Lecture 23. Infectious Disease Epidemiology Introduction

Question 1

What are microparasites?

Answer 1

Small, difficult to count. Multiply in their host
Viruses
Bacteria
Fungi
Protozoa

Question 2

What are macroparasites?

Answer 2

Large, can be counted. Multiply external of the host
Endoparasites - Worms (helminths)
Ectoparasites (ticks, flees, lice)

Question 3

What are the one-to-one contact transmission routes?

Answer 3

Direct
Indirect
Droplet

Question 4

What are the non-contact transmission routes?

Answer 4

Airborne
Vehicle
Vector borne

Question 5

What is Disability Adjusted Life Year (DALYs)?

Answer 5

The number of healthy years of life lost due to premature death and disability

Question 6

What is the formula to calculate DALY?

Answer 6

DALY = Years lived with disability (YLD) + Years of life lost (YLL)

Question 7

What causes bubonic plague?

Answer 7

Infection of the lymphatic system

Question 8

What causes septicaemic plague?

Answer 8

Infection of the blood

Question 9

What causes pneumonic plague?

Answer 9

Infection of the lungs

Question 10

What are the symptoms of bubonic plague?

Answer 10

Painful lymph nodes (buboes)
Fever
Headache
Chills
Weakness

Question 11

What is the mortality rate of bubonic plague?

Answer 11

30%

Question 12

What are the symptoms of pneumonic plague?

Answer 12

Fever
Headache
Weakness
Pneumonia (shortness of breath, chest pain, cough, sometimes bloody or watery mucous)

Question 13

What is the mortality rate of pneumonic plague?

Answer 13

80%

Question 14

What are the symptoms of septicaemic plague?

Answer 14

Fever
Chills
Abdominal pain
Shock
Possible bleeding into the skin and other organs. Skin and other tissues may turn black and die, especially extremities

Question 15

What is the mortality rate of septicaemic plague?

Answer 15

100%

Question 16

What does incidence mean?

Answer 16

Number of new cases

Question 17

What does Trypanosoma cruzi cause?

Answer 17

Human Chagas disease in central and S. America

Question 18

What does Trypanosoma brucei spp cause?

Answer 18

African sleeping sickness in humans in Africa

Question 19

What does Plasmodium spp (P. falciparum, P. malariae, P. vivax) cause?

Answer 19

Malaria on many continents

Question 20

What is a vector?

Answer 20

Living organisms that can transmit infectious disease between humans or from animals to humans

Question 21

What are the routes of transmission of Trypanosoma cruzi?

Answer 21

Vector-borne by “kissing bugs” – Triatominae subfamily (80%)
Transfusion of infected blood (20%)
Congenital: mother to foetus (Vertical transmission) Accidental ingestion of infected sources

Question 22

What do ruptured pseudocysts release?

Answer 22

Inflammatory mediators

Question 23

What is chronic chagas disease?

Answer 23

Type III Hypersensitivity
Kidney disease
Chronic myocarditis
Fibrosis and necrotic damage (black area)
70 to 80% of people infected remain asymptomatic for life and may be unaware they are infected

Question 24

What does infection mean?

Answer 24

Presence of the pathogen/parasite in the host

Question 25

What does disease mean?

Answer 25

Clinical state of the host

Question 26

What are the features of macroparasites?

Answer 26

Chronic recurring infections (little/no immunity)
High morbidity, low mortality
Endemic in nature
Continual reinfection (limited post-recovery immunity)
Age-related exposure, burden, pathology

Question 27

Where is schistosomiasis found?

Answer 27

Globally in tropical and subtropical areas, especially in poor communities without access to safe drinking water and adequate sanitation
90% of those requiring treatment for schistosomiasis live in Africa