question 20

Hookworms

Answer 20

Necator americanus 
    Ancylostoma duodenale
penetrates skin
‘cutaneous larva migrans’
Pruritic
GI symptoms and nutritional deficiency
TX:  Fe Replacement.  albendazole x 1

Question 21

Trichinosis

Answer 21

more common in Europe and America
T. spriralis group
improperly stored and cooked pig, bear, horse or walrus.
GI phase with n/v diarrhea, constipation and pain vs asymptomatic
muscle invasion phase with triad of myalgia, palpebral edema and eosinophilia
high fever somewhat unique compared to other helminthic infections
Tx: mebendazole for 2 weeks.
albendazole seems effective

Question 22

Ascaris lumbricoides

Answer 22

largest nematode with worldwide distribution, highest in Africa and Asia
most asymptomatic or mild with end of infection a couple of months with expulsion of adult worms.
intestinal obstruction/jaundice esp kids
Tx: albendazole or sometimes surgical.

Question 23

Strongyloides stercoralis

Answer 23

SE USA
causes GI/Lung symptoms. also skin reactions “ground itch”.
enters through skin
lung with wheeze, dry cough, throat irritation, hemoptysis
too small to see on gross exam. see granuloma
think of endemic person with late onset asthma +/- GI.
Tx: Ivermectin

Question 24

Intestinal Tapeworms

Answer 24

Taeniasis

Diphyllobothriasis

Question 25

Taenia

Answer 25

most asymptomatic

Taenia solium (pig)
can live 25 yrs
can go to CNS
‘mexican with seizures’
worm dies and causes inflammation 

Taenia saginata (cow or beef)
can live 10
mainly GI symptoms

Question 26

Diphyllobothrium latum

Answer 26

longest of human tapeworms. (4-15m)
complex life cycle with crustaceans, 2 fish and people.
decreasing in US but in Japan still around and we eat a lot of sushi…..
most asymptomatic but can use praziquantel

Question 27

Non-(human) intestinal tapeworms

Answer 27

Echinococcosis – tiny tapeworm found in animals. human infection mainly asymptomatic but cysts can cause issues- lungs and liver and rare brain.
echinococcus granulosus
echinococcus multilocularis
Cystic echinococcosis causes hydatid cysts which can cause anaphylaxis when opened
Tx: Surgery. adjunctive albendazole can be used

Question 28

Schistosomiasis

Answer 28

(Katayama fever, bilharzia, snail fever)

most have acquired immunity in endemic areas and asymptomatic
Tx: praziquantal
Many forms of disease

skin (cercarial dermatitis)
delayed type hypersensitivity

Intestinal
small intestine and colon with multiple polyposis

Hepatosplenic
granulomas and then portal hypertension 2nd to portal vein vasculitis. In fact, in path specimen, only portal artery and bile ducts are present in the fibrosed area which is pathognomonic.

GU
Really only S. haematobium (less japonicum). ‘Sandy patches’ are calcified ova seen through atrophic epithelium = pathognomonic. bloody
high incident of bladder CA
Salmonella in urine is tip off as Schisto colonized with salmonella

Cardiopulmonary
similar path with fibroses. pulmonary endarteritis with angiomatoid changes =pathognomonic

CNS
egg granulomata and necrosis. meninges often involved.
can cause Jacksonian epilepsy and compression of the spinal cord (transverse myelitis)

Question 29

Katayama Fever

Answer 29

first observed in Katayama, Japan
S. japonicum most common
cercarial invasion primes the pump, then adult worms lay a bunch of eggs and the immune system reacts.
Fever, chills, eosinophils (also urticaria), hepatosplenomegaly, generalized lymphadenopathy, and GI symptoms.
convalesces in a 4-8 weeks.

Question 30

Flukes

Answer 30

Fascioliasis- Fasciola hepatica. ‘common liver fluke’ ’sheep liver fluke’
Fasciolopsiasis – Fasciolopsis buski, largest liver fluke
Paragonimiasis- Paragonimus westermani; ‘lung fluke’
Asia, 22million infected
Chonorchiasis/opisthorchiasis