Your application spans several major areas of computing technology. First, you would need a highly efficient data capture system - most epidemic information (flu etc.) come from non-structured inputs such as web search trends, texting, hospital emergency call patterns, Hospital staff reports, CDC tracking, PCP tracking etc. These inputs are like fire-hoses. So, you must have an efficient input interface. Keywords here are XMPP, eJabberD, SMS Gateway, etc.

Next the data must be stored and sorted efficiently, so that the analytical engines can easily produce intelligent outcomes. Here the keywords are: NoSQL, Hadoop, Map-Reduce, BigTable, Mongo, etc. Read various High Scalability case studies such as Twitter, Facebook, Flicker, etc.

Next you need to deploy an analytical engine so that the visitors can run their own decision making queries. You probably have to prepare some standard/canned reports also. Here the Keywords are: Machine Learning (ML), Weka, Bayesian Partitioning, Markov Chains, PMML, etc.

Then you have to actually write the web app and put it in a hosting facility for the world to access. Here there are many options. Keywords are: Python, Rails, Heroku, AWS, EC2, Rackspace, Azure etc.

Yes, it's a good idea to hire a hacker at least part-time or even find a Tech Co-founder. In your case, it is better if the person has some domain knowledge (Social Health issues).