The most imminent threat is due to a limited fresh water supply and no system in place to eliminate human waste. Enteric diseases such as E. Coli, cholera, typhoid, and shigellosis can break out due to these conditions. And while these illnesses may not be fatal in the United States, in Southeast Asia they will not only be fatal but highly contagious.
Dr. Vincent Young of MSU's Infectious Disease Medicine says because there is poor sanitation and no plumbing system or toilets at the shelters, infections can easily spread through shelters.
Another threat is the risk of a spike in population of mosquitoes. This could lead to deadly mosquito-borne viruses and parasites like malaria, and dengue and yellow fever.
Because these diseases could kill more than the actual tsunami itself, aid workers are quickly working to distribute fresh water and set up water sanitation systems.