Agenda:

It is widely accepted that, in recent years, there have been more frequent "spillovers" of disease from animals into the human population than in the past.

This increase has been linked to humanity's ever-greater influence in reworking the Earth's environments by creating new eco-systems and altering existing ones. At a local level, human alteration of the landscape can have a range of unintended effects on animal populations, wiping out some and supporting others, for instance the populations of rodents and scavengers that thrive in cities.

The rapidly growing informal areas of cities in the global south represent the fastest changing environments on the planet. Such communities are poorly supported through infrastructure (city authorities and national governments simply cannot keep up with the speed of urbanisation) so people live without adequate water or sanitation services and are often tightly packed together.

These are ideal conditions for the emergence and spread of many diseases, including those that can be acquired through contact with rodents (for instance leptospirosis, transmitted via infected rat urine).

Climate change is shifting the pattern of diseases spread by insect vectors. Malaria affects people at higher altitudes and diseases such as dengue are reported from more areas year on year. Changing migration patterns of wild animals and livestock herders in search of dwindling supplies of food and water also provide new bridging points for possible disease transfers between humans and animals, bringing different populations into contact with diseases such as brucellosis, leptospirosis and Q fever that are all maintained in livestock. The recent spread of African strains of foot-and-mouth disease virus into north Africa have also been associated with shifting patterns of livestock movements.

While it is the potentially global reach of new flu strains or the haemorrhagic fevers such as Ebola that have captured headlines, it is the endemic zoonoses that have the significant burdens throughout the world.

These burdens are felt most acutely in the countries of the global south. Many of these zoonoses affect production livestock, resulting in a "double whammy" effect; there is not only a greater risk of disease for people as a result of more regular and close interactions with livestock, but there is also a greater impact on the livelihoods of people who are dependent on farming.

In such societies, there is often chronic under-funding of health services for animals and people and this is compounded by low levels of education and difficulties in the dissemination of information.

However, the recent growth of the "One Health" approach has begun to address some of these challenges. One Health recognises the important intersections of, and interdependencies between, human and animal health, and so the need for joined-up thinking.

Research is being designed and undertaken by teams of human health researchers, vets, ecologists, economists and social scientists working together to understand which people are at greater risks of acquiring zoonotic diseases, where risks of disease transmission might arise, and thus the points at which prevention measures can be addressed.

The IPCC report points to areas where adaptation strategies may be necessary to combat the effects of climate change. In healthcare, too, it is clear we will have to adapt some of our approaches.