Generally, all Health Insurance in Malaysia cover pandemics and communicable diseases, save when the persons infected are required by the government to be quarantined. Quarantine can be within the confines of the government-designated areas or in the house. By means of the government declaring a need to be quarantine like what happened for this A H1N1 disease (which has already spread to most of the countries around the world) the medical expenses incurred would be borne by the government. Thus there is actually no necessity to claim against your Health Insurance policy.
In this regard, we always expect the government to pick up the bills when we walk into the designated areas for complying with a quarantine declaration. However, we are not sure if you are infected after landing in a foreign country like the US. The US government will surely have you quarantined but will they eventually insist that you settle the bills on the day you are to be discharged from the hospital? No one knows as of now…. looks like unlikely for any government to enforce recovery of the expenses incurred in the quarantine process otherwise most people would seek to avoid being quarantined.
Whatever that is, you are safe as for now (in as far as the policy cover is concerned) but avoid travelling overseas to avoid those unnecessary coverage shock. Who knows, you may land onto Somali soil and the next moment you are requested to settle a hefty bills for being quarantined for A H1N1.
Anyway, in some countries, this is how they quarantine people suspected of being infected.