Parasitic Diseases Flashcards
1
Q
first-line tx for severe malaria
A
Artemisinin Derivatives (artemether-lumefantrine, artesunate)
**Retains activity vs all spp
- SEs: hemolysis can occur after IV admin (post-artesunate delayed hemolysis) - can occur >7 days after infusion
- resistance noted to be appearing in SE Asia (esp Cambodia)
Chloroquine (4-aminoquinolone)
in areas of known chloroquine sensitivity (i.e. Central America, Panama Canal)
- SEs: pruritis (palms, soles, scalp), cardiac and CNS tox w/ IV tx
2
Q
SEs of 4-aminoquinolones (antimalarials)
- chloroquine
- mefloquine
- quinine/quinidine
A
- pruritis (palms, soles, scalp), cardiac, CNS
- dizziness, diarrhea, N/V. Neuropsych = most serious
- cinchonism (combo of tinnitus, deafness, HA, visual disturbances, dysphoria, vomiting, postural hypotension). Cardiac tox (postural hypotension, QT prolongation, ventricular arrhythmias)
3
Q
First line for malaria ppx (or tx for uncomplicated falciparum/unknown spp) in region w/ chloroquine resistance
A
atovaquone (an 8-aminoquinolone) + proguanil
Also w/ activity vs: Babesia, toxo, crypto, leishmaniasis, trichomonas
4
Q
General dx of intestinal, liver, keratitic amebae
A
two stages: trophozoite (active feeding stage) or cysts (infectious resting form)
- intestinal - both forms can be visualized via microscopy of stool sample. Preferred = stool Ag or PCR. Can see on histopath using PAS or H&E
- liver - imaging (u/s, CT), serology most helpful, or can aspirate and use PCR
- keratitis - corneal scraping for microsopy and cx
5
Q
A
Entamoeba histolytica (diff to distinguish from other spp)
(L = trophozoite w/ ingested RBCs; R = cyst)
- cyst - 12-15um; trophozoite - >20um
- will see trophozoites only in abscesses
6
Q
chronic severe diarrhea in children and IC adults
a cause of cholangitis in AIDS
A
cryptosporidium
7
Q
Dx of Giardia
A
- usually via demonstration of cysts in stool (occasionally trophozoite)
- 11-12um, oval, 4 nuclei
- trichrome, iron-hematoxylin stains
- variable shedding - requires multiple stool samples
- bx tissue - trichrome/Giemsa stain
8
Q
opportunistic intestinal pathogens
(HIV-assoc diarrhea, as well as diarrhea in other IC pts)
A
think of intestinal coccidia and microsporidia
= cryptosporidium, cyclospora, cystoisospora, sarcocystis
*obligate intracellular pathogens
9
Q
protozoan infection w/ myositis and fever
Malasia
A
sarcocystitis
10
Q
Free-Living Amebae Pathogens
A
- Naegleria fowleri
- Acanthamoeba
- Balamuthia mandrillaris
- Sappinia pedata (new, emerging)
11
Q
dx of acanthamoeba
A
can be cx on nutrient agar w/ layer of GN bacteria (they feed on bacteria and act as hosts for legionella, MAC, listeria)
most reliable = 18S rDNA sequencing
12
Q
Geo spread of malaria
- falciparum
- vivax
- ovale
- malariae
A
- all tropical regions (densest in Sub-Sarahan Africa)
- most prevalent in Asia (also Central/South America, Middle East, N Africa)
- Africa, Asia
- limited to SE Asia
13
Q
Which malaria spp persist in liver as hypnozoites and cause relapse?
A
vivax, ovale
“It’s not OVer!”
14
Q
A
P falciparum
- parasitised RBCs not enlarged
- RBCs containing mature trophozoites
- total parasite biomass = circulating parasites + sequestered parasites
15
Q
A
P vivax (ring, trophozoites, schizonts)
- parasites prefer young RBCs
- RBCs enlarged
- all stages present in peripheral blood
16
Q
A
P malariae (ring, trophozoites, schizonts)
- parasites prefer old RBCs
- pRBCs not enlarged
- all stages present in peripheral blood
17
Q
Epi of Trypanosomal brucei sbb
- favors riverine vegetation
- favors savannah
A
- Tb gambiense
- Tb rhodesiense
related to outdoor activities
18
Q
Most often detection of helminthic diseases
A
ID adult worm, egg, or larvae
19
Q
Soil transmitted helminths/nematodes (roundworms)
A
- Ascaris lumbricoides
- Necator americanus
- Ancylostoma duodenale
- Trichuris trichiura
- Strongyloides
- Enterobius (pinworm)
20
Q
raccoon exposure
severe encephalitis (eosinophilic) or ocular infection
A
Baylisascaris procyonis (roundworm)
21
Q
Taiwan, Thailand
eating snails
eosinophilic meningitis
A
angiostrongyliasis (caused by molluscun-borne rat lungworm)
humans = incidental hosts
22
Q
Dracunculiasis - epi, life cycle, infection
A
-
epi - poor communities in rural areas
- Chad, Ethiopia, Mali
- transmitted via small crustacean vector (Cyclops spp) - seasonal
- larvae swallowed in stagnant water → swallowed and penetrate through gut wall into abd cavity/retroperitoneum → females induce a blister, which forms an ulcer, causing person to stick leg in water, where female emerges from SQ tissue
23
Q
Vector for wuchereria bancrofti
A
mosquitos (culicine most common; also Aedes in Pacific Islands, Anopheles in Africa)
24
Q
vector for Onchocerca volvulus
A
blackfly - Simulium damnosum
requires running water for larval development, so transmission occurs in close prox to water sources
25
vector of loa loa
deer fly (Chrysops spp) = day biters
West and Central Africa
26
natural hosts and epi of Fasciola hepatica
found in sheep-rearing areas (highest prevalence in Bolivia, Peru)
acq by ingestion of water/leafy plants that grow in fresh water
humans = accidental hosts
27
schistosoma spp w/ terminal spine
S haematobium
28
schistosoma spp that looks like the rising sun
S japonicum
29
Schistosoma spp with subterminal spine
S mansoni
30
intestinal trematode (fasciolopsis buski = giant fluke)
how transmitted
snails are important vectors
ingestion of raw watercress, bamboo, water chestnuts
31
alveolar echinococcus hosts
E multilocularis
definitive host = raccoons, foxes, domestic dogs
32
Stain most useful for ID of blood parasites
Giemsa stain
33
Timing of blood samples to coincide w/ peak time of microfilaremia
Day (1000-1400)
Night (2200-0200)
Anytime
* Day: Loa loa
* Night: W bancrofti, B malayi, B timori
* Anytime: Onchocerca, Mansonella
34
Key areas of distribution for P vivax
Korea
former Soviet Union
35
Fever patterns of malaria
1. erythrocyte cycle duration = 48hrs. Fever pattern = irregular tertian fever
2. "" = 48hrs. Fever pattern = tertian fever
3. same as #2
4. "" = 72hrs. Quartan fever
5. "" = 24hrs. Quotidian fever
1. P falciparum
1. fever w/ no clear pattern. sounds "false"
2. P vivax
3. P ovale
4. P malariae
1. malariae is "meh" about fever (only occurs every 4 days or so)
5. P knowlesi
1. every day you "**know**lesi" the fever is coming
36
Mgmt of complicated malaria
ideal = IV artesunate
alt: quinine or chloroquine
37
Romana sign
u/l palpebral edema at site of inoculation of T cruzi (Chagas)
38
Acute and Chronic phases of Chagas
* _Acute_: fever, inflammation @ inoculation site (Romana sign if involves conjunctiva), local LAD, HSM
* _Chronic_:
* cardiac - biventricular HF, electrical abnormalities, thromboembolic disease, **apical aneurysm**
* GI - megaesophagus or megacolon, motility dysfunction
39
morphologic features of babesiosis (via thick/thin smear, stained via Wright or Giemsa)
* infected RBCs are **normal sized**
* no intracellular pigment
* delicate rings w/ varying morphologies
* multiply infected RBCs
* extracellular forms common (NOT seen in malaria)
* maltese cross (rare)
40
Toxoplasma Dx
serology, PCR, tissue all available
* IgG+/IgM- : past infection, NOT acute
* IgG-/IgM+ : likely acute infection
* if both IgG and IgM+ : could be either acute or chronic. IgM Abs can remain + for up to 12mos
in adv HIV or SOT: helpful to have IgG results prior to tx, as they can be misleading when IS. Will go with clinical picture most often + histo or PCR
41
Tx of toxoplasma
* Immunocompentent: self-limited. If end-organ disease, can use pyrimethamine + sulfadiazine + leucovorin x2-4wks
* Immunocompromised: either TMP/SMX or dapsone+pyrimethamine or atovaquone x6wk minim until reconstitution
42
* from drinking water or swimming pools (R to chloronation)
* Immuncompetent: asx - acute - subacute - chronic high V watery diarrhea (can continue d/t autoinfection from poor hand hygiene)
* Immunocompromised: profound D and severe wasting
* can have biliary tract involvement (acalculous chole, cholangitis, pancreatitis)
cryptosporidium
43
Dx cryptosporidium
Ag detection assays (DFA, ELISA)
NAAT
stool microscopy (4um) via mAF stain
44
Tx of cyclospora
TMP/SMX
45
Tx of cystoisospora
TMP/SMX
46
**giardia duodenalis**
* left: trophozoite
* pear-shaped, 2 nuclei, flagella
* righ: cyst
* 10-14um, mature w/ 4 nuclei, immature w/ 2 nuclei
47
granulomatous skin lesion in midface/nose → wks-mos of HA, F, visual changes, behavioral changes, focal deficits, increased ICP
balamuthia mandrillaris
48
two organisms that will show feeding tracks if cultured on a lawn of nonnutrient agar covered with enteric bacteria (E coli)
Acanthamoeba
Naegleria
49
Early: eosinophilia + F + dry cough/SOB/CP
Most pathology after 6-8wks: malnutrition, pancreatic/hepatobiliary d/t obstruction, intestinal obstruction rare
consider ascaris infection
50
50-70 x 40-50 um from stool sample
Ascaris lumbricoides
Tx: albendazole x1 dose
51
recurrent rectal prolapse
tichuris trichiura
52
chronic abdominal pain
eosinophilia
iron deficiency anemia
think hookworms (necator, ancylostoma)
53
migratory urticarial rash
fast moving
may have periumbilical purpura
larva currens w/ strongy
54
co-infection a/w strongy hyperinfection
HIV
HTLV-1
55
clinical manifestations of loa loa
* calabar swelling - angioedema of face and exposed extremities
* myalgias, arthralgias, fatigue
* "eye worm" - migration to conjunctiva
* endomyocardial fibrosis leading to myocarditis
* immune-complex nephropathy
* encephalitis (? d/t rx w/ DEC)
56
calabar swelling of R hand d/t angioedema from loa loa worm traveling through SQ tissue
57
Mazzotti reaction
fever, urticaria, swollen/tender LN, tachycardia/hypotension, edema, abdominal pain, followed by fatal encephalopathy ~7 days posttx w/ DEC
**d/t rapid killing by DEC of microfilaria in high burden loa loa infection → acute severe inflammatory reaction**
**\*\*also occurs w/ Onchocerciasis**
pretreat w/ albendazole or apheresis
also avoid DEC in individuals co-infected w/ onchocerciasis (tx oncho first, then can tx w/ DEC afterwards)
58
What and where
S japonicum
China and SE Asia
59
What and where
S mekongi
Mekong river basin (Cambodia to Laos)
60
What and where
S haematobium
sub-Saharan and Northern Africa
61
What and Where
S intercalatum
western/central Africa
62
What and where
S mansoni
sub-Saharan Africa and S America
63
Tx of schistosomiasis
1. praziquantal = gold standard
1. not recommended unless dx microscopy and/or serology
2. not initiated until at least 6wks from presumed exposure (need full adult maturation, as PZQ doesn't work vs larval stages)
3. exposes parasite Ag to host immune system
2. Adult disintegration can release a bunch of eggs
1. expulsion by peristalsis
3. confirm cure w/ egg excretion surv 2-6mos
64
complications of chronic infection with fasciola hepatica
* biliary
* pain, cholangitis, cholelithiasis, obstructive jaundice, pancreatitis
* sclerosing cholangitis
* biliary cirrhosis
65
General tx of parasitic disease
* nematodes
* trematodes
* cestodes
* nematodes (roundworms) - albendazole (except for...)
* strongy - ivermectin
* wuchereria - DEC
* loa loa - DEC (except co-infection w/ oncho or w/ heavy burden)
* oncho - ivermectin (avoid DEC)
* trematodes (flukes) - PZQ
* except fasciola - triclabendazole
* cestodes (tapeworms) - albendazole and/or PZQ
66
_IC pt w/:_
* encephalitis w/ mass lesions
* HSM
* F
* myocarditis
chagas (T cruzi)
67
_IC pt w/:_
* visceral or cutaneous disease noted (reactivation)
* visceral - F, HSM, pancytopenia
leishmania
68
_IC pt w/:_
* encephalitis w/ mass lesions
* pneumonitis
* retinitis
toxoplasma
69
dx and tx of microsporidia
* _dx_: modified trichrome stain, calcofluor white, IFA
* _tx_: albendazole
70
punctate keratoconjunctivitis (contact lens use, after eye surgery, bathing in hot springs)
**Many spp of microsporidia** (including vittaforma corneae)
## Footnote
\*a microsporidia (obligate intracellular fungi) - produces extracellular infective spores
71
**Encephalitozoon intestinalis**
* watery diarrhea
* biliary disease
* disseminated disease (liver, kidney, lung, sinuses)
\*a microsporidia (obligate intracellular fungi) - produces extracellular infective spores
72
**enterocytozoon bieneusi**
* watery diarrhea
* biliary disease (cholangitis, acalc chole)
\*a microsporidia (obligate intracellular fungi) - produces extracellular infective spores
73
* flask-shaped ulcerations in GI tract
* can have extraintestinal (liver, brain) in young men
**Entamoeba histolytica**
## Footnote
wide range of presentation: asx, traveler's diarrhea (common cause), colitis, ameboma, extraintestinal (liver, brain)
74
Dx and Tx
**Balantidium coli** = the only ciliated pathogen of humans. Single-celled, huge cell (70um x 200um)
* WW (esp Central/S America, SE Asia, Papua New Guinea)
* a/w ingestion of contaminated pig feces
_Tx_: tetracycline, metronidazole
75
Dx and Tx
**Entamoeba histolytica**
* _Dx_:
* **stool Ag testing (\>90% sens** for intestinal dz)
* stool OP (50% sens for colitis and abscess). Poor spec (unable to d/w histolytica from non-path dispar and diarrhea-only moshkovskii)
* **Serology - helpful in liver abscess (95% sens), and in intestinal (85% sens)**
* _Tx_: tinidazole or metro then paromomycin
76
20um
cystoisospora
77
10um
cyclospora
78
4um
cryptosporidium
79
protracted watery diarrhea
peripheral eos (the ONLY protozoa that does this)
cystoisospora belli (20um)
80
* **protracted diarrhea** (often w/ abrupt N/V, fever) often a/w bloating, flatus
* anorexia, wt loss, fatigue later
* food-assoc outbreaks - usually imported (**fresh fruits and vegetables - raspberries, lettuce, herbs**)
* tropical/subtropical - esp from Nepal, Peru, Guatemala
**cyclospora cayetanensis**
## Footnote
In NA - most cases from imported food
*(oocysts immature when first shed, require days-wks to sporulate and become infectious; P2P therefore unlikely)*
81
protracted watery diarrhea
cattle workers, daycare outbreaks
water supply outbreaks **(R to chlorine) = #1 cause of water park/swimming pool outbreaks**
cryptosporidium
82
when to suspect intestinal protozoan infection
**_protracted (wks-mos) watery diarrhea_**
and/or:
* h/o travel (domestic or foreign)
* recreational water activities
* altered immunity
* exposure to group care (daycare)
83
subacute granulomatous encephalitis
chronic **granulomatous keratitis** (contact lens, **LASIK**)
soil, water exposure
enters via LRT or broken skin
seen in IC hosts
acanthamoeba
84
fulminant meningoencephalitis
warm freshwater exposure
naegleria folweri
85
Typical presentations of T cruzi in IC pts (AIDS, SOT)
* _AIDS_: primarily reactivation neuro disease - acute, diffuse, necrotic meningoencephalitis. Focal CNS (similar to toxo)
* _SOT_: F, HSM, myocarditis (usually mos post-tx)
86
What is this?
Dx and Tx?
**Chagas disease**
## Footnote
_Acute disease_: ID parasites in blood
_Chronic_: IgG Abs (2 tests rec for dx)
_Tx_: benznidazole or nifurtimox
87
* _acute_: w/in 1 wk of infection, persists for 8wks. F, local LAD, unilateral painless periorbital edema
* _indeterminate_ stage: serology+ but not evidence of dz
_Chronic_: dilated CM, megaesophagus
**Chagas disease (tryp cruzi)**
88
Tx of African trypanosomiasis
**_must do CSF analysis to decide_** (if \>5 WBC = late stage)
* _early_:
* W Africa (gambiense) - pentamidine
* E Africa (rhodesiense) - suramine
* _late_:
* W Africa - eflornithine+nifurtimox;
* E Africa - melarsoprol *(co-admin w/ steroids to reduce rate of reactive encephalopathy)*
89
unique lab finding with African trypanosomiasis
**elevated IgM**
* *d/t persistent changing of their outer surface protein (contains as many as 1000 genes encoding different variant surface glycoprotein)*
* each trypanosome expresses one VSG at a time. But individual parasites can spont switch VSG
90
**chancre** at bite site + **regional LAD**
clears, then for wks: F, HSM, LAD, faint rash, HA
_late_: AMS, neuropsych/sleep d/o, terminal somnolent state
**African trypanosomiasis (sleeping sickness)**
tse tse fly
Trypanosoma brucei gambiense (W Africa)
rhodesiense (E Africa)
91
Tx of visceral leishmaniasis
***(L donovani, L infantum chagasi)** = amastigotes in macrophages go to local LNs then hematogenously spread to liver, spleen, BM*
## Footnote
_Dx_: intracellular amastigotes in BM or splenic aspirate. Can dx w/ serology.
_Tx_: LAMB (miltefosine for donovani)
92
Tx of mucosal leishmaniasis
*(**usually L (V) braziliensis,** also guyanensis, panamensis) = slow, progressive, destructive*
## Footnote
IV antimony or IV liposomal AMB or PO miltefosine
93
Tx of cutaneous leishmaniasis
* If **L (V) braziliensis, guyanensis, panamensis**:
* tx systemically w/ PO **miltefosine** (fluc or keto, but not FDAa)
* or IV pentavalent antimony (LAMB, but not FDAa)
* if none of the above:
* ok to obs as long as few lesions, \<5cm, not on face/fingers/toes/genitals, and a normal host
94
Dx of leishmaniasis
Standard = amastigotes in tissue using Giemsa
* _Cutaneous_ = edge of ulcer: scraping, aspirate, punch
* _Visceral_ = BM, LN, splenic aspirates (PCR)
touch prep under oil - look for amastigotes
culture - triple N media (wks to grow)
Histo via punch bx
PCR fairly sensitive
95
**chronic** cutaneous ulceration, usually **painless**
induration, scaliness, central depression, **raised border**
papule --\> nodule --\> ulcerative lesion --\> atrophic scar
usually self-resolves. Can see reactivation w/ friction
cutaneous leishmaniasis
96
Leishmaniasis spp likely to cause visceral disease
* L infantum chagasi
* L donovani
97
Leishmaniasis spp likely to cause mucosal disease
L **braziliensis** (also subgenus Viannia guyanensis, L V panamensis)
98
**Leishmania life cycle**
1. **Promastigote** - *extracellular*, in sandfly. Long. +flagella. large central nucleus w/ band-shaped kinetoplast
2. **Amastigote** - *intracellular* (macrophages). Round/oval. Wright-Giemsa stain = small, rod-shaped kinetoplast
99
**Babesiosis**
* _Transmission_ - **Ixodes** tick. NE and upper MW.
* _Sx_ - **Co-infection w/ Lyme/anaplasma**. Transfusion important source. HA, F/C, myalgias. Severe disease in HIV, asplenia
* _Labs_ - anemia, thrombocytopenia, mild increased LFTs. nl/l/h WBCs
* _Dx_ - small ring forms in RBCs, PCR
* _Tx_ - azithromycin + atovaquone. XChange for severe disease
100
Tx of P vivax or P ovale
* chloroquine x3 days --\> then primaquine x14 days (gets rid of hypnozoites)
OR
* tafenoquine
\*\*check G6PD prior to primaquine or tafenoquine
101
Tx of P falciparum
| (or uncomplicated knowlesi)
* _Uncomplicated_: chlor sens area - chloroquone; chlor R area - atovaquone/progaunil (Malarone)
* _Severe_: IV artesunate
102
malaria ppx in pregnant women in area of chloroquine resistance
**mefloquine**
\*\*beware of SEs: neuro sx, hallucinations, anxiety/depression
103
**Malaria ppx**
* Central America, Middle East
* Everywhere
* chloroquine (the only places w/ chloroquine sensitive malaria)
* atovaquone/proguanil, or doxy. Can use mefloquine (but not in SE Asia)
104
Dx of Malaria
* Ag capture (95% sens for falciparum; 85% for other spp), smear
_tx_ if no other explanation for fever in traveler. Repeat testing can help confirm (12-24hrs)
105
**P falciparum**
banana-shaped gametocyte
106
**P malariae**
band form
(also seen in P knowlesi)
107
**P ovale**
mature schizont
6-12 merozoites
108
**P vivax or ovale**
enlarged infected RBCs
**Schuffner's dots**
109
presentations of complicated malaria
* cerebral malaria
* respiratory distress/pulm edema
* severe anemia (hct \<15% kids; \<20% adults)
* renal failure
* hypoglycemia
* shock, acidosis
* jaundice
* bleeding d/o (evidence of DIC)
* \*\*\*usually w/ falciparum (when parasitemia \>20%). **In absence of end-organ damage, cutoff for severe dz = \>10% parasitemia**
110
General labs and sx of uncomplicated malaria
fevers/chills, HA, fatigue
abdominal pn w/ 20% as presenting sx
thrombocytopenia in 50%, mild anemia in 30% (+may see hemolysis w/ TBili and LDH), no leukocytosis usually
111
Malaria with shortest incubation period
also most lethal (**can infect RBC of ANY age**)
falciparum. knowlesi
\*\*\*generally w/ higher parasitemia
_Note_:
* pref younger RBCs - vivax
* pref older RBCs - malariae
112
Stages of Malaria parasite
* **Sporozoites** - infective stage from mosquito
* Liver **schizont** - asx **replicative** stage (become 10-30k merozoites)
* **Hypnozoite** - **dormant** liver stage (in **vivax and ovale**). Releases merozoites weeks-mos after primary infection
* **Merozoites** - infects RBCs and develops into ring-stage trophozoites. Matures into schizonts, which release merozoites --\> infects more RBCs
* **Gametocytes** - infective stage for mosquitos
113
MCC of fever in returned traveler
MALARIA
## Footnote
M falciparum = medical emergency
114
typically more ill than P malariae (d/t high parasitemia), but with morphologic similarities
Myanmar, Phillipines, Indonesia, Thailand
P knowlesi
115
eosinophilia + F + elevated AST/ALT in child
consider visceral larva migrans (toxocariasis)
116
abdominal pain after sushi
think anisakis
117
eosinophilic meningitis
angiostrongylus (most common)
118
muscle pain + eosinophilia
trichinella
119
SQ nodules
onchocerca volvulus
| (nonpainful, vascular fibrous nodules)
120
gram negative sepsis after TNF inhibitor
strongy hyperinfection
121
itchy feet return to tropics
ground itch d/t hookworms
122
allergic sx after trauma
echinococcus
123
crab/crayfish + pulm sx + eos
paragonimus
124
freshwater exposure + eosinophilia
schistosomiasis
125
Gnathostoma spinigerum and hispidum clinical picture
dx and rx
* _skin_: migratory, painful SQ swellings (q few 2wks); creeping eruption/cutaneous larva migrans
* _tissue_: visceral, eosinophilic meningoencephalitis, radiculomyelitis, ocular disease
* empiric dx or via bx. No Ab test.
* Rx: 3+ wks of albendazole
126
dx of toxocariasis
* clincal + Ab (ELISA via serum or IO fluid)
\*\*IgG only supportive - many individuals have prior exposure
* Tx: usually self-limited disease. Acute VLM/OML - albend + steroids
127
* fever, eos, HM + wheezing/PNA/SM. 2-5yo
* retinal lesions (look like solid tumors). 10-15yo
acq via animal feces ingestion
**raccoon + CNS disease (eos meningitis)**
**toxocariasis**
* visceral larva migrans
* ocular larva migrans
raccoon + CNS (eos meningitis)/more severe: baylisascariasis
128
* invasion of worm = pain, vomiting
* allergic reaction to worm = mild urticaria, itchy sensation back of throat, anaphylactic shock
raw/undercooked seafood (WW)
anisakis
## Footnote
\*\*\*ok if food frozen for a few days first **(do not eat fresh off the dock)**
129
trichinellosis
130
**MC parasitic cause of eosinophilic meningitis**
## Footnote
a/w ingestion of **snails/slugs (often eaten on vegetables)** or paratenic hosts (freshwater shrimps, crabs, frogs)
SE Asia, pacific basin, Caribbean
angiostrongylus cantonensis
131
abdominal cramps, diarrhea (if heavy infection)
striated muscle involvement: severe muscle pain, periorbital edema
eosinophilia
+/- fever, urticaria
**hunting pig, boar, horse - "wild game"**
**trichinellosis**
* larvae released from cysts by gastric acid and migrate to striated muscle, encyst, then live in "nurse cells"
* adults invade small bowel
132
clinical manifestations of loiasis
* asx microfilaremia
* non-spec: fatigue, urticaria, arthralgias/myalgias
* calabar swelling
* eyeworm
* end organ (rare): endomycocardial, encephalopathy, renal failure
133
progressive cognitive dysfunction
nodding seizures (esp when children start to eat)
growth stunting
tanzania, south sudan, northern uganda
Nodding syndrome
a/w onchocerciasis
134
Dx and tx of onchocerciasis
* serology (anti-filarial, onchocerca-specific)
* parasitologic: skin snips, nodulectomy
* _Tx_: ivermectin, moxidectin (FDA appr 2018 - longer 1/2-life)
* alt = doxy x6wks (kills endosymbiotic Wolbachia bacteria, kills adult worms)
135
ocular manifestations of onchocerciasis
punctate keratitis, sclerosing keratitis, chorioretinitis
136
Dx lymphatic filariasis (W bacrofti, B malayi)
* **Def**: ID of microcilariae in nighttime blood, detection of circulating Ag in blood (only Wb), ID of adult worm (by tissue bx or u/s "filaria dance sign")
* **Presumptive**: compatible clin picture + positive antifilarial Abs
* **Tx**: DEC
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paroxysmal nocturnal asthma
pulmonary infiltrates
peripheral blood eos (\>3k)
elevated serum IgE
likely d/t excessive immune response to microfilariae in lung vasculature
tropical pulmonary eosinophilia
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clinical presentations of W bacrofti, B malayi
asx
lymphangitis - retrograde
lymphatic obstruction (lymphedema, elephantiasis, hydrocele)
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tx of filariasis
* _lymphatic filariasis_ (Wuchereria, Brugia), loa loa - DEC
* _onchocerciasis_ - ivermectin
when to avoid DEC: loa w/ high microfilaremia (leads to encephalopathy and death); oncho (leads to severe skin inflammation and blindness)
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Body location (adults and microfilariae) of the following filarial infections:
* Wuchereria bancrotti, Brugia malayi - lymphatic filariasis (mosquitoes)
* loa loa - eyeworm (Chrysops flies)
* onchocerciasis - river blindness (blackflies)
* adults - lymphatics; microfil in blood (at night)
* adults - SQ tissues (moving); microfil - blood (day)
* adults - SQ tissues (nodules); microfil - skin
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child in MW - no travel hx
plays in sandbox
pet dog
F, HSM, wheezing, eos
toxocara canis (visceral larval migraines)
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peri-anal itching
fecal/oral route
**Enterobius vermicularis (pinworm)**
_Dx_: scotch tape test; eggs with one flat side
_Tx_: albendazole, mebendazole, or pyrantel pamoate in single dose followed by another in 2wks
tx all members of household
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dx and tx of strongy
serology = TOC
stool o/p: low sens
Tx: ivermectin
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life-cycle and dx
heavy infections = loose/freq stools, tenesmus, occ frank blood, rectal prolapse in children
trichuris trichiura (whipworm)
dx = eggs are **football shaped** w/ two **polar plugs**
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clinical presentations of hookworms (ancylostoma duodenale and necator americanus)
* **MAJOR cause of anemia and protein loss (b/c of plasma loss)**
* pneumonitis a/w wheezing, dyspnea, dry cough
* urticarial rash
* mild abd pn (they're chewing on GI mucosa)
if sensitized: papulovesicular dermatitis at entry site "ground itch" --\> worms migrate laterally leads to cutaneous larvae migrans
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**ascaris lumbricoides**
eggs in stool - once they migrate to gut (makes 200k/day)
\*will not find eggs until 2-3mos after pulm sx occur (they are just migrating at this time)
tx w/ albendazole or mebendazole
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_can cause the following syndromes_
* abdominal distention/pain or intestinal obstr
* eosinophilic pneumonitis w/ transient infiltrates
* cholangitis and/or pancreatitis (aberrant migration)
note this is dx if boards show barium swallow w/ silhoutte of worm
ascaris lumbricoides
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lifecycle of intestinal nematodes (roundworms)
* strongy, hookworms: skin (pruritic rxn) --\> lungs (can have Loeffler's syndrome) --\> gut
* ascaris (ingestion of eggs): gut --\> liver --\> lungs (MCC of Loeffler's) --\> gut
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_Acq of nematodes (roundworm)_
* which obtained via ingestion of eggs from fecally contaminated food/soil?
* which via direct penetration of skin?
* which via ingestion of larvae in food?
* which via vector transmission?
* ascaris, trichuris, enterobius, toxocara
* hookworms, strongy
* trichinella, angiostrongylus, anisakis
* wuchereria, brugia, oncho, loa
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MC intestinal nematodes (roundworms)
* ascaris lumbricoides
* ancylostoma duodenale
* necator americanus
* trichuris trichiura
* strongy
* enterobius vermicularis
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pruritic rash
recently moved to... (e.g. FL)
anyclostoma braziliense (cutaneous larval migrans)
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* Left: E granulosus
* Right: E multilocularis - infiltrative, tumor-like growth, poorly demarcated, semi-solid nature. **fox/rodent life cycle**
boards may show large liver cyst w/ multiple daughter cysts = multilocularis (to confuse you w/ granulosus)
multilocularis will not have multiple loculations like granulosus grossly on imaging (only see loculations under micro)
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Tx of echinococcus granulosus
*\*\*depends on stage of liver cyst*
## Footnote
*_Note to remember_: tx w/ albendazole for several days prior to surgery or PAIR or FNA (usually 2D-1W prior, then 1-3mos after)*
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How to DX?
Echinococcus granulosus
## Footnote
**IgA ELISA = 85% sens for liver cysts (50% sens for lung cyst)**
_\*\*if need FNA for dx --\> start albendazole for a few days prior to prevent growth of spilled cystic material in the peritoneal cavity_
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Presentations of echinococcus granulosis
* _most common_
* _uncommon_
*most cysts in the liver (65%). 25% in the lung (RLL MC). The rest can appear anywhere*
* _Common (occur w/ rupture of a cyst)_ - allergic sx/anaphylaxis. Cholangitis/biliary obstruction. Peritonitis. PNA
* _Uncommon_: bone fracture. Mechanical rupture of heart w/ tamponade. Hematuria/flank pain (renal cysts)
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anatomy of echinococcus granulosus (hydatic cyst)
= watery vessel
* outer acellular laminated layer - will see surrounding inflammatory response of fibrosis and chronic inflammation
* inner, nucleated germinal layer (pluripotential tissue)
* internal cystic fluid + daughter cysts
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acq of echinococcus granulosus
adult worms live in dog intestines
humans = accidental hosts
**infection by ingestion of eggs in dog feces**
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Tx of neurocysticercosis
* **Rx tx dec risk of future seizures, but inc immediate risk of seizures**
* _If hyrdocephalus/diffuse edema_: steroids+surgery. **not antiparasitic therapy**
* if _no inc ICP_: 1-2 cysts - albendazole; \>2 cysts - albendazole + praziquantel
* start corticosteroids _prior to_ antiparasitic tx
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Dx of neurocysticercosis
* **Def**: tissue bx. Multiple cystic lesions w/ scolex on imaging. Retinal cysticercus on fundo
* presumptive: suggestive lesions on imaging (_be wary of single lesion, even if typical_)
* cysticercosis serology = supportive (sens if high burden of disease)
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2 effects of neurocysticercosis
(remember: d/t ingestion of eggs/larval form of solinium from human stool)
1. pressure effect of cortical area (cysts usually grow slowly and push normal cells apart)
2. inflammatory response to dying cyst --\> scarring (most common)
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D latum
* acquisition
* sx
* dx
* tx
* acq via ingestion of **fish** with larvae
* **B12 deficiency (~40% of pts)**
* DX: eggs/proglottids in stool
* TX: praziquantel
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Taenia saginatum
* acquisition
* sx
* dx
* tx
* acq via larvae in **undercooked beef**
* few sx (though can grow up to 10m)
* DX: eggs/proglottids in stool
* TX: praziquantel
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Major Cestodes (flatworms/tapeworms)
* basic info
* Intestinal tapeworms:
* Larval cysts:
all (except D latum) have suckers w/ surrounding hooklets on the scolex (head) to attach to intestine
have proglottid segments (contain repro organs)
* Intestinal: taenia, diphyllobothrium latum
* Larval cysts: taenia solium, echinococcus
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passing flat tissue fragments in stool
flatworm infection
very common complaint
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helminths a/w the following complications/syndromes
* HTLV-1 infection
* bladder cancer
* appy
* liver abscess
* seizures
* strongy (that is, diff to eradicate strongy if pt has HTLV-1; often require multiple ivermectin tx)
* S. haematobium
* enterobius
* none - a/w protozoa
* cystecercosis
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Metagonimus yokagawi
* acquisition
* sx
* tx
(intestinal fluke)
* ingestion of larvae in **undercooked fish**
* sx: diarrhea and abdominal pain
* tx: praziquantel
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Fasciolopsis buski
* acquisition
* sx
* dx
* tx
(intestinal fluke)
* eating encysted larvae on aquatic vegetation
* SX: depends on burden. Usually asx. Can see D, F, abd pn, ulceration, hemorrhage
* DX: eggs in stool
* TX: praziquantel
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Paragonimus westermani
* life cycle (how acq)
* common syndromes
* dx
* tx
**(lung fluke)**
* eggs --\> snails --\> **freshwater crabs/crayfish (in US - crayfish in MO)**
* acq via ingestion of undercooked seafood
* adults migrate to lungs
* SX:
* **Acute migration** - fever, cough, D; **migration through lungs** - may dev chest pain
* **Chronic** - chronic pulmonary symptoms (chronic PNA often a/w eos, can be confused w/ TB)
* DX: sputum and/or stool exam for eggs
* TX: praziquantel
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Clonorchis sinsensis
Opisthorchis viverrini
(both similar)
* life cycle
* common syndromes they cause
(liver flukes)
eggs --\> snails --\> freshwater fish
acq by ingestion of undercooked fish
develop in duodenum --\> reside biliary ducts/GB/pancreatic ducts
\*\*CMI doesn't develop - repeated infections engender cumulative worm burden
\*\*\*can live for 50yrs, making 2000 eggs/day
_syndromes_
* **biliary obstruction**
* **cholelithiasis**
* **cholangiocarcinoma**
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dx and tx of fasciola hepatica
* eggs in stool (low sensitivity), serology
* triclabendazole (FDA-appr in 2019)
* **\*\*\*this is the only trematode that doesn't respond well to praziquantel**
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life cycle of fasciola hepatica
(liver fluke)
* acq via eating encysted larvae on acquatic vegetation (eg water chestnuts) --\> migrates through liver **(RUQ pn, hepatitis)** --\> arrives at biliary ducts
* matures over 3-4mos
* can induce biliary obstruction
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when to consider schisto
freshwater exposure in endemic region
* _acute_ syndrome: F, abd pn, myalgias, eos, etc
* _chronic_ syndrome: abd/pelvic pn, blood in stool, diarrhea, portal HTN, hematuria, eos
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1. S mansoni (lateral spine)
2. S haematobium (terminal spine)
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Manifestations of chronic schisto
* mansoni
* haematobium
* japonicum
* mansoni (**GI**): granulmatous colitis, portal HTN, colonic ulceration
* haematobium (**GU**): will see hematuria/pyuria. Granulomatous cystitis, bladder fibrosis/cancer, obstructive uropathy, calcified eggs in bladder wall. Immune complex nephrotic syndrome. Can see chronic genital disease as well (epididymitis, prostatitis; uterine abn)
* japonicum: **CNS** disease (eggs to brain/spinal cord)
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Basics of Acute Schistosomiasis (Katayama Fever)
* who
* when
* sx
* labs
* dx
* occurs in previously unexposed hosts
* occurs ~3-8wks (**correlates w/ adult maturation and onset of egg-laying**)
* fever, myalgias, abd pn, HA, D, urticaria (can look quite ill)
* striking eosinophilia, elevated AST and alk phos
* no reliable way to confirm dx acutely (serology and OP often negative d/t few/no eggs in stool yet)
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Acute schistosomiasis (cercarial dermatitis/swimmer's itch)
urticarial plaques/pruritic papules upon **re-exposure** to cercariae penetrating skin in a sensitized individual
usually just a nuisance - infection never takes
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Schistosomiasis life cycle
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Basic info re trematodes (flukes)
* usually w/ two muscular suckers
* usually hermaphroditic (except Schisto)
* require intermediate hosts
* praziquantal tx all (exc fasciola)
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_List of Flukes_
* blood flukes
* liver flukes
* lung flukes
* intestinal flukes
* schistosoma (mansoni, japonicum, haematobium)
* fasciola hepatica, clonorchis sinensis, opisthorchis viverrini
* paragonimus westermani
* fasciolopsis buski, metagonimus
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effect of schistosome flukes in the portal V system
releases eggs --\> travel through GI wall and cause eosinophilic colitis
181
The few exceptions of helminths that multiply within the host
* strongyloides
* paracapillaria
* hymenolepis
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Groups of pathogenic helminths
(all eukaryotic, multicellular animals)
* Phylum Platyhelminth - trematodes (flukes), cestodes (tapeworms)
* Phylym Nematode (roundworms)
