Lecture 9: Parasitic Diseases Flashcards
What is the main cause of amebic dysentery?
Entamoeba histolytica
What is the transmission of amebic dysentery?
Fecal-oral, ingestion of cyst form.
Worldwide, mainly in subtropical/tropical
Crowding, poor sanitation, poor nutrition
What are the main hosts for amebic dysentery?
Humans
How does mild-moderate amebic dysentery present?
Gradual onset diarrhea, abd pain, bloating, AFEBRILE.
PE: Abd distension & tenderness, hyperperistalsis, hepatomegaly
Microscopic hematochezia common
How does moderate-severe amebic dysentery present?
Colitis, dysentery with 10-20 bloody stools/day
FEVER, prostration, abd pain, vomiting
PE: abd distension & tenderness, hepatomegaly, hypotension.
Hematochezia common.
Who is severe amebic dysentery MC in?
Young children
pregnant pts
malnourished
steroids
What are intestinal complications common in amebic dysentery?
Necrotizing colitis, intestinal perforation, mucosal sloughing, hemorrhage, death
Chronic diarrhea with weight loss, bowel ulcerations, amebic appy
Amebomas: localized granulomatous lesions.
What is the extraintestinal complication in amebic dysentery?
Amebic liver abscess.
MC in men, causes wt loss and anorexia.
What are the tests for checking for intestinal amebic dysentery?
Stool microscopy/O&P - E. histolytica
Preferred:
Stool antigen
Stool PCR
What are the tests for checking hepatic abscess?
Anti-amebic antibodies: almost always +
Stool O&P: usually -
Imaging: US or CT liver
What is the treatment for amebic dysentery?
Metronidazole (10d) or tinidazole (3d) for trophozoites
Paromomycin (7d) for cysts (PO aminoglycoside)
What causes giardiasis?
Giardia lamblia (smiley face protozoa)
How is giardia transmitted?
Fecal-oral
MC intestinal protozoan in the US.
What are the risk factors for giardia transmission?
Endemic areas: tropical regions
Swallowing dirty water
MSM
Immunocomped
What is giardiasis sometimes called? Why?
Beaver fever
Humans, dogs, cats, numerous wild animals are all hosts.
What does symptomatic giardiasis look like?
Acute diarrheal syndrome with no vomiting and afebrile. Watery diarrhea only.
Chronic diarrheal syndrome with greasy/frothy diarrhea . No fever or vomiting.
How is giardiasis diagnosed?
Stool O&P for cysts and trophozoites without blood/leukocytes.
Preferred:
Stool antigen assay
Stool PCR
How is giardiasis treated?
Main: Tinidazole x1 dose
Nitazoxanide for pts 1-3
Metro for infants < 1
TNM
What is nitazoxanide used for? Main SE?
Cryptosporidium and giardia.
Only for young pts
Can cause yellow green urine
What two protozoa cause cryptosporidiosis?
Cryptospodirium parvum
Cryptosporidium hominis
How is crypto transmitted?
Ingestion of oocyst
Swimming pool outbreaks are MC.
MC in HIV+
swimming in crypto
What is unique about crypto survival?
Can survive in chlorinated water
How does acute crypto infection present?
Watery diarrhea
low-grade fever
How does chronic crypto infection present?
chronic diarrhea in AIDS pts.
Foul-smelling stool
Malabsorption and weight loss
Extraintestinal disease
What two things appear in extraintestinal disease in a crypto infection?
Biliary tract infection
Sclerosing cholangitis
CBS
How is crypto diagnosed?
Stool O&P with acid fast stain.
Stool antigen assay
Stool PCR
How is crypto treated?
Acute is supportive and self-limiting.
Can use nitazoxanide or paromomycin.
What causes cyclosporiasis?
Cyclospora cayetanensis
What is the MC transmission of cyclosporiasis?
Foodborne outbreaks in the US from imported produce.
How does symptomatic cyclosporiasis present?
Flu-like prodrome phase
Watery diarrhea
Fever only 1/4 of pts.
2+ weeks
Note:
Cyclo = cycles, Prodrome and then diarrhea
How does cyclosporiasis present in immunocomped pts?
Severe and prolonged
Chronic and fulminant watery diarrhea
How is cyclosporiasis diagnosed?
Preferred:
Stool microscopy/O&P with acid-fast stain
Colonoscopy with biopsy.
No rapid antigen test!
cycle fast
What is the first-line treatment for cyclosporiasis?
Bactrim x10 days. Also used as prophylaxis in AIDS.
Cycle back
What are the second-line treatments for cyclosporiasis?
Cipro
Nitazoxanide (not as well studied) (good for sulfa allergy pts)
What causes trichomoniasis?
Trichomoniasis vaginalis
How is trichomoniasis transmitted?
STI
Very common cause of GU infections
MC in women, esp. non-hispanic black females.
Who is recommended to get annual screenings for trichomoniasis?
HIV+ and high-risk females
How does symptomatic trichomoniasis present in females?
Frothy, green, yellow non-malodorous vaginal discharge.
Vulvovaginal pain/discomfort
Dysuria, dyspareunia, pruritis
Strawberry cervix
How does symptomatic trichomoniasis present in males?
Dysuria
Scant, thin urethral discharge
How do you diagnose trichomoniasis?
Wet prep of vaginal or urethral secretions:
Presence of motile, flagellated organisms.
Rapid antigen testing
Nucleic acid assay (PCR)
How do you treat trichomoniasis?
Tinidazole or secnidazole x1 dose
Metronidazole x 1week possibly
Must treat sexual partners
TSM are letters in trichomoniasis and not trichinosis
What causes toxoplasmosis?
Toxoplasma gondii
How is toxoplasmosis transmitted?
Fecal-oral
Cats, cat litter, undercooked pork/meat
One of the leading causes death from foodborne illness in US.
Usually only immunosuppressed or pregnant ppl get severe s/s.
What is the definitive host for toxoplasmosis?
Cats
How does toxoplasmosis present in immunocompetent people?
GI tract => lymphatics => disseminated
Symptomatic: mono-like.
Rare: hepatitis, meningoencephalitis, polymyositis, retinochoroiditis
How does toxoplasmosis present in immunocompromised people?
Reactivated in AIDS pts, pts on immunosuppressive rx, cancer pts.
MC: encephalitis with necrotizing brain lesions.
How does a congenital toxoplasmosis infection present?
Early: still birth, spontaneous abortion
Neuro: seizures, psychmotor retardation, deafness, hydrocephalus.
Other s/s: fever, jaundice, HSM, V/D, pneumonitis, myocarditis, retinochoroiditis
Mild: Normal at birth, but later development of LAD, HSM, CNS, or eye disease.
Late: Retinochoroiditis
Eye and brain symptoms
What is the general recommendation for pregnant women regarding toxoplasmosis?
Stay away from cats and cat litter.
How do you diagnose toxoplasmosis?
Serum Ig detection
ID of parasite via tissue biopsy
PCR of amniotic fluids, blood, CSF, etc
Body fluid culture
What is not recommended for toxoplasmosis?
Routine pregnancy screening NOT RECOMMENDED
How is toxoplasmosis treated?
Immunocompetents do not require tx in acute disease.
Pregnancy: spiramycin (reduce transmission risk)
Immunodeficiency/fetal infection: pyrimethamine + Sulfadiazine
DO NOT USE pyrimethamine early in pregnancy due to teratogenic effect.
What is the MC of malaria?
Plasmodium FALCIPARUM
How is malaria transmitted?
Bite of infected Anopheles FEMALE mosquito.
Highest transmission: Sub-saharan africa
How does malaria present acutely?
Periodically:
1. cold phase
2. hot phase
3. sweating stage
When is malaria risk greatest relative to travel?
Within 2 months of exposure (falciparum malaria)
What are the complications of severe malaria?
Coma (Cerebral malaria)
Severe anemia, DIC, hemolysis
Secondary bacterial infections
How is malaria diagnosed?
Giemsa-stained blood smears (preferred)
PCR/rapid assays
What is malaria treatment dependent on?
Depends on species, area and status, etc….
What is the treatment for non-falciparum malaria?
Chloroquine (resistance increasing)
First-line usually based on region now.
What is the treatment for resistant non-falciparum malaria and falciparum malaria?
ACTs (artemether-lumefantrine) (Coartem)
What is the treatment for severe malaria?
IV artesunate from CDC.
What do all malaria pts require?
Hospitalization and treatment.
What drug categories treat selective malaria?
Quinoline derivatives
Antifolate (atovaquone-proguanil)
ACT (artemether-lumefantrine or artemether-amodiaquine)
What are quinoline derivatives mainly for in regards to malaria?
Activity vs erythrocytic stage of infection, since malaria eats hemoglobin.
What is the main SE of chloroquine?
pruritis
When is primaquine used?
After tx with chloroquine.
What are the CIs of primaquine?
G6PD
Pregnancy
Breastfeeding
pregnant primaquine
Which antimalarial drugs are dosed weekly for prophylaxis?
Mefloquine
Chloroquine
MCW
What antimalarial drug has a SE of cinchonism?
Quinine/Quinidine
When do we use arteminisin derivatives for malaria?
Fast parasite clearance in combo regimen.
NOT for prophylaxis due to short half-life.
If a patient books a trip to Africa and is leaving in the next 3 days, what antimalarials can they take for prophylaxis?
Primaquine
Atovaquone-proguanil
Doxycycline
PAD themselves
If a patient is pregnant but is going to an area with high rates of malaria, what antimalarials can they take?
Chloroquine
Mefloquine
Weekly & pregnancy same
What are the 3 causative organisms for tapeworms/taeniasis?
Taenia saginata (beef)
Taenia solium (pork)
Diphyllobothrium latum (fish)
Where do tapeworms live?
In your intestine, growing up to several feet long.
Which tapeworms incubates the fastest?
Fish
What is the MC finding of intestinal tapeworms?
Proglottids in stool
What kind of deficiency can a fish tapeworm cause?
B12
How does invasive tapeworm present?
Cystericosis
Altered cognition, psychiatric s/s, seizures, etc.
Known for causing epilepsy in LA and SEA
How do you diagnose a tapeworm infection?
Microscopic identification of proglottids in stool
How do you treat intestinal taeniasis?
Praziquantel x 1 dose.
How do you treat neurocysticercosis?
Albendazole but may cause massive inflammation in brain.
What exactly does albendazole do?
Worm detachment, which may cause secondary inflammation when they die.
What are the causative organisms for hookworms?
Ancylostoma duodenale
Necator americanus
How do hookworms transmit?
Transcutaneous or ingesting larvae.
MC in tropical/subtropical with 1billion prevalence worldwide.
How does a hookworm infection present?
Pruritic maculopapular rash at site of infection
Fever, wheezing, dry cough, bloating, abd pain.
What is the concern regarding a hookworm infection in children?
Cognitive delay and impaired growth
How do we diagnose a hookworm infection?
Stool microscopy/O&P: eggs in feces
Rapid stool PCR
Anemia, blood in stool and hypoalbuminemia
How is hookworm treated?
Albendazole x1 dose
Mebendazole x 1-3 days
HAM
What should you take with albendazole?
High-fat meal or snack
Which benzimidazole can cause neutropenia/agranulocytosis?
Albendazole in long-term
What is the causative organism for pinworm/enterobiasis?
Enterobius vermicularis
How is enterobiasis transmitted?
Fecal-oral
Egg ingestion
MC in school-age children
How does enterobiasis typically present?
Perianal pruiritis, especially nocturnal.
Secondary impetigo and excoriation
perianal pinworms
How is enterobiasis typically diagnosed?
Scotch-tape test in the early AM, getting the eggs from the perianal skin.
How is enterobiasis treated?
Albendazole x1 dose or
Mebendazole x1 dose
Repeat in 2 weeks.
AM treatment, PM symptoms
What is the causative organism for trichinosis?
Trichinella spiralis
How is trichinosis transmitted?
Larvae in undercooked pork or meat.
MC for US: ingesting wild game
How does normal trichinosis present?
V/D, abd pain.
Systemic:
fever, myalgia, periorbital edema, eosinophilia, HA, cough. etc.
How does severe trichinosis present?
Muscle pain and weakness
Myocarditis, pneumonitis, encephalitis
How is trichinosis diagnosed?
-Elevated serum muscle enzymes (CK, LDH, AST)
-ELISA assay 2+ weeks after infection (but cross-reacts with other parasites)
-Muscle biopsy
Trichinosis lives in your muscles?
How is trichinosis treated?
Early: albendazole or mebendazole.
Supportive.
TAM
Full-blown = no specific treatment.
What is the causative organism for roundworms/ascariasis?
Ascaris lumbricoides
How is ascariasis transmitted?
Fecal-oral
MC intestinal helminth infection worldwide.
Who usually presents with heavy ascariasis?
Children
How does ascariasis present lung wise?
Lung migration:
-fever, eosinophilia
-dry cough, dyspnea, chest pain
-eosinophilic pneumonia sometimes
How does ascariasis present intestinal wise?
-+/-eosinophilia
-bloating, decreased appetite, obstruction
-pancreatitis, appendicitis, cholangitis
-coughed up, vomited up, passed rectally
-emerging through nose or anus
How is ascariasis diagnosed?
Stool microscopy/O&P: eggs in feces
Adult worms out of bodily orifices.
How is ascariasis treated?
Same as hookworm
Albendazole x1 dose
Mebendazole x1 or 3
AAM HAM TAM
