overview X Chapter 2 also considers the public health consequences of conflicts, such as the outbreak of Marburg haemorrhagic fever against the background of the 1975-2002 civil war in Angola, and the cholera epidemic in the Democratic Republic of the Congo in the aftermath of the crisis in Rwanda in 1994. In July of that year, between 500 000 and 800 000 people crossed the border to seek refuge in the outskirts of the Congolese city of Goma. During the first month after their arrival, close to 50 000 refugees died in a widespread outbreak of combined cholera and shigella dysentery. The speed of transmission and the high rate of infection were related to the contamination with Vibrio cholerae of the only available source of water and the absence of proper housing and sanitation e problem of microbial adaptation, the use and misuse of antibiotics and zoonotic diseases, such as human bovine spongiform encephalopathy(BSE)and Nipah virus, is discussed. The history of Nipah virus emergence provides another example of a new human pathogen that originated from an animal source, initially caused zoonotic disease, and subsequently evolved to become a more efficient human pathogen This trend calls for closer collaboration among sectors responsible for human health ternary health and wildlife. Infectious diseases following extreme weather-related events and the acute public health impact of sudden chemical and radioactive events are also discussed. These now fall within the scope of IHR (2005)if they have the potential to cause harm on an international scale, including the deliberate use of biological and chemical agents, and industrial accidents. Among the examples of accidents given here is the chernobyl nuclear accident in Ukraine in 1986, which dispersed radioactive materials into the atmosphere over a huge area of Europe. Put together, the examples in this chapter reveal the alarming variety of threats to global health security towards the end of the 20th century.Chapter 2 also considers the public health consequences of conflicts, such as the outbreak of Marburg haemorrhagic fever against the background of the 1975-2002 civil war in Angola, and the cholera epidemic in the Democratic Republic of the Congo in the aftermath of the crisis in Rwanda in 1994. In July of that year, between 500 000 and 800 000 people crossed the border to seek refuge in the outskirts of the Congolese city of Goma. During the first month after their arrival, close to 50 000 refugees died in a widespread outbreak of combined cholera and shigella dysentery. The speed of transmission and the high rate of infection were related to the contamination with Vibrio cholerae of the only available source of water and the absence of proper housing and sanitation. The problem of microbial adaptation, the use and misuse of antibiotics and zoonotic diseases, such as human bovine spongiform encephalopathy (BSE) and Nipah virus, is discussed. The history of Nipah virus emergence provides another example of a new human pathogen that originated from an animal source, initially caused zoonotic disease, and subsequently evolved to become a more efficient human pathogen. This trend calls for closer collaboration among sectors responsible for human health, veterinary health and wildlife. Infectious diseases following extreme weather-related events and the acute public health impact of sudden chemical and radioactive events are also discussed. These now fall within the scope of IHR (2005) if they have the potential to cause harm on an international scale, including the deliberate use of biological and chemical agents, and industrial accidents. Among the examples of accidents given here is the Chernobyl nuclear accident in Ukraine in 1986, which dispersed radioactive materials into the atmosphere over a huge area of Europe. Put together, the examples in this chapter reveal the alarming variety of threats to global health security towards the end of the 20th century. overview xvii