An analysis of global trends in new infectious diseases suggests that we are looking in the wrong places for the world’s next major outbreak.
The study is the work of Dr Kate Jones, Senior Research Fellow, based at Institute of Zoology, London, and colleagues, and was published on 21st February in the online issue of Nature.
Writing in the same issue of Nature, science writer Michael Hopkin, said the study gave a “fresh perspective on global disease”, and helped “to quantify the effect of well-known risk factors, such as population density, on the probability of a disease taking hold in a given area”.
Emerging infectious diseases (EIDs) are thought to be largely driven by “macro” factors such as socioeconomics, environment and ecology, but until this study, nobody had tied them down in terms of global patterns of time and place.
Jones and colleagues, led by co-author Dr Peter Daszak of the Consortium for Conservation Medicine, based in New York, looked at the emergence and spread of 335 infectious diseases from 1940 to 2004 to find non-random global patterns.
These included many diseases that have spread and taken hold in many regions of the globe, bringing devastation and misery to millions, such as drug-resistant tuberculosis, chloroquine-resistant malaria and HIV, wrote Hopkin.
The report tells of how the rapid spread of these diseases is tied to increases in population density, changes to agriculture, and rising international trade and travel.
The results showed that:
- Emergent infectious disease (EIDs) outbreaks rose steadily from 1940 to 2004, peaking in the 1980s.
- Over 100 new pathogens emerged in this peak period (1980s), which coincided with the emergence of HIV.
- Most of the 335 EIDs (60 per cent) started in animals (zoonoses), and among these, most (72 per cent) originated in wildlife.
- Examples of wildlife originated infectious diseases are SARS (severe acute respiratory virus) and the Ebola virus.
- Emergent disease outbreaks originating in wild animals are increasing significantly over time.
- Over 50 per cent of emergent disease outbreaks are caused by bacteria, many of them drug-resistant.
- Many outbreaks are significantly linked to socioeconomic, environmental and ecological factors.
- These factors give a basis for predicting where new diseases might break out (hotspots).
- They also predict that new disease outbreaks are more likely in lower latitude regions where monitoring efforts are fewer.
Jones and colleagues concluded that:
“Global resources to counter disease emergence are poorly allocated, with the majority of the scientific and surveillance effort focused on countries from where the next important EID is least likely to originate.”
Hopkin said the authors were suggesting “watchdog groups should invest more in monitoring regions such as tropical Africa, Latin America and Asia”.
Jones told Hopkin that a globally coordinated strategy was needed to find future hotspots and stop new outbreaks from spreading around the world.
“We need to think more broadly, with a global vision,” said Jones, “everyone will be affected, we are all on the same planet.”
“There’s nowhere to hide,” she added.
“Global trends in emerging infectious diseases.”
Kate E. Jones, Nikkita G. Patel, Marc A. Levy, Adam Storeygard, Deborah Balk, John L. Gittleman, and Peter Daszak.
Nature 451, 990-993.
Published online, 21 February 2008.
DOI:10.1038/nature06536.
Sources: Nature (news report & article abstract), Institute of Zoology, London.
Written by: Catharine Paddock, PhD