Definition of epidemiology as a Definition of epidemiology as a science. Epidemic process as a science. Epidemic process as a

subject of studing of  subject of studing of  epidemiology and his main epidemiology and his main

driving forces. Classification of driving forces. Classification of infectious diseases. Epidemic infectious diseases. Epidemic method of  infectious and not method of  infectious and not infectious morbidity research. infectious morbidity research.

Directions of struggle with Directions of struggle with infectious diseases and their infectious diseases and their

preventive maintenance.preventive maintenance.

EpidemiologyEpidemiology – – science about science about mechanisms of epidemic process and mechanisms of epidemic process and measures of it’s prevention and overcoming.measures of it’s prevention and overcoming.

Epidemiological processEpidemiological process – – circulation circulation of infectious diseases among people of infectious diseases among people epizootological processepizootological process – circulation of – circulation of infectious diseases among animals.infectious diseases among animals.

D. SamoilovichD. Samoilovich (1724-1810)(1724-1810)

D. K. ZabolotnyD. K. Zabolotny (1866-1929)(1866-1929)

M. F. HamaliaM. F. Hamalia (1859-1949)(1859-1949)

EE.. N N. . PavlovskyPavlovsky (1884-1965)(1884-1965)

L. V. L. V. GromashevskyGromashevsky (1887-1980)(1887-1980)

Main motive forces Main motive forces of epidemiological processof epidemiological process::

Source of infectious agentSource of infectious agent Mechanisms of infectious agent transferMechanisms of infectious agent transfer Receptive organismReceptive organism

Secondary motive forces Secondary motive forces

of epidemiological processof epidemiological process::

Social factorsSocial factors Environmental factorsEnvironmental factors

Source of infectious agentsSource of infectious agents

HumanHuman – – patient or carrier (patient or carrier (fromfrom the the end of the incubation period; prodromal end of the incubation period; prodromal period; period of acute illness; period; period of acute illness; convalescence, when microorganism convalescence, when microorganism excretion occurexcretion occur) - ) - antroponosisantroponosis

AnimalsAnimals (domestic, wild) – (domestic, wild) – zoonosiszoonosis EnvironmentEnvironment - - sapronosissapronosis

PRINCIPLES OF EPIDEMIOLOGYPRINCIPLES OF EPIDEMIOLOGY

I principleI principle

Source of infectious agent is Source of infectious agent is infected (sick or carrier) infected (sick or carrier) organism - human or animalorganism - human or animal

(object which is the site of natural (object which is the site of natural habitation and multiplication of habitation and multiplication of pathogenic organisms, from where pathogenic organisms, from where they can infectthey can infect healthy people)healthy people)

PRINCIPLES OF EPIDEMIOLOGYPRINCIPLES OF EPIDEMIOLOGY

II principleII principle

Infectious agent’s localization in the Infectious agent’s localization in the organism and mechanism of it’s organism and mechanism of it’s transmission from one individual to transmission from one individual to another form persistent connection, another form persistent connection, which provide pathogenic species which provide pathogenic species preservation in the environment and preservation in the environment and continuitycontinuity of epidemic process of of epidemic process of infectious disease.infectious disease.

Mechanism of infectious Mechanism of infectious agent’s transmissionagent’s transmission

1st phase:1st phase: e excretion of the causative agent xcretion of the causative agent from the infected macroorganismfrom the infected macroorganism

2nd phase:2nd phase: staining of the causative agent staining of the causative agent in environmentin environment

3rd phase:3rd phase: infectious agent’s penetration infectious agent’s penetration into healthy (susceptible) organisminto healthy (susceptible) organism

PRINCIPLES OF EPIDEMIOLOGYPRINCIPLES OF EPIDEMIOLOGY

III principleIII principle

Infectious diseases can be rationally Infectious diseases can be rationally classified according to specific classified according to specific localization of infectious agent in localization of infectious agent in the organism, corresponding the organism, corresponding mechanism of transmission and mechanism of transmission and main biological properties of main biological properties of causative agent:causative agent:

intestinal infectionsintestinal infections respiratory infections respiratory infections blood infectionsblood infections infections of infections of external covers external covers

PRINCIPLES OF EPIDEMIOLOGYPRINCIPLES OF EPIDEMIOLOGY

IVIV principleprinciple

Epidemic process originates and Epidemic process originates and maintained only due to combined maintained only due to combined action of three main motive forcesaction of three main motive forces::

Presence of infectious agent’s sourcePresence of infectious agent’s source;; Realization of transmission mechanismRealization of transmission mechanism;; Population susceptibility to the infection.Population susceptibility to the infection.

If any of these factors is excluded, If any of these factors is excluded, epidemic process stop epidemic process stop

PRINCIPLES OF EPIDEMIOLOGYPRINCIPLES OF EPIDEMIOLOGY

VV principleprinciple

Natural and social factorsNatural and social factors stipulate stipulate quantitativequantitative and qualitative changes in and qualitative changes in the epidemic process (the epidemic process (increase or increase or decreasedecrease), thus they are), thus they are

secondary motive forces secondary motive forces of epidemic processof epidemic process

EPIDEMICAL FOCUSEPIDEMICAL FOCUS- site of infectious agent site of infectious agent

habituation, including habituation, including surrounding territorysurrounding territory with the with the limitslimits where it can be where it can be contagious for otherscontagious for others..

Epidemical focus exist in time Epidemical focus exist in time (maximal incubation period of (maximal incubation period of the disease) and in area the disease) and in area (determined by transmission (determined by transmission mechanism) mechanism)

ANTIEPIDEMIC MEASURES INANTIEPIDEMIC MEASURES IN THE FOCUS OF INFECTION THE FOCUS OF INFECTION

Measures concerning infectious agent’s Measures concerning infectious agent’s sourcesource

Disease diagnosisDisease diagnosis RegistrationRegistration Isolation of the patient (carrier)Isolation of the patient (carrier) Etiological treatmentEtiological treatment

Measures concerning transmission Measures concerning transmission mechanisms mechanisms

disinfectiondisinfection ( (disinsectiondisinsection, , deratizationderatization) – ) – currentcurrent, , finalfinal

Measures concerning contact persons:Measures concerning contact persons: Sanitary processingSanitary processing Medical observationMedical observation Laboratory examinationLaboratory examination Specific prophylaxis Specific prophylaxis

DEGREES OF INFECTION’S DEGREES OF INFECTION’S SPREADINGSPREADING::

1.1. Sporadic Sporadic – – normal level of morbidity normal level of morbidity for the given territory in a given for the given territory in a given period of timeperiod of time

2.2. EpidemicEpidemic – – morbidity in a few times morbidity in a few times more higher than sporadicmore higher than sporadic

3.3. Pandemic Pandemic – – extraordinary intensive extraordinary intensive epidemic process and considerably epidemic process and considerably greater than epidemic.greater than epidemic.

Endemic infections Endemic infections – – connected to connected to certain territory.certain territory.

Exotic infectionsExotic infections – – diseases, which are diseases, which are not characteristic for the local not characteristic for the local territory, but can be transferred from territory, but can be transferred from other countriesother countries..

PRINCIPLES OF INFECTIOUS DISEASESPRINCIPLES OF INFECTIOUS DISEASES CLASSIFICATIONCLASSIFICATION

((ACCORDING TO L. GROMASHEVSKYACCORDING TO L. GROMASHEVSKY))

1.1. Localization of infectious Localization of infectious agent in organismagent in organism

2.2. Mechanisms responsive for Mechanisms responsive for transmission of infectious transmission of infectious agentagent

GROUPS OF INFECTIOUS GROUPS OF INFECTIOUS

DISEASESDISEASES (according (according to to Gromashevsky)Gromashevsky)

1.1. Intestinal infectionsIntestinal infections – – are transferred by fecal-are transferred by fecal-oral mechanismoral mechanism

2.2. Respiratory infectionsRespiratory infections – – are transferred by the are transferred by the droplet mechanismdroplet mechanism

3.3. Blood infectionsBlood infections – – by means of transmissive by means of transmissive mechanism of transfermechanism of transfer

4.4. Infections of external coversInfections of external covers – – by means of by means of contact or contact-wound mechanismcontact or contact-wound mechanism

Distinguished Distinguished trans-placental trans-placental ((verticalvertical)) mechanism of mechanism of transfertransfer, , and accordingly, infections which are and accordingly, infections which are transferred by trans-placental waytransferred by trans-placental way

Infectious agents, Infectious agents, discovered during recent 25 discovered during recent 25

yearsyearsYear Year Micro organismMicro organism DiseaseDisease

19801980 HTLVHTLV-1-1 (human T-cell (human T-cell lymphotropic virus)lymphotropic virus)

Acute leukemia of T-lymphocytesAcute leukemia of T-lymphocytes ( (ATLATL))Tropical spastic affectionTropical spastic affection ( (TSPTSP))MyelopathyMyelopathy, , connected withconnected with HTLV-1 (HAM)HTLV-1 (HAM)

19821982 HTLVHTLV--22 Leukemia Leukemia 19821982 Borrelia burgdorferiBorrelia burgdorferi borreliosisborreliosis ( (Laim’s diseaseLaim’s disease))

19831983 HIV-1, HIV-2HIV-1, HIV-2 HIV-infectionHIV-infection//AIDSAIDS, , AIDS-dementiaAIDS-dementia

19831983 JCJC virus virus Progressive multifocal leuko-encephalopathyProgressive multifocal leuko-encephalopathy

19831983 Escherichia coli O157:H7Escherichia coli O157:H7 Enterohemorrhagic EscherichiosisEnterohemorrhagic Escherichiosis, , hemolytic-hemolytic-uremic syndromeuremic syndrome

19831983 Helicobacter pyloriHelicobacter pylori Gastrodeudenitis Gastrodeudenitis

19861986 Herpes virus-6Herpes virus-6hh type type ((HHV-6HHV-6)) Sudden exanthemaSudden exanthema ( (three-day feverthree-day fever))

19891989 Ehrlichia spp.Ehrlichia spp. EhrlichiosisEhrlichiosis

19891989 Hepatitis C virusHepatitis C virus (HCV)(HCV) Hepatitis CHepatitis C

Year Year Micro organismMicro organism DiseaseDisease

19891989 Chlamidia pneumoniaeChlamidia pneumoniae Nasopharyngitis, pneumonia, bronchial asthma, Nasopharyngitis, pneumonia, bronchial asthma, angina pectoris, endocarditis.angina pectoris, endocarditis.

19901990 Herpes virus-7Herpes virus-7thth type type((HHV-HHV-7)7) Chronic fatigue syndromChronic fatigue syndrom

19901990 Hepatitis E virusHepatitis E virus ( (HHЕЕVV)) Hepatitis EHepatitis E

19199292 Vibrio cholerae O139:H7Vibrio cholerae O139:H7 Cholera Cholera

19921992 Bartonella henselaeBartonella henselae Benign lymphoreiculocytosis Benign lymphoreiculocytosis ((disease of cat’s disease of cat’s scratchesscratches))

19931993 ChlamidiaChlamidia pecorumpecorum Nasopharyngitis, pneumonia, bronchial asthma, Nasopharyngitis, pneumonia, bronchial asthma, angina pectoris, endocarditis.angina pectoris, endocarditis.

19931993 Sin Nombre virusSin Nombre virus Gantaviral pulmonary complexGantaviral pulmonary complex

19199494 Sabia virusSabia virus Brazilian hemorrhagic feverBrazilian hemorrhagic fever

19941994 Herpes virus 8Herpes virus 8thth type type((HHV-HHV-8)8) Sarcoma KaposiSarcoma Kaposi

19941994 Gendra virusGendra virus Meningitis and encephalitisMeningitis and encephalitis

19951995 Hepatitis G virusHepatitis G virus Hepatitis GHepatitis G

Year Year Micro organismMicro organism DiseaseDisease

19199696 PrionsPrions

Prions diseasesPrions diseases: : Crointsfeldt-Jacob, Kuru, Crointsfeldt-Jacob, Kuru, Gerstman-Strausslar-Sheinker syndrome, fatal Gerstman-Strausslar-Sheinker syndrome, fatal family insomnia, Alpers disease, amyotrophic family insomnia, Alpers disease, amyotrophic leukospogiosis, myositis with prion-associative leukospogiosis, myositis with prion-associative inclusionsinclusions

19971997 Influenza virus A - HInfluenza virus A - H77N1N1 Influenza Influenza ((Hong KongHong Kong))

19971997 Hepatitis TT virusHepatitis TT virus Hepatitis TTVHepatitis TTV

19971997 Enterovirus -71Enterovirus -71stst type type Epidemic meningitisEpidemic meningitis19199999 Nipag virusNipag virus Meningitis and encephalitisMeningitis and encephalitis19991999 Influenza virus A - HInfluenza virus A - H99NN22 Influenza Influenza ((Hong KongHong Kong))19991999 Hepatitis Sen virusHepatitis Sen virus Hepatitis SenVHepatitis SenV

20022002 Severe acute respiratory Severe acute respiratory syndrome virussyndrome virus ( (SARSSARS)) Severe acute respiratory syndromeSevere acute respiratory syndrome

Epidemical method of Epidemical method of investigation. investigation.

Epidemic diagnosis. Epidemic diagnosis. Prevention of Prevention of

Infectious Diseases & Infectious Diseases & Measures to Control Measures to Control

ThemThem

Epidemiological Epidemiological methodsmethods

ObservationObservation – studying of the focus – studying of the focus Inspection – Inspection – revealing of the sourcerevealing of the source Examination – Examination – studying of morbiditystudying of morbidity Analysis of morbidityAnalysis of morbidity Experiment – Experiment – microbiological and microbiological and

serological examination, physical and serological examination, physical and chemical studies, experiment on chemical studies, experiment on humans and animalshumans and animals

Historic pandemics Historic pandemics Plague of Justinian, from 541 to 750, killed between 50% and Plague of Justinian, from 541 to 750, killed between 50% and

60% of Europe's population. 60% of Europe's population. The Black Death of 1347 to 1352 killed 25 million in Europe The Black Death of 1347 to 1352 killed 25 million in Europe

over 5 years (estimated to be between 25 and 50% of the over 5 years (estimated to be between 25 and 50% of the populations of Europe, Asia, and Africa - the world population populations of Europe, Asia, and Africa - the world population at the time was 500 million). at the time was 500 million).

The introduction of smallpox, measles, and typhus to the The introduction of smallpox, measles, and typhus to the areas of Central and South America by European explorers areas of Central and South America by European explorers during the 15th and 16th centuries caused pandemics among during the 15th and 16th centuries caused pandemics among the native inhabitants. Between 1518 and 1568 disease the native inhabitants. Between 1518 and 1568 disease pandemics are said to have caused the population of Mexico pandemics are said to have caused the population of Mexico to fall from 20 million to 3 million.to fall from 20 million to 3 million.

The first European influenza epidemic occurred between 1556 The first European influenza epidemic occurred between 1556 and 1560, with an estimated mortality rate of 20%. and 1560, with an estimated mortality rate of 20%.

Smallpox killed an estimated 60 million Europeans during the Smallpox killed an estimated 60 million Europeans during the 18th century (approximately 400,000 per year). Up to 30% of 18th century (approximately 400,000 per year). Up to 30% of those infected, including 80% of the children under 5 years of those infected, including 80% of the children under 5 years of age, died from the disease, and one third of the survivors age, died from the disease, and one third of the survivors went blind. went blind.

In the 19th century, tuberculosis killed an estimated one-In the 19th century, tuberculosis killed an estimated one-quarter of the adult population of Europe; by 1918 one in six quarter of the adult population of Europe; by 1918 one in six deaths in France were still caused by TB. deaths in France were still caused by TB.

The Influenza Pandemic of 1918 (or the Spanish Flu) killed 25-The Influenza Pandemic of 1918 (or the Spanish Flu) killed 25-50 million people (about 2% of world population of 1.7 billion). 50 million people (about 2% of world population of 1.7 billion). Today Influenza kills about 250,000 to 500,000 worldwide Today Influenza kills about 250,000 to 500,000 worldwide each year. each year.

Prevention & control Prevention & control include:include: Mass-scale measures aimed at Mass-scale measures aimed at

improvement of public health, prevention improvement of public health, prevention of infectious diseases spreading;of infectious diseases spreading;

Medical measures aimed at reduction of Medical measures aimed at reduction of infectious morbidity & eradication of infectious morbidity & eradication of some diseases;some diseases;

Health education & involvement of Health education & involvement of population in prevention or restriction of population in prevention or restriction of infectious diseases spreading;infectious diseases spreading;

Prevention of infectious diseases Prevention of infectious diseases importing from other countriesimporting from other countries

Prophylaxis

PreventiveAnt-

epidemic

The basic factors The basic factors for development of for development of an epidemic an epidemic process:process: the source of infection;the source of infection; transmission mechanism;transmission mechanism; susceptibility of populationsusceptibility of population

Control of infection Control of infection sourcesource

Timely revealing of sick Timely revealing of sick personspersons. . Active detection is performed by Active detection is performed by medical personnel at hospitals, medical personnel at hospitals, polyclinics, medical posts polyclinics, medical posts

Isolation (in hospital, at home)Isolation (in hospital, at home) TreatmentTreatment EExamination for the carrier statexamination for the carrier state

(sanation)(sanation)

Disruption of infection Disruption of infection transmission pathwaystransmission pathways

General sanitary measures General sanitary measures (community hygiene)(community hygiene)

Health education of populationHealth education of population DisinfectionDisinfection SterilizationSterilization DisinsectionDisinsection DeratizationDeratization

Disinfection

Focal Preventive

Current Final

Preventive disinfection

Mechanical PhysicalChemical

Chlorine-,oxygen-

containing substances,

Phenols,Acids,Alkalis,

hydrogen peroxide,

formaldehyde

Boiling, Steam, UV radiation &

others

Biological

SterilizationSterilization complete eradication of pathogenic complete eradication of pathogenic

and non-pathogenic microorganisms and non-pathogenic microorganisms (spores included) in the (spores included) in the environment. Sterilization is used environment. Sterilization is used for surgical, gynaecological, for surgical, gynaecological, stomatological and other tools, stomatological and other tools, dressing materials, linen, needles, dressing materials, linen, needles, syringes, etc. Nutrient media, syringes, etc. Nutrient media, laboratory ware, tools and laboratory ware, tools and instruments are sterilized in instruments are sterilized in microbiologymicrobiology. .

Disinsection

DestroyingPreventive

Mechanical Physical

Biological ChemicalGenetic

Deratization (rodent control)

DestroyingPreventive

Mechanical

Biologycal

Chemical

Quarantine measuresQuarantine measures medical examination of persons who arrive medical examination of persons who arrive

into or depart from a given country, their into or depart from a given country, their vehicles & belongingsvehicles & belongings

availability of special medical availability of special medical documentation (international certificate of documentation (international certificate of vaccination, certificate of deratization & vaccination, certificate of deratization & the like) must be checkedthe like) must be checked

revealing & isolation of persons with revealing & isolation of persons with infectious diseases, and isolation of infectious diseases, and isolation of persons who require medical observationpersons who require medical observation

disinfection, disinsection, deratization of disinfection, disinsection, deratization of means of transportation, of cargo & means of transportation, of cargo & luggage (for specisl indications)luggage (for specisl indications)

Measures to increase Measures to increase opportunityopportunity

Specific – preventive Specific – preventive vaccinations, immune globulins, vaccinations, immune globulins, serums serums

Non-specific – improving of living Non-specific – improving of living and labour conditions, nutrition, and labour conditions, nutrition, physical trainingphysical training

Contraindications to Contraindications to prophylactic vaccinationprophylactic vaccination

Acute feverAcute fever Recently sustained infectionsRecently sustained infections Chronic diseasesChronic diseases Second half of pregnancy, first Second half of pregnancy, first

nursing periodnursing period Allergic diseases and statesAllergic diseases and states Oncology pathology Oncology pathology

Antepidemic measures in Antepidemic measures in the focusthe focus

Examination by epidemiologist or a Examination by epidemiologist or a rural physicianrural physician

Final desinfection Final desinfection Taking of material for microbiologic Taking of material for microbiologic

investigationinvestigation Observation during the incubation Observation during the incubation

periodperiod Health education of populationHealth education of population