L1 - Introduction

Question 1

What were some of the major human pathogenic viruses from the past?

Answer 1

Smallpox virus (eradicated), yellow fever virus, poliovirus (nearly eradicated)

Question 2

What are some of the major human pathogenic viruses currently circulating?

Answer 2

SARS-CoV-2, Hepatitis B virus, Hepatitis C virus, HIV, HPV, Herpes virus, Arboviruses (dengue, yellow fever), Measles virus, RSV, Rotavirus, Influenza virus

Question 3

What are some of the possible major human pathogenic viruses that could be a concern in the future?

Answer 3

Hantavirus, Ebola and Marbug virus, nvCJD, SARS-CoV-3, MERS-CoV-2

Question 4

In what circumstances can relatively common virus infections be associated with severe complications?

Answer 4

In the young, elderly and immunocompromised e.g SARS-CoV-2, Influenza and RSV

Question 5

What is unusual about the disease burden of SARS-CoV-2 compared to other respiratory infections such as Influenza or RSV?

Answer 5

COVID, like other respiratory infections, has an uneven disease burden on different age groups. However, mortality rates in the very young are almost 0% for COVID compared to relatively high mortality in older individuals. Infections such as Influenza/RSV have significant mortality in both the very young and elderly groups.

Question 6

Define zoonotic infections

Answer 6

An infection or infectious disease transmissible under natural conditions from vertebrate animals to man

Question 7

Give some examples of oncogenic viruses and the types of cancer they cause

Answer 7

RNA viruses:
Hepatitis C virus -> Hepatocellular carcinoma
Retroviridae -> Haematopoietic cancers, sarcomas and carcinomas

DNA viruses:
Papillomaviruses -> papillomas and carcinomas
Herpesviridae -> Lymphomas, carcinomas and sarcomas
Poxviridae -> Myxomas and fibromas

Question 8

Define endemic, epidemic and pandemic

Answer 8

Endemic - disease is continuously occurring e.g. RSV

Epidemic - disease incidence much higher than background endemic rate

Pandemic - worldwide epidemic

Question 9

Define incubation period and period of infectivity

Answer 9

Incubation period - period between infection and appearance of symptoms (may still be infectious e.g. with SARS-CoV-2)

Period of infectivity - period during which patient is infectious or capable of viral transmission

Question 10

Define morbidity and mortality

Answer 10

Morbidity - occurrence of disease

Mortality - occurrence of death

Question 11

What factors determine virus transmission and survival in a population?

Answer 11

• Virus stability in environment
• Transmissibility - period of shedding and ability to establish an infection
• Effectiveness of host immunity