Whenever there is an outbreak of a disease in the world - such as monkeypox - it is up to the World Health Organization (WHO) to consider what sort of weight to give it, including whether or not it constitutes a public health emergency of international concern.

Global efforts to manage epidemics are documented as far back as the black plague in Europe in the 14th century. Since that time, rules have been developed and honed to keep up with the emergence of new diseases as well as with the growing complexities of a world that's increasingly connected.

There are many diseases that can affect large numbers of people. But not all diseases are considered public health emergencies.

The seriousness of an epidemic is a function of several factors.

These include the degree of contagiousness and potential for rapid spread, severity of infection, case fatality rate (the number of infected people who die), availability of vaccines or treatment (it's more serious if there are none), impact on travel and trade, and the socioeconomic context.

Read more: Why the DRC Ebola outbreak was declared a global emergency and why it matters

What it triggers

Declaration of a "public health emergency of international concern" by the WHO triggers a number of things.

The first is that it signals a commitment to provide international resources for the response.

The second is that it enables other provisions of the International Health Regulations. These originated from the International Sanitary Regulations of the mid 1900s, which were used to control cholera epidemics. At this time, there was increasing awareness of the social and economic effects of epidemic diseases across borders, as well as concern about undue interference with trade.

In 1969 the regulations were renamed the "International Health Regulations" by the WHO. They were then modified in 1973 and 1981. But even then they provided a framework for only 3 diseases - cholera, yellow fever and plague. The principles behind them was

In 1995, formal revision commenced to expand the scope of the regulations with six proposed categories of reportable syndromes:

• acute haemorrhagic fever syndrome,

• acute respiratory syndrome,

• acute diarrhoeal syndrome,

• acute jaundice syndrome,

• acute neurological syndrome, and

• other notifiable syndromes.

In addition, five factors were proposed to determine if a cluster of syndromes was urgent and of international importance. These were rapid transmission in the community, unexpectedly high case fatality ratio, a newly recognised syndrome, high political and media profile, and trade or travel restrictions.

The last revision to the regulations was done in 2005 following the SARS epidemic of 2003.

The five substantive changes from the prior version were:

• a dramatic expansion of the scope of the regulations,

• the creation of obligations on states to develop minimum core surveillance and response capacities,

• granting WHO the authority to access and use non-governmental sources of surveillance information,

• granting WHO the power to declare a public health emergency of international concern and to issue recommendations on how states-parties deal with it; and

• the incorporation of human rights concepts into the implementation of the regulations.

The regulations set down how an emergency will be managed. This includes setting up a roster of experts appointed by the Director General of WHO in all relevant fields of expertise. Then an emergency committee is drawn from this roster for advice. The committee has to decide on a range of issues to do with managing the epidemic. This includes whether an event constitutes a global emergency and when it should be ended.

More than a health issue

But the regulations can only go so far. Many countries cannot comply with them due to lack of resources.

Many of the problems of global emergencies are not specific health problems, but relate to civil society, community engagement, law and order and border control. In the 2014 Ebola epidemic, for example, a health promotion team was massacred in Guinea because local people were fearful of outsiders coming to their village. During COVID-19 we also saw civil unrest in some countries. All of these issues are considerations for the WHO when deciding whether to declare a public health emergency of international concern.

This is a revised extract from an article previously published by The Conversation Africa written by C Raina MacIntyre and Obijiofor Aginam.

Authors: C Raina MacIntyre - Professor of Global Biosecurity, NHMRC Principal Research Fellow, Head, Biosecurity Program, Kirby Institute, UNSW Sydney | Obijiofor Aginam - Principal Visiting Fellow & Former Deputy Director, International Institute for Global Health (UNU-IIGH), United Nations University