KwaZulu-Natal

Ecology

The contamination of the lakes and rivers by NR. fowleri is done by transport of water droplets by the wind. Thanks to that, NR. fowleri can move towards other sites where its presence is normally not observed the such sewers, the badly maintained swimming pools, hydropathic establishments…

Its distribution is cosmopolitan, but the cases of méningoencéphalite amoebic acute primitive were detected only with the the United States, in Australia, in England, in Belgium and Slovakia. No case was announced in France.

Pathogenic capacities

Naegleria fowleri is responsible for extremely serious a Pathologie extremely fortunately extremely rare: the primitive amoebic Meningoencephalitis (MEAP). The treatments are the amphotéricine B, in partnership with the rifampicine managed by oral way; the topics application of propamidine isethionate is effective; other drugs are effective, in particular the clotrimazole, the miconazole and the pimaricine (1).

Neagleria fowleri is an agent classified in P3 (Pathogenic of group 3), it can be handled only in laboratories of biological Sûreté of level 3 and superior.

If, during a fresh water bath (swimming pools, ponds…), the vegetative forms of Naegleria fowleri are brought in contact with the nasal mucous membranes, they settle initially - period of invasion - in a rhino-pharyngée symptomatology: fever with 39-40 °C, nauseas, cephalgias and pains ocular. Then, through the sifted plate of the ethmoïde (bone odd and median of the head, which trains the upper part of the skeleton of the nose and of which the sifted blade, located at the base of cranium, is crossed by the olfactive nerves), they gain spaces meninges actively, and it is the period of state with its table of aseptic meningoencephalitis puriforme. Very quickly the patient is sub-comatose and death occurs, except exception, into 5 to 10 days.

Structural characters

The Naegleria is that of the whipped Amibe S but it happens however that certain stocks of NR. fowleri do not produce whip, even in poor medium nutritional, which makes the test of scourging unreliable at 100%. Moreover, the whipped amoebas are not in a constant form. One distinguishes three forms at Naegleria fowleri :

- The vegetative form (trophozoïde): 15-25 µm, whip them do not appear. The cellular body into deformable (not of rigidity of the membrane) abundant formation of Pseudopode S: the cell is known as in " bouillonnement".

- The whipped form: 12-18 µm, whip them appear in the form of two whip polar. The cells keeps a form ovalaire more or less and little deforming.

- The cystic form: 10-20 µm, whip them do not appear. The cell round and is surrounded by its cystic wall.

Biochemical characters

For the identification of NR. fowleri there exists a method more reliable than the test of scourging. It is the test of pathogenicity on mouse. However, other amoebas are pathogenic for the mouse and can create interferences like NR. australiensis .

One uses a profile of Isoenzyme S specic of the species for his identification by techniques of electrophoresis and Iso-electrofocusing in order to determine the presence of Lactate déshydrogénase (LDH), superoxide Dismutase, acid Phosphatase (CAP), malate déshydrogénase, Leucine aminopeptidase (LAP) and L Thréonine déshydrogénase.

One uses also techniques immunological S (more precisely Immunofluorescence indirect), of Sérogroupage with monoclonal Anticorps anti Naegleria . One can practice methods of sequencing of DNA amibien.
These methods are both regarded as reliable for the identification of NR. fowleri .

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