You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Emergence or reemergence seen in which of the following organisms - and explain in detail?
<p> Nipah virus is a new infectious disease recognised in 1999. Emerging infectious diseases are those whose incidence in humans has increased during the last two decades or which threaten to increase in the near future. Reference:Park&;s textbook of preventive and social medicine,K.Park,23rd edition,page no:355-357. <\p>