Survey of Naegleria fowleri in geothermal recreational waters of Guadeloupe (French West Indies)

Abstract

In 2008 a fatal case of primary amoebic meningoencephalitis, due to the amoeboflagellate Naegleria fowleri, occurred in Guadeloupe, French West Indies, after a child swam in a bath fed with geothermal water. In order to improve the knowledge on free-living amoebae in this tropical part of France, we investigated on a monthly basis, the presence of Naegleria spp. in the recreational baths, and stream waters which feed them. A total of 73 water samples, 48 sediments and 54 swabs samples were collected from 6 sampling points between June 2011 and July 2012. The water samples were filtered and the filters transferred to non-nutrient agar plates seeded with a heat-killed suspension of Escherichia coli while sediment and swab samples were placed directly on these plates. The plates were incubated at 44°C for the selective isolation of thermophilic Naegleria. To identify the Naegleria isolates the internal transcribed spacers, including the 5.8S rDNA, were amplified by polymerase chain reaction and the sequence of the PCR products was determined. Thermophilic amoebae were present at nearly all collection sites. The pathogenic N. fowleri was the most frequently encountered thermophilic species followed by N. lovaniensis. The concentration of N. fowleri was rather low in most water samples, ranging from 0 to 22 per liter. Sequencing revealed that all N. fowleri isolates belonged to a common Euro-American genotype, the same as detected in the human case in Guadeloupe. These investigations need to be continued in order to counsel the health authorities about prevention measures, because these recreational thermal baths are used daily by local people and tourists.

Figure 1. Geographical distribution of sampling sites in the hot waters of the Basse-Terre of Guadeloupe.

(1) the Bains Jaunes on the volcano near Saint Claude, (2) the Bains des Amours, (3) Capes River, (4) the bath of Dolé and Dolé Amont and (5) Dolé Escalier in Gourbeyre.

Figure 2. Levels of Free_living amoebae according to the type of water in Guadeloupe in 2011–2012.

(A) free-living amoebae and (B) and Naegleria fowleri.

Figure 3. Levels of Free-living amoebae according to the temperature of water in Guadeloupe in 2011–2012.

(A) free-living amoebae and (B) Naegleria fowleri.

Figure 4. PCR results for the three major thermophilic amoeba species found in Guadeloupe.

PCR detection and agarose gel electrophoresis of ITS rDNA of N. fowleri (A), N. lovaniensis (B) and Hartmannella sp. (C). M : 100 bp ladder, PC : Positive control (DNA of Naegleria fowleri (#. 359)) gives a single PCR product of 359 bp with the NFITS primers and a 448 bp with the ITS primer set. N.f : Naegleria fowleri, N.l : Naegleria lovaniensis, the ITS amplification gives a 403 bp PCR product while no band was obtained with the NFITS primers, Hart . : Hartmannella sp., the ITS amplification gives a 900 bp while no band was observed with the NFITS primer set.