Parasitic Infections - SP Flashcards
(51 cards)
1
Q
Summary
A
Nematodes
- Pinworms
- Ascaris
- Trichuris (Whipworms)
- Hookworms
- Strongyloides
Protozoa
- Giardia
- Cryptosporidium
Platyhelmethes
- Trematodes: Schistosomes, Clonorchiasis, Paragonimiasis
- Cestodes: Diphyllobothrium latum
2
Q
Meds: Albendazole/Mebendazole
A
- Binds nematode Beta-tubulin
- Blocks microtubule assembly
- Inhibits glucose uptake in worm
- Death of worm takes days
3
Q
Albendazole/Mebendazole
A
Albendazole
- Better GI absorption and high tissue distribution (vs tissue migrating larvae)
- Take with food
- Pregnancy class C
- If STH (soil transmitted Helminths) exceeds 20%, presumptive tx of pregnant women should occur in third trimester with 400 mg albendazole x 1
- Use during breastfeeding is acceptable
Mebendazole
- Poorly absorbed, activity vs adults only
- Both safe > 1yr, probably safe under
4
Q
Ivermectin
A
-Works by binding nerve and muscle chloride channels causing hyperpolarization, paralysis, and death
Active vs.
- Strongyloides
- Ascaris, Trichuris (not hookworm)
- Lice, Scabies
- Pregnancy class C, avoid during breast feeding as well
- Avoid where Loa Loa (African Eye worm is found.. May cause encephalopathy
5
Q
Helminths: overview
A
Trematodes (flukes)
A. venous: Schistosoma
B. Biliary tract: Clonorchis, Fasciola
C. Lung: Paragominus
Cestodes (tapeworms)
A. Tanea saginata, T. Solium, Hymenolepsis nana
Nematodes (round worms)
A. Intestinal
B. Blood/lymphatic, subcutaneous
6
Q
Common Intestinal Parasites
A
Nematodes
- Pinworm
- Ascaris
- Trichuris
- Hookworm
- Strongyloides
Protozoa
- Giardia
- Cryptosporidium
- Entamoeba hystolytica
7
Q
Nematode Facts
A
Nonspecific presentation:
- Often asymptomatic until worm burden is huge
- Weight loss, GI discomfort
- Rare for diarrhea or fever
-Look for polyparasitism
-Tropical and subtropical predominance
-Burden greatest in children
Do not multiply in host (2 exceptions)
1. Strongyloides: autoinfection
2. Pinworm: self-reinfection
-Life span: 2 months—5 years
8
Q
Nematodes
A
- Eosinophilia occurs with worms penetrating tissue (>450)
- Larval migratory stage (O+P neg?)
- GI mucosal penetration
If persistent eosinophilia…
- Toxocariasis (T. canis) with kids eating dirt
- Strongyloides (Africa, SE Asia)
- Schistosomiasis (sub-Saharan Africa)
9
Q
Nematode: Pinworms (Enterobius vermicularis)
A
- World wide…tropical and temperate climate
- Adult habitat: cecum and appendix
- Gravid female nocturnally deposits eggs onto perianal skin
- Eggs stick to skin and hatch with 4-6 hours of oxygen
- Transmission is fecal oral, reinfection, person to person, and fomite
- Scratching the anus/butt, use scotch tape at night to capture
- Prepatent period is 3-4 weeks
- Diagnosis: Scotch tape test (clear), place clear tape on anus at bedtime and check in the morning
- No eosinophilia
10
Q
Pinworm Treatment
A
- Albendazole or mebendazole 100 mg single dose
- Repeat in 2 weeks
- Treat entire family
11
Q
Nematode: Roundworms (Ascariasis infections)
A
- 1/8 of world is infected
- Largest nematodes infecting humans (40cm/15-18 inches)
- Adult habitat: jejunum
- Obligatory extra-intestinal migration (eosinophilia)
- Lifespan 1-2 years
- Most intense in children ages 5-10
- Larval phase: migration = eosinophilia, pneumonitis (<3weeks)
Adult worm phase:
- Heavy infection-malnutrition, impaired growth
- Mild abdominal pain—can create SBO
- Wandering hepatobiliary-pancreatic ascarisis: pancreatic and liver abscess
-Treatment: Albendazole 400 mg x 1
12
Q
Nematode: Ascaris
A
- More prevalent in wet and warm climates
- Females can lay 200k eggs per day
- ONLY worm which may be shed in stool, by cough, and by vomiting
13
Q
Nematode: whipworms (Trichuris trichiuria)
A
- Adult Habitat: caecum, colorectum
- No extra-intestinal phase
- Lifespan 1-3 years
- 90% are asymptomatic
- Heavy infections may cause symptoms (peak at 10 y/o)
14
Q
Whipworm Life Cycle
A
- Female produces eggs.
- Human feces with eggs deposited in soil, where they lay prepatent for 2-8 weeks
- Eggs are ingested and hatch in the small intestine, penetrating villae
- Adults migrate to Cecum and cycle repeats
15
Q
Whipworms: Symptoms & Tx
A
- 90% asymptomatic
- Anemia of Chronic Disease
- Stool frequency 12+/day
- Chronic abdominal pain
HEAVY INFECTIONS:
- Tichuris dysentery syndrome
- Trichuris colitis (mimics IBD)
- Rectal Prolapse (children)
- Self limiting w/o reinfection
Mebendazole (100 mg), Albendazole (400 mg)x 3 days
16
Q
Nematode: Human Hookworms (Necator americanus and Ancyclostoma duodenale)
A
- 1/10 of world population infected
- Significant cause of anemia and protein malnutrition
- Adult habitat: small intestine
Lifespan:
- 1-3 years for A. duodenale
- 3-7 years for N. Americanus-
- Worm burdens do not decline in adult years
- Pre-Patency: months to a year before symptomatic
- 600 million cases worldwide
- Adult worms injure host by causing intestinal blood loss:
- Anticoagulants, Hemolysins, Hemoglobinases
- 30-200 microliters bloodloss per day
- Intestinal bloodloss
- Iron Deficiency Anemia
Adult size: .5-1 cm
Egg production: 5-20K eggs per day
17
Q
Hookworms: Clinical Features & tx
A
- Ground itch in primary infection: enters skin thru foot travels to blood, lungs cough up then ingest and goes into intestine and feces.
- Abdominal discomfort
- Progressive iron deficiency
- Failure to thrive, extreme fatigue
- Lost work, missed school
- IQ loss
Albendazole 400 mg qd x 1 dose
18
Q
Nematode: Strongyloidiasis (Strongyloides stercoralis)
A
- Causes most mortality in the US
- 100 million infected world wide
- Adult habitat: duodenum, jejunem
- Lifespan: unknown. Ongoing autoinfection
- Has been documented greater than 60 years
19
Q
Strongyloides Larvae
A
Rhabditiform
- Non-infective stage
- May be in intestine or soil and mature to Filariform
Filariform
- Infective stage
- Penetrates skin
- Penetrates intestine, into blood stream
- Penetrates alveoli and is then is coughed and swallowed (auto inoculation)
20
Q
Strongyloidiasis
A
- Asymptomatic eosinophilia
- Abdominal pain
- Dermatitis—larva currens
- Pulmonary infiltrates with eosinophilia
- Dissemination with sepsis
21
Q
Strongyloides Hyperinfection:
A
- Intestinal perforation
- Hemorrhagic shock
- Shock, sepsis, gram negative meningitis
- Eosinophilia may be limited
Disease Associations
- Steroid usage (Medrol)
- Steroid directly effects parasite by upregulating molting hormones
- Malignancy, solid organ transplants
- HTLV-1 Infection (Human T-Cell Leukemia Virus): Not HIV
- PRESENT WITH Malnutrition
22
Q
Strongyloidiasis: dx
A
- Detection of rhabditiform larvae in stool
- Larvae output in stool varies
- Repeat stool samples if suspicious
- Single stool is 30%, 7 stools = 100%
- Blood augar plate looking for larval tracks
- Serologic (IGg) tests (not great)
- Cannot distinguish current vs prior infection
- Cross reactions with helminths (ascaris, shisto) filariae
23
Q
Strongyloides Treatment
A
Ivermectin (1st line)
- Intestinal: 200mcg/kg/d x 2 days…repeat in 14 days
- Autoinfection and hyperinfection: 200 mcg/kg/day x 7-10 days
- Taper steroids
Albendazole (2nd line)
- 400 mg bid x 2 days, repeat if needed
- Lower cure rate
24
Q
Disseminated Strongyloides:
A
- Avoid steroid use in refugees and immigrants until knowing results of eosinophil count and stools for O&P, especially methylprednisilone
- SE Asians have highest risk for Strongyloides
- Vigorously pursue eosinophilia in refugees and immigrants (Strongyloides in Africa/Asia) and Schistosomiaisis (Africa)
- Empirically treat eosinophilia with ivermectin if evaluation is negative, particularly those who will receive immunosuppressives
25
Protozoa: Giardiasis (Girardia intestinalis)
- Worldwide
- Most commonly reported enteric Pathogen
- Commonly found in immigrant screening (approx 20% of reported cases)
- Often carried by children in daycare
- Fecal – oral transmission
- Person to person (young children)
- Waterborne: Swimming/drinking untreated surface water
26
Symptoms of Giardiasis
- Diarrhea—95% horrible smelling
- Fatigue—82%
- Gas or bloating—74%
- Abdominal Pain—73%
- Nausea—62%
- Asymptomatic 50%
- Vomiting—rare
- Chills or fever—rare
27
Giardiasis in MN 2003
- Median Duration—23 days
- Incubation—7-10 days
- Symptoms may be intermittent and relapses can occur
- Highest % cases in children less than 5
- Cases occur all year with a spike in August-October
28
Giardiasis: tx
Metronidazole (flagyl) (vomiting with ETOH, so dont drink) 250 TID x 7 days
Tinidazole 50mg/kg x 1 dose (max dose=2 g)
Nitazoxanide bid 3 days
29
Protozoa: Cryptosporidiosis
- parasite
- Fecal-oral transmission
- 7 day incubation
- Waterborne, daycare outbreaks
- Cattle contact
- Responsible for an outbreak involving 369 children, who came in contact with a water fountain at the MN Zoo in 1997.
- Under-recognized by most labs
- Routine O+P does not look for Cryptosporidium
- Must specify Cryptosporidium/Giardia ELSIA
30
Cryptosporidiosis: sxs, tx
- Cramping, nonbloody diarrhea
- Median 7 days (2-28 days)
- Chronic diarrhea in HIV
- FEVER, vomiting common
Limited therapies…
- Nitazoxanide adult dose 500 bid x 3 days
- AIDS patients 1 g bid x 14 days
31
Entomoeba hystolytica: Amebiasis, amebic dysentery, Amebic hepatitis
- World wide, tropical and temperate
- Incidence 0.2-50%, based on sanitary conditions
- Humans are principal host and source
- Cyst contaminated food and water cause infection
- Infective cysts pass out in feces and are immediately infective
- Immature amebas move to large intestine(primary, cecal, sigmoidal)
- Excystment (secondary)takes place in Ileum (portal v, liver, lung, brain, skin)
- Reproduction is by binary fission
32
Entomoeba hystolytica: Symptoms
Acute:
- Fever
- Dysentery, blood, mucous, necrotic mucosa
- Abdominal pain
Chronic:
- Recurrent dysentery/relapsing
- Abdominal pain, RUQ
- Amebic hepatitis, abscess, hepatomegaly
- Less frequently: lung, spleen, brain abscess, and cutaneous lesions
33
Entomoeba hystolytica: Diagnosis
- O+P, cysts(solid stool), trophozoites (diarrhea)
- Aspiration (abscess)
- Serology (IFA, ELISA(best)) for specific Ab to E. hystolytica
- PCR
34
Entomoeba hystolytica: tx
Metronidazole (flagyl) 500 mg tid x 10 days
Tinidazole: 500 mg tid x 10 days
Ornidazole: 500 mg bid x 10 days
35
Platyhelmenthes:Trematoda = flukes
- Flattened, leaf like body
- Simple digestive tract
- ALL parasitic
- attachment typically involving hooks and suckers, specialize glands for penetration, and encystment
- Schistosoma spp.
- Chlonorchis –human liver fluke
- Paragonium—human lung fluke
36
Trematodes: Schistosomiasis
- Infections occur via contact with contaminated water
- Infective stage is called cercaria (free swimming)
- Cercercaria burrow into skin an matures to schistosomula stage, which migrates to lungs and liver and develops into adult
- Adult migrates to bladder, rectum, portal vein, intestine, spleen, lungs
- Mostly Tropical (thankfully)
- Incubation 14-84 days
- Often asymptomatic
May involve:
- Intestinal
- Respiratory
- Urinary
- Neurologic
- Reproductive
37
Schistosomiasis: Symptoms
- Heavy infections: (Katayama syndrome) fever, chills, lymphadenopathy, hepato/splenomegaly
- Initial invasion may cause itching (swimmer’s itch)
- Abdominal pain, bloody diarrhea, constipation, ulceration, portal hypertension
- Polyuria, dysuria, hematuria,
- Myalgias
- Eosinophilia
- Neurogranulomas (space occupying)
38
Schistosomiasis: Testing
- CBC (wbc, Eos)
- O+P x 2
- Tissue biopsy
- Antischistosomal antibody(can’t differentiate between new and old)
- UA
39
Schistosomiasis: Treatment
-Should occur 6-8 weeks after exposure as Praziquantel is most effective against adult worms
Praziquantel:
- Adults: 75 mg/kg tid x 1 day
- Children: 60mg/kg tid x 1 day
- Repeat in 2-4 weeks
Severe infections: corticosteroids
40
Nematode -> Chlonorchiasis: Chinese Liver Fluke Disease
- Infection in dogs, and other fish eating carnivores in Korea, China, Viet Nam
- Humans are substitute host
- Occurs after eating raw or poorly cooked, salted, pickled, smoked, marinated, dried, or poorly processed fish
41
Clonorchiasis: symptoms
Asymptomatic in light infections
Heavy:
- Fever
- RUQ pain
- Hepatobiliary fibrosis
- Cholangiohepatitis
- Pyogenic cholangitis
- Cholangiocarcinoma
42
Clonorchiasis: Diagnosis
- Anamnestic recall of eating raw fish
- Eosinophilia
- U/S findings
- CT
- MRI
- O+P
- Ig, not very effective
- PCR, experimental
43
Clonorchiasis: Treatment
Praziquantel: 40 mg/kg x 1 dose or 25mg/kg tid x 3 days
44
Trematodes -> Paragonium: Lung Fluke
- P. westermani, P. heterotremus and P. philippinensis
- China, Korea, Laos, Phillipines,Thailand, Viet Nam
- Others found in West Africa, North/Central/South America
- Common parasite of crustacean-eating animals (cats, dogs, mongooses, opossums, monkeys)
- Adult flukes live in lungs and lay eggs that are coughed up or swallowed and defecated
- Eggs reach fresh water and penetrate snails
- Cercariea (larvae) penetrate crustaceans
- When crustaceans are eaten (Raw), young worms hatch and penetrate intestinal wall and migrate to lungs
45
Paragonimiasis: Symptoms
- Cough
- Hemoptysis
- Chest pain
- Dyspnea
- Fever
- Pleural effusion
- Pneumothorax
- Abnormal migration can include, -Abdomen, Sub Q, and frequently the brain (abd pain, headaches, visual impairment, seizures)
46
Paragonimiasis: testing
- Anamnestic recall of eating raw crustaceans
- Eosinophilia
- U/S,XR,CT,MRI
- Consider Tb
- O+P
- Ig, not confirmatory
- PCR, developing
47
Paragonium: Treatment
Triclabendazole 20 mg/kg bid x 1 day
Praziquantel 25mg/kg tid x 3 days
48
Cestodes
Diphyllobothrium Latum (Fish Tapeworm): mc and largest
Hymenolepsis Nana (Dwarf)
Taenia Saginata (Beef)
Taenia Solium (Pork)
49
Cestodes: Diphyllobothrium latum
- Largest and most common tapeworm in humans
- Acquired by eating raw or undercooked fish
- Found in rivers and lakes of Northern Europe, North America and Southern South America
- Eggs are passed in humans, mature in fresh water within 3 weeks
- Larva (coracidia) develop and are eaten by copepods , which are eaten by fish
- Procercoid larvae migrate into gut and muscle and develop into plerocercoid larvae which infect humans
- Segments of the tapeworm absorb nutrients and have their own digestive system
- Adults may produce up to a MILLION eggs per day
- May live 20-25 years
- Length can exceed 10 meters
50
Diphyllobothrium latum: symptoms
- Usually asymptomatic
- B 12 deficiency, Pernicious Anemia
- Constipation, Obstruction
- Diarrhea
- Fatigue
- Subacute combined degeneration of spinal cord (B12 deficiency)
- Abdominal pain
- Vomiting
- Weight loss
- Cholecystitis, Choledochocystitis
51
Diphyllobothrium latum: Treatment
Praziquantel: 10-25 mg/kg qd x 1 day plus
Albendazole 400 mg bid x 14 days
Niclosamide: 2 g (crushed) qd x 1 day, then1g bid x 6 days
Diatrizoic Acid injection into intestinal wall edoscopically
