Free-living Acanthamoeba and Naegleria spp. amebae in water sources of León, Nicaragua

free-living amebae (FLA) are known to occur worldwide in water-related biotopes, but only limited information is available on these organisms in developing countries and so far no information on their presence is available from Nicaragua. The aims of this study were to evaluate the prevalence of potentially pathogenic Acanthamoeba spp. and Naegleria spp. in different water sources to which the population of León municipality is exposed. Since pathogenic amebae are thermotolerant, we were especially interested in the occurrence of FLA in geothermal areas. Water samples were collected from León area in Nicaragua: 88 samples were from rivers and springs, 111 from wells, 74 from water taps and 21 from water tanks in urban and suburban León and from three nearby geothermal areas of San Jacinto, Posoltega and Tipitapa. Amebae were identified using morphological and physiological criteria, immunohistochemical staining procedures and molecular methods. Indirect immunofluorescent test was performed on cysts and trophozoites fixed on microscopical slides and incubated for 30 min at room temperature in separate experiments with the following antibodies: rabbit-anti N. fowleri/N. lovanensis (Nf-Pab), mouse monoclonal antibody anti N. fowleri (Nf-5D12u), rabbit antibodies against Acanthamoeba spp. And fluorescent in situ hybridization (FISH) was performed using 18S rRNA-targeted fluorescent oligonucleotide probes. Probes: GSP for the detection of Acanthamoeba and NAEG1088 for the detection of Naegleria. Free-living amebae were recovered from approximately 43 % of the samples. Acanthamoeba spp was found in 21 % of samples from León municipality and in 2 % of samples from geothermal areas. Amoeboflagellates were found in 10 % of samples from León and in 19 % in geothermal areas. Fifty three percent of tested wells in the geothermal area contained thermotolerant amoeboflagellates. Naegleria spp. was identified in 24 out of 39 (61.5 %) of isolated amoeboflagellates. Twelve of them were assigned to N. lovanenesis while none of the isolates could be identified as N. fowleri. However, the common presence of thermotolerant Naegleria in water, specially N. lovanensis, which is an indicator species for N. fowleri, suggests that also this pathogenic amoeba may pose a risk to public health in the area. On the other side, direct pathogenicity, free-living amebae are receiving increasing attention as reservoirs and potential vehicles for the transmission of bacteria in the environment. Thus the information provided in this study may serve as base-line for future studies on the role of free-living amebae e.g. in waterborne-disease outbreaks in the region. Among such potentially important enteropathgens are Vibrio cholerae, E. coli 0157, and Helicobacter pylori. Rev. Biol. Trop. 56 (2): 439-446. Epub 2008 June 30.

Las amebas de vida libre (AVL) son un grupo de organismos de distribución mundial. Entre las AVL hay parásitos facultativos en humanos y otros animales, los cuales pertenecen a los géneros Acanthamoeba, Naegleria y Balamuthia que causan infecciones severas en el sistema nervioso central. Sin embargo no se tiene ninguna información de Nicaragua. El objetivo de este estudio fue evaluar la presencia de amebas de vida libre, en diferentes fuentes de agua de la parte urbana y rural del Departamento de León, y áreas geotérmicas de Nicaragua. Estas amebas fueron identificadas usando criterios morfológicos, fisiológicos, histoquímicos y moleculares. En los resultados se encontró amebas de vida libre en el 43% del total de las muestras. En la municipalidad de León, se encontraron 21% de Acanthamopeba sp. y en las áreas geotérmicas un 2%. Las amebaflagelados tipo Naegleria fueron 10% y 19% respectivamente. Del grupo amebaflagelados fueron 24, de las cuales 12 se dentificaron como N. lovanensis. En estas muestras no se aisló N. fowleri (ameba patógena), sin embargo, la presencia de N. lovanensis es in indicador de la presencia de N. fowleri, la cual puede ser un riesgo a la salud pública. Además, estas amebas pueden servir como vectores de bacterias enteropatógenas.

Free-living Acanthamoeba and Naegleria spp. amebae in water sources of León, Nicaragua.

Free-living amebae (FLA) are known to occur worldwide in water-related biotopes, but only limited information is available on these organisms in developing countries and so far no information on their presence is available from Nicaragua. The aims of this study were to evaluate the prevalence of potentially pathogenic Acanthamoeba spp. and Naegleria spp. in different water sources to which the population of Le6n municipality is exposed. Since pathogenic amebae are thermotolerant, we were especially interested in the occurrence of FLA in geothermal areas. Water samples were collected from Le6n area in Nicaragua: 88 samples were from rivers and springs, 111 from wells, 74 from water taps and 21 from water tanks in urban and suburban Le6n and from three nearby geothermal areas of San Jacinto, Posoltega and Tipitapa. Amebae were identified using morphological and physiological criteria, immunohistochemical staining procedures and molecular methods. Indirect immunofluorescent test was performed on cysts and trophozoites fixed on microscopical slides and incubated for 30 min at room temperature in separate experiments with the following antibodies: rabbit-anti N fowleri/N lovanensis (Nf-Pab), mouse monoclonal antibody anti N. fowleri (Nf-5D12u), rabbit antibodies against Acanthamoeba spp. And fluorescent in situ hybridization (FISH) was performed using 18S rRNA-targeted fluorescent oligonucleotide probes. Probes: GSP for the detection of Acanthamoeba and NAEG1088 for the detection of Naegleria. Free-living amebae were recovered from approximately 43 % of the samples. Acanthamoeba spp was found in 21% of samples from León municipality and in 2% of samples from geothermal areas. Amoeboflagellates were found in 10 % of samples from Le6n and in 19% in geothermal areas. Fifty three percent of tested wells in the geothermal area contained thermotolerant amoeboflagellates. Naegleria spp. was identified in 24 out of 39 (61.5 %) of isolated amoeboflagellates. Twelve of them were assigned to N. lovanenesis while none of the isolates could be identified as N fowleri. However, the common presence of thermotolerant Naegleria in water, specially N. lovanensis, which is an indicator species for N. fowleri, suggests that also this pathogenic amoeba may pose a risk to public health in the area. On the other side, direct pathogenicity, free-living amebae are receiving increasing attention as reservoirs and potential vehicles for the transmission of bacteria in the environment. Thus the information provided in this study may serve as base-line for future studies on the role of free-living amebae e.g. in waterborne-disease outbreaks in the region. Among such potentially important enteropathgens are Vibrio cholerae, E. coli 0157, and Helicobacterpylori.

Overdiagnosis of Entamoeba histolytica and Entamoeba dispar in Nicaragua: a microscopic, triage parasite panel and PCR study.

BACKGROUND: Based on stool microscopy, an E. histolytica/E. dispar prevalence of 18.6% was found in León, Nicaragua about 10 years ago. Since then, new non-microscopic methods have been developed to discriminate between pathogenic E. histolytica and nonpathogenic E. dispar. The main objectives of the present study were to evaluate the true prevalence of E. histolytica among individuals with diarrhea and to assess the diagnostic procedures carried out at the health center level. METHODS: A descriptive study was carried out on patients with diarrhea. Parasite detection was performed by conventional microscopy on native preparations or concentrated and stained specimens, Triage Parasite Panel and by PCR for both E. histolytica and E. dispar. RESULTS: In 134 individuals with diarrhea, the prevalence of intestinal parasites was 69% as detected by direct stool examination. E. histolytica/E. dispar was found in eight (6%) of the samples, but the health centers reported 24%. In the Triage Parasite Panel only one case of E. histolytica/E. dispar was found. Analysis by PCR showed E. dispar in ten (7.5%) and E. histolytica in two cases (1.5%). The detection of intestinal coccidia and Dientamoeba fragilis required additional staining methods. CONCLUSIONS: PCR results showed that E. histolytica is a rare finding in patients with diarrhea. At the health centers, E. histolytica, E. histolytica/E. dispar were clearly overdiagnosed, with the consequence of overtreatment.

Antibodies in mother's milk protect children against giardiasis.

The protective effect of anti-Giardia antibodies in mother's milk on the acquisition of Giardia infection in their children during the first 2 y of life was analysed as part of a prospective study on infant diarrhoea in a group of 307 mothers and children in Leòn, Nicaragua. Among 24 children acquiring infection within the first 6 months, 23 were born to mothers lacking antibodies. These children also developed more severe diarrhoea. A significant difference between children born to mothers with and without antibodies with respect to the age at which the first Giardia infection was acquired was demonstrated by survival analysis and log rank test (p = 0.036). In conclusion, children born to non-immune mothers are at significantly higher risk of acquiring Giardia infection and developing giardiasis with more severe symptoms compared with children of immune mothers.