(2) With examples differentiate between emerging and re-emerging infectious diseases (10 marks)

Emerging and re-emerging infectious diseases are two categories of diseases that pose significant threats to public health.

1. Emerging Infectious Diseases (5 marks)

Emerging infectious diseases are diseases that have not been previously observed in humans. They are often caused by newly identified and previously unknown infectious agents. They can also be diseases that have existed in small, isolated locations but are now beginning to spread into larger areas.

For example, HIV/AIDS was an emerging disease in the 1980s when it was first identified. It was a new disease that had not been seen in humans before. Similarly, the recent COVID-19 pandemic is caused by a novel coronavirus (SARS-CoV-2), which was not previously identified in humans.

2. Re-emerging Infectious Diseases (5 marks)

Re-emerging infectious diseases, on the other hand, are diseases that were once major health problems globally or in a particular country, and then declined dramatically, but are again becoming health problems for a significant proportion of the population.

For example, Tuberculosis was a major health problem in the early 20th century, then declined in many countries with the development of effective antibiotics, but it has re-emerged as a serious health problem in recent years, partly due to the emergence of multi-drug resistant strains. Similarly, measles is a re-emerging disease in some countries where it was previously under control, due to falling vaccination rates.

In conclusion, the main difference between emerging and re-emerging diseases is that emerging diseases are caused by newly identified and previously unknown infectious agents or are diseases spreading into new areas, while re-emerging diseases are known diseases that were once under control but are now seeing a resurgence.