Globalisation: Catalyst for the spread of zoonotic diseases

The wealth of a nation, it is said, is measured by the health of its people. Therefore any nation that relegates the healthcare of its people to the background will be denied a healthy population to engage in productive ventures for its socio-economic development.

As the world celebrates the 2009 World Veterinary Day, it is appropriate to reflect on the effect of globalisation of trade and its impact on the spread of zoonotic diseases.

Zoonotic diseases or zoonoses are those diseases and infections which are naturally transmitted from animals to man Zoonosis is a concept primarily useful to public health and veterinary disease control authorities. It defines an area of cooperative activity in both research and in control. Mutual concern for zoonoses furnishes an opportunity for communication between the physician interested in disease in no-human animals and the veterinarian interested in disease in man.

Central to the complex and close relationship linking humans and animals, infections diseases, especially zoonoses, have played a part in shaping the destiny of mankind.

Today, the world human and animal populations in ever-increasing numbers and in a perpetual state of movement and interaction have never been so close together through nature, agriculture and livestock; through the growth of trade in animals and animal products, and through our food. Yet globalisation also encourages the circulation of pathogens and helps to make them more aggressive.

The worldwide upsurge in animal diseases, especially zoonoses is a dangerous reality. Dramatic events and spectacular crises serve as constant reminder of the devastating consequences of these emerging and re-emerging diseases and the fear they can arouse.

Today, the natural or deliberate spread of these diseases is a threat without precedent in the history of mankind.

There are over 134 zoonotic diseases of virus, bacteria, fungi, parasitic or rickettsia origin which can be transmitted from animals to man. These include rabies, anthrax, brucellosis, tuberculosis clostridial diseases like tetanus, ringworm, Echinococcosis, Fish tapeworm, Pork Tapeworm, Salmonellosis and Highly Pathogenic Avian Influenza virus (HPAI) which has already caused outbreak in 62 countries and caused the death of about 140 million birds, 407 human infections with 254 deaths as at March 20, 2009.

Modem modes of transportation allow more people and animal products to travel around the world at a faster pace. They also open airways to the transcontinental movement of infectious diseases. One example of this is the West Nile virus.

It is believed that this disease reached the United States via "mosquitoes that crossed the ocean by riding in airplane wheel wells and arrived in New York City in 1999. With the use of air travel, people are able to go to foreign lands, contract a disease and not have any symptoms of illness until they get home, having exposed others to the disease along the way.

Globalisation, the flow of goods, capital and people across political and geographic boundaries have also helped to spread some of the deadliest infectious diseases especially zoonotic ones known to humans. The spread of diseases across wide geographic scales has increased through history.

In the current era of globalisation the world is more interdependent than at any other time. Efficient and inexpensive transportation has left few places inaccessible, increased global trade in agricultural products and brought more and more people in contact with animal diseases that have subsequently jumped species barriers.

Accordingly food and livestock feed need to be closely monitored during production as well as during handling, processing and distribution.

It is not enough to blame outbreaks on conditions during production if product control at latter stages is substandard. Similarly, the whole chain of responsibility must be transparent from beginning to the end. Intersectoral collaboration and dynamic leadership is needed to achieve this because a disease outbreak in one country cannot be seen as merely a local disease, it must be perceived as a global problem.

No country is sufficiently isolated or protected to ensure that the population, human and animal, is safe. It is vital for the control and maintenance of health to have forward defences to prevent and control food-borne infectious diseases. This process demands an international partnership capable of guaranteeing food quality and food safety programmes that are integrated with strategies for public health and sanitary control.

The emergence and re-emergence of zoonotic diseases may be the consequence of the new patterns of food trade or in some cases increased awareness and surveillance. Enterohaemorrhagic escherichia coli, for example, was confined to North America until the mid 1990s, but is now found throughout the world. Salmonella enteritis and the multidrug-resistant form of salmonella typhimurium via eggs have likewise spread widely since they were first detected in U.K. Bovine spongiform encephalopathy (BSE) has also spread rapidly from the UK to a number of countries since the 1980s and now threatens to become endemic in certain European countries.

Further examples of the potential dangers in the new patterns in food trade can be found in the pig industry.

In 1997 the pig industry in Taiwan was virtually ruined by the foot and mouth disease. This was the first outbreak there since 1930 and the implicated viral strain was closely related to strains found in Hong Kong. Classic Swine Fever cost the pig industry in Germany US$l000 million in 1995 and caused additional problems in Belgium and Netherlands. Back home in Ghana, the African Swine Fever which is now endemic dealt a devastating blow to the pig industry in 1996 with an outbreak during which government paid large compensation to farmers whose animals were destroyed.

The current outbreak of swine flu in Mexico which has claimed 150 lives with over 2,000 people hospitalised is spreading with lightning speed in many countries due to infected persons travelling from one place to another.

Notwithstanding the potential animal and human health problems, enhanced international trade in food and live animals has been and will continue to be of positive benefit to importing and exporting countries.

Among these benefits are; an improved nutritional status, job creation and improved diplomatic relations between the countries.

Nonetheless, increased global trade necessitates new and different approaches to food safety and to the control of exotic and zoonotic animal diseases.

The goals of these approaches should be to prevent livestock infection and food contamination in the exporting country. These goals could be accomplished through food safety assurance programmes developed by the International Organisation for Standardisation.

However, reliance on testing and other forms of inspection, by either the exporting or the importing country or both is likely to be inadequate. What is required is an effective control programme in the exporting nation.

Credit: Dr Kwasi Bowi (Daily Graphic)
(The writer is the president of the Ghana Veterinary Medical Association)