Does alteration in biodiversity really affect disease outcome? – A debate is brewing

Abstract

How changes in biodiversity alter the transmission of infectious diseases is presently under debate. Epidemiologists and ecologists have put a lot of effort to understand the mechanism behind biodiversity-disease relationship. Two important mechanisms, i.e. dilution and amplification theories have in some manner made it clear that biodiversity and disease outcome have an intimate relationship. The dilution effect theory seems to answer some overarching questions, but paucity of information about many disease systems is a real obstacle for its acceptance. Also, there is hardly any agreement on host population threshold and critical community size vis-à-vis wild life diseases. We suggest a multidimensional approach whereby the same disease system needs to be studied in different ecological zones and then the effect of biodiversity on disease outcome needs to be ascertained. Nonetheless, caution is to be taken while jumping to any conclusion as biodiversity-disease relationship is a multifactorial process.

Climate change, biodiversity, ticks and tick-borne diseases: The butterfly effect

“…Accordingly, there is now weighty evidence that decreases in biodiversity increase risk of transmission of different infectious diseases ( Keesing et al., 2010 , Cardinale et al., 2012 , Civitello et al., 2015 ). Zargar et al. (2015) highlighted that the biodiversity-disease relationship is a multifactorial process and suggested the use of a multidimensional approach, whereby the same disease system could be studied in different ecological zones.…”

Bioecological Drivers of Rabies Virus Circulation in a Neotropical Bat Community

“…Nevertheless, this observation was limited by the programmes implemented and the ability of the different countries to investigate rabies virus circulation [ 2 ]. The debate remains active on the relative and contradictory importance of the dilution effect, claiming that loss of diversity would favour the risk of emergence as well as the amplification effect, which assumes a positive correlation between biodiversity and disease risk [ 30 ]. Rabies occurrence has been reported in the Brazilian state of Pará, in Ecuadorian and Peruvian Amazonia, as well as in Colombia and Trinidad.…”

The Ecology and Phylogeny of Hosts Drive the Enzootic Infection Cycles of Hantaviruses

“…These environmental alterations can increase the risk of human interaction with infected rodents [9,92,93,94]. Patch networks have been shown to artificially increase the number of different potential hosts, thereby creating an artificial localized increase in species richness [95,96,97] while decreasing species diversity [39,40,72,79,80,98].…”

“…The resulting “dilution effect” [37] is typically attributed to a relationship between the dominance of generalist host species and the reduced abundance of rarer species comprising the assemblage [19,38]. This phenomenon is thought to occur when increased assemblage diversity suppresses the density of the main host species and thus dilutes disease prevalence and density-dependent transmission events [37,39]. However, an opposite “amplification effect” is also known to occur when there is an increase in the transmission rate in assemblages with higher diversity [40].…”