Dr Margaret Chan, director general of the World Health Organisation, has warned that the “explosive” recent increase in emerging and re-emerging diseases is set to continue.
Dr Margaret Chan, director general of the World Health Organisation, has warned that the “explosive” recent increase in emerging and re-emerging diseases is set to continue.
Speaking in Geneva, Switzerland earlier this week (December 17) during a meeting on global health security between the Global Partnership Against the Spread of Weapons and Materials of Mass Destruction and international organisations such as WHO, Dr Chan said emerging and re-emerging diseases have become “a much larger menace in a world of radically increased interdependence.”
The WHO chief said changes in the way humans inhabit the planet has given microscopic organisms multiple opportunities to exploit and has led to infectious diseases that are “volatile and constantly evolving.”
“These organisms are well-equipped to exploit every opportunity to infect new species, change their modes of transmission, spread to new areas and become established there, and develop resistance to antimicrobials [liquids that kill or inhibit the growth of microorganisms],” said Dr Chan.
“The climate is changing. Unusual weather patterns are reflected in unusual patterns in the distribution of wild animals and disease vectors. Dengue has exploited these opportunities to become the most important mosquito-borne viral disease in the world.”
Dr Chan gave the example of the emergence of the hanta virus in the USA in 1993, which was linked to a long period of drought followed by heavy rainfall. In turn, this brought deer mice into closer contact with humans, leading to the virus.
Dr Chan added: “For all of these reasons, stronger collaboration among the veterinary, public health, and agricultural sectors has become imperative as a way to gather early disease intelligence and improve our collective defences. New networks have been established that unite the existing surveillance and early warning systems maintained by the three organisations.
“WHO operates some mechanisms, like the Global Outbreak Alert and Response Network, or GOARN, that help compensate for weaknesses in national capacities. The International Health Regulations have provisions for requesting international assistance when domestic capacities are inadequate or overwhelmed.
“But these are fail-safe measures. True global health security, and true biological security, will be achieved only when more countries have stronger systems for routinely collecting disease intelligence, detecting and investigating unusual events, sounding the alarm, and mounting a response. The microbial world is full of surprises. It is well-equipped to defy predictions and shatter long-held assumptions,”
Dr Chan highlighted how, until the start of this century, most experts assumed new diseases would not gain a foothold in wealthy nations because “good health systems and high standards of living would prevent further cases or stop transmission quickly.”
But she said: “SARS proved otherwise as it spread fastest and most efficiently in sophisticated urban hospitals. Until this year, most epidemiologists regarded Asia and sub-Saharan Africa as the breeding grounds of new pathogens and the most likely source of new diseases. The detection of a new coronavirus in three Middle-Eastern countries proved that assumption wrong. We must never let down our guard.”
Dr Chan said although much about Ebola and Marburg fevers remains cloaked in mystery, many outbreaks are associated with the consumption of bush meat by just a few people. She said the globalisation of trade has increased the flow of animals, their pathogens, and disease vectors.
“As recent trends show, the demand for foods of animal origin is growing as societies modernise and income levels rise. The industrialisation of food production and the globalisation of its marketing have vastly complicated the investigation of food borne diseases and increased their consequences for health and multiple national economies.
“The future looks bright for microbes. They have certainly had a stellar year, with outbreaks of Marburg and Ebola haemorrhagic fever, epidemic cholera, hanta virus in the USA, the worst epidemic of yellow fever to hit Africa in two decades, and the emergence in the Middle East of a new SARS-like coronavirus.”
Dr Chan said one of the best ways to detect the unusual or the unexpected is to “have good data on the normal.”
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