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In recent years migration has regularly been triggered by humanitarian crises. This can arise from natural disasters such as cyclones, tsunamis, and earthquakes; human-made disasters like nuclear and industrial accidents; environmental degradation which is likely to be exacerbated by climate change; as well as situations of general violence and political instability. In contrast health crises – such as SARS or H1N1 – very rarely result in mass migration.

Why not?

One reason is that in health crises, individuals or communities have the ability to cope with, or to mitigate the effect of, the crisis. The gradual improvement of the understanding of infectious diseases, their causative agents, modes of transmission, and evidence-based ways to control their spread have empowered individuals, communities, and governments to adopt their preventive behaviour, pre-empting migration in most cases.

Individuals can take an active stance against disease themselves, by practicing good personal hygiene or drinking from an alternative source. Such responses in effect offer an alternative to fleeing. And they can be supported by government policy - in the H1N1 pandemic, for example, social distancing, voluntary isolation, quarantine and mass vaccinations were offered to the populations of many affected countries as a pragmatic and evidence-based approach to deal with the health crisis.

Second, the international support mechanism for responding to health crises is better developed than for many other crisis situations, and in particular to support appropriate responses in resource and infrastructure-poor countries, where the majority of health crises occur. The International Health Regulations (IHR) have been amended over the years to enable the international community to respond to cross-border health crises rapidly, by enabling global communication channels and encouraging local public health capacity-building, both in the detection and management of health crises. The regulations allow for a tailored response to be advocated as crises arise, focusing on limiting the spread of disease while keeping travel and trade restrictions to a minimum.

A third reason why health crises usually do not result in mass migration is that they may result in individuals or even communities that are too sick or frail to travel long distances. In July 2012, an Ebola outbreak in Western Uganda led to some patients fleeing a hospital where some of the infected patients had died. But the really sick and elderly patients were unable to leave, and thus their chances of becoming exposed to the virus increased.

Certainly there have been examples of migration resulting from health crises, but usually within the country and for a relatively short period of time. Large-scale internal migration occurred in Surat, India, in 1995, when over half a million people left the city in response to the outbreak of pneumonic plague. Once means of prevention and control had been deployed most returned quickly. Internal migration was also reported during the 2003 SARS crisis in China, and in Mexico as a result of the H1N1 pandemic.

Beyond borders

Cross-border migration as a result of health crises is far less common. Where is does occur, as for example during the cholera outbreak in Zimbabwe in 2008-09, it can be difficult to distinguish the underlying causes of migration – the exodus to South Africa took place against the backdrop of large-scale migration from Zimbabwe to South Africa before the medical emergency, as a result of political persecution and economic collapse. There are examples of sick people crossing borders to seek better healthcare, as has occurred in the context of HIV, but even in these cases the underlying causes may be disparities in healthcare and often stigma and discrimination against HIV positive individuals.

International Health Regulations do encompass travel-related public health measures to limit the spread of disease, such as control measures at points of entry by air, sea or land. But these are part of a much broader range of responses. Indeed current understanding of transmission dynamics makes it clear that diseases cannot be stopped at borders. Modern outbreaks such as SARS or H1N1 have shown that diseases can disseminate globally in a matter of days, and the volume and speed of global travel makes it impossible to stop infections at borders. Mathematical models provide little evidence for a benefit to travel restrictions on the spread diseases. Nevertheless some countries still attempt to restrict population movements during health crises – during the SARS outbreak in 2003 Kazakhstan closed its border with China, and Russia closed the majority of its border crossings with Mongolia and China.

Action points

More research is needed on the impact of health crises and migration. Furthermore, there needs to be greater coherence between IHR and migration policies, and more effort to encourage states to implement IHR. Above all there needs to be continued promotion of and access to healthcare. In fact, the most significant interaction between health crises and migration is probably not where migration results from health crises, but where health crises result from migration and among migrant populations, as currently witnessed in the Syrian refugee crisis, and this is where attention should be focused.

Note: This expert comment is based on a background paper co-authored with Michael Edelstein and David Heymann, as a contribution to the Crisis Migration Project hosted by the Institute for the Study of International Migration (ISIM) at Georgetown University.

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