Surveillance of infections;
pandemic plans
MUDr. Marie Kolářová, CSc.
Ústav ochrany a podpory zdraví LF MU
Spring 2018
EPIDEMIOLOGY
is the study (scientific, systematic, data-driven)
of the distribution (frequency, pattern)
and determinants (causes, risk factors)
of health-related states or events (not just
diseases)
in specified populations (patient is community,
individuals viewed collectively),
and the application (since epidemiology is a
discipline within public health) of this study to the
control of health problems.
3
Solving
health
problem
Step 1
Date collection
Step 2 Assessment
Step 3
Hypothesis testing
Step 4
Action
Surveillance; determine
time, place and person
Inference
Determine how and why
Intervention
Solving health
problem
Epidemiologists arrange their data in various
ways,
depending on what aspect of the information
they want to emphasize.
One of the most powerful tools an
epidemiologist can use is case
reporting:
reporting specific diseases to
* local,
* state and
* national health authorities,
who accumulate the data
Solving health
problem
Epidemiologic
investigations
Epidemiologic investigations are largely
mathematical descriptions of persons in
groups, rather than individuals.
The basic quantitative measurement in
epidemiology is
a count of the number of persons in the group
being studied who have a particular disease.
SURVEILLANCE
The systematic
 collection,
 analysis,
 interpretation, and
 dissemination of health data on an ongoing basis,
to gain knowledge of the pattern of disease
occurrence and potential in a community,
in order to control and prevent disease in the
community.
SURVEILLANCE
Surveillance represents a number of long-term and
complex programmes, in which experts of various
medical fields participate together, for example
epidemiologists, microbiologists, hygienists, clinicians
etc. Other non-medical personnel, such as statisticians,
vets and ecologists, may also participate alongside
medical personnel.
The epidemiologist is usually the initiator and organiser
of the program.
Surveillance was initially started in the field of infectious
diseases.
SURVEILLANCE
 Surveillance is put into effect in three successive stages:
 Obtaining the necessary data such as the number of sick, the
number of dead, data from microbiological laboratories on
circulation and qualities of etiological agent, clinical information
on symptomatology of individual diseases, monitoring of
vaccination and collective immunity of population, monitoring of
infections with animals, and data of natural sciences on vectors.
 Analysis of collected data, including evaluation of information
and suggestion of measures. Long-term surveillance gives the
possibility of making a prognosis of the occurrence of a given
disease for the future.
 Guaranteeing qualified information to all concerned people who
can further use it for improvement of their own measures and
theories.
SURVEILLANCE
Surveillance programmes can be carried out on a large
scale such as for districts and regions.
In the Czech Republic, surveillance programmes exist
for poliomyelitis, pertussis, diphtheria, measles, viral
hepatitis, alimentary infections and influenza.
Under the general guidelines released by WHO,
surveillance of influenza is carried out on an
international level.
 BENCKO, Vladimir, et al. Hygiene and Epidemiology : Selected Chapters. 2nd edition. Prague. 2008. ISBN 80-246-0793-X.
European
Tuberculosis
Surveillance Network
The European Tuberculosis Surveillance Network consists
of TB surveillance experts from all 53 countries belonging to
the World Health Organization’s European Region, including
30 EU/EEA Member States.
Under the joint coordination of ECDC and the World Health
Organization’s Regional Office for Europe, the network
collects, validates, analyses and disseminates European TB
surveillance data.
The purpose of the network is to identify the epidemiological
patterns of TB in the Region and monitor progress towards
TB elimination, with key surveillance and monitoring findings
published in an annual report.
In addition, the network aims to further strengthen TB
surveillance in Europe.
Terminology and
Definitions
 Sporadic disease
 Endemic disease
 Epidemic(outbreak)
 Pandemic disease
 Zoonosis,
epizootic and
enzootic
 Eradication
 Elimination
 Nosocomial
infection
 Attack rate
 Opportunistic
infection
 Immunity passive
active
 Individual
immunity
 Herd immunity
 Virulence
 Incubation period
 Infectivity period
 Latent period
 Probability ratio
 Chain of infection
 Host (source)
 Reservoir
 Transmission
Direct
Indirect
Biologic
Vertical
 Susceptible host
 Incidence and
 prevalence
 Case definition
Chain of infections
(epidemic proces)
THE CAUSATIVE AGENT OF INFECTION (bacteria, viruses, fungi, prions, protozoa)
1. the presence of rezervoir (source) of infection
man, animal at the ende of incubation period
acute stage
cariers
2. the way of transmission A/ direct contact
touching, kissing or sexual intercourse (Staphylococcus spp., Gonococcus spp.,HIV …),
- vertical transmission – from mother to fetus (VHB, VHC, HIV, listeria, rubella,
cytomegalovirus…)
B/ indirect contact
- inhalation of droplets containing the infectious agents (TBC, measles, influenza…)
- ingestion of food or water that is contaminated (salmonella, giardia, Norwalk virus, VHA….)
- biological transmission by insects (malaria, borellia….)
3. the susceptibility of the population or its individual members to the
organism concerned Host factors : a g e , n u t r i t i o n, g e n e t i c s
i m m u n i t y – natural (nonspecific),
- acquired
THE INFECTION
= 1. source of infection
……….
Disease trends
 Incidence - measures the number of new cases over time.
This number measures an individual chances of developing or
contracting the disease.
Number of new cases within a specified time period
Total number of people in the population
 Prevalence – measures the total number of cases of disease
in a population.
Total number of diseases individuals
Total number of people in the population at a given time
Occurrence of
Diseases
Sporadic Disease that occurs occasionally in a
population.
Endemic Disease constantly present in a population
at all times – malaria is present in Africa at all time
because of the presence infected mosquitos.
Epidemic or outbreak Disease occurence among
a population that is in excess of what is expected in a
given area in a short time – the Ebola virus in parts of
Africa is in excess of what is expectes for this region.
Pandemic Disease or condition that spread across
world - – HIV/AIDS is one of the worst global diseases
in history.
Terminology and
definitions
 Case definition: a set of standard criteria for deciding whether a person has
a particular disease or health-related condition, by specifying clinical,
laboratory andd epidemiological criteria and limitations on time, place and
person.
 Attack rate: proportion of non-immune exposed individuals who become
clinically ill.
 Zoonosis is an infection that is transmissible under natural conditions from
vertebrate animals to man, e.g. rabies, plague, bovine tuberculosis…..
 An epizotic is an outbreak (epidemic) of disease in an animal population,
e.g. rift valley fever.
 An enzotic is an endemic occurring in animals, e.g. bovine TB.
 Nosocomial (hospital acquired) infection is an infection originating in a
patient while in a hospital or another health care facility. It has to be a new
disorder unrelated to the patient’s primary condition.
Eradication and
Elimination
Eradication is an absolute process, an “all or
none” phenomenon, restricted to termination of
infection from the whole world.
Smallpox eradication was officially
announced at the 33rd General Assembly
WHO
8. May 1980.
 The term elimination is sometimes used to
describe eradication of a disease from a large
geographic region. Disease which are amenable
to elimination in the meantime are polio,
measles and diphtheria.
Herd immunity
(also called herd effect,
population immunity, or
social immunity)
is a form of indirect protection from infectious disease
that occurs when a large percentage of a population
has become immune to an infection, thereby providing
a measure of protection for individuals who are not
immune.
In a population in which a large number of individuals are
immune, chains of infection are likely to be disrupted,
which stops or slows the spread of disease.
The greater the proportion of individuals in a community
who are immune, the smaller the probability that those
who are not immune will come into contact with an
infectious individual.
Individual immunity
can be gained through recovering from a natural
infection or through artificial means such as
vaccination.
Some individuals cannot become immune due to
medical reasons and in this group herd immunity
is an important method of protection.
Herd immunity
(also called herd
effect,
population immunity,
or social immunity)
Once a certain threshold has been reached, herd immunity
gradually eliminates a disease from a population.
This elimination, if achieved worldwide, may result in the
permanent reduction in the number of infections to zero, called
eradication.
This method was used for the eradication of smallpox in 1977
and for the regional elimination of other diseases] Herd
immunity does not apply to all diseases, just those that are
contagious meaning that they can be transmitted from one
individual to another.] Tetanus, for example, is infectious but not
contagious, so herd immunity does not apply].
21.3.2018
Definition of
a pandemic
A pandemic is an epidemic extending over a wide
geographic area, affecting whole continents.
It involves the high incidence of a disease over a
large territory (continent) over a specific period of
time.
According to the WHO definition, an influenza
pandemic is characterized by the spread of a
pandemic virus within communities in at least 2
countries of a single WHO region and at least
one other country in another WHO region.
21.3.2018
The rise of the
pandemic strain
21.3.2018
The rise of the
pandemic strain
21.3.2018
Pandemic
preparedness
Pandemic preparedness is most effective if it is built on
general principles that guide preparedness planning for
any acute threat to public health. This includes the
following:
Pandemic preparedness, response and evaluation
should be built on generic preparedness platforms,
structures, mechanisms and plans for crisis and
emergency management.
To the extent possible, pandemic preparedness should
aim to strengthen existing systems rather than
developing new ones, in particular components of
national seasonal influenza prevention and control
programmes.
New systems that will be implemented during a pandemic
should be tested during the inter-pandemic period.
Adequate resources must be allocated for all aspects of
pandemic preparedness and response.
21.3.2018
Pandemic
preparedness
 The planning process, implementing what is planned, testing and revising
the plan in order for key stakeholders to familiarise themselves with the
issues at hand, may be even more important than the pandemic plan
itself.
 Pandemic response requires that business continuity plans and surge
capacity plans be developed for the health sector and all other sectors
that could be affected by a pandemic to ensure sustained capacity during
a pandemic.
 The response to a pandemic must be evidence-based where this is
available and commensurate with the threat, in accordance with the IHR.
Planning should be based on pandemics of differing severity while the
response is based on the actual situation determined by national and
global risk assessments.
 Not all countries will be in a position to contribute to global risk
assessment, nor conduct evaluations such as pandemic vaccine
effectiveness. They must all have the capacity to access and interpret
data for risk assessment provided by WHO, ECDC, and from other
countries or sources.
21.3.2018
Pandemic
preparedness
Preparing for an influenza pandemic is a continuous
process of planning, exercising, revising and translating
into action national and subnational pandemic
preparedness and response plans.
A pandemic plan is thus a living document which is
reviewed at intervals and revised if there is a change in
global guidance or evidence-base; lessons learned
from a pandemic, an exercise, or other relevant
outbreak; or changes to national or international
legislation related to communicable disease prevention
and control :
21.3.2018 ECDC
Pandemic
preparedness