Lecture 23. Infectious Disease Epidemiology Introduction Flashcards
What are microparasites?
Small, difficult to count. Multiply in their host
Viruses
Bacteria
Fungi
Protozoa
What are macroparasites?
Large, can be counted. Multiply external of the host
Endoparasites - Worms (helminths)
Ectoparasites (ticks, flees, lice)
What are the one-to-one contact transmission routes?
Direct
Indirect
Droplet
What are the non-contact transmission routes?
Airborne
Vehicle
Vector borne
What is Disability Adjusted Life Year (DALYs)?
The number of healthy years of life lost due to premature death and disability
What is the formula to calculate DALY?
DALY = Years lived with disability (YLD) + Years of life lost (YLL)
What causes bubonic plague?
Infection of the lymphatic system
What causes septicaemic plague?
Infection of the blood
What causes pneumonic plague?
Infection of the lungs
What are the symptoms of bubonic plague?
Painful lymph nodes (buboes)
Fever
Headache
Chills
Weakness
What is the mortality rate of bubonic plague?
30%
What are the symptoms of pneumonic plague?
Fever
Headache
Weakness
Pneumonia (shortness of breath, chest pain, cough, sometimes bloody or watery mucous)
What is the mortality rate of pneumonic plague?
80%
What are the symptoms of septicaemic plague?
Fever
Chills
Abdominal pain
Shock
Possible bleeding into the skin and other organs. Skin and other tissues may turn black and die, especially extremities
What is the mortality rate of septicaemic plague?
100%
What does incidence mean?
Number of new cases
What does Trypanosoma cruzi cause?
Human Chagas disease in central and S. America
What does Trypanosoma brucei spp cause?
African sleeping sickness in humans in Africa
What does Plasmodium spp (P. falciparum, P. malariae, P. vivax) cause?
Malaria on many continents
What is a vector?
Living organisms that can transmit infectious disease between humans or from animals to humans
What are the routes of transmission of Trypanosoma cruzi?
Vector-borne by “kissing bugs” – Triatominae subfamily (80%)
Transfusion of infected blood (20%)
Congenital: mother to foetus (Vertical transmission) Accidental ingestion of infected sources
What do ruptured pseudocysts release?
Inflammatory mediators
What is chronic chagas disease?
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
What does infection mean?
Presence of the pathogen/parasite in the host
What does disease mean?
Clinical state of the host
What are the features of macroparasites?
Chronic recurring infections (little/no immunity)
High morbidity, low mortality
Endemic in nature
Continual reinfection (limited post-recovery immunity)
Age-related exposure, burden, pathology
Where is schistosomiasis found?
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
