<P> Effective preparations for a response to a pandemic are multi-layered . The first layer is a disease surveillance system . Tanzania, for example, runs a national lab that runs testing for 200 health sites and tracks the spread of infectious diseases . The next layer is the actual response to an emergency . According to U.S. - based columnist Michael Gerson, only the U.S. military and NATO have the global capability to respond to such an emergency . </P> <P> Gates proposed that the world responded slowly to the Ebola virus outbreak because of a lack of preparation . Two weeks after the 2013 typhoon hit the Philippines, over 150 foreign medical teams were on the ground helping with injured victims . After the 2005 earthquake in Pakistan, a team of aid workers who had been helping Afghan refugees for several decades were able to get to the victims in less than 24 hours . Dr. Bruce Aylward, assistant director general for emergencies at the World Health Organization, says that in the case of the Ebola outbreak, "there was no way anyone could guarantee the right of medical evacuation for people affected by Ebola ." Aylward said that for future emergency health workforces, it is critical to offer a "duty of care", meaning the ability to ensure that aid workers will be taken care of in terms of health and safety . </P> <P> The term epidemic derives from a word form attributed to Homer's Odyssey, which later took its medical meaning from the Epidemics, a treatise by Hippocrates . Before Hippocrates, epidemios, epidemeo, epidamos, and other variants had meanings similar to the current definitions of "indigenous" or "endemic ." Thucydides' description of the Plague of Athens is considered one of the earliest accounts of a disease epidemic . By the early 17th century, the terms endemic and epidemic referred to contrasting conditions of population - level disease, with the endemic condition at low rates of occurrence and the epidemic condition widespread . </P>

N the communicable disease model the cause of a disease or health problem is the host