As our society advances with communication and the dissemination of information, health related topics have been a growing concern for many. The emergence of infectious disease has garnered attention by those concerned with public health and safety; these diseases appear on populations or have existed before but have evolved and increase the rate of incidence on those within its range. There are many factors that can lead to the emergence of disease on a population from ecological or demographic changes, to evolution of microorganisms.
However, international travel and trade has been a powerful force in the emergence of infectious disease on a population. The migration of humans has been a pathway for the distribution of diseases throughout the world and in history. This factor has shaped the emergence, frequency and spread of disease on specific geographical areas and on populations at alarming rates. As human movement throughout the world increases exponentially due to the advancements in transportation, infectious disease will have a first class ticket on these journeys as the vectors, humans, animals and or plants are transported to different corners of the world.
Humans’ traveling for business or pleasure only constitutes a small fraction of total human movement. Migration of people can include individuals or groups of immigrants, refugees, students, workers, soldiers, etc. Also, traveling may consist of short journeys or crossing borders one thing to note is that the volume of human movement is very large. International travel and trade is a factor that favors the emergence of infectious diseases through many different mechanisms. They can carry pathogens in or on their bodies, or carry and transport disease vectors such as lice or mosquitoes.
Diseases can emerge and grow due to nation’s technological capabilities (or lack of) in agriculture and health. People also change the environment in many ways when they travel or migrate, they will often start to plant, clear land, build, and consume. Travel is relevant in the emergence of disease if it changes an ecosystem. Visitors to a region may lack immunity to locally infections, such as hepatitis A and sand-fly fever. Visitors may suffer severe or different manifestations of infection or disease at an age when the local population is immune to it.
Resettlement of populations into malaria-endemic regions can lead to a high death rate from the disease. The SARS epidemic was a global phenomenon that emerged in 2003, an American businessman traveled from China was infected and experienced pneumonia like symptoms while on a flight. The plane landed in Vietnam where he was taken to be treated but died in hospital. It was at this moment the disease would advance, as several hospital workers who treated that man began to develop similar symptoms despite basic hospital procedures. Dr.
Carlo Urbani, the doctor who identified the threat, informed the World Health Organization and local government, and became the latest victim of this mysterious disease. The severity of the symptoms and the infection of the hospital staff created an alarming global fear of an emerging pneumonia-like epidemic. The introduction of a species to a new geographical location has been present throughout the history of the world, but the increase in global populations has affected caused a direct increase in other areas such as travel and trade.
Infectious diseases can spread in an environment based on reproductive rates; the ability to invade and remain is a host and population. Migration can introduce parasites to an area its never been to with a new potential of hosts to infect thus changing the incident rate of that disease causing an epidemic. The emergence of the infectious disease can be successful because of large susceptible populations. In the United States, there was an outbreak of malaria in California that occurred because migrant workers were employed in an area that had a large population of mosquitoes, which have been known to be vectors of malaria.
Mosquitoes have been known to be present on international flights, African mosquitoes that are known carriers of malaria were suddenly appearing in other areas of the world like Europe and the United States. Since its emergence in 1982, the African mosquito has established itself in many states across the United States of America, and has at the same time acquired local viruses. The introduction of infected species to a new environment can cause devastating effects, as there are more susceptible hosts to spread the infection around which in turn can cause an epidemic.
The movement of humans constitutes only a fraction of the matter moved about the earth. Humans carry and send a huge volume of plants, animals and other materials all over the face of the globe. Much of this movement results from the planned transport of goods from one place to another, but some is an unintended consequence of shipping and travel. Animals and plants can carry human pathogens that can be potentially infectious to our health. The globalization of our markets brings a large array of meats, fruits and vegetables to our dinner tables from nations that are thousands of miles away.
With the mass distribution of goods, this has implied the dissemination of harmful pathogens. Mad cow disease outbreaks occurred in Europe, Asia, and North America due to an epidemic that started in South East Asia. The effects of globalization, industrialization, the restructuring of the agricultural sector, and the growing and sustained demand for animal proteins are changing the foundations and the application of policies directly related to animal health and food safety as well as to the safety of the food supply.
The emergence of infectious diseases has been present throughout the course of history, and will continue to adapt in new environments and evolve stronger than ever at accelerated rates. However, humans are not powerless against these pathogens. Knowledge of the factors that contribute to the emergence of disease can help us to focus our resources to handle epidemics. We can develop effective prevention strategies against emerging diseases. The most important step to protect ourselves is an effective global disease surveillance that will give us an early warning of the emergence of an infectious disease.
The surveillance helps to recognize and report cases of unusual disease that seem to be emerging at an exponential rate. By discovering the characteristics of the disease, its signs and symptoms will help create awareness and help us focus on how to respond to it through intervening and containing the outbreak. Some surveillance systems monitor laboratory test results, use analysis of patient samples routinely collected clinicians, derive data from routine computer-based searches of patient or public health records; and use media reports of disease outbreaks.
As human movement throughout the world increases exponentially due to the advancements in transportation, infectious disease will have a first class ticket on these journeys as the vectors, humans, animals and or plants are transported to different corners of the world. The emergence of infectious diseases will continue due to the advancements in international travel and trade. New disease will spawn and known disease will change in distribution, severity and frequency. Research and proper surveillance of the movement of infectious diseases, will help us to intervene and contain disease before they can contribute to mass infections.