This was perhaps not an easy problem for children, but I got correct responses from Suman Saraf, Abhinav Jain and Pratik Poddar.
The correct answer is ~0.01%, that is the probability of you having the disease is very low, even if you have tested positive. Here is a link to the video with the explanation:
This is a class of problems in conditional probability commonly known as Bayes’ Theorem. The problem given was similar to the Bayes’ Mammogram Problem, for which the solution is explained at:
Hope you all enjoyed the puzzle!