Lecture 4: Infectious disease pt 4 Flashcards
1) The most common parasitic infection in the world is what?
2) What else is it the most common of?
3) Describe the pathophysiology
4) Describe its life cycle
5) Is it reportable?
1) Giardia Lamblia
2) Most common waterborne illness in the US; 15,000-20,000 per year in the US
3) Pear-shaped Flagellated protozoan; transmitted Fecal-oral.
4) Life cycle: Cyst ingested; Trophozoites in colon
5) Yes
Giardia Lamblia:
1) Risk factors
2) Signs/ Sx
3) Labs you need to order?
4) Tx?
1) Poor sanitation or poor hygiene, daycare outbreaks, oral-anal sex, water supply from shallow well, wilderness travel with ingestion of contaminated water
“Beaver Fever”
2) Diarrhea 1-3 weeks, fatty greasy stools, foul smelling
3) Stool Giardia Antigen PCR
4) Tinidazole 2 gm orally x 1
Malaria:
1) Etiology? (incl. species)
2) Epidemiology?
1) Plasmodium parasite inside the Anopheles mosquito.
-Species: P. falciparum (most virulent), P. malaria, P. ovale, P. knowlesi, P. vivax
2) Epidemiology: Africa, Asia, Latin America. endemic in most tropics, ~229 million cases & ~409K deaths worldwide in 2019, >94% in Africa
Malaria:
1) Describe its signs/ Sx.
2) Describe 2 stages
3) What labs would be abnormal? (3)
1) Fever, sweats, headache, periodic chills every 3 days (paroxysms). Hepatosplenomegaly
2) Liver stage: asymptomatic, then
-Erythrocyte stage: symptomatic
2) Atypical lymphocytes, decreased platelet count, elevated lactate dehydrogenase level
Malaria:
1) How is it diagnosed?
2) Tx?
3) Prevention?
4) Is it reportable?
1) Gimesa stain peripheral smear; thick and thin blood smears
2) Chloroquine/Hydroxychloroquine
3) Antimalarial drugs before, during and after travel Personal mosquito protection (barrier nets)
4) Yes
Amebiasis: Entamoeba Histolytica-
1) Epidemiology?
2) Risk factors?
3) What are its two forms? Describe each
1) 10% world wide
Asymptomatic cyst carrier 90% of cases
Fatalities per year 100,000
2) Mental health institutions, crowded living conditions, poor sanitation, travel to endemic areas: Asia, Africa and Latin America
3) Cyst: Can survive weeks in moist environment
Trophoziote: Moves toward colon (results in enterocolitis)
Amebiasis: Entamoeba Histolytica-
1) S/Sx?
2) Labs?
3) Tx?
1) Bloody profuse Diarrhea, fever, dehydration, weight loss, LIVER ABSCESS
-Can also go to the lung or brain
2) Stool PCR: Sensitivity 87%, Specificty >90%
-Liver function tests
-Alkaline phosphatase increased in 75% of cases
3) Asymptomatic: Paromomycin x 7 days
-Mild diarrhea: Metronidazole oral 7-10 days
-Severe Disease: Metronidazole IV x 10 days
Helminths: Define it and its classifications
1) Infections caused by worm-like parasites; defined by shape & host organ inhabited
2) Classified by external & internal morphology of egg, larval, & adult stages
Helminths:
1) Flukes (trematodes)
2) Tapeworms (cestodes)
3) Roundworms (nematodes)
1) Leaf-shaped flatworms (ie, schistomomiasis, fascioliasis)
2) Adult flatworms that inhabit intestinal lumen (larvae inhabit extraintestinal tissues (ie, beef, pork, fish, dwarf, cysticercosis).
3) Roundworms inhabiting intestinal & extraintestinal sites (ie, ascariasis)
Describe the pathologic stages of flukes, tapeworms, and roundworms
1) Flukes: Egg+, larva+, adult+
2) Tapeworms: Egg-, larva+, adult+
3) Roundworms: Egg-, larva+, adult+
Schistosomiasis:
1) Also called what?
2) Epidemiology?
3) Sx?
4) Complications?
1) “Snail Fever”
2) 252 million cases per year
3) Abdominal pain, diarrhea, bloody stool, blood in the urine
4) Liver damage, kidney failure, infertility, bladder cancer
Schistosomiasis:
1) How is it Dx’d?
2) Tx?
3) Prevention?
1) Finding eggs in the urine or stool, antibodies in the blood
2) Praziquantel (4-6 weeks after exposure)
3) Access to clean water
Where do you contract tapeworms?
From pig/ cow muscle (undercooked)
Cysticercosis:
1) Etiology?
2) Epidemiology?
1) Taenia Solium
2) Immigrants from Central America and South America. US natives 15% of deaths.
-Most common cause of acquired epilepsy.
-Endemic to Asia, India, Sub-Saharan Africa, Central and South America.
Cysticercosis: Describe the signs/ Sx
-Can be asymptomatic for years.
-Neurocysticercosis (90% of cases).
-Seizures.
-Headache, parkinsonism, encephalopathy, hydrocephalus, papilledema, chronic meningitis, cranial nerve palsy, eye lesions
Cysticercosis:
1) Describe how it’s Dx’d
2) How’s it treated?
1) -MRI brain. Single <2 cm lesion, no midline shift. Larval sucking parts may be visible (pathognomonic).
-Cysticercal Antibody: Sensitivity>65%, Specificity >67%. Biopsy of infected tissue.
2) Consult! Might need surgical excision. Albendazole with Dexamethasone. Seizure prophylaxis
Describe roundworm infections
-Found in soil
-Human stool as fertilizer
-Famous for migrating to lungs
Ascariasis (type of round worm):
1) Etiology
2) Epidemiology?
1) Ascariasis Lumbricoides
2) Epidemiology: Asia (75%), Africa (10%), Latin America (10%)
Ascariasis (type of round worm): Signs/ Sx?
-Eggs hatch in the intestines and migrate to the lungs.
-Often asymptomatic at first. Lower abdominal pain for days. Might see worms in stool.
-SOB, fever, diarrhea, malnutrition. Intestinal blockage.
-Allergies. Eosinophilia.
Ascariasis:
1) How’s it diagnosed?
2) Tx?
3) Prevention?
1) Identifying the appearance of the worm in eggs or feces. Fecal smears.
2) Albendazole
3) Improved sanitation.
Pinworms (enterobiasis):
1) Definition
2) Etiology
3) Epidemiology
4) Clinical features
1) Definition: most common helminthic infection in U.S. & Western Europe
2) Person-person via ingestion of Enterobius vermicularis (roundworm) eggs (hands, perianal region, food, fomites, bedding, clothing) or autoinfection
3) School-aged children, ~40 million in U.S.
4) Most asymptomatic
m/c symptom: nocturnal perianal pruritis
Insomnia, restlessness, enuresis
What are 3 ways to Dx pinworms (enterobiasis)?
1) Worms or eggs on perianal skin
Eggs usually not found in stool
2) Clear cellophane tape to perianal skin (ideal in early am), then micro exam for eggs
3) Nocturnal exam of perianal or gross exam of stools (adult worms)
How are pinworms (enterobiasis) treated?
1) Single PO mebendazole (alt. albendazole, pyrantel pamoate)
-Repeat Tx in 2 wks due to frequent re-infection
2) Concurrent Tx of infected (& uninfected) close contacts
3) Wash clothes & bedding (kills eggs)
Toxoplasmosis:
1) Etiology?
2) Epidemiology?
1) Intracellular protozoan parasite, Toxoplasma gondii
Infects HIV patients with CDV<50. Pregnant women exposed to cat feces.
2) Worldwide, in U.S. infects ~1.1 million annually (chorioretinitis ~21K & vision loss ~4,800)