Ambler parasites Flashcards
Entamoeba histolytica
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
Blastocystis hominis
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
Cryptosporidiosis
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
Cyclospora
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
Isospora
contaminated water/food.
Self limited in healthy otherwise months to years (record 26 yrs) and mainly in HIV/AIDS
Tx: sulfa/TMP
suspect a -spora? try this test
acid-fast
Primary Amebic Meningoencephalitis (PAM)
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.
Toxoplasmosis
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.
Toxoplasmosis - Clinical (acute and chronic)
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.
toxoplasmosis- congenital
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.
Toxoplasmosis - HIV
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
Toxoplasma gondii
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.
Lymphatic Filariasis
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.
Onchocerca volvulus
transmitted by black fly
‘river blindness’
Tx: Ivermectin
Dirofilaria immitis
dog/coyote heartworm
human not normal host but can happen in pulm arteries causing lesion.
tx surgical for granuloma or no tx
Dracunculiasis
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
Toxocariasis
“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
Enterobiasis
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.
Trichuriaisis
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.
Hookworms
Necator americanus
Ancylostoma duodenale
penetrates skin
‘cutaneous larva migrans’
Pruritic
GI symptoms and nutritional deficiency
TX: Fe Replacement. albendazole x 1Trichinosis
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
Ascaris lumbricoides
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.
Strongyloides stercoralis
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
Intestinal Tapeworms
Taeniasis
Diphyllobothriasis
Taenia
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
Diphyllobothrium latum
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
Non-(human) intestinal tapeworms
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
Schistosomiasis
(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)
Katayama Fever
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.
Flukes
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
