2. INTRODUCTION
• Among the many genera of free-living
amoebae that exist in nature, members of
only four genera have an association with
human disease: Acanthamoeba spp.
Balamuthia mandrillaris, Naegleria fowleri and
Sappinia pedata.
• They are aerobic unlike other amoebae which
are anaerobic

3. • They have also been called amphizoic
amoebae because these amoebae have the
ability to exist as free-living organisms in
nature and only occasionally invade a host and
live as parasites within host tissue.

4. • Naegleria fowleri, commonly found in warm
freshwater (like lakes, rivers, and hot springs) and
soil, is the only species of Naegleria known to
infect people.
• Naegleria fowleri is an amoeboflagellate, as it has
a transitory, pear-shaped flagellate stage along
with amoeboid trophozoite and resistant cyst
stages in its life cycle

5. • N.fowleri exists in three
forms
- trophozoite or
amoeboid form
- flagellate form
- cyst or resting
form

6. • Found on surface of vegetation and mud.
• The trophozoite moves rapidly by producing
rounded pseudopodia(lobopodia) .
• Size → 6-15µm in diameter.
• Slug shaped
• Observed in the CSF and in tissue of brain .

7. • Pear shaped cell with 2 flagella
• Found in surface layer of the water
• Rapidly motile
• Not found in CSF or brain

8. • They are uninucleated and possess double
cyst wall.
• Found on the surface of vegetation and mud.
• Not found in CSF or in brain.

9. • The amoeba grows well on monolayers of E6
and HLF cell cultures.
• N. fowleri can be grown in a cell-free axenic
medium.
• Proteose peptone glucose medium

10. • Naegleria fowleri has three stages, cysts
, trophozoites , and flagellated forms , in its life
cycle.
• The soil amoeba gets transformed from
trophozoite form to flagellate form in the water.
• Trophozoites can turn into temporary non-
feeding flagellated forms which usually revert
back to the trophozoite stage.
• The trophozoites multiply by binary fission.

12. • Trophozoites encyst under unfavorable
condition and excyst under favorable
condition.
• Trophozoites infect humans or animals by
penetrating the nasal mucosa and migrating
to the brain via the olfactory nerves causing
primary amoebic meningoencephalitis
(PAM).
• N. fowleri trophozoites are found in
cerebrospinal fluid (CSF) and tissue, while
flagellated forms are occasionally found in
CSF.

13. • Naegleria fowleri causes an acute, fulminating
hemorrhagic meningoencephalitis principally in
healthy children and young adults with a history
of recent exposure to warm fresh water.
• The striking feature of PAM is the rapid onset of
symptoms following exposure.
• The disease progresses rapidly, and, without
prompt diagnosis and intervention, death usually
occurs within a week or less

14. • The time from initial contact(swimming, diving, water
skiing, or simply immersing head in water) to onset of
illness is usually 5–7 days, and may even be as short at 24
h.
• The earliest symptoms are sudden onset of bifrontal or
bitemporal headaches, high fever,nuchal rigidity, followed
by nausea, vomiting, irritability and restlessness.
• Photophobia may occur late in the clinical course, followed
by neurological abnormalities, including
lethargy, seizures, confusion, coma, diplopia or bizarre
behavior, leading to death within a week.

15. • A wet-mount of the CSF -
for the presence of
actively moving
trophozoites.
• Smears of CSF should be
stained with Giemsa or
Wright stains to identify
the trophozoite.
• Cultivation
• Fluorescent antibody
staining of CSF
• PCR

16. • Few patients have survived PAM.
• Large dose of antifungal agent amphotericin-B
(1 mg/Kg/day I.V. for several days) or
ketoconazole (800 mg daily orally for one
month).
• Azithromycin, a macrolide antimicrobial, has
been shown to be effective against Naegleria
both in vitro and in vivo

17. • Chlorination of heavily used
swimming pools, especially
during summer months.
• In high-risk
areas, monitoring of
recreational waters for N.
fowleri amoebae should be
considered by local public
health authorities and
appropriate warnings
posted, particularly during
the hot summer months.

18. • Acanthamoeba is a microscopic, free-living amoeba
that can cause rare, but severe infections of the
eye, skin, and central nervous system.
• Several species of Acanthamoeba, including A.
culbertsoni, A. polyphaga, A. castellanii, A.
astronyxis, A. hatchetti, A. rhysodes, A.
divionensis, A. lugdunensis, and A. lenticulata are
implicated in human disease.
• The important species is A.culbertsoni

19. • Acanthamoeba spp. have
been found in soil;
fresh, brackish, and sea
water; sewage; swimming
pools; contact lens
equipment; medicinal
pools; dental treatment
units; dialysis machines;
heating, ventilating, and air
conditioning systems;
mammalian cell cultures;
vegetables; human nostrils
and throats; and human
and animal brain, skin, and
lung tissues.

20. Morphology
• There are two morphological forms
(a)Trophozoite
-A trophozoite is 20-50µm in size
-Rough exterior with several spine
like projections(acanthopoda).
(b)Cyst
-Spherical and 15µm in diameter.
• Both forms can be the source of infection

21. • Acanthamoeba has only two stages, cysts and
trophozoites , in its life cycle. No flagellated stage
exists as part of the life cycle.
• The trophozoites replicate by mitosis.
• When Acanthamoeba spp. enters the eye it can
cause severe keratitis in otherwise healthy
individuals, particularly contact lens users .
• When it enters the respiratory system or through
the skin, it can invade the central nervous system
by hematogenous dissemination causing
granulomatous amebic encephalitis (GAE) or
disseminated disease , or skin lesions in
individuals with compromised immune systems

22. • Granulomatous Amebic Encephalitis (GAE)
and disseminated infection primarily affect
people with compromised immune systems.
• Commonly seen in immunocompromised
patients, including those with
neoplasia, systemic lupus
erythematosus, human immunodeficiency
virus and tuberculosis
• Incubation period - unknown but estimated at
weeks to months. The route of infection is
aerosol or direct inoculation with
hematogenous spread to the CNS.

23. • Risk factors - alcoholism, drug
abuse, chemotherapy, corticosteroids and
organ transplantation
• Presentation:
– Symptoms -
headache, confusion, fever, lethargy, nausea and
vomiting, seizures, photophobia and neck
stiffness. Patients may become frankly psychotic.
– Signs - neck stiffness and focal neurological
deficits. Patients may also develop raised
intracranial pressure.

24. • Chronic amoebic keratitis is
a progressive disease of the
cornea, which is sight-
threatening
• Commonly seen in -
immunocompetent
patients. However, infection
does not confer immunity
and reinfection is common.
• Risk factors - poor contact
lens hygiene, corneal
abrasion or exposure of the
eye to contaminated water

25. • Epidemiology - the incidence of AK is 3 per
100,000 and around 85% of cases occur in people
who wear contact lenses
• Presentation - secondary bacterial infection
occurs commonly, making it difficult to diagnose.
– Symptoms - watering of eyes, eye pain with
photophobia, blurred vision and irritation are
common.
• Signs - include conjunctival
hyperemia, episcleritis, scleritis and loosening of
the corneal epithelium. Rarely, trophozoites can
infiltrate the corneal nerve and retina, leading to
chorioretinitis

26. Diagnosis
• CSF wet mount (usually
lymphocyte predominance
and low glucose)-motile
trophozoites
• Culture-Agar plates seeded
with E.coli
• Immunofluorescence or
polymerase chain reaction
(PCR).
• Corneal scrape or biopsy

27. • GAE is treated with pentamidine, usually in
combination with one or more of the following:
ketoconazole, hydroxystilbamidine, paromomycin, 5-
fluorocytosine polymyxin, sulfadiazine, trimethoprim-
sulfamethoxazole and azithromycin
• CAK-Therapy should include the cationic antiseptic
agents, of which chlorhexidine or polyhexamethylene
biguanide (PHMB) is the most effective.
• Ocular lesions –enucleation of ulcer and corneal
transplant

28. • killing Acanthamoeba spp. from the contact
lens.
• Tap water should not be used to rinse contact
lenses

29. • It was first identified in 1986 in a specimen
from the brain of a baboon that died in the
San Diego Wild Animal Park.
• Since then, approximately 200 cases of
Balamuthia disease have been reported
worldwide.
• Little is known at this time about how a
person becomes infected.

30. • Trophozoite- Two forms of pseudopodia either
broad lobose or finger like.
- 12-60µm in length
- sluggishly motile
• Cyst – It is spherical
-6-30µm in size

31. • Balamuthia amoebas are thought to enter the
body when soil containing Balamuthia comes in
contact with skin wounds and cuts, or when dust
containing Balamuthia is breathed in or gets in
the mouth.
• Once inside the body, the amoebas can then
travel to the brain and cause Granulomatous
Amebic Encephalitis (GAE).
• GAE is a severe disease of the brain that is fatal in
over 95% of cases.
• It can take weeks to months to develop the first
symptoms of Balamuthia GAE after initial
exposure to the amoebas.

32. Some early symptoms might include a combination of the
following:
• Severe headache
• Stiff neck, or neck pain with neck movement
• Sensitivity to light
• Nausea and vomiting
• Unusual fatigue
• Fever
• Difficulty walking or talking
• Sudden one-sided weakness
• Behavioral changes
• Seizures
• Unusual skin lesions that persist over months

33. • Microscopical examination
of CSF –Trophozoites
• Tissue culture
• The indirect
Immunofluorescence assay
(IFA) is a test used to detect
antibodies attached to
Balamuthia amoebas in
body tissues.
• PCR

34. • A combination of
flucytosine, pentamidine, fl
uconazole, sulfadiazine and
either azithromycin or
clarithromycin.
• Surgical excision of the
lesion may reduced the
parasite load.

35. • Gelman et al. (2001) reported the first and only
case of Sappinia amoebic encephalitis in a 38-
year-old previously healthy, immunocompetent
male .
• It had been isolated from soil, fresh water, forest
litter, mammalian faeces and the rectum of lizard.
• It has been described from Europe, North
America, Egypt, the Middle East, the West
Indies, and Japan

36. • Both trophozoite and cyst stages are
binucleate.
• The trophozoite measures 40–80 mm, is ovoid
or oblong, and appears to be flattened with
occasional wrinkles on the surface.
• The mature cyst is round and measures
15–30mm

37. • Description - meningoencephalitis associated
with cerebral tumor-like lesion, described in
one case only.
• Incubation period, mode of spread and risk
factors - all remain unknown. It is likely to be
reach the CNS either through the nasal
mucosa or the bloodstream.

38. • Epidemiology - only one case described in the
literature.
• Presentation - sinus infection was followed by
headache, vomiting and photophobia.

39. • CT brain scan in the single reported case
revealed a tumor-like mass.
• PCR is likely to be a very important tool in
diagnosing this particular infection.

40. • In the reported case, the cerebral lesion was
surgically removed and
azithromycin, pentamidine, itraconazole and
flucytosine were also administered.