ID Epidemiology Flashcards
what is an epidemic?
when does it become a pandemic?
epidemic:
an outbreak; an increase in numbers of cases of an infection over and above expected levels
OR
a single case, or small number of cases of an unusual organism
pandemic: epidemic that travels (epidemic with passport)
whats the difference between epidemic and endemic?
An endemic is a disease outbreak that is consistently present but limited to a particular region. This makes the disease spread and rates predictable. e.g. malaria in SSA
epidemic: an unexpected increase in the number of disease cases in a specific geographical area.
what is
a) incidence (& incidence rate)
b) prevalence?
a) incidence: measure of probability of infection. infection rate is no. of new cases per pop. at risk in given time
b) prevalence: proportion of infection found to be affecting a particular pop.
X conveys information about the risk of contracting the disease, Y indicates how widespread disease is:
what are X and Y?
incidence conveys information about the risk of contracting the disease, prevalence indicates how widespread disease is:
what are different modes of transmission? for ID
what is the first case called of transmission?
what is a primary case?
what is a clinica and sub-clinical case
- *index:** first case identified
- *primary case:** the case that brings infection into population (also get 2/3 cases)
- *sub-clinical case:** transfer virus to cases
- *clinical:** where symptoms and virus spread (could be 1/2/3 people)
what are factors that influence disease transmission?
what are 6 e.g. of resp. tract infections (viruses)
- resp. syncytial virus
- influenza
- COVID
- adenovirus
- rhinovirus
- nipah
which resp. viruses stay in upper resp tract? (4)
which resp. viruses go to low resp tract? (3)
infections of upper resp. tract
- rhinitis: inflammation of the nose
- pharyngitis: inflammation of the pharynx
- laryngitis: inflammation of the larynx
- conjunctivitis: inflammation of the mucus membrane of the eye
infections of lower resp. tract:
- croup: swelling of trachea (causes barking cough)
- bronchilotis
- pneumonia
how does a bacterial superinfection occur?
viral resp tract infections followed by bacterial superinfection:
- *-mucociliary escalator** (moves mucous out of lungs to be expelled by coughing) **damaged
- **viral infection OR inflammation can damaeg mucociliary escalator
- mucous not expelled
- followed by bacterial superinfection
how u diagnose resp. tract infections? (2)
what is a ct value / high or low ct value?
PCR - using a nasal pharyngeal swab:
- nucleic acids from virus is picked by virus panel -> recognise the viruses
- (can also check for bacterial panel to d/c if pneumonia is bacterial)
- ct value: no. of rounds of replication required to ID virus on swab
- high ct value: need lots of rounds of replication (low virus no.)
- low ct value: need few rounds to detect to virus
what is order, family, subfamily and genus of COVID?
how are coronaviruses diviied?
what were the intermediate hosts for SARs CoV-1, MERS, SARs CoV-2?
- *order:** Nidovirales
- *family:** Coronaviridae
- *subfamily:** Coronaviridae
- *genus:
- alpha coronavirus:**common colds (HCoC-NL63, HCoV-229E
- *- beta coronavirus:** common colds (HCov-HKU1/0), worse: (SARs CoV-1, MERS, SARs CoV-2)
(what could have been the intermediate host for covid?)
unsure atm, could be:
- fish market
- civet cat
- racoon dog
- snake
- pangolin
whats the difference between droplet and airbourne transmission?
- *droplet t:** larger, coughs and sneezes can spread droplets of saliva and mucus.
- *airborne t:** tiny particles (e.g. produced by talking), are suspended for longer. travel further
what is difference between SARS-CoV-2 and COVID 19?
SARS-CoV-2: virus
COVID 19: disease
what are symptoms of COVID-19?
- resp. distress
- fever
- dry cough
- GI symptoms
- dyspnea (Shortness of breath)
- MSK symptoms (fatigue, joint pain)
- altered mental status
- anosmia (loss of smell), dysgeusia (loss taste)
- alveoli infected: pneumonia
differences between SARS-CoV-1/ MERS / COV-2 in :
a) setting
b) infected pop
c) transmission (symptomatic?)
d) death / infections?
- *SARS CoV-1:** Hospital setting, 100% infected had disease, transmission = 24-36hrs after contact, 8098 infections, 774 deaths
- *MERS:** Hospital setting, most had disease, few asymptomic transmissions, camel reservoir, 866 deaths (34% death rate) , 2521 infections
- *SARs CoV-2:** public domain, >65 with co-morbid, many asymptomatic transmissions, only 30% have severe disease
first two: disease was obvious - so could be contained
what does ebola virus cause?
spread by?
(named after?)
when was big outbreak?
ebola virus caueses: haemorrhagic fever
spread: zoonotic disease, then spreads by: transmission of infected blood / bodily fluids (sex, contaminated needles, among family members
infects: primary spread - into blood, secondary spread: lungs, spleen liver
named: after river in Congo
big out break: 2013-15 - 39.5% death rate
describe the initiation of Zaire Ebola Virus Outbreak
Zaire Ebola Virus Outbreak:
- Patient Zero: Dec 2013 in Guinea
- Grandmother infected (who was a nurse), spread different hospital settings: 28 000 people infected
what are clinical features / symptoms of ebola?
why were ebola outbreaks not controlled in 2014?
- poor countries with fragile healthcare systems
- hight rate of infection of healthcare workers
- lack of PPE
- movement across porous borders
how does surveillance and and ring vaccination occur (with ebola?)
- *contact tracing:** sick individuals asked to ID contacts -> traced
- *community monitoring:** communities w/ infected individuals monitored daily
- *ring vaccination:** all those near to patient 0, neighbours etc - given vaccine
= reduced infection to zero by 28 june 2018 (in DRC)
