Transmission electron micrograph (TEM) depicts a number of Nipah virus virions that had been isolated from a patient's cerebrospinal fluid (CSF) specimen. Nipah virus is a member of the family Paramyxoviridae. Nipah virus was initially isolated in 1999 upon examining samples from an outbreak of encephalitis and respiratory illness among adult men in Malaysia and Singapore. Infection with Nipah virus was associated with an encephalitis characterized by fever and drowsiness and more serious central nervous system disease, such as coma, seizures, and inability to maintain breathing. Illness with Nipah virus begins with 3-14 days of fever and headache, followed by drowsiness and disorientation characterized by mental confusion. These signs and symptoms can progress to coma within 24-48 hours. Among emerging viruses, Nipah virus is particularly deadly, killing up to 70 percent of the people it infects. With this high mortality rate, health officials are concerned about it potentially becoming an emerging threat as an agent of biological terrorism.