Infectious Disease Epidemiology Flashcards
what is the importance of infectious epidemiology
assessing changes in pattern of infectious disease - geographical or seasonal
- discovery of new emerging infections
- potential link between infection and chronic disease
what is an infectious disease
illness due to a specific infectious agent or its toxic products capable of being directly or indirectly transmitted from man to man, animal to man from animal to animal or from environment
COMMUNICABLE DISEASE
what is infection
entry and development or multiplication of an infectious agent in body
an infection does not always cause illness or symptoms
what are the 3 stages of infection
colonization
subclinical or inapparent infection
latent infection
what is a host
person or animal that affords subsistence to an infectious agent under natural conditions
what is a vector
living carrier that transports an infectious agent from infected individual or its waste to susceptible individual or food
both biological and mechanical transmission is possible
e.g insect in malaria
what is a resevoir
any person animal plant soil or substance where the infectious agent lives and multiplies , depends on it for survival and reproduces
natural habitat of the infectious agent
why may there be a problem in calculating incidence of infectious diseases
often get repeats/multiple infections
is prevalence useful for infectious diseases
no
what is an endemic
constant presence of disease or infectious agent within a given geographic area or population but at low frequency e.g chicken pox
what is an epidemic
sudden severe outbreak of disease within a region or within group of individuals e.g HIV in intravenous drug users
what is a pandemic
epidemic becoming more widespread e.g covid
what are exotic diseases
those which are imported into a country in which they do not otherwise occur e.g rabies in UK
what is zoonosis
infection that is transmissable under natural conditions directly from vertebrate animals to man e.g rabies, plague
but also ebola and covid
how can a sporadic disease be the starting point of an epidemic
if the conditions are favourable for its spread
what is CJD
prion disease of both sporadic, genetic and acquired forms
rare fatal neurodegenrative disorder, very long incubation period, transmission by blood, its products and surgery
outline BSE
discovered in cows in 1986, caused by single strain of scrapie from a sheep
caused mad cow disease
contaminated sheep brains were in the cows food
what is the difference between variant and sporadic CJD
variant onset age is 26 whereas sporadic is 64
most cases int he Uk are variant, affects wider range of tissues and lasts longer causing behavioural and psychiatric changes
what did WHO say about surveillance
its the cornerstone of infectious disease prevention and control
what is passive surveillance
routine information sources
automatic reporting e.g lab reports
what is active surveillance
special effort to contact healthcare providers to collect data and confirm diagnosis
public health response may be needed e.g contact tracing
what is enhanced surveillance
additional info collected for each case
capture of clinical, risk factor info
merging data from different sources
merging results from micobiological characterisation to routine reports
what is the purpose of surveillance
monitor secular trends
detection of outbreaks and emerging epidemics
monitor changes in infectious agents
generate hypotheses for public health research
why is nil return needed within surveillance
clinics must report that no cases have occurred in the period of interest for nil return to be treated as zero
what are the challenges of HIV in the uk
undiagnosed HIV
late presenters
increasing ageing HIV population with comorbidities
contact tracing
prevention
retention and standard of care
what do public health records show about HIV from 1981 -2013
aids and deaths closely related
diagnoses peak in 2007
why is late diagnosis not good for HIV
once people are treated for HIV, chance of infecting someone else is really small, as reduces viral load
women have higher risk of being diagnosed later as well as older people
what are characteristics associated with late HIV presentation
heterosexual men
african people
heterosexual females
outline the Newcastle thousand families study
the influence of early infections on hearing at age 61-63yrs
association varied on type of infection - tonsilitis, otorrhea or bronchitis in first 5 years or severe respiratory infection in first year more likely to have worse hearing
associations independent of early SES and occupational noise
what is the interpretation of the newcastle thousand families study
hearing was measured using pure tone audiometry so unable to determine if hearing loss was conductive or sensoneural
lack of associations with infections like measles reflect pre-vaccination status of cohort
suggests that some antecedants of impaired hearing may lie early in life and some insults to hearing may have lifelong effects
what are some examples of infections as risk factors
HPV and cervical cancer
HIV and Kaposi’s sarcoma
helicobacter pylori and stomach cancer
