Iron, Climate change and the ‘brain eating amoeba 'Naegleria fowleri'

Naegleria fowleri is the causative agent of primary amoebic meningoencephalitis (PAM), a rare but devastating infection with a 96.4% mortality rate. Iron is a limiting factor for N. fowleri growth, and its presence during growth activates its human pathogenic potential. Analysis of the Naegleria genome reveals the presence of genes encoding proteins present in anaerobic organisms, many of which are iron-containing enzymes. Here we propose a pathway involving ferroproteins that facilitates the anaerobic growth of Naegleria. Climate change is modelled (by others) to increase soil erosion and to lead to a more reducing regime in some areas, both of which are expected to result in increased iron availability in soils and waterways. We posit that an increased iron supply will permit N. fowleri to survive in low-oxygen environments through the increased expression of several iron-binding proteins involved with ATP production and pathogenic potential. Together with general warming, increased iron availability may increase the incidence of PAM, causing the geographic range of N. fowleri to spread poleward. Competition with other free-living amoebae, including other Naegleria species, is likely to limit the distribution and abundance of N. fowleri and more details of these interactions are required to predict and intervene.