Molecular aspects of host-parasite interactions, such as host recognition, infection and damage, have been in the forefront of infection research for the last few decades. Such obsession with the biochemistry of the interaction, to a large extent, was driven by the advent of advanced technologies in the fields of “omics”, structural biology and microscopy. While such approaches have their own values in understanding biochemical and molecular interactions between specific host and its parasite, more general and wider mechanisms that drive host-parasite interactions have mostly been elusive. Such reductionist approach, for instance, has proven to be less successful in explaining reasons for virulence in parasites, tolerance and resistance in hosts and more recently emergence of new infectious diseases.
It has also been realized that there are more to the story of infectious disease than the simple one to one interaction between a host and its parasite. Recent evidences suggest that emergence of a particular infection probably stems from a complex interplay between many parasites and their host communities. To make the matters worse, anthropogenic interference and climate change may also play an important role at a larger scale in the emergence and spread of parasites.
One of the ways these issues could be approached is to consider the host-parasite interactions as an outcome of many interacting biological modules. Next, we can apply concepts of community ecology of prey and predator, trophic interactions and evolutionary ecology to this complex system to understand how parasite communities influence hosts and vice versa. We can, therefore, address some of the burning questions in host-parasite interactions through this approach:
How does host ecology (home range, density, sociality and so on) influence the composition and dynamics parasites in an ecosystem?
How do landscape characteristics shape parasite communities?
What role do humans play in driving the wildlife disease dynamics in modified landscapes?
Can habitat modification/fragmentation increase infectious disease risk in human living close to wilderness?
On a more practical aspect, can parasites be useful bio-indicator to environmental change?
Is there any connection between a host’s microbiome and its susceptibility to infections?
Why there are fewer generalist parasites than specialist ones?
We work at the tropical rainforest remnants of the Anaimalai Tiger Reserve and the adjoining Valparai plateau in the Anaimalai hills, southern Western Ghats, India to address few of the above questions. The plateau once was covered by continuous tropical rainforest vegetation, most of which was cleared between 1890s and 1930s in favour of tea, coffee and cardamom plantations. As a result, the plateau now, consists of several rainforest patches with sizes varying between two to 2000 ha which are interspersed by tea, coffee and cardamom estates, settlements of estate workers, the Valparai township, metalled roads and numerous trails cutting across the estates and the rainforest fragments. In spite of such severe habitat fragmentation, surprisingly, the rainforest patches still retains much of their original wildlife, along with some of the wide-ranging species such as Asian elephant (Elephas maximus), tiger (Panthera tigris) and leopard (Panthera pardus). The western side of the reserve, however, is relatively undisturbed with long stretches of primary rainforests punctuated intermittently with secondary forests of Teak plantations. Consequently, Anaimalai Tiger Reserve provides one with a gradient of disturbance across its range with many vertebrate hosts and their parasites. Our goal is to exploit this set up to investigate and understand community level interactions between hosts and parasites and the role of anthropogenic interventions in shaping such interactions.