Throughout the decade, our research found 3,197 recorded natural disasters, 363 recorded complex emergencies, and 1,374 recorded epidemics. The median duration of the largest 30 natural disasters (table ) during the past decade was 1 day (0.003 years) with a range of 1 to 2,555 days (0.003 to 7 years). The outlier in these data is North Korea where a famine occurred over a 7 year period. As stated in the analysis, the North Korea disaster could be classified as a CE or a natural disaster; the Emergency Disaster Database classified it as a natural disaster. The overall estimated mortality in the recorded natural disasters ranged from 1,500 deaths to 2.5 million deaths. The majority occurred in Asia (67%) followed by Latin America and the Caribbean (13%; figure ). The link with any CE was 27%, any epidemic was 23%, and both eventsa was 13% (figure ).
Largest 30 events according to mortality for natural disasters, complex emergencies and epidemics during the last decade (1995–2004) with concurrent events
Largest 30 natural disaster, complex emergency and epidemic events based on mortality during the last decade (1995–2004) by region.
Figure 2 Occurrences of natural disasters, complex emergencies and epidemics during the last decade (1995–2004)*. * For each of the large-scale events in the above three categories, the occurrence in the same location of the other two types of events, (more ...)
The median duration of the largest 30 CEs during the past decade (table ) was 4,563 days (12.5 years) with a range of 365–14,965 days (1 to 41 years). The estimated mortality ranged from 1,000 deaths to 3 million deaths. The majority occurred in Africa (53%) followed by Asia (33%; figure ). The link with any natural disaster was 87%, with any epidemic was 63%, and with both events was 60% (both events refer to the other two categories of events that occurred during or after the large-scale event but necessarily at the same time or same location).
The median duration of the largest 30 epidemics during the past decade (table ) was 107 days (0.29 years) with a range of 31 to 397 days (0.08 to 1.09 years). The estimated mortality ranged from 550 deaths to 4,500 deaths. The majority occurred in Africa (83%) followed by Asia (17%; Figure ). The link with any natural disaster was 30%, with any CE was 47%, and with both eventsb was 10% (Figure ).
The need to prepare for the possible occurrence of epidemics following natural disasters [4
] and during complex emergencies [4
] is well documented. However, the data show that epidemics have occurred much more frequently during large-scale CEs than following large-scale natural disasters. During the past decade, 63% of the largest CEs had at least one epidemic compared with 23% of the largest natural disasters. Some possible explanations include the much longer duration of CEs; the preponderance of CEs occurring in Africa, where numerous diseases of epidemic potential exist, poverty is pervasive and poor public services provide favorable environments for epidemics to prosper [23
]; increased malnutrition and population movements; and the more effective prevention measures to avert epidemics following natural disasters than CEs possibly due to easier access to affected populations [4
]. The data presented in this paper do not support the oft-repeated assertion that epidemics, especially large-scale epidemics, commonly occur following large-scale natural disasters, as was recently loudly claimed by the WHO and widely repeated in the media worldwide following the recent Asian tsunami [2
]; historically, this is incorrect.
Although epidemics do not commonly follow large-scale natural disasters, when large-scale epidemics do occur, they often occur during CEs of any magnitude, and to a lesser extent following natural disasters. One-third of the 30 largest epidemics during the last decade occurred on their own; 47% occurred during at least one CE, 30% following at least one natural disaster, and 10% with both events. Thus, governments, United Nations agencies and non-governmental organizations must continue to prepare for the possibility of epidemics following natural disasters and particularly during CEs.
The occurrence of natural disasters and CEs in the same geographic location has not been well studied [4
]. Some articles or books have separately examined natural disasters and complex emergencies but have not explored the overlap between the two categories [17
] Our analysis shows that 27% of the largest natural disasters during the past decade occurred in areas with at least one ongoing CE while 87% of the largest CEs had at least one natural disaster. Thus, there is significant overlap between natural disasters and CEs; this was larger than the authors expected. There is a clear need for training and tools [24
] that help to bridge the gap between the different type of organizations and professionals who respond to natural disasters and CEs; these include trainings on the different types of injuries and infectious diseases that occur according to different events and geographical locations which influence preparedness and response strategies as well as initial assessment and monitoring and evaluating tools that take into account both types of events. Similar arguments have been made to bridge the gap between humanitarian response and development programs [25
]. This is particularly important in Asia and Africa, where most of the natural disasters and CEs have occurred between 1995–2004.
Early warning systems for natural disasters and epidemics, although technologically challenging and costly, have been shown to be effective [17
]. Despite attempts to develop early warning systems for CEs [26
], the complexity of the situation and the political will required to act in a timely manner makes their effectiveness unclear. During the 1990s, the International Decade for Natural Disaster Reduction, mitigation emerged as a major strategy for reducing the impact of natural disasters. Such mitigation strategies proved effective but were not implemented uniformly throughout the world and remain under funded, particularly in developing countries [27
]. As with early warning systems, mitigation strategies for CEs are more complicated due to the inherent political nature of the situations.
There are a number of limitations in this article. The data show only an ecological association between events and not a cause and effect relationship. The temporal and spatial occurrence of events may not necessarily be related to one another as the data did not allow us to definitively ascertain if they occurred among the same population. If there was a relationship among these events, its effect was not examined. Some events may not have been captured by the databases used. However, whenever possible, we attempted to triangulate the data from different sources. Some disasters were not easily classified into one category and thus misclassification may have occurred; for example, the famine in North Korea could be categorized as a natural disaster or CE; we chose the former. The largest natural disasters, CEs and epidemics during the past decade were arbitrarily limited to the biggest 30 according to mortality; this limited our sample size and does not include other important ways to categorize disasters, such as morbidity and persons affected. Mortality was chosen because it is an essential outcome and the most commonly reported data in the databases used. However, for some types of epidemics and natural disasters, mortality may not be a major outcome and thus morbidity may have been a better outcome to measure the magnitude of these events. Chronic diseases, such as HIV/AIDS and tuberculosis, although causes of major mortality throughout the world, have not been classified as epidemics according to the definition and databases used in this paper.
One strong conclusion of the article is that the longer an event, the higher the risk to have a concomitant event. Since CEs occur over a much longer time period than natural disasters and epidemics, the conclusion that epidemics occur much more commonly during large-scale CEs than following natural disasters is intuitive; however, it is important to have data to support this assertion, which our paper clearly provides. Furthermore, this conclusion has important policy and programmatic implications. Appropriate stockpiling of vaccines, medications and other essential supplies need to be kept up to date and accessible over a long period of time. Since accessibility may be difficult in these emergency situations, proper preparedness planning must occur, including having multiple stockpiles within the same country in order increase the possibility of distributing the supplies. This type of stockpiling must be weighed against the increased cost of having multiple stockpiles in a country. A functioning epidemic alert and response system needs to be established and maintained. Furthermore, the high turnover of staff working in CEs means that continuous training needs to be provided over many years.
Ethiopia case study
Ethiopia has been subject to recurrent drought and food shortages which have sometimes been exacerbated by civil strife [28
]. These crises have often resulted in massive excess mortality and population displacement. Beginning in 1999, data from early warning systems in many regions of Ethiopia indicated that the food security and nutrition situation was deteriorating rapidly [30
]. The World Food Program estimated that more than 10 million people needed food assistance at the peak of the crisis. The Somali region in Ethiopia was the worst affected; this region is inhabited by predominantly pastoralist and agro-pastoralist communities which are highly vulnerable to changing climactic conditions and are subject to recurrent food security crises. Furthermore seasonal migration is one of the key coping strategies for these communities. The situation in Somali region was exacerbated by insecurity, conflict and poor health infrastructure.
In early 2000, cases of severe malnutrition and measles began to be reported by non-governmental organizations but it was not until April 2000 when media attention began to focus on Gode in Somali region that a large-scale international humanitarian response was triggered. The humanitarian response was not only delayed but was also overly focused on food-based interventions such as the general food ration and therapeutic and supplementary feeding for severely and moderately malnourished individuals-the so called 'food first bias' [5
]. While such interventions are critical for preventing and treating malnutrition, by attracting people to population centers in the absence of health-related interventions, these interventions risk contributing to mortality while paradoxically addressing malnutrition. In Gode, the crude mortality rate (CMR) was 3.2/10,000/day or over 6 times the CMR for sub-Saharan Africa. Measles-related mortality was particularly important among remote, rural communities who may not have been exposed to measles wild-virus and have not been reached by immunization services. Such communities do not normally benefit from herd immunity which generally requires a population coverage of more than 90% for measles immunization. The measles epidemic in the conflict-affected and food insecure was severe; measles alone or in combination with acute malnutrition accounted for 22% of deaths among children under 5 years and for 17% of deaths among children 5 to 14 years of age [5