Potentially pathogenic free-living amoebae at very high altitude: Detection by multiplex qPCR in the Northern Altiplano fascioliasis hyperendemic area in Bolivia

Abstract

Free-living amoebae (FLA), which are frequently found in the environment, include opportunistic pathogenic genera/species such as Acanthamoeba spp., Balamuthia mandrillaris, Naegleria fowleri and Vermamoeba vermiformis. These pathogenic FLA are causative agents of amoebic encephalitis and keratitis in the case of Acanthamoeba genus and V. vermiformis. In addition, amoebic infections are often related to contamination of domestic and recreational water sources. This study aimed to identify potentially pathogenic FLA in the hyperendemic area of human fascioliasis in a very-high-altitude area (3800-4100 m a.s.l.) of Bolivia and examine whether an association between both pathogens could be established from the environmental point of view. A total of 55 samples (28 soil and 27 water samples) were collected from various locations in the Northern Altiplano of Bolivia. Samples were processed by multiplex qPCR to detect the four pathogenic FLA genera/species. All samples were positive for the presence of V. vermiformis, followed by Acanthamoeba spp. which was positive in 18 soil and 10 water samples. In contrast, B. mandrillaris was only detected in soil sources, whereas N. fowleri was not detected in any of the samples. The coexistence and diverse distribution of multiple FLA species in many locations at such a high altitude is worth mentioning and indicates a potential risk of coinfections. These findings suggest that FLA surveillance is a crucial factor to be considered when implementing preventive measures and improving public health in fascioliasis hyperendemic areas.

Keywords: Acanthamoeba; Balamuthia mandrillaris; Bolivia; Free-living amoebae; Hyperendemic area of human fascioliasis; Multiplex q-PCR; Naegleria fowleri; Vermamoeba vermiformis; Very high altitude.

Graphical abstract

Fig. 1

Map of the Northern Bolivian Altiplano human fascioliasis hyperendemic area (HFHA), located between Lake Titicaca and the city of El Alto and the valley of La Paz city, showing the distribution of the sampling locations for free-living amoebae. Coordinates and altitudes of each site are indicated in Table 1. Red circles = soil sampling locations; blue circles = water sampling locations; light brown shaded area = HFHA prospected zone [[13], [15], [29]]. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 2

Map of the Northern Bolivian Altiplano human fascioliasis hyperendemic area showing the locations where free-living amoeba were detected. Coordinates and altitudes of each site are indicated in Table 1. Green triangles = Balamuthia mandrillaris; purple circle = Acanthamoeba spp.; red crosses = Vermamoeba vermiformis. Red circles = soil sampling locations; blue circles = water sampling locations. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 3

Geographical distribution of detected FLA according to the three main corridors of the fascioliasis hyperendemic zone.