E. histolytica

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Review of
parasitic
infections
 Fungal and parasitic skin
and soft tissue infections
Assoc.Prof.Dr.Yesim Gurol
CASE 1
A 31-year-old man was admitted to a local hospital with fever, chills,
myalgia, and fatigue. His travel history included a two week workrelated trip to Cambodia and a one week vacation in Connecticut
immediately after that trip.
His symptoms began about 3 days after returning from Connecticut. He
indicated that he did take anti-malarial prophylaxis while in Cambodia
but failed to take the remainder of his medication before going to
Connecticut.
Blood smears were ordered, stained with Giemsa, and examined. Figures
show what was observed at 1000x oil magnification. What is your
diagnosis? Based on what criteria?
This was a case of babesiosis caused by Babesia sp. Morphologic
features included:
·
pleomorphic and vacuolated intraerythrocytic ring-like parasites in
normal-sized red blood cells.
·
an absence of malarial pigment found in Plasmodium species.
In general, identification of Babesia to the species or strain level is not
possible by morphology, and requires molecular analysis of a blood
specimen. Regrettably, no pretreatment blood was available in this case
for subsequent testing so the final diagnosis remains Babesia sp.
CASE 2
 A seven year old child was taken to the doctor for
abdominal pain, gas, bloating, and intermittent diarrhea.
The symptoms started two days after returning from
summer camp. Stool specimene were collected for ovaparasite examination. Check the figures and what is the
best diagnosis?
This was case of giardiasis caused by Giardia intestinalis. Also
present was Chilomastix mesnili, a flagellate generally considered
nonpathogenic. Diagnostic morphologic features included:
- ovoid cysts of G. İntestinalis ( showing nuclei, axonemes and
median bodies.)
- oval to lemon-shaped cysts of C. mesnili (showing a single
nucleus and a cytostome running along a lateral edge.
- The Chilomastix cysts are slightly smaller than the Giardia
cysts.
CASE 3
A 30-year-old man presented to his primary care provider with
abdominal pain, fatigue, and diarrhea (sometimes tinged with
blood). The patient had recently returned after two weeks in
Armenia.
A stool specimen was collected in both 10% formalin and polyvinyl alcohol (PVA) for routine ova-and-parasite (O&P)
examination. A smear was prepared from the PVA-preserved
specimen and stained with trichrome.
The objects of interest measured on average 25 micrometers in
length. What is your diagnosis? Based on what criteria?
This was a case of amebiasis caused by Entamoeba
histolytica. Morphologic features shown included:
·
trophozoites showing ingested red blood cells.
·
nuclei showing evenly distributed peripheral chromatin and a
centrally-located karyosome.
·
some trophozoites showing progressive pseudopods.
If ingested red blood cells are observed, a species-level
identification of E. histolytica may be given. Specimens presenting
with these morphologic features, but without ingested RBCs, should
be reported as E. histolytica/dispar and further testing such as PCR
should be performed.
CASE 4
A 27-year-old male from Cameroon, who immigrated to the U.S.
six years ago, presented to his health care provider with ocular
pain and swelling. He told his health care provider that he had an
episode of "a worm crawling in his eye" three years prior. Upon
examination, the man was found to have a worm-like object
below the conjunctiva (Figure) and it was removed surgically.
Figure B shows the object after it was removed; it measured a
little over 4 cm. Figure C shows one end of the object at 40x
magnification. A blood specimen was also collected and thick
smears were prepared and stained with Giemsa. What is your
diagnosis? Based on what criteria?
This was a case of loiasis caused by Loa loa. Diagnostic
features included:
• location of the worm in the eye.
• the presence of irregularly-spaced bosses on the
cuticle
• robust microfilaria with a short head space and a
tapered tail with nuclei spaced irregularly to the tip of
the tail
CASE 5
 The patient was 3 year old female. Her mother
was an elementary school teacher and on school
days the patient attended a day care center.
The patient presented with a 3 day history of
increasingly severe diarrhea with three episodes
of vomiting.
 In physical examination the child was lethargic
and appeared dehydrated. She had a
temperature 38oC. The child had lost weight
since the last visit to the doctor.
 A stool specimen was collected and reported as
watery, no white or red cell was seen in
microscopy.
 Culture was negative. A modified acid fast stain
of fecal specimen is shown.
 The child’s diarrhae persisted for 1 more week
before resolving.
 What organism is infecting this patient? What
other intestinal pathogens share similar staining
characteristics with this organism?
 What other techniques besides modified acid
fast stains are available for detection this
organism?
 How do you think the child acquired this
organism?
 What kind of patients have a risk to be infected
with this agent as a chronic diarrhae?
CASE 6
 The patient was a 23 year old male with a 3 year
history of pain and itching of the toes of both
feet and his left palm and fingers. Small red
raised lesions were visible on his left fingers. In
the past 3 months he had lost the nails from his
great toes.
 He was in good health which included training
for triathlons (swimming 1 hour a day, running
and biking).
 He got medications and stopped for some time
he got worsened.
 Culture of the organism and microscopy is as
shown.

Cases in Medical Microbiology and Infectious
Diseases, 3 rd edition, ASM
 The outstanding clinical diagnostic symptom is intense
itching, usually in the interdigital folds and sides of the
fingers, buttocks, external genitalia, wrists, and elbows.
The uncomplicated lesions appear as short, slightly raised
cutaneous burrows.
 At the end of the burrow, there is frequently a vesicle
containing the female mite. The intense pruritus usually
leads to excoriation of the skin secondary to scratching,
which in turn produces crusts and secondary bacterial
infection.