Patients were mainly pig-farm or abattoir workers who were in close contact with the infected pigs. The natural hosts of the Nipah virus have yet to be established but it is possible that they may also be fruit bats. If this is so, contact between bat and pig must have occurred recently. It is tempting to speculate that the inter-species contact occurred as a consequence of deforestation and other land development which had affected the natural habitat of the bats, thus forcing them to forage elsewhere for food. Whether such a theory is true remains to be proven.
New technology can also affect the way infections can spread.
New methods is mass food production, processing, storage and distribution has resulted in outbreaks of food-poisoning that affect many thousands of people. This outbreak was traced to a brand of ice-cream where the premix was contaminated with Salmonella enteritidis . Contamination took place during transport of the premix in trailer trucks which were previously used to transport non-pasteurised liquefied eggs. There are two main challenges to overcome. The first is to prevent the infection from emerging and the second to contain it should it emerge.