Emerging Infectious Diseases

Question 1

What is an emerging Infectious disease?

Answer 1

It is an infectious disease that has recently appeared in a population, and for which the incidence or geographic range is rapidly increasing or threatening to increase in the near future.

Question 2

Mention 3 causes of emerging infectious diseases.

Answer 2

1. Previously undetected or unknown infectious agents
2. Known agents that have spread to new geographic locations or new populations
3. Previously known agents whose role in specific diseases has previously gone unrecognised

Question 3

What is a re-emerging infectious disease?

Answer 3

Diseases caused by infectious agents whose incidence had significantly declined in the past but has now reappeared.

Question 4

Mention 7 drivers of emerging or re-emerging infectious diseases?

Answer 4

1. More frequent travels to far greater distances than in the past
2. Urbanisation: living in more densely populated areas
3. Closer contact with wild animals
4. Deliberate introduction into human, animal, or plant populations for terrorist purposes ( e.g., anthrax, smallpox, and tularemia)
5. Climate change : warm climate alters habitats, enabling diseases to spread into new geographic areas e.g. warming temperatures allow mosquitoes - and the diseases they transmit - to expand their range into new regions
6. Antimicrobial resistance: the acquired resistance of pathogens to antibiotics over time is an important factor in re-emergence of infectious diseases.
   The mcr-1 gene causes resistance to colistin, which is considered to be a “last resort “antibiotic. This gene is borne on plasmids and could be spread to from one bacterium to another.
7. Decline in vaccine coverage: decline due to refusal to take vaccine for personal reasons or philosophical belief has led to re-emergence of measles

Question 5

What are the factors involved in the emergence or re-emergence of infectious diseases?

Answer 5

a. Natural processes such as the evolution of pathogens over time e.g., genetic drift and shift in influenza A

b. Human behavior
and practices e.g. population growth, migration, international air travel, poverty, wars, and destructive ecological changes due to economic development and land use

Question 6

Highlight how an emerging disease gets established.

Answer 6

The infectious agent is introduced into a vulnerable population.
This agent possess the ability to spread readily from person to person and cause disease, sustaining itself in the population.

Question 7

What are zoonotic infections?

Answer 7

These are infections that are transmitted from animals to humans, either by direct contact, food, water or the environment.

Question 8

Briefly discuss how Corona virus diseases emerge.

Answer 8

Coronaviruses SARS-CoV, MERS-CoV, and SARS-CoV-2 cause the diseases SARS, MERS, and COVID-19 respectively.

They move from animals into humans, acquire the ability to spread from person to person and then, with great speed, reach around the globe as a result of air travel

Question 9

Briefly discuss how Chikungunya disease emerged.

Answer 9

Chikungunya disease is a tropical disease that spread recently into new areas due in part to climate change.
It is caused by the chikungunya virus, a relative of the Dengue virus, and transmitted by the tiger mosquito

In the past, it was confined to tropical regions around the Indian Ocean but
spread to Ravenna, Italy in summer of 2007

By 2014, chikungunya outbreaks have been reported in countries in Europe, Asia, Africa, and the Americas

The virus arrived in the United States in the summer of 2014 though transmission has been limited to Texas and Florida.

Question 10

Briefly discuss how Influenza diseases (the flu) emerged.

Answer 10

Influenza virus is infamous for its ability to change its genetic information.
Large changes in the influenza virus can cause pandemics because the human immune system is not prepared to recognise and defend against the new variant.

• Avian H5N1 influenza (or bird flu)- emerged more than a decade ago, limited to relatively rare instances of infection in humans who came into direct contact with diseased birds.
  The H5N1 virus is very deadly, but lacks the ability to pass efficiently between humans.
• In contrast, the H1N1 influenza, which passed into humans from pigs, transmitted easily from person to person and traveled quickly around the particularly due to air travel.
  Fortunately, it was much less deadly than the H5N1 virus.

**Emergence of an influenza virus that is as deadly as the avian H5N1 virus and is spread between people as easily as the swine H1N1 virus would be a very serious threat to human health