Fighting infectious diseases

Biotechnology is used extensively in the study of emerging infectious diseases. These diseases are:

  • new and previously unrecognised, such as SARS (severe acute respiratory syndrome)
  • known diseases that have increased in number and spread over the past two decades, such as foot-and-mouth disease
  • diseases that threaten to increase in occurrence and severity in the near future, such as influenza.

Infectious diseases pose a threat to humans, because they can pass quickly from person to person, and affect a large number of people in a very short time.

A disease-causing agent is called a pathogen and can be a virus, bacterium or a prion (a type of protein). A pathogen's ability to infect and cause disease is referred to as its pathogenicity.

A number of issues are involved in emerging infectious diseases.

  • Growing tourism, trade, or political instability that results in more people and animals moving from one place to another. This can lead to a drop in standards of health or increase in the spread of infectious diseases, increasing the risk of transmitting disease from one place to another.
  • The evolution of new and more deadly disease-causing pathogens. Viruses and bacteria can naturally modify their genetic material over time (mutate). Some of these changes can increase their pathogenicity, while others can allow normally harmless pathogens to transmit disease.
  • Changes in climate and ecology can contribute to increases in vector-borne diseases (carried by insects). The pathogens, their vectors (the insects that transmit them) and their hosts (the animals, including humans, that can be infected by them) can all be influenced by the environment.
    • For example, mosquitoes, which carry a lot of diseases, prefer a warm climate. Global warming could increase the range of places where mosquitoes can live, allowing malaria to spread.
    • Alternatively, people are increasingly encroaching into wilderness areas to farm, as vacant land becomes scarce. This increases those people’s exposure to wild animals, many of which may harbour bacteria or viruses that do not cause disease in the animal because they have evolved together, but may cause diseases in people who have never had contact with these bacteria or viruses before.

Human behaviour also allows pathogens such as hepatitis C, HIV, SARS and variant CJD (the human form of mad cow disease) to exploit new niches.

Biotechnology is used to study the genetic material of viruses, bacteria and other organisms like prions.

Scientists can work out whether a disease is caused by a totally new pathogen, or a new type (strain) of a known pathogen. This information can be used to develop rapid diagnostic tests that enable specific detection and identification of a disease. Speedy detection of a pathogen can allow for a quick response to eradicate the disease, or to develop vaccines and effective drugs for treating infections.