Studied by 1 person
active immunity and example
protection produced by own immune system stimulated by a antibody and cell-mediated immunity
provides long term protection
2 ways to acquire active immunity
via infection and recovery, if rexposed, the memory B cells begin to replicate and produce antibodies to reestablish protection
get vaxxed, which contain antigens that trigger the immune system to act (immune response)
what factors affect immune response? (4)
maternal antibodies, nature & dose of antigen, route of administration, presence of adjuvant (additives to improve immunogenicity of vaccine)
what are some host factors that affect the immune response? (4)
age, nutrition, genetics, comorbidity
What are live attenuated vaccines?
They are weakened but still active organisms (viruses) - a milder version but doesn't cause disease
e.g. MMR, rotavirus, smallpox, chickenpox, yellow fever
Inactivated vaccines
contains killed viruses/bacteria/pathogens that were cultured and killed to destroy their disease-causing capacity
e.g. pertussis, rabies, Hepatitis A, poliovirus
how does the immune system work
ability of human body to tolerate the presence of foreign material (bacteria, viruses, fungi) and to eliminate them
develops defence against antigens via the production of protein molecules by B cells (antibodies) which are immunoglobulins and production of T lymphocytes
What do B cells produce? and for what?
antibodies (immunoglobulins) as an immune response
What is an example of a vaccination scheme?
at 3 months, 5 months, 11 months, 14 months, until 14 years etc. children would get certain vaccines throughout their lives
what is the purpose of a vaccination scheme?
eradicate conditions, decrease mortality rates (child)
What is herd immunity?
a large community becomes immune to a disease
what are key determinants of herd immunity?
reproduction number (R0) - expected number of cases generated by one case in a population where everyone is susceptible for an infection
what should the reproduction number be for the disease to be eradicated?
smaller than 1
what may affect the R0 number
heterogenous population (diverse), which are more interconnected will increase transmission and thus requires a larger vaccination threshold
what are freeloaders?
people who don't participate in vaccination for herd immunity and depend on others to achieve herd immunity
they will be very vulnerable for a focal outbreak around them
how can social media influence vaccination decisions?
by delivering info that changes perceived personal risk of vaccine preventable diseases or side effects
what would be a solution to have a better platform to provide information for vaccines
implement interactive, customized communication
increase effectiveness of existing communicatoin
when there is less knowledge, need for reliable info on benefits & risks
What is Web 2.0?
Describes blogs, social networks, and internet-based services that emphasize collaboration and sharing
what are some web 2.0 challenges
for PH communication, online info influences people and everyone reacts to it, which makes it difficult to communicate safely (misinformation, etc.)
how do people get influenced easy on social media?
confirmation bias - they search for info that fits their beliefs rather than info that opposes their beliefs
how could the government have better communication?
natural frequencies (statistic representation)
visual support (infographics, videos9
focus on facts and alternative explanations for myths
what are challenges in global immunization? (6)
vaccines are not available to the poorest (inequality in distribution)
false claims for associations for autism and vaccinations
vaccines take a long process, expensive and difficult to make
as more vaccines are added to the immunisation schedule, there is a need for more immunological interference when given together (a lot of research)
confirmation bias
vaccine hesitancy - delay in acceptance or refusal of vaccines despite the availability of them
what solutions are there for vaccine inequality?
better ways to target vulnerable communities with interventions
what are reasons for vaccine hesitancy (6)
language barrier
social media influences with false info
cultural, religious beliefs
politics
gender
trust in government or health system
what is TB?
infectious disease caused by a TB bacteria and attacks the lungs mostly
what is latent TB?
bacteria stays in body and is inactive, only activates when getting older and immune system suppresses + if comorbidities (esp. HIV/AIDS coinfection)
how is tb caused?
bacteria (Mb.), can survive in dry environment, only grows in living organism
part of a family of bacteria
where can TB be detected as well? and how was the vaccine made (with what)
in cattle
the vaccine was made with the weakened living Mb. Bovis that causes TB in cattle
how does tb transmit
human to human, by coughing, sneezing etc. (airborne)
goes into alveoli in lungs
what is the primary infection of tb
immune system is battling the antigen locally (not yet spread further)
no symptoms
what is the secondary infection of tb
latent tb, when it stays inactive
what is open tb?
when inflammation ruptures and gets into the airways and spreads into lungs
what is miliary tb
when inflammation ruptures and gets into the bloodstream and spreads throughout the body
what are symptoms of active tb
active --> fever, night sweats, weight loss, fatigue
in lung --> prolonged coughing, sputum, cough blood, chest pain, shortness of breath
how do you diagnose tb?
case history (symptoms, traveling or born in prevalent country)
physical exam (listening to abnormal sounds)
lab & radiological investigation (interferon gamma test, skin test tuberculin, smear sputum, XpertMBT/RIF pcr test, x-ray)
what is the interferon gamma test
measures t cell response to the TB antigens and sees whether there is TB infection from BCG or actual infection
what is the skin test tuberculin (latent or active tb?)
for latent tb, inject tuberculin antigen (protein extract) into skin and if person develops a rash/swelling/redness after 2-3 days larger than 1cm, theyre positive for TB
wont be positive in primary infection since the antibodies arent formed properly yet
what are drawbacks to the tuberculin skin test?
if vaccinated, false positive would show since antibodies form vaccination formed (not infected with TB)
if immune system is suppressed, (HIV/AIDS), false negative may come up (weak antibody production for anything)
what is the smear sputum? (latent or active?)
active, if antigen is high, red dots can be seen on a microscopic level
what was the old and new golden standard for tb testing?
(old) culture --> breeding/culturing the antigen in its ideal environment and testing what type it is and whether it is sensitive to treatments
see what drugs work best, if sensitive it will not grow and drug can be used, however, very slow process
(new) pcr XpertMTB/RIF --> DNA is multipled and see if there is TB-bacterium DNA, detects resistance of rifampicin (most important drug for tb)
very expensive but fast
what is the x-ray for tb? (latent or active?)
active, showing presence for active disease
what is the prolonged multi-drug treatment for tb?
combining drugs to prevent resistance too
what are the treatments for tb and mtb
prolonged multi-drug
chemoprophylaxis
(MTB) antibiotics and chemotherapeutics (not related to chemo, just made in lab)
what is chemoprophylaxis for tb?
prevention of disease after exposure
used in children after contact with contagious patient
how to treat active tb
2 month long with 4 drugs Isoniazide (I), Rifampicin (R), Ethambutol (E), Pyrazinamide (P)
decrease bacteria and limit contagiousness
then 4 months with 2 drugs (I) and (R)
downsides of treating active TB
lots of side effects --> hepatitis, nervous disorders, eye disorders
if comorbidity, alcohol or other drugs are used, need to be careful
what are the consequences if active TB treatment is not consistent? (6)
development of resistance against drugs
reactivation of TB
complex and long process
size of tablets
further issues with comorbidities, addiction and low SES
not cheap
what is a treatment for mtb?
antibiotics (organic origin) and chemotherapeutics (not linked to chemotherapy, just made in lab)
what are the risk factors for the activation of TB? (5)
immune-suppressing conditions (HIV/AIDS)
immune-suppresive drugs
alcoholism
diabetes, undernutrition
genetic susceptibility
what are the risk factors for death from TB? (5)
comorbidity
accessibility of treatment
resistance to drugs
What is MDR and XDR?
mdr - multidrug resistant tb (2 drugs)
xdr - extensively drug-resistant (almost every drug (4 drugs))
why are people developing mtb or even xdr?
weak health systems
inadequate treatment process (difficult to stay on track
high transmission between communities
unnecessary antibiotic provision for other infections
what happened after the collapse of the USSR? (MDR)
prevalence increased with weak health systems (fewer drugs, drugs are expensive)
why are elderly prevalent in TB?
because their immune system weakens once theyre old, and the latent infection that they had activates
where is mtb frequent?
Eastern Europe and Africa
what is the aim of surveillance of TB?
reduce burden of morbidity and mortality from TB via contact tracing (notifying when there are cases) and seeing trends & patterns
What is the vaccine for TB?
BCG vaccine
how effective is the BCG vaccine
not effective, but protection is reported in children and newborns
what are types of control for TB? (4)
surveillance
vaccination
screening
outbreak management
how would you usually screen for TB?
x-ray of thorax when coming from a region with high TB prevalence
then treat and supervise the case
what are 2 issues with the BCG vaccine and positive test results in tuberculin skin test?
1- if a vaccination was made, the test will come back positive - making it difficult to distinct and infection from the vaccine
2- false negative if the individual has a immune suppressive condition, the results will be negative, not showing how the body fights back
outbreak management in TB (stone-in-the-pond principle)
investigate contacts closest and longest contact with index-case (e.g. group, family) first
--> if then no. of infected is bigger than expected, expand to bigger circle via DNA fingerprinting to identify source of infection
What are EIDs/newly emerging infectious disease?
emerging infectious diseases, newly appeared in a population
what causes the spread of infections (moving)
travelling for reasons such as work, tourism, leisure
what are zoonoses? and what factors cause it? (5)
infectious disease spread from animals to humans
farming, keeping domestic pets, hunting, camping, deforestation/habitat destruction
what are the 4 categories of EIDs? (ARND)
accidentally emerging infectious diseases
re-emerging infectious diseases
newly emerging infectious diseases
deliberately emerging infectious diseases
what is newly emerging infectious disease
one example
disease recognised in humans for the first time
e.g. COVID-19
what is accidentally emerging infectious disease
one example
disease created by humans unintentionally
e.g. vaccine derived polioviruses (over time changed into a wild or naturally occuring virus)
what is re-emerging infectious disease
one example
when a previously known disease has re-entered human population in new locations or in a resistant form
e.g. HIV/AIDS, TB
what is deliberately emerging infectious disease
one example
disease associated with the intent to harm (e.g. bioterrorism)
e.g. engineered microorganisms such as inserting genetic virulence to worsen a disease
what factors influence these infections? (3 categories)
host --> humans who are susceptible to those infections
agent --> susceptibility to an agent
environment
what are the environment factors for infections? (7)
animal exposures
traveling, commerce, tourism
environmental degradation (urbanisation, deforestation, economic development, land use)
climate & weather events
poverty (lack of PH infrastructure, availability & accessibility, lack of surveillance & monitoring for infections)
lack of political will (countries focus on different things)
deliberate use of terror and harm
what are the objectives for surveillance? (4)
time - how are these disease trends, do they coincide with interventions? (e.g. vaccines)
place - where is the disease, geographic variations & factors
person - who is affected, minority groups, gender, age, culture, SES, race, occupation
disease characteristics - clinical or lab characteristics, severity and outcome
why is covid and ebola so different? they are two pandemics tho..
covid spreads really fast to others and mostly passes with light symptoms
whereas ebola also spreads fast but symptoms are severe and cause death so transmission is slower (since ppl are dying, they cant spread to anyone much)
what is risk assessment?
research and evaluation on effects of substances or practices --> gaining understanding of positive & negative effects
what is risk estimation
scientific judgement on past events to predict size and likelihood of future events and estimates of uncertainty
what is risk evaluation
relies on social & political judgement to determine importance of hazards and estimated risks
what is the process of risk communciation
estimate risk evaluate risk
define options
make decisions
take action
monitor outcome
what needs to be considered for risk communication? (4)
different stakeholders to get a broader perspective
potential pitfalls
consider target audience risk perceptions (including beliefs and cultural/religious contexts)
be open and accept uncertainty (transparency)
language of risk with clear and only useful info that everyone understands (building on existing info, verbal info is perceived better where numeric info is difficult)
who did a good and bad job in SARS control ?
Singapore restricted travel to contain
China did not restrict
Canada was slow in communication
British ministry denied risk of infection
what is a biased way of individuals thinking about risk estimation example
when there are news on high rates of accidents, individuals would think that they themselves wont be in that rate because they drive carefully
how do you achieve herd immunity?
only a part of the population needs to be immune to prevent huge outbreaks (when R is less than 1)
how do you achieve herd immunity with vaccination when infection rate is very high?
larger vaccination rates the larger the infections rate
what is CVD?
group of disorders of the heart and blood vessels
what is atherosclerosis
happens in coronary heart disease, when plaque (cholesterol deposits) builds up in the walls of the coronary arteries, they narrow over time
how do you diagnose CVD?
ECG
blood measures (cholesterol levels, blood pressure)
what are the 2 types of CVD tereatments?
pharmacological --> medication to control and reduce risk factors (statins, aspirin, surgery (bypass),
non-pharmacological --> lifestyle changes (smoking cessation, increase PA, limit alcohol, focus on healthy diet, stress, reduce obesity)
what are risk factors of CVD (12)
smoking hypertension
obesity
unehalthy diet
limited PA
excessive alcohol consumption
family history & genetics of strokes
diabetes & metabolic syndromes
age
sex
chronic kidney disease
prior CVD experience
which age and sex group experiences hypertension more?
men 65 and older
how could primary and secondary prevention look like for CVD?
primary --> lifestyle change for people who experience risk factors
secondary --> prevent from further progression of CVD via medication and lifestyle changes
in which age group and sex has a higher CVD mortality rate ?
men have higher rate at 84 but for women it starts at 85-95 due to their longer life expectancy (the longer they live, the more CVD peaks) and menopause (estrogen decreases, risk of CVD increases)
what are risk prediction models?
estimate populations risk to develop CVD and to be able to control it in time with prevention strategies
to predict fatal and non fatal CVD
how does the prevalence looks like in CVD?
mortality and prevalence decrease lately
what do risk prediction models include? (7)
age, smoking, blood pressure, cholesterol, sex, diabetes, systolic blood pressure
what are cons of risk prediction models? (3)
most of them are not externally valid and are different in countries, some risk factors (e.g. diabetes) are missing
what are the 3 risk prediction models?
SCORE model
Framingham model
Q-risk model (up to 10 years in future)
what is preconception carrier screening (PCCS)?
investigating whether a genetic disorder is present in someone who is about to get pregnant (before pregnancy)
what is selective preconception care?
screening on request of the patient
what is premarital screening?
testing couples before getting married for genetic blood disorders and infectious diseases
what is universal preconception care
screening offered to populations from healthcare professionals
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