Water sources aggregate parasites with increasing effects in more arid conditions

Abstract

Shifts in landscape heterogeneity and climate can influence animal movement in ways that profoundly alter disease transmission. Water sources that are foci of animal activity have great potential to promote disease transmission, but it is unknown how this varies across a range of hosts and climatic contexts. For fecal-oral parasites, water resources can aggregate many different hosts in small areas, concentrate infectious material, and function as disease hotspots. This may be exacerbated where water is scarce and for species requiring frequent water access. Working in an East African savanna, we show via experimental and observational methods that water sources increase the density of wild and domestic herbivore feces and thus, the concentration of fecal-oral parasites in the environment, by up to two orders of magnitude. We show that this effect is amplified in drier areas and drier periods, creating dynamic and heterogeneous disease landscapes across space and time. We also show that herbivore grazing behaviors that expose them to fecal-oral parasites often increase at water sources relative to background sites, increasing potential parasite transmission at these hotspots. Critically, this effect varies by herbivore species, with strongest effects for two animals of concern for conservation and development: elephants and cattle.

Divergent water requirements partition exposure risk to parasites in wild equids

“…Surface water serves as an attraction point for many species, and its effects on concentrating animals, their feces, and/or intermediate hosts and vectors, promoting parasite transmission, have been seen in many studies, including on red deer (Vicente et al, 2006), big-horn sheep (Whiting et al, 2009), and the willow tit and crested tit (Krama et al, 2015). Such effects were recently demonstrated for a suite of herbivore species in our study area, with a particularly strong increase in parasite exposure risk close to water for elephants and cattle (Titcomb et al, 2021). Zebra dung density was not shown to change with distance from water, but this was based on 150-m long transects; our study builds on this to show that, when measured at a greater spatial scale, zebra dung density declines with distance from water up to about a kilometer away.…”

“…Grevy's zebras should thus be able to range much farther from water holes and to graze in areas plains zebras and other more water-dependent ungulates cannot reach. Because water holes serve as attraction points, we expect that dung would be more concentrated in proximity to water (Titcomb et al, 2021) and that plains zebras would be constrained to feed in areas with higher dung density. Active fecal avoidance (choosing to feed on grass swards uncontaminated with dung) is unlikely to be of great influence on exposure risk in zebras.…”

Artificial Water Troughs Use by the Mountain Ungulate Ovis gmelini ophion (Cyprus Mouflon) at Pafos Forest

“…Intraspecies and interspecies disease transmission has been identified as a potential risk at artificial watering sites [ 83 , 84 ]. Considering that disease is responsible for one-third of all known mouflon mortalities [ 27 ], the artificial water troughs should be periodically cleaned [ 85 ].…”

Toward waterborne protozoa detection using sensing technologies

“…In contrast, global warming, as a coming challenge in the world, decreases access to healthy water resources and increases emerging water and food safety concerns (Duchenne-Moutien and Neetoo, 2021). In fact, drought due to climate changes increases seasonal water resources, which aggregates animals and human communities in a region, recycled water resources, groundwater, and even lagoon water, and therefore, the risk of transmission of potentially pathogenic microorganisms, particularly parasites, from animals to humans (Titcomb et al, 2021). Moreover, because of the presence of a resistant stage, cyst/oocyst/egg, in the life cycle of parasites, particularly protozoa, these microorganisms endure harsh conditions such as drought much more than other microorganisms.…”