OPPORTUNISTIC OPPORTUNISTIC AMOEBAAMOEBA

FACULTATIVE FACULTATIVE PARASITESPARASITES

• Naegleria is an amoeba commonly found in warm freshwater and soil. Only one species of Naegleria infects people, Naegleria fowleri. It causes a very rare but severe brain infection. Most infections are fatal.

• Naegleria fowleri (also known as "the brain-eating amoeba") is a free-living amoeba typically found in warm fresh water, from 25–35 degrees Celsius (77–95 degrees Fahrenheit) in an amoeboid or temporary flagellate stage. It belongs to a group called the Percolozoa or Heterolobosea.

• N. fowleri can invade and attack the human nervous system; although this occurs rarely, such an infection will nearly always result in the death of the victim.

Naegleria FowleriNaegleria Fowleri

Location in host: CNS, CSF Definitive host: HumanIntermediate host: Not present; direct

transmission By inhalation of trophozoite stage.

Infective stage: Trophozoite stage.Diagnostic stage: Trophozoite in CSF, or in

brain section of fatal cases.Disease: Primary Amoebic

Meningoencephalitis.

InfectionInfection• In humans, N. fowleri can invade the central nervous system

via the nose, more specifically the olfactory mucosa and nasal tissues. The penetration initially results in significant necrosis of and hemorrhaging in the olfactory bulbs. From there, amoebae climb along nerve fibers through the floor of the cranium via the cribriform plate and into the brain. It then becomes pathogenic, causing primary amoebic meningoencephalitis (PAM or PAME).

• PAM is a syndrome affecting the central nervous system, characterized by changes in olfactory perception (taste and smell), followed by vomiting, nausea, fever, headache, and the rapid onset of coma and death in two weeks.

• PAM usually occurs in healthy children or young adults with no prior history of immune compromise who have recently been exposed to bodies of fresh water.

Life Cycle of Naegleria Life Cycle of Naegleria FowleriFowleri

• Naegleria fowleri, often referred to as simply “naegleria,” exists in nature in three forms: a flagellate, an amoeba, and a cyst.

• The flagellate stage, a small pear-shaped organism with two long whip-like flagellae at one end, is very mobile and is probably the stage that infects people who are exposed through water.

• Within the body, the flagellate converts to an amoeba, a slow moving single-celled organism that proliferates by dividing repeatedly.

• Returned to water, and occasionally in human spinal fluid, the amoeba will once again assume the flagellate form.

• The cyst stage, a tough spherical stage found only in the environment, forms when conditions are unfavorable for naegleria.

Life CycleLife Cycle

Naegleria FowleriNaegleria Fowleri TrophozoiteTrophozoite

Amoeboid Form:

• Free living in warm water.• Infective stage for human. • Large kinetoplast.• No peripheral chromatin

Where is Where is NaegleriaNaegleria found?found?

The ameba grows best in warm or hot water. Most commonly, the ameba may be found in:

• Bodies of warm freshwater, such as lakes, rivers

• Geothermal (naturally hot) water such as hot springs • Geothermal (naturally hot) drinking water sources

• Warm water discharge from industrial plants

• Poorly maintained and minimally-chlorinated or unchlorinated swimming pools

• Soil

• Naegleria is not found in salt water locations like the ocean.

PreventionPreventionThe only known way to prevent Naegleria infections is to refrain

from water-related activities. However, some measures that might reduce risk by limiting the chance of contaminated

water going up the nose include:

• Avoid water-related activities in bodies of warm freshwater, hot springs, and thermally-polluted water such as water around power plants.

• Avoid water-related activities in warm freshwater during periods of high water temperature and low water levels.

• Hold the nose shut or use nose clips when taking part in water-related activities in bodies of warm freshwater such as lakes, rivers, or hot springs.

• Avoid digging in or stirring up the sediment while taking part

in water-related activities in shallow, warm freshwater areas.

Naegleria FowleriNaegleria Fowleri

SummarySummaryNaegleria Fowleri• Found in freshwater lake or ponds, swimming pools• Life Cycle:

a) Trophozoite– Amoeboid form.– Flagellate form

b) Cyst• Pathogenesis

– Portal of Entry: olfactory neuroepithelium– Causes Primary Amoebic Meningoencephalitis– Seen in healthy individuals

• Diagnosis– Amoebas in tissues are present ONLY as trophozoite– NO cysts seen in tissues.

• Treatment: Amphotericin B• Prevention:

Avoid contact with stagnant waters. Hyperchlorination not effective. Baguacil

Video about Naegleria Video about Naegleria FowleriFowleri

• Acanthamoeba is a microscopic, free-living ameba commonly found in the environment that can cause rare but severe illness. Acanthamoeba causes three main types of illness involving the eye (keratitis), the brain and spinal cord (Granulomatous Amebic Encephalitis), and infections that can spread from an entry point to the entire body (disseminated infection).

• Acanthamoeba is a genus of amoebae, one of the most common protozoa in soil, and also frequently found in fresh water and other habitats. The cells are small, usually 15 to 35 μm in length and oval to triangular in shape when moving. The pseudopods form a clear hemispherical lobe at the anterior, and there are various short filose extensions from the margins of the body. These give it a spiny appearance, which is what the name Acanthamoeba refers to. Cysts are common. Most species are free-living bacterivores, but some are opportunists that can cause infections in humans and other animals.

• Acanthamoeba (pronounced ah-canth-ah-me-baa) literally means spiny amoeba, and that’s exactly what Acanthamoeba spp. are—single celled amoebae that produce spiny pseudopodia as they move slowly along. About five times the size of a human red blood cell, acanthamoebae are large as microbes go, but still much too small to be seen with the naked eye. The most common amoebae in fresh water and soil, Acanthamoeba spp. sometimes cause human infections.

• In water, moist soil, mud, and decaying organic material, acanthamoebae feed on bacteria and other microscopic organisms. In water supply systems, these amoebae live in the biofilm of organisms that proliferate on the inside surfaces of pipes, grazing on the other organisms in the biofilm. When the environment gets dry, they wrap themselves up inside a tough cyst wall and wait for the moisture and the food to return. They’re resistant to drying, chlorine, and many antiseptics. They are tough and ubiquitous.

Life Cycle of Life Cycle of AcanthamoebaAcanthamoeba

• 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 (nuclear membrane does not remain intact) .  The trophozoites are the infective forms, although both cysts and trophozoites gain entry into the body through various means. 

• Entry can occur through the eye, the nasal passages to the lower respiratory tract , or ulcerated or broken skin.

• 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.

• Acanthamoeba spp. cysts and trophozoites are found in tissue.

Life CycleLife Cycle

Symptoms of InfectionSymptoms of Infection• The symptoms of Acanthamoeba keratitis can be very similar to the

symptoms of other more common eye infections. The symptoms, which can last several weeks to months, are not the same for everybody and might include:

– Eye pain – Eye redness – Blurred vision – Sensitivity to light – Sensation of something in the eye – Excessive tearing

• Eye infection with Acanthamoeba has never been known to cause infections in other parts of the body.

• Acanthamoeba can also cause skin lesions and/or disseminated infection. These infections usually occur in people with compromised immune systems. Acanthamoeba can cause a serious, most often deadly, infection of the brain and spinal cord called Granulomatous Amebic Encephalitis (GAE). Once infected, a person may suffer with headaches, stiff neck, nausea and vomiting, tiredness, confusion, lack of attention to people and surroundings, loss of balance and bodily control, seizures, and hallucinations. Symptoms progress over several weeks and death usually occurs. Skin infections do not necessarily lead to disseminated disease.

PreventionPrevention• Even though acanthamoeba keratitis is much more common than

it used to be, it is still rare even among contact lens wearers. To avoid this devastating infection:– Never allow lenses or cases to come in contact with tap water. – Never swim with contact lenses in, even in a chlorinated

swimming pool. – Don’t shower with contact lenses in your eyes. – Never wear contact lenses when your eyes are irritated or if

you suspect you have even a tiny scratch. – Do not keep lenses or solutions past their expiry date. – Do not wear lenses for longer periods than your eye

professional recommends. – Always carefully follow your eye professional’s instructions for

cleaning contact lenses. – A lens cleaning routine that requires rubbing is preferable to

one that only requires soaking.• Contact lenses and lens care disinfectants are improving;

however, contact lens wearers still have to be careful. Taking the precautions listed above should keep this opportunistic amoeba where it belongs—in the environment.

Where is Where is AcanthamoebaAcanthamoeba found?found?

• Acanthamoeba is found worldwide. Most commonly, Acanthamoeba is found in the soil and dust, in fresh water sources such as lakes, rivers, and hot springs, in brackish water, and in sea water. Acanthamoeba can also be found in swimming pools, hot tubs, in drinking water systems (e.g., slime layers in pipes, taps), as well as heating, ventilating, and air conditioning (HVAC) systems and humidifiers.

AcanthamoebaAcanthamoeba

SummarySummary

Acanthamoeba• Most common species: Acanthamoeba culbertsoni• Found in soil or stagnant waters

Source of infection: dust or water Resistant to chlorine and drying

• Life cyclea) Trophozoite - no flagellate formb) Cyst

• Pathogenesis Portal of Entry: broken or ulcerated skin/eyes lungs and GIT

• Disease: Chronic Meningoencephalitis in immunocompromised

host Corneal ulceration

• Treatment: Sulfadiazine• Prevention: early diagnosis

prompt treatment of lesions

Free-Living AmoebasFree-Living Amoebas

Submitted To:Submitted To:Dr. Celino

Elizabeth G. QuerubinMon Aldrin E. Evangelista

Tricia A. NaridoBSN 2-B

Tuesday 4:30-7:30

Prepared By:Prepared By: