Occurrence and overlap of natural disasters, complex emergencies and epidemics during the past decade (1995–2004)

All natural disasters, CEs and epidemics occurring within the past decade (1995–2004) that met the inclusion criteria were included. The largest 30 events in each category were based on the total number of deaths recorded. The main databases used were the Emergency Events Database for natural disasters, the Uppsala Conflict Database Program for CEs and the World Health Organization outbreaks archive for epidemics.During the past decade, 63% of the largest CEs had ≥1 epidemic compared with 23% of the largest natural disasters. Twenty-seven percent of the largest natural disasters occurred in areas with ≥1 ongoing CE while 87% of the largest CEs had ≥1 natural disaster.Epidemics commonly occur during CEs. The data presented in this article do not support the often-repeated assertion that epidemics, especially large-scale epidemics, commonly occur following large-scale natural disasters. This observation has important policy and programmatic implications when preparing and responding to epidemics. There is an important and previously unrecognized overlap between natural disasters and CEs. Training and tools are needed to help bridge the gap between the different type of organizations and professionals who respond to natural disasters and CEs to ensure an integrated and coordinated response.The causes of disasters are not always clear and often overlap. For example, Sen argues that famines are usually caused by a lack of purchasing power or entitlements and not necessarily due to drought and consequent food shortage, which can be exacerbating factors [1]. An epidemic may be controlled easily under certain circumstances and thus not turn into a disaster; however, if the population's ability to respond to the epidemic is reduced due to external factors, such as a natural disaster or complex emergency (CE), then the epidemic may indeed become a disaster (see table 1 for definitions).There are few articles and data that examine the frequency of occurrence and overlap among