Infectious Disease Epidemiology

Question 1

what is the importance of infectious epidemiology

Answer 1

assessing changes in pattern of infectious disease - geographical or seasonal
- discovery of new emerging infections
- potential link between infection and chronic disease

Question 2

what is an infectious disease

Answer 2

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

Question 3

what is infection

Answer 3

entry and development or multiplication of an infectious agent in body
an infection does not always cause illness or symptoms

Question 4

what are the 3 stages of infection

Answer 4

colonization
subclinical or inapparent infection
latent infection

Question 5

what is a host

Answer 5

person or animal that affords subsistence to an infectious agent under natural conditions

Question 6

what is a vector

Answer 6

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

Question 7

what is a resevoir

Answer 7

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

Question 8

why may there be a problem in calculating incidence of infectious diseases

Answer 8

often get repeats/multiple infections

Question 9

is prevalence useful for infectious diseases

Answer 9

no

Question 10

what is an endemic

Answer 10

constant presence of disease or infectious agent within a given geographic area or population but at low frequency e.g chicken pox

Question 11

what is an epidemic

Answer 11

sudden severe outbreak of disease within a region or within group of individuals e.g HIV in intravenous drug users

Question 12

what is a pandemic

Answer 12

epidemic becoming more widespread e.g covid

Question 13

what are exotic diseases

Answer 13

those which are imported into a country in which they do not otherwise occur e.g rabies in UK

Question 14

what is zoonosis

Answer 14

infection that is transmissable under natural conditions directly from vertebrate animals to man e.g rabies, plague
but also ebola and covid

Question 15

how can a sporadic disease be the starting point of an epidemic

Answer 15

if the conditions are favourable for its spread

Question 16

what is CJD

Answer 16

prion disease of both sporadic, genetic and acquired forms
rare fatal neurodegenrative disorder, very long incubation period, transmission by blood, its products and surgery

Question 17

outline BSE

Answer 17

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

Question 18

what is the difference between variant and sporadic CJD

Answer 18

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

Question 19

what did WHO say about surveillance

Answer 19

its the cornerstone of infectious disease prevention and control

Question 20

what is passive surveillance

Answer 20

routine information sources
automatic reporting e.g lab reports

Question 21

what is active surveillance

Answer 21

special effort to contact healthcare providers to collect data and confirm diagnosis
public health response may be needed e.g contact tracing

Question 22

what is enhanced surveillance

Answer 22

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

Question 23

what is the purpose of surveillance

Answer 23

monitor secular trends
detection of outbreaks and emerging epidemics
monitor changes in infectious agents
generate hypotheses for public health research

Question 24

why is nil return needed within surveillance

Answer 24

clinics must report that no cases have occurred in the period of interest for nil return to be treated as zero

Question 25

what are the challenges of HIV in the uk

Answer 25

undiagnosed HIV
late presenters
increasing ageing HIV population with comorbidities
contact tracing
prevention
retention and standard of care

Question 26

what do public health records show about HIV from 1981 -2013

Answer 26

aids and deaths closely related
diagnoses peak in 2007

Question 27

why is late diagnosis not good for HIV

Answer 27

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

Question 28

what are characteristics associated with late HIV presentation

Answer 28

heterosexual men
african people
heterosexual females

Question 29

outline the Newcastle thousand families study

Answer 29

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

Question 30

what is the interpretation of the newcastle thousand families study

Answer 30

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

Question 31

what are some examples of infections as risk factors

Answer 31

HPV and cervical cancer
HIV and Kaposi’s sarcoma
helicobacter pylori and stomach cancer