According to an excellent article at the New York Times and from regular articles on PubMED and Crawford Kilian , there is an annual epidemic of encephalitis of undefined origin that sweeps through India peaking around mid-May, each year.
It is not clear what is being routinely tested for ("known causes of brain swelling" is not very informative) or what resources are available to the laboratories and patients in this region(s) of India. Some detailed postings to emerging disease sites like ProMED might attract some suggestions and encourage much needed discussions in an open forum that could help the hunt.
There are many infectious potential causes of such disease and from the article, many, many potential sources for acquiring such pathogens, which includes a wide range of viruses. Some of these viral culprits have only recently been discovered - the picornaviruses - klassevirus, parechovirus cosavirus and the Saffold viruses - among many better-known viruses.
The NYT article notes that the US CDC is collaborating on a project to seek a cause(s). Hopefully that will yield solid leads before another year passes and more children succumb. Beyond financial issues underpinning PCR-based diagnostic testing, it is hard for me to understand why this has not been tackled in a collaborative manner, earlier. Obtaining basic knowledge ("what is causing this disease?") may not be a sexy topic for grant funding, but it is the cornerstone on which a solid public health foundation is built.
To know and understand what bug (I mean virus, but I include bacteria!) you face you could:
- Screen for known bugs using existing PCR assays
- If unsuccessful, hunt using next generation sequencing technology
- Characterise the culprit if it's new or if it's a variant of something already known - get the genome, feed that information back into assay design to make sure your assay works properly and that the first hit wasn't luck, design a second and third assay to different regions of the genome to provide detection redundancy, continue searching to find all the strains
- Create serological assays to determine the nature of infection by measuring antibodies
- Incorporate the new target into the existing diagnostic menu - and keep revising that menu
- Publish the results, update your peers, modify your patient management and advisories and include social media to keep everyone up-to-date.
- Do lots of other high-tech research which I know only a little about, to understand what the virus does in, and to, its host