acanthamoeba polyphagga acanthamoeba ppt

acanthamoeba

1. Name :- Dasu Giri Naga Sai ram Group :-37 ,sem :-. 1 Subject :- biology ACANTAMOEBA POLYPHAGA

2. Classification

3. Morphology Virions  of Acanthamoeba polyphaga mimivirus (APMV) are 400 nm in diameter, spherical in shape and surrounded by an icosahedral  capsid . They are not filterable through 0.2 μ m  pore size  filters. No envelope has been observed.  Fibrils  80 nm in length can be seen attached to the capsid. Virions resemble small  Gram-positive cocci  when Gram stained and was therefore named “mimivirus” (for mimicking microbe). PHYSICAL PROPERTIES :- Nucleic acid :- double standard DNA PROTEINS :- not present

4. Lipids – not present Carbohydrateses -not present BIOLOGICAL PROPERTIES :- HOST RANG -Acanthamoeba a polyphaga mimivirus was isolated from the water of a coolingtower . TRANSMISSION-Unknown. GEOGRAPHICAL DISTRIBUTION -ndirect ct evidences (serology) indicated human infection in England, Canada and France.

5. Life cycle

6. TYPES Acanthamoeba are among the most prevalent environmental protozoa and have been classified by 18s rDNA sequencing into at least 20 genotypes, designated T1-T20. The most common environmental and human pathogens belong to the T4 genotype. The following species of  Acanthamoeba  have been associated with human disease:   Acanthamoeba   castellanii  (T4) Acanthamoeba   polyphaga  (T4) Acanthamoeba culbertsoni  (T10) Acanthamoeba   palestinensis  (T2)

7. Acanthamoeba astronyxis  (T7) Acanthamoeba hatchetti  (T11) Acanthamoeba rhysodes  (T4) Acanthamoeba   byersi  (T18) Acanthamoeba divionensis  (T4) TRANSMISSION :- A . polyphaga  is a direct pathogen when it enters the respiratory tract and causes GAE or when contact lens wearers come in direct contact and contract  Acanthamoeba  keratitis. However, the amoeba can serve as an indirect pathogen as it becomes a host to other pathogenic organisms

8. DISEASE CAUSED A. polyphaga  can be pathogenic to humans with compromised immune systems and cause a rare but fatal nervous system disease called Granulomatous Amebic Encephalitis (GAE) . The amoeba enters the body through the respiratory tract and invades the alveolar blood vessels, ultimately passing through the blood-brain barrier and entering the central nervous system (CNS)  Granulomatous amoebic encephalitis  ( GAE )is a rare, usually fatal, subacute-to-chronic  central nervous system  disease caused by certain species of free-living  amoebae of the genera  Acanthamoeba ,  Balamuthia  and  Sappinia pedata . The term is most commonly used with  Acanthamoeba . In more modern references, the term " balamuthia amoebic encephalitis " (BAE) is commonly used when  Balamuthia mandrillaris  is the cause

9. MRI showing result of GAE caused by an infection of  Acanthamoeba , granulomatous amoebic encephalitis (GAE), which occurs most commonly in humans with compromised immune systems in the setting of advanced human immunodeficiency virus (HIV) infection, organ transplant, or chronic debilitating illness. 

10. CLINICAL SYMPTOMS GAE starts slowly, with symptoms like headache, nausea, dizziness, irritability and a low-grade fever. The CNS symptoms depend on the part of the brain that is infected. Changes in behavior are an important sign. Other CNS signs may include  seizures ,  focal neurologic signs ,  diplopia  (double vision),  cranial nerve palsies ,  ataxia , confusion, and personality changes. Some of the symptoms may mimic  glioma  (especially  brainstem glioma ), or other brain diseases, which may hamper timely diagnosis. The symptoms are caused by inflammatory  necrosis  of brain tissue brought on by compounds released from the organisms

11. TREATMENT Treatment of  granulomatous amebic encephalitis  rarely is successful, probably because of a combination of late diagnosis and  antimicrobial  failure. Although no standard regimen exists, anecdotally successful regimens have involved combination therapy including  pentamidine ,  sulfadiazine ,  trimethoprim-sulfamethoxazole ,  flucytosine , and  fluconazole ,  ketoconazole , or  itraconazole . Treatment of  granulomatous  amebic encephalitis in  immunocompromised hosts  can be particularly challenging; however, treatment success has been reported with combination therapy using fluconazole,  pyrimethamine , and sulfadiazine along with surgical resection of the CNS lesion.Oral regimens including a combination of trimethoprim-sulfamethoxazole,  rifampin , and ketoconazole have been used successfully to treat children with chronic  Acanthamoeba  meningitis.

12.  A small retrospective analysis suggested that adding  miltefosine  to treatment regimen may increase survival, but more data are needed to make definitive conclusions. Miltefosine is currently available through the Centers for Disease Control and Prevention as an investigational drug to treat free-living  ameba infections .

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