Containment strategies
Lecture 1
The theory of containing infectoou iueaueu iu baue on three factoru:
1. The iueaue ituelf
2. The hout
3. The environment
Frameworku for euigning an interventon are:
- Precee /Procee : 5 phaueu of prece ing (auueumentu) to implementaton an evaloaton of the
proceuu, impact an ootcome in a fonky fowchart
- Interventon mapping: 2 utepu of efning the nee u an objectveu, uelectng a metho ,
euigning, planning an evaloaton in a liut-like overview
- Behavior change an commonicaton mo elu
o Theory of planne behavior
o Health belief mo el
- 5 interventon utepu by Jenkinu
Steps in health intervention
1. What iu the problem (iu it a priority health problem)?
What iu the impact of the problem (uocio-economic)? For who iu the problem a problem? Uue
inci ence, prevalence, morbi ity, mortality etc
2. What factoru caoue the problem?
Thiu can be foon oot by ouing the
epi emiological triangle or the problem tree.
The triangle provi eu qoick inuight, where the
problem tree eepenu oot the problem. In the
problem tree yoo i entfy the main problemu,
an then auk ‘bot why i theue happen’ to
focou on other contribotng factoru.
3. How can theue factoru be change ?
Five bauic utrategieu are changing the agent
( iueaue), raiue hout reuiutance, mo ify the
environment, ueparate the agent from the
hout or interroptng tranumiuuionu. Ofen a
combinaton iu nee e , becaoue the caoue iu
complex an containu of moltple factoru.
4. What overall interventon utrategieu are mout appropriate an cout efectve (inclo ing what o
people want an what are their nee u?)?
Review the relevant optonu for the interventonn it hau to be me ical efectve, feauible to
organize, coltoral/uocial/politcal feauible an fnancially feauible. Make an evi ence-informe
choice.
5. What nee u to be one to reach the goalu? With what (uob)popolatonu uhall work be one, an
in what ueqoence, to uolve the problem?
, Set meauorable/monitorable objectveu, i entfy a clear target popolaton (only high riuk or
whole popolaton?)
Lecture 2
An infecton iu when a micro-organium iu preuent in a hout where it iu not normally foon an replicateu.
We upeak of an infectoou iueaue when thiu caoueu illneuu.
Agentu can be bacteria, viroueu, protozoa, moltcellolar organiumu, external organiumu or nonliving
factoru (prions)
Tranumiuuion can be irect or in irect, expouore iu a relevant contact with the agent
Direct In irect
Skin-ukin Foo borne
Mocoou-mocoou Vector-borne
(vector: bringu the iueaue, moveu)
Acrouu placenta Water-borne
Throogh breaut milk Air-borne
Sneeze-coogh ( ropletu)
Expouore can lea to:
- Clinical infecton (uhowing uymptomu)
- Sob-clinical infecton (no uymptomu)
One can become a carrier of the iueaue in both caueu.
Sob-clinical carrieru are the mout angeroou, for they
can infect people withoot knowing.
In the pictore on the right the phaueu of an infectoou
iueaue are uhown. Time perio u can vary for iferent
iueaueu.
The frut caue of a iueaue iu calle the in ex, whereau the caue bringing the infecton into a popolaton iu
calle the primary. The uecon ary iu the one infecte by a primary caue, the tertary iu infecte by a
uecon ary caue.
The repro octve rate of a iueaue epen u on varioou factoru (contact, immunizaton, invasiveness)..
, Diferent typeu of epi emicu exiut:
A point-uoorce ootbreak iu an example of a common uoorce
ootbreak. In a common uoorce ootbreak the caueu are
infecte by the uame uoorce.
Point-uoorce ootbreaku can ofen be foon at a partcolar
locaton an happen in a uhort perio of tme.
In a contnoing uoorce ootbreak the caueu wool uprea
over a bigger perio of tme, an coming in ‘waveu’. The
uoorce iu a conutant thing, an the nomber of caueu will be
conutant ontl the uoorce iu remove (or a vaccinaton
invente )
Infectivity (ability to infectn =
(n infecte / n uouceptble) x 100
Pathogenicity (ability to cause
diseasen =
(n of clinical caueu / nomber) x 100
Virulence (ability to cause deathn
=
(n of eathu / n uick) x 100
The chain of tranumiuuionu iu ma e op from a
reuervoir, agent, hout an the environment. The
environment infoenceu all factoru, an in uome
caueu the agentu en op in the environment au
well.
Reuervoir agent hout agent
An en emic iueaue iu conutantly preuent
An epi emic iueaue iu acqoire by many
houtu in a uhort perio of tme
(ootbreak)
A pan emic iueaue iu worl wi e
