Indonesian authorities are being confused by the disease as they are unable to find any explanation on bird flu deaths. They always said that the virus that strike the victims cannot be transferred human to human. However, there has been cases where a member of a family is infected, the other family members are also infected.

Cited from CTV:

A large cluster of human cases of H5N1 avian flu in Indonesia is raising questions about whether genetic susceptibility explains why some people exposed to the dangerous virus become infected while many more do not. Scientists have been puzzled by why H5N1 doesn't jump to humans from birds more often, given the vast numbers of exposures people have had to infected poultry in affected countries.

Molecular Nanotechnology would enable discriminatory attack toward certain population or tribes with certain genetic codes. What does International Law said about it?

This is what the ICJ decides in its Advisory Opinion, on the legality of nuclear weapon:

      By seven votes to seven, by the President's casting vote,

It follows from the above-mentioned requirements that the threat or use of nuclear weapons would generally be contrary to the rules of international law applicable in armed conflict, and in particular the principles and rules of humanitarian law;

However, in view of the current state of international law, and of the elements of fact at its disposal, the Court cannot conclude definitively whether the threat or use of nuclear weapons would be lawful or unlawful in an extreme circumstance of self-defence, in which the very survival of a State would be at stake;

I dont know why the ICJ did not consider Geneva Conventions (and its protocols) on the prohibition of indiscriminatory attack between civil and military targets as a general prohibition on the utilization of WMD. Maybe this is rather a political question and than a legal one. But I guess, the use of Nuke and other means of WMD is basically prohibited under International Law, whether or not there is a convention regulating it.

In addition to that, race in Molecular nanotechnology weaponry would make Mutually Assured Destruction (MAD) scenarios obsolete. So I believe, the future world court would be in no position to weigh it in its future decision.