Parasitic Diseases and Antiparasitics Flashcards
presentation of amebiasis
-
Intestinal Disease - Mild-Moderate - gradual onset diarrhea, abd pain, bloating, usually afebrile
- PE - abd distension, abd tenderness, hyperperistalsis, hepatomegaly
- Microscopic hematochezia is commonly found
- Periods of remission-recurrence may last for weeks -
Moderate-Severe - colitis, dysentery with 10-20 bloody/watery stools per day
- High fevers, prostration, vomiting, abd pain
- PE - abd distension, abd tenderness, hepatomegaly, hypotension
- Hematochezia is common
- MC - in young children, pregnant pts, malnourished, pts on steroids
MC: Asx, noninvasive commensal organism
complications with amebiasis
- Acute - necrotizing colitis, intestinal perforation, mucosal sloughing, hemorrhage, death
- Chronic - chronic diarrhea with weight loss, bowel ulcerations, amebic appendicitis
-
Amebomas - localized granulomatous lesions
- Pain, obstructive symptoms, hemorrhage -
Extraintestinal Disease
- Amebic Liver Abscess
what is the MC extraintestinal manifestation
Amebic Liver Abscess
* abd pain, fever, enlarged/tender liver, anorexia, wt loss
* MC - men; can occur without any hx of colitis
* Can rupture (fatal)
how do you diagnose amebiasis
Intestinal Disease, Hepatic Abscess
- Intestinal Disease
* Stool Microscopy/O&P - E. histolytica
trophozoites and cysts
* Stool antigen test
* Stool PCR - Hepatic Abscess
* Anti-amebic antibodies - almost always +
Stool O&P or antigen - often negative
* Imaging - US/CT of liver
Tx for amebiasis
- Initial
- metronidazole (10 days) or tinidazole (3 days) - Followed by
- paromomycin
- PO aminoglycoside
initial eliminates E. histolytica **trophozoites **
f/u eliminates E. hi
prevention of amebiasis
- Avoid fruits, vegetables, and
water in endemic areas - Handwashing
- Boiled water
- Thoroughly cooked food
Central and South America,
India, Indonesia, tropical
and sub-Saharan Af
what is the MC intestinal protozoal pathogen in US
Giardiasis
risk factors of Giardiasis
- Travelers to Giardia-endemic areas
- Tropical regions with poor sanitation - Swallowing contaminated water during wilderness or recreation travel
- Men who have sex with men
- Immunocompromised
incubation for giardiasis
1-3 weeks
presentation of giardiasis
symptomatic disease
- Acute Diarrheal Syndrome
- diarrhea, wt loss, dehydration
- afebrile, no vomiting - Chronic Diarrheal Syndrome
- Diarrhea
- Greasy or frothy, foul-smelling stools
- abd cramps, bloating, flatulence, nausea, malaise; no fever or vomiting
- Symptoms can persist weeks to months
MC not discernible
May see malabsorption in chronic
how do you diagnose giardiasis
- Stool Microscopy/O&P
- (+) cysts and trophozoites - Stool antigen assay for Giardia
- Stool PCR for Giardia
No blood or leukocytes
tx for giardiasis
- tinidazole
- nitazoxanide - for pts 1-3
- metronidazole - for pts < 12 months
which antiparasitic drug interferes with normal reproduction cycle of Cryptosporidium and Giardia
Nitazoxanide (Alinia)
SE of Nitazoxanide (Alinia)
usually minimal - GI upset, HA, dizziness, discolored (bright yellow) urine
how is cryptosporidiosis spread?
- Ingestion of oocyst form of parasite
- Swimming pool outbreaks
MC in HIV+ pts, but can be seen in immunocompetent pts as well
incubation of crytosporidiosis
1-14 d
presentation of cryptosporidiosis
- Acute - 5-10 days of diarrhea; other s/s for up to 2 weeks
- Watery, nonbloody diarrhea
- N/V, abd pain, cramping
- Low-grade fever possible
- May have milder or asx course - HIV/AIDS Patients - typically chronic
- Chronic diarrhea
- Malabsorption and wt loss
- Extraintestinal disease - Pulmonary infiltrates and dyspnea; Biliary tract infection and sclerosing cholangitis
diagnosing crypto
- Stool microscopy/O&P with acid-fast stain
- Stool antigen assay for Cryptosporidium
- Stool PCR testing
No blood or leukocytes
tx for crypto
- Acute form - self-limiting; supportive
- nitazoxanide or paromomycin
which protozoa is Often linked to foodborne outbreaksin US from imported produce
Endemic to Haiti, Peru, Nepal
Cyclosporiasis
Ingestion of oocyst form of parasite
incubation of Cyclosporiasis
2-14 d
presentation of cylcosporiasis
- Asx
- Symptomatic Disease
- May see a flu-like prodrome
- Watery diarrhea, nausea and abdominal cramping
- Fatigue, malaise, anorexia - Immunocompromised Pts
- More severe, prolonged symptoms
- Chronic, fulminant watery diarrhea and weight loss
diagnosing cyclosporiasis
- Stool microscopy/O&P with acid-fast stain
- Colonoscopy with biopsy
tx for cyclosporiasis
- First-line - TMP-SMX (Bactrim)
- Second-line options
- Ciprofloxacin (Cipro)
- Nitazoxanide (Alina) - May be good for pts with sulfa allergy
which protozoa is a very common cause of GU infections
Trichomoniasis
Trichomonas vaginalis
Trichomoniasis is MC seen in who?
women
Especially non-Hispanic black females
Annual screening in HIV+ and higher-risk
Female pts recommended
incubation of trichomoniasis
5-28 d
presentation of tichomoniasis
- Asx - M>F
- Symptomatic Females
- Discharge - Frothy, yellow/green nonmalodorous
- Pain - Vulvovaginal discomfort, abd pain
- Dysuria, dyspareunia, pruritus
- PE - inflamed vaginal mucosa and cervix with punctate hemorrhages; “Strawberry Cervix” - Symptomatic Males
- Dysuria
- Scant, thin urethral discharge
how do you diagnose trichomoniasis
- Wet prep
- motile, flagellated organisms - Rapid antigen testing
- Nucleic acid assay (PCR)
tx for trichomoniasis
- Tinidazole or Secnidazole
- metronidazole
which protozoa is one of the leading causes of deaths from foodborne illness in US
Toxoplasmosis
Toxoplasma gondii
incubation of toxoplasmosis
1-2 wks
presentation of toxoplasmosis
-
Primary Infection (Immunocompetent)
- GI tract → lymphatics → disseminated
- Asx - MC
- Symptomatic - mono-like - fever, malaise, sore throat, HA, myalgias, LAD, HSM
- Rare - hepatitis, meningoencephalitis,
polymyositis, retinochoroiditis -
Primary Infection (Immunocompromised)
- Reactivated - in AIDS pts, pts on immunosuppressive rx, cancer pts
- MC presentation - encephalitis with necrotizing brain lesions
- Fever, HA, signs of focal brain lesion
- May also see retinochoroiditis, pneumonitis, myocarditis -
Congenital Infection
- Mother - +/- s/s
Overall infection risk increases as
pregnancy progresses
- Severe infection risk decreases as
pregnancy progresses
- Early - stillbirths, spontaneous abortions possible
- Neuro - seizures, psychomotor retardation, deafness, hydrocephalus
- Other s/s - fever, jaundice, HSM, V/D, pneumonitis, myocarditis, retinochoroiditis
- Mild - normal at birth with later development of LAD, HSM, CNS or eye disease
- Late - retinochoroiditis - in teenagers/young adults
how do you diagnose toxoplasmosis
- Serum IgM and IgG antibody detection
- ID of parasite on tissue biopsy
- PCR of amniotic fluids, blood, CSF, body fluids
- Cx body fluids
Routine pregnancy screening - not recommended
tx for toxoplasmosis
- Immunocompetent - none for acute
- Pregnancy - Spiramycin (reduces transmission risk)
- Immunodeficiency/Fetal Infection - pyrimethamine + sulfadiazine
- not used in early pregnancy
Pyrimethamine is teratogenic
Plasmodium falciparum MC causes what infection
malaria
what infection is transmitted by the bite of infected Anopheles female mosquito in endemic areas
Transmitted by Vector (mosquito) in endemic regions
malaria
Highest transmission - Sub-saharan Africa
incubation of malaria
9-14 days
describe the pathogenesis of malaria
- Sporozoites injected into the bloodstream, travel to liver
- Hepatocytes become infected, release merozoites
- Merozoites infect erythrocytes
- Becomes disseminated through bloodstream
clinical presentation of malaria
acute attack
- Prodrome - HA and fatigue
- Malarial paroxysm - High fever, chills, sweats
* General - malaise, anorexia, fever
* GI - abd pain, N/V/D
* MSK - myalgias, arthralgias
* Cardiopulmonary - chest pain, dry cough
* Neuro - seizures, HA
* Exam - may be benign; May show signs of anemia, jaundice, mild HSM
Recent Travel
Risk for falciparum malaria is greatest within ____ of exposure
time frame
2 months
presentation of malaria
complications/severe
- Severe illness, organ dysfunction, or high parasite load
* Peripheral parasitemia >5% or >200,000 parasites/mcL - Neuro - altered consciousness, repeated seizures, coma (“cerebral malaria”)
- Heme - severe anemia, hemolysis, DIC, other bleeding abnormalities
- CV - hypotension and shock
- Pulm - ARDS, pulmonary edema
- GI - jaundice, hepatic dysfunction
- Renal - acute kidney injury
- Metabolic - acidosis, hypoglycemia
- Infectious - secondary bacterial infections (pneumonia, Salmonella)
how do you diagnose malaria?
- Giemsa-stained blood smears
- PCR/Rapid Assays
tx of malaria is dependent on what?
- type (species) of the infecting parasite
- area where the infection was acquired and its drug-resistance status
- clinical status of the patient
- Any accompanying illness or condition
- Pregnancy status
- Drug allergies, and DDI
First-line for susceptible (non-falciparum) malaria
Chloroquine
Resistance is increasing
First line drugs now based on region acquired
First-line for Falciparum and resistant non-falciparum malaria:
ACTs: Artemisinin-based combination therapy
- Contain a SA artemesinin and LA partner drug
- Artemether-lumefantrine (Coartem)
what tx to use if resistance to ACT therapy/inability to tolerate
- Malarone (atovaquone-proguanil)
- Quinine + tetracycline, doxycycline, or clindamycin
- Mefloquine (Lariam) - resistance increasing
first line tx for severe malaria
- IV artesunate - must be obtained from CDC
- IV quinidine/IV quinine - no longer available in the US
antimalarial drugs - Quinoline Derivatives
Chloroquine
Quinine/Quinidine
Mefloquine (Lariam)
Primaquine
what is an Antifolate antimalarial drug
Atovaquone-proguanil (Malarone)
what are the Artemisinin Combination Therapy (ACT)
for malaria
- Artemether-lumefantrine (Coartem) - approved in the US
- Artesunate-amodiaquine (Camoquin)
- Artesunate-mefloquine
- Artesunate-pyronaridine
- Artesunate-sulfadoxine-pyrimethamine
- Dihydroartemisinin-piperaquine
which antimalarial drug class has activity against the erythrocytic stage of infection
Quinoline Derivatives
which quinoline derivatives also kills intrahepatic forms and gametocytes (seen with P. vivax and P. ovale)
Primiquine
First line for tx and prophylaxis of susceptible pathogens for malaria
Chloroquine
which drug
accumulates in parasite food vacuole and complexes with heme, preventing heme breakdown and allowing cytotoxic free heme to accumulate
Chloroquine
which antimalarial drug has a rapid onset - clears fever in 24-48 hrs and parasitemia in 48-72 hrs
Chloroquine
SE of Chloroquine
usually minor; pruritis (MC); HA, N/V, abdominal pain, malaise
Drug of choice for elimination of dormant liver cysts (P. vivax, P. ovale)
antimalarial drug
Primaquine
what drug is typically used after tx with chloroquine or quinine
Primaquine
SE of Primaquine
prolonged QT, cardiac dysrhythmia, N/V/D, abdominal pain
CI with primaquine
G6PD Deficiency, pregnancy, breastfeeding
which quinoline derivative:
Often used for prophylaxis - can be dosed weekly
Greater problems with toxicity when used therapeutically
Mefloquine
SE of Mefloquine
cardiac dysrhythmias, psychologic disturbances, seizures, N/V/D, HA, abdominal pain
CI with Mefloquine
hx of seizure disorder
hx of major psychiatric disorders
hx of dysrhythmia
which antimalarial is
Derived from the bark of the South American cinchona tree
a class IA antiarrhythmic agent
Quinine/Quinidine
MOA not well understood
SE of Quinine/Quinidine
“cinchonism” - nausea, HA, tinnitus, blurred vision, dizziness
1. Hypersensitivity - rash, angioedema, urticaria, bronchospasm
2. Hematologic - hemolysis, agranulocytosis, leukopenia, thrombocytopenia
3. Cardiac - ECG changes (prolonged QT), arrhythmias
Quinine/Quinidine is often combine with what abx to shorten tx/toxicity
doxycycline
which antimalarial interferes with folate metabolism, blocking nucleic acid synthesis
Atovaquone-proguanil (Malarone)
SE of Atovaquone-proguanil (Malarone)
generally well tolerated
N/V, HA, abdominal pain, pruritis; transient AST/ALT elevation
which antimalarial
encourages formation of free radicals that damage parasite; active against all forms
Artemether-lumefantrine (Coartem)
Derived from leaves of Artemisia annua, an herb used in Chinese medicine
which antimalarial has the fastest parasite clearance times of any antimalarial
Rapid absorption, rapid onset
Artemether-lumefantrine (Coartem)
Short half-life - not good for chemoprophylaxis, and only given in combo regimens
SE of Artemether-lumefantrine (Coartem)
generally well tolerated
HA, N/V/D, anorexia
Rare - neutropenia, hemolysis, anemia
what are the 3 Taeniasis
- Taenia saginata (beef tapeworm)
- Taenia solium (pork tapeworm)
- Diphyllobothrium latum (fish tapeworm)
transmission of tapeworms
ingestion of cysts in undercooked meat
incubation of tapeworms
2-3 months
proglottids in stool is MC in what parasitic infection?
Tapeworms (Taeniasis)
which tapeworm specifically causes prolonged infection leading to B12 deficiency
Diphyllobothrium latum - fish
presentations of tapeworms
- Noninvasive (Intestinal)
* May be asymptomatic
* May have abdominal pain, nausea,
* diarrhea, flatulence, hunger, wt loss
* Eosinophilia is possible - Invasive - Cysticerosis (Brain)
* Altered cognition, psychiatric s/s, seizures,
* HA, focal neuro deficits
* Important cause of epilepsy in Latin America, SE Asia
how do you diagnose tapeworms?
Microscopic identification of proglottids and
eggs in feces
tx for tapeworms
- Intestinal - praziquantel (Biltricide)
- Neurocysticercosis - controversial
* Clearance of cysts vs. inflammatory response to dead/dying pathogens
* When pharmaceutical treatment performed - albendazole
which antiparasitic drug allows increased calcium to enter parasitic cells, causing muscle spasms and paralysis and leading to worm detachment from host
Praziquantel (Biltricide)
CI of Praziquantel (Biltricide)
allergy to medication, ocular cysticercosis
DDI of Praziquantel (Biltricide)
antimalarials
grapefruit juice
cimetidine
SE of Praziquantel (Biltricide)
GI upset, HA, dizziness
May see secondary inflammatory response following pathogen death
what parasite have its larvae penetrate skin and migrate through bloodstream to lungs, eventually ending up in the intestines
Hookworms
Helminth
etiology of Hookworms
Ancylostoma duodenale
Necator americanus
incubation of hookworms
4-8 wks
pt presents with
pruritic maculopapular rash
fever, wheezing, dry cough
Bloating, abdominal pain, anorexia, nausea, diarrhea
what is their diagnosis
Hookworms
Can also see low protein, anemia
In children - may lead to cognitive delay and impaired growth
diagnosing hookworms
- Stool microscopy/O&P - microscopic eggs in feces
- Rapid stool PCR testing
- Often also see anemia, blood in stool, hypoalbuminemia
tx for hookworms
- Albendazole
- Mebendazole
- 3-day regimen (100 mg BID)
- Tx for anemia and low protein as appropriate
Albendazole (Albenza)
Benzimidazoles
Mebendazole (Vermox, Emverm)
Benzimidazoles
which benzimidazole should be taken with a high-fat meal or snack
Albendazole (Albenza)
what antiparasitic drug inhibits helminth microtubule formation and glucose uptake
Benzimidazoles
DDI of Benzimidazoles
antimalarials
grapefruit juice
cimetidine
anticonvulsants
SE of benzimidazoles
Abdominal pain, N/V/D
which benzimidazole may cause elevated LFTs and/or, in long-term tx, neutropenia or agranulocytosis
Albendazole
Pinworms (Enterobiasis) is Mc in what demographic
school-age children
incubation of Pinworms (Enterobiasis)
1-2 months
a 10y/o presents with
Perianal pruritus, especially nocturnal
excoriation and secondary impetigo of perianal skin
what is their diagnosis?
**Pinworms (Enterobiasis)
**
asx - majority of pts
Children may also have insomnia, restlessness, enuresis
diagnosing pinworms
eggs and/or adult worms on perianal skin
* “Scotch tape test”/“Paddle test” - in early AM - examined microscopically
* eggs are NOT found in feces
tx for pinworms
- Albendazole or mebendazole - Repeat in 2 weeks!
- Tx of infected family members and close contacts
- Washing bed sheets, clothing
- Avoid perianal scratching
- Education on hand hygiene
transmission of Trichinosis
Ingestion of larvae from undercooked pork or other meat
Typically in areas where pigs feed on garbage
incubation of trichinosis
1-7 days
presentation of trichinosis
- GI stage - V/D, abdominal pain
-
Systemic - larvae migration
- Fever, myalgias, periorbital edema, eosinophilia
- May see HA, cough, dyspnea, hoarseness, dysphagia, rash, eye hemorrhages
- Peak in 2-3 wks; can last for 2 months -
Severe - signs of muscle involvement
- Muscle pain and weakness
- Myocarditis, pneumonitis, encephalitis
how do you diagnose trichinosis
- Elevated serum muscle enzymes (CK, LDH, AST)
- ELISA assay 2+ weeks after infection - cross-reactive with other parasites
- Muscle biopsy
tx for trichinosis
- No specific treatment for full-blown trichinosis
- If suspected early - albendazole or mebendazole may limit intestinal infection
- Supportive - analgesics, antipyretics, bed rest, steroids
- Prevention - thoroughly cooking meat
what is the MC intestinal helminthic infection worldwide
Roundworms (Ascariasis)
incubation of Roundworms (Ascariasis)
6-8 weeks
presentations of roundworms
- asx - up to 85% of pts
-
Migration through Lungs
* General - Fever, eosinophilia
* Pulmonary - Dry cough, dyspnea, chest pain
* May see eosinophilic pneumonia -
Intestinal Manifestations
* +/- eosinophilia
* Bloating, decreased appetite, obstruction
* Pancreatitis, appendicitis, cholangitis
* May be coughed up, vomited up, or passed rectally
* May migrate and emerge through nose or anus
diagnosing roundworms
- Stool microscopy/O&P - microscopic eggs in feces
- Emergence of adult worms (cough, nose, anus, feces)
tx for roundworms
- Albendazole
- Mebendazole
similar to hookworms
