Climate change will allow tropical disease to spread to Europe

Paul Eccleston
Last Updated: 3:01pm BST 07/10/2008
Climate change will allow wildlife diseases to spread more easily, a new report warns.

The Wildlife Conservation Society (WCS) lists the "deadly dozen" diseases which could threaten human health and global economies.
The study shows the impact climate change could have on the health of wild animals and how it can cascade onto human populations.
Avian flu, TB and Ebola are just some of the broad range of infectious diseases that threaten both humans and animals.
Pathogens that originate in or move through wildlife populations can also inflict massive economic damage. Since the mid 1990s avian inluenza is estimated to have caused $100bn in losses to the global economy.
The report, The Deadly Dozen: Wildlife Diseases in the Age of Climate Change, says better monitoring of wildlife is needed to detect how diseases are moving so health professionals can restrict their impact.
Dr Steven E Sanderson, president and CEO of the WCS, said: "The term 'climate change' conjures images of melting ice caps and rising sea levels that threaten coastal cities and nations, but just as important is how increasing temperatures and fluctuating precipitation levels will change the distribution of dangerous pathogens.
"The health of wild animals is tightly linked to the ecosystems in which they live and influenced by the environment surrounding them, and even minor disturbances can have far reaching consequences on what diseases they might encounter and transmit as climate changes.
"Monitoring wildlife health will help us predict where those trouble spots will occur and plan how to prepare."
WCS leads an international consortium that helps to monitor the movements of avian influenza through wild bird populations around the world.
The Global Avian Influenza Network for Surveillance (GAINS) was created in 2006 and now involves dozens of private and public partners that monitor global wild bird populations for avian flu.
Congresswoman Rosa L DeLauro, who supports GAINS, said: "Emerging infectious diseases are a major threat to the health and economic stability of the world.
"What we've learned from WCS and the GAINS program is that monitoring wildlife populations for potential health threats is essential in our preparedness and prevention strategy and expanding monitoring beyond bird flu to other deadly diseases must be our immediate next step."
The disease list includes some of the pathogens that may spread as a result of climate change:
•Avian influenza: Like human influenza, avian influenza viruses occur naturally in wild birds, though often with no dire consequences. The virus is shed by infected birds via secretions and faeces. Poultry may contract the virus from other domestic birds or wild birds. A highly pathogenic strain of the disease-H5N1-is currently a major concern for the world's governments and health organisations.
•Babesiosis: Babesia species are examples of tick-borne diseases that affect domestic animals and wildlife, and Babesiosis is an emerging disease in humans. In some instances, Babesia may not always cause severe problems by themselves but when infections are severe due to large numbers of ticks, the host becomes more susceptible to other infectious diseases.
•Cholera: Cholera is a water-borne diarrhoeal disease affecting humans mainly in the developing world. It is caused by a bacterium, Vibrio cholerae, which survives in small organisms in contaminated water sources and may also be present in raw shellfish such as oysters. Once contracted, cholera quickly becomes deadly.
•Ebola: Ebola hemorrhagic fever virus and its closely related cousin - the Marburg fever virus - easily kill humans, gorillas, and chimpanzees, and there is currently no known cure. As climate change disrupts and exaggerates seasonal patterns, we may expect to see outbreaks of these deadly diseases occurring in new locations and with more frequency.
•Intestinal and external parasites: Parasites are widespread throughout terrestrial and aquatic environments. As temperatures and precipitation levels shift, survival of parasites in the environment will increase in many places, infecting an increasing number of humans and animals.
•Lyme disease: This disease is caused by a bacterium and is transmitted to humans through tick bites. Tick distributions will shift as a result of climate change, bringing Lyme disease into new regions to infect more animals and people.
•Plague: Plague, Yersinia pestis - one of the oldest infectious diseases known - still causes significant death rates in wildlife, domestic animals, and humans in certain locations. Plague is spread by rodents and their fleas and alterations in temperatures and rainfall are expected to change the distribution of rodent populations.
•"Red tides": Harmful algal blooms off global coasts create toxins that are deadly to both humans and wildlife. These occurrences - commonly called "red tides"- cause mass fish deaths, marine mammal strandings, penguin and seabird mortality, and human illness and death from brevetoxins, domoic acid, and saxitoxins (the cause of "paralytic shellfish poisoning").
•Rift Valley Fever: Rift Valley fever virus (RVFV) is an emerging zoonotic disease of significant public health, food security, and overall economic importance, particularly in Africa and the Middle East. In infected livestock such as cattle, sheep, goats and camels, abortions and high death rates are common. In people (who can get the virus from butchering infected animals), the disease can be fatal.
•Sleeping sickness: Also known as trypanosomiasis, this disease affects people and animals. It is caused by the protozoan, Trypanosoma brucei, and transmitted by the tsetse fly. The disease is endemic in certain regions of Sub-Saharan Africa, affecting 36 countries, with estimates of 300,000 new cases every year and more than 40,000 human deaths each year in eastern Africa. Effects of climate change on tsetse fly distributions could play a role in the distribution of the disease.
•Tuberculosis: As humans have moved cattle around the world, bovine tuberculosis has also spread. It now has a global distribution and is especially problematic in Africa, where it was introduced by European livestock in the 1800s. Climate change impacts on water availability due to drought are likely to increase the contact of wildlife and livestock at limited water sources, resulting in increased transmission of the disease between livestock and wildlife and livestock and humans.
•Yellow fever: Found in the tropical regions of Africa and parts of Central and South America, this virus is carried by mosquitoes, which will spread into new areas as changes in temperatures and precipitation levels permit. One type of the virus-jungle yellow fever-can be spread from primates to humans and vice-versa via mosquitoes that feed on both hosts.
www.wcs.org