Question

Name and describe four different transition patterns that emerging diseases have followed through history. Provide an example for each. 24.

Answer 1

Emerging diseases have followed certain patterns in transition of diseases since ancient times. The first pattern of transition of emerging disease is known as crowd transition. In this type of transition the diseases and pathogens transmitted from one person to other due to close contact and crowded living of people. This type of transition also allowed the spread of diseases from animals to humans through zoontic transition. Later, the mutations acquired by pathogens restricted them to cause disease in a specific host. The development and spread of SARS (severe acute respiratory syndrome) in China is an emerging disease by crowd transition.

The European society invaded into other groups of population through trade or war was known to exchange the infectious pools which can be considered as second pattern of transition of emerging diseases. Typhus was an emerging disease during 430 BC through Peloponnesian War.

The third type of emerging disease transition was through urban civilization and colonization and industrialization. The humans were being in contact with completely new pathogens that have emerged into new infections in newly colonized population. The infections like measles, small pox, tuberculosis and syphilis etc. have been observed since 1500 years ago and introduced into Pacific Island populations who were completely new to such infections.

The global urbanization is the fourth pattern of transition caused due to development of civilizations, settling in urban areas with crowded colonization coupled with various factors. The factors may include poverty, social inequality, technology development, climate changes and environmental hazards that influence the pattern of diseases to emerge and re-emerge and spread rapidly than before. This can be observed in the case of re-emergence of infections once eradicated such as measles, small pox or polio and many other diseases that are potentially infecting the human populations.