How did Bird Flu reach Britain?
The UK has reported its first case in a wild bird of the deadly H5N1 virus.
It is unclear whether the dead bird, which came from outside of the UK, picked up the disease abroad.
The disease has been blamed for 169 human deaths in Asia and the Middle East.
At the time of writing, a 1.8-mile protection zone had been placed around Cellardyke in Fife, where a dead infected swan was recently found.
What are the origins of this disease?
Why has it spread globally so quickly?
How might it threaten the economic development of many Asian nations?
What could the impacts for UK consumers be?
Avian flu (shorthand for influenza) is a disease naturally occurring in bird populations. It can spread to other animals and to unlucky human beings that come into direct contact with infected birds. However, it is not passed on from infected humans to other people under normal circumstances.
The current outbreak began in 1997 in Hong Kong and has now spread throughout Asia and Europe and parts of Africa. Since it was first reported, at least 108 lives have been claimed across Asia and the Middle East.
Vietnam has been particularly badly hit, with 42 deaths. Other fatalities have been recorded in Azerbaijan, Cambodia, China, Egypt, Indonesia, Iraq, Turkey and Thailand. A total of 191 people have actually contracted the virus, making the survival rate less than fifty percent.
The disease has become a cause of great concern for the World Health Organisation (WHO), who fear that this particular strain of avian flu could potentially spread amongst human populations in dramatically large numbers.
Under normal circumstances, infection only occurs when people come into direct contact with infected birds. However, the risk to humans can dramatically increase if the avian flu combines with pre-existing human viruses, through a process called antigenic shift, to create a new form of flu for which our immune systems have no defence. It can then also be spread from human to human.
Serious global outbreaks of avian flu involving antigenic shift have occurred only three times before in the past century, most seriously in 1918-19 when over 40 million people died.
Experts say that there is no evidence that similar human-to-human transmission has occurred in any of the recently recorded cases. For instance, health officials attributed all of the H5N1 infections in Vietnam to direct contact between poultry workers and the faeces of sick birds (Reuters).
H5N1 has been around for a while: it claimed its first human victim, a three-year-old boy, in Hong Kong in May 1997. On that occasion, the virus infected 18 people and caused 6 deaths. The immediate slaughter of around 1.5 million poultry in Hong Kong is thought to have averted a larger outbreak in humans at the time.
The disease was not detected again until February 2003, when a father and son were diagnosed with H5N1, again in Hong Kong. Soon after, one of the most serious recorded outbreaks took place in Vietnam in October 2003. Hospitals in Hanoi and surrounding provinces admitted 14 people with severe respiratory illness and 12 of them died. Over nine million chickens and ducks have were immediately slaughtered in an attempt to stop the further spread of infection.
Despite mass culls, exclusion zones and other measures put in place to prevent its spread, the H5N1 virus continued to travel after 2003. It quickly moved westwards through Asia and the Middle East into Europe and Africa. By February 2006, the World Health Organization (WHO) had confirmed cases in humans in Indonesia, Vietnam, Thailand, Cambodia, China, Turkey and Iraq.
Shortly afterwards, Italy, Greece, Bulgaria, Germany, Austria, France, Slovenia, India, Iran and Egypt all confirmed their first cases of H5N1 in wild birds. In October 2005, the UK recorded its first case of H5N1 in a quarantined parrot from South America, but because the bird was held in isolation the UK's disease-free status remains unchanged (BBC news, 06 April 2006). With the discovery of an infected swan in Fife, that has now changed.
Bird viruses spread very quickly for natural reasons, due to the long migratory journeys that many birds take at certain times of the year. The spread of the disease is therefore closely linked to birds’ well-established migration paths, which is why scientists have been anticipating its arrival in the UK.
The sudden spread of the virus throughout Europe occurring in February and March 2006 corresponds with the return of birds that would have spent the winter elsewhere. For instance, Northern Nigeria, where the H5N1 strain was confirmed in early 2006, is a favourite wintering ground for birds from Europe. Guardian - Return of migrating birds could spread avian flu in Europe
In addition to natural causes, a combination of modern farming methods and mass transportation of chicken carcasses to distant markets means that potential for the rapid spread of such viruses amongst bird populations is now greater than ever before.
Finally, massive demand for chicken has led to factory (battery) farming which provides ideal conditions for viruses to spread between birds both orally and via excreta which inevitably contaminates food in the cramped conditions that most birds are kept in. Such conditions also raise the risk of the disease spreading to the human population, as farm workers come into close contact with the birds and their faeces.
The seriousness with which governments view H5N1 was displayed back in 2004, when Japan experienced one isolated outbreak of H5N1. The case was recorded in the Yamaguchi prefecture and led to a ban on eggs and chickens leaving an area within a 30-km radius. Japan immediately halted chicken imports from Thailand, China and the United States, three of its top four foreign suppliers (Reuters).
The European Union banned all poultry imports from Thailand when the disease struck there in 2004. Clearly, H5N1 can have a severe impact upon economic systems in LEDCs such as Thailand and other major chicken-producing nations where the disease has struck.
Farmers in LEDCs lack the subsidies and benefits that their MEDC counterparts have access to in times of difficulty. Loss of markets, and in many cases the forced destruction of their chickens, will almost certainly result in devastating poverty for many.
Local economies will also experience a negative multiplier effect as supply services (transportation and haulage firms) are hit. Local services may then suffer, as incomes dwindle and consumer spending falls in those communities that have been dependent upon poultry farming.
The avian flu outbreak may also impact upon the tourist industry. Bali - Indonesia's popular tourist destination – experienced an early outbreak of avian flu that deterred visitors (just as English tourist destinations were badly hit by the Foot and Mouth outbreak in 2001).
However, some groups may gain economic benefits from the crisis. When British supermarkets restricted their sources of chicken in 2004, European poultry farmers experienced rising demand for their own supplies of meat. During 2004, Sainsbury’s entire range of ‘Asian’ (Indian, Thai and Chinese) Ready-Meals were re-packaged to read ‘Made with British or European chicken’! However, following the discovery of the dead swan, UK consumers may no longer regard this as a guarantee of safety.
Another firm to benefit from fears about H5N1 has been the chemical giant GlaxoSmithKline (GSK) who produce an anti-viral drug. GSK has taken on 12 new workers to man its Ulverston production line and has also delayed the departure of 16 staff who were taking redundancy (BBC 06 February 2006).
There are many opportunities for discussing the alarming spread of avian flu or other diseases within a KS3, GCSE or AS/A-level geography course:
The spread of disease can be a consequence of migration As flows of people (and their favoured animals and plants) move across the globe, so too do the diseases and viruses that they carry with them. Bird populations naturally make seasonal migrations that expose them to disease.
The spread of disease has often been a direct consequence of globalisation. Spanish invaders decimated indigenous populations in South America by bringing diseases such as measles with them in the Fifteenth Century. More recently, the spread of AIDS has been linked with the movement of migrants both between MEDC destinations, such as New York and London, and also between rural and urban areas in LEDCs. Demand for chicken by supermarkets and fast-food outlets in Europe has given rise to a global supply chain, with much meat sourced from Thailand. This supply chain has assisted the rapid spread of avian flu.
The spread of disease constitutes a biological hazard Environmental. (temperature, humidity) and human factors (migration, settlement, vaccination programmes, availability of clean water) result in different levels of risk for people in different regions or countries. Attempts to control biological hazards have often met with great levels of success (compared with geophysical hazards such as earthquakes), notably with the world-wide eradication of smallpox in 1980.
The spread of diseases may be a product of intensive farming systems. Modern farming practices often result in animals living in cramped and unhygienic conditions. Battery chicken farming is the most notorious example of this, as farmers attempt to maximise outputs per unit area of land.
The spread of disease can be a negative consequence of development processes. When indigenous populations in wilderness areas of the world are first contacted by outside forces, the hope may be to bring benefits of modern healthcare and science to them, in an attempt to improve their quality of life. Unfortunately, such attempts to improve levels of social development have sometimes resulted in tragedy. According to John Hemming, speaking at the Royal Geographical Society recently, the worst cases of first contact with indigenous peoples in the Brazilian rainforest resulted in 85% mortality. Common illnesses were spread to people whose immune systems were unprepared.
Geographers refer to the spread of a phenomenon through space and time as diffusion. Associated particularly with Hägerstrand’s (1953) work on the spread of innovations, diffusion can be represented by a series of maps of an area at successive points of time, displaying those people who have adopted the innovation. Such distributional changes are also well-suited to the spread of disease.
Hägerstrand recognised that there is always an element of chance in distributional changes and developed a technique known as ‘Monte Carlo simulation’ to assist his studies. His ideas are still applied by geographers interested in epidemiological modelling (most recently in relation to AIDS). Historical studies have often focused upon the great avian flu outbreak of 1918-19, the roots of which lie in the end of the First World War. The huge military training and hospital camp of Etaples, in northern France, may well have been the source of a deadly flu virus derived from avian flu. Men, chickens and pigs were crowded together, providing the ideal circumstances for viral cross-species infection through antigenic shift. The disease spread globally following the armistice, when troops started returning to their homes. A spread of disease occurring on this scale is termed a pandemic.
Essay topics could focus upon how disease and infection are usually found in some areas more than others, and usually spread along certain routes, or form certain patterns. As this article has stressed, these patterns may be linked with natural migration corridors for bird species as well as the growth of global food supply networks. This study may be especially helpful if you are investigating:
spatial variations that occur in the distribution and spread of infections
the consequences of disease: not just death and debilitation but also long-term effects on local economies
BBC interactive map
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