Lecture 23: Epidemiology introduction Flashcards
26th November 2024
What is epidemiology?
The study of infectious disease in populations (humans and animals).
Can parasites (pathogens) cause infectious disease?
Yes
Describe microparasites
- They are small, difficult to count, and replicate inside their host.
Give some examples of microparasites
Viruses
Bacteria
Fungi
Protozoa
Describe macroparasites
- Large, can be counted. Multiply external of the host.
Give some examples of macroparasites
Endoparasites - Worms (helminths)
Ectoparasites (ticks, flees, lice)
What 2 ways can infectious disease be transmitted?
Through one to one contact, and through non-contact.
What are some examples of one to one contact method of infectious disease transmission?
- Direct contact
- Indirect contact (i.e touching contaminated surfaces).
- Droplets (contact, but transmission is through air, for example with respiratory ilnesses).
What are some examples of non-contact method of transmission?
- Airborne (transmission through air but is carried further, for example measles, chicken pox).
- Vehicle (single contaminated source, like poison, which infects multiple hosts).
- Vector borne
What does DALY stand for?
Disability Adjusted Life Year
What is DALYs?
The number of healthy years of life lost due to premature death and disability (combination of mortality and morbidity).
What type of infectious disease has the greatest impact on health and life expectancy?
Lower respiratory infections
Give an exmaple of an infectious disease that used to have a massive impact on quality of life and longevity of life
The plague
What bacteria causes the plague?
Yersinia pestis
What vector carried the plague?
Fleas
What was the carrier of the vector, the fleas?
Rodents
What are the 3 types of plague and what do each of them infect?
Bubonic plague – infection of the lymphatic system
Septicaemic plague – infection of the blood
Pneumonic plague – infection of the lungs
How many deaths did the black death of the 14th century cause?
The ‘Black death’, 14th Century causing 25-50 million deaths in Europe (*but not relying on rats)
What does the untreated mortality of the plague range from?
Untreated mortality ranges 30% - 100%.
What is effective treatment for the plague?
Early antibiotic treatment is effective
Describe bubonic plague
Painful lymph nodes (buboes)
Fever
Headache
Chills
Weakness
Mortality = 30%
Describe pneumonic plague
Fever
Headache
Weakness
Pneumonia
shortness of breath, chest pain, cough, sometimes bloody or watery mucous
Mortality = 80%
Describe 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 ectremities
Mortality = 100%
What does cycle 1 of the plague transmission cycle mean?
Cycle 1 means that the pathogen is endemic in nature.