EPIDEMIOLOGY PRACTICALS 2014 2015 PRACTICALS SUBJECTS I Epidemiological

EPIDEMIOLOGY PRACTICALS 2014 - 2015

PRACTICALS - SUBJECTS I. Epidemiological inquiry for transmissible diseases II. Elements of Immunoepidemiology. Vaccines available under the National Immunisation Program III. Vaccines used in special epidemiological situations IV. Serum-prevention, Immunoglobulin-prevention Immunomodulators V. Decontamination and sterilization VI. Laboratory investigations in practical epidemiology VII. Epidemiological surveillance of transmissible diseases

EPIDEMIOLOGICAL PROCESS (EP) - All the factors, phenomena and biological, natural and social mechanisms, which participate, in a determining or favouring way, to the occurrence, extension and particular evolution of a disease in a population.

“If you have an apple and I have an apple and we exchange these apples then you and I will still each have one apple. But if you have an idea and I have an idea and we exchange these ideas, then each of us will have two ideas. ” George Bernard Shaw

A. DETERMINING FACTORS I. SOURCE OF PATHOGENIC AGENTS • humans sick persons – with typical disease - with atypical disease (subclinical, asymptomatic) carriers of pathogenic agents: - pre-infectious = “before infection “ carrier (influenza, measles, HBV) - healthy carrier - post-infectious = “after infection”carrier (people in their recovering period / chronic) • animals (including birds) ill / carrier • biologic active vectors ( , , )

A. DETERMINING FACTORS II. MODES AND WAYS OF TRANSMISSION • direct mode - agents with low environment resistance - Pflügge drops - blood transfusion - transplacental - unprotected sexual contact - direct contact with skin lesions • indirect mode - agents with strong environment resistance - through contaminated routes of transmission: → air, water, soil, → food, objects, hands, → biologic passive vectors

A. DETERMINING FACTORS III. RECEPTIVE HOST → receptivity status in relation to: 1. non-specific general resistance (mucosal barriers, cough or sneeze reflex) specific resistance (immunity) 2. • • natural - species immunity - active acquired - passive acquired artificial - active acquired just a part of animals’ diseases can be transmitted to human Ag Ab → as a result of a disease → transplacental + breastfeeding → vaccination - passive acquired → Ig, immune serum

B. FAVOURING FACTORS → bring together the three determining factors → modulate the manifestation forms of epidemiological process I. Natural factors: • Cosmic - radiations, sun activity • Meteorologic - temperature, atmospheric pressure, air currents • Climatic - latitude and altitude • Geographic - landforms

B. FAVOURING FACTORS II. Socio-economic factors: 1. living and working conditions: - income - level of education - home - diet - healthcare 2. occupational conditions: - qualification - seniority - work area - agents of aggression

PRACTICAL I Epidemiological inquiry (epidemiological investigation) in transmissible diseases

EPIDEMIOLOGICAL INQUIRY/ INVESTIGATION (E. I. ) • all the investigations performed in different groups of people • in order to identify causes of transmissible or non-transmissible diseases and their evolution • to elaborate the measures prevention and control of their

OBJECTIVES 1. to solve epidemiological emergencies 2. to know the risk factors involved in the occurrence of some non-transmissible diseases (NTD) Ex. H. pylori → peptic ulcer Chlamydia → atheromatous disease 3. to identify the multifactorial aetiology of NTD with a large distribution among population Ex. tobacco, HTA, dyslipidemia, obesity, stress – for CVD 4. to make predictions about natural history of transmissible diseases (TD)

OBJECTIVES 5. to avoid the “import” and the “export” of some TD Ex. - “import” for Romania → malaria brought from Turkey - “export” for Romania → TB for persons from areas where the disease is under control (West European countries) – when they travel to Romania 6. orientation of biological materials production 7. improving national and international programs of prevention and control 8. to evaluate the effectiveness of prevention and control measures applied in population

METHODS FOR ACHIEVING THE E. I. 1. patient history → from him and/or from his family 2. epidemiological observation → identification of a phenomenon in the population 3. descriptive method → detailed representation of a phenomenon 4. analytical method → identification and studying the components of a health problem in order to achieve its characterization within the population that emerged and the factors that have competed at the onset morbid phenomenon 5. analytical method + biostatistics → meta-analysis = systematic procedure of combining the results of different studies on the same topic

METHODS FOR ACHIEVING THE E. I. 5. the epidemiological experiment → verification of hypothesis regarding the occurrence and evolution of an epidemiological process 6. comparison (historical, geographical, between population – by age, sex, profession) → knowledge of the natural history of a disease, temporal and spatial features of the EP and clinical symptoms 7. the screening → identification of probably affected individuals detected in a population of apparently healthy in order to be subject to further investigation or to implement early prevention measures 8. biostatistics → can be associated with any of the methods listed above, to increase efficiency in synthesizing and interpreting information obtained 9. mathematical method → involves transposition of biological, medical and social parameters into mathematical equations, using epidemiological and mathematical models

Types of epidemiological inquiry A. Operational epidemiological inquiries – for prevention – for control (emergency) B. Special epidemiological inquiries (for research) 1. descriptive (transversal observational / cross-sectional) – development of hypothesis - case raport - case series - ecological studies / correlational studies - prevalence studies 2. analytical – demonstration of hypothesis a) etiological observational: -case-control study - cohort study b) interventional – clinical trial 3. meta-analysis – verifying of hypothesis 4. decision analysis studies – application in practice

A. Operational Epidemiological Inquiry

I. Epidemiological inquiry for prevention • assess population health and the risks to which it is exposed • health status → indicators: - average lifespan (F=75, 8 years; M=68, 7 years) • may be single or repeated ~ for the same person, to the entire population or only to a sample • Cross-sectional EI • Longitudinal type of EI

II. Epidemiological inquiry for control (emergency) • to stop the evolution of the epidemiological process and to eradicate its development • practical utility in transmissible diseases • performed by family doctor (general practitioner) from urban or rural areas • is addressed to all categories of persons from the outbreak: - sick individuals - with typical or atypical forms of disease - suspects (persons alleged to present atypical or unapparent disease) - known carriers of pathogenic agents - former patients which are in the convalescent stage and for whom the diagnosis was determined retrospectively - direct and indirect contacts with “index” case or cases

Stages of Epidemiological Inquiry

a) The stage of orientation (preliminary stage) → performed by the family doctor - early detection and diagnosis of disease cases - establishing the main characteristics for the factors of the epidemiological process - development and implementation of emergency anti-epidemic measures → isolation of patients, suspects and possible contacts - decontamination, disinsection, deratization - reinforcement of health education measures of the population - operative information transmitted to superior health units about the epidemiological situation and preliminary measures adopted (notification) - epidemiological inquiry sheet (reporting sheet)

b) The studying stage (final stage) → family doctor + epidemiologist + other specialities → the final epidemiological inquiry is performed and the epidemiological inquiry sheet is completed – isolation mode and treatment of patients throughout the disease – final diagnosis of the disease and of the evolutionary form – epidemiological situation of the patient clinically cured and discharged → carrier – follow up - after returning at home – modes and routes of transmission of pathogenic agents and the effectiveness of their neutralization → DDD methods – epidemiological and clinical surveillance of contacts → maximum of the incubation period of the disease – evaluation of the population receptivity (immune background) – evaluation of preventive measures used in the outbreak and around its – health education measures

E. I. Methodology I. Knowledge of the E. P. factors using the collection, analysing and interpretation of epidemiological information II. Elaboration of measures to eradicate the epidemiological process and to prevent its recurrence

E. I. Methodology III. Checking the correct application of hygienico-sanitary and anti-epidemic measures and monitoring their effectiveness IV. Elaboration of the E. I. sheet

I. Knowledge of the E. P. factors using the collection, analysing and interpretation of epidemiological information

1. Collection of the data → is achieved by : conversation (anamnesis or interview) epidemiological observation laboratory investigations special information

The conversation (anamnesis, interview) → obtaining information about epidemiological factors ~ from sick people and / or their family – probable date and circumstances of contamination – date of real onset of illness → to determine the incubation period of the disease (retrospective) – to specify the infectious moment » identification of a single infectious moment » sometimes – many probable infectious moments – possible association between consumption of food, water first symptoms and

The conversation (anamnesis, interview) – relationships with certain people in the family, relatives, community, workplace, public transport → among contacts we can find the source of pathogenic agents → receptive contacts - preventative measures (ATB, Ig) - travels - infectious pathologic history and what immune measures are taken → information about receptivity - patient environment → domestic animals, wild rodents, birds, arthropods → and established relationships with them, continuously or accidentally → information about the sources and about the routes of transmission

Epidemiological observation • assessing the hygienico-sanitary conditions of the house • personal hygiene and food quality • how the residues are removed • the situation of plumbing installations • animal maintenance → in the outbreaks/ at work place / in the collectivity (community)

Laboratory investigations • useful for: – sources detection of pathogenic agents – knowledge of population receptivity – knowledge of the modes and routes of transmission

Special information – topographical situation of the village – type of soil and water sources – communications network – climate and weather conditions – morbidity, mortality – the situation of TD and vaccinations – food, drinking water

2. Analysis of epidemiological data systematization of information including in various documents (EIS, tables, graphs, drafts, maps etc. ) facilitate the application of prevention and control measures

3. Data interpretation • Analysing data from the diagnosed people table: - repeating the same name → existence of a family outbreak - repeating the same address → possible existence of a source in that home or community - repetition of the same age group→ the receptivity to the disease - mentioning the same profession → the professional character of the disease • Analysing the drawings (maps) of the village or community where the epidemiological outbreaks occurred → possible clustering of disease in the area near the source of drinking water → information regarding the source of pathogenic agent, the modes and routes of transmission • Data presented in the graphs → conclusions regarding the onset, the evolution mode, the peak of the epidemiological event, the decreasing period etc.

II. Elaboration of measures to eradicate the epidemiological process and to prevent its recurrence

1. Hygienico-sanitary measures (general) - Recommended by the law and specific regulation - Their objective is to improve the individual, family or community hygiene conditions, and of the natural or occupational environment

2. Anti-epidemic measures (for control) a) Measures for ill persons - Active early detection Isolation in the hospital or at home Nominal or numeric reporting Decontamination and deratization Example: the VHB ill person b) Measures for suspects

2. Anti-epidemic measures (for control) c) Measures for contacts - isolation in family or community, quarantine - surveillance for the maximum duration of the incubation period of the disease - clinical examination, temperature - laboratory examination - chemical/antibiotic/serum/immunoglobulin/vaccine - prevention - D. D. D. measures - health education Example – contact with confirmed case of meningococcal meningitis

2. Anti-epidemic measures (for control) d) Measures for carriers - registration and follow up - microbiological “sterilisation” - surveillance - health education - exclusion from population risk sectors Example – healthy carrier of type A beta-haemolytic Streptococcus

2. Anti-epidemic measures (for control) e) Measures for convalescents - follow up (surveillance) Example - convalescent after type B viral hepatitis 1. Clinical and laboratory surveillance for 1 year: -at 1 month, at 3 months, at 6 months: -examination of liver size - transaminases, bilirubin -at 1 year: - transaminases, bilirubin -total proteins -HBs antigen 2. Exclusion from blood donation for the entire life

3) Other measures - vaccination, revaccination in the outbreak or among population immunoglobulin-prevention and chemo- - tests for population to evaluate the receptivity (ex. IDR for tuberculin) - special measures - temporary cessation of activity in some areas of public interest - health education

III. Verifying and monitoring the efficiency of hygieno-sanitary and anti-epidemic measures • Control of the way each doctor/nurse undertakes the proposed measures • Determination of the surveillance period → maximum duration of the disease incubation period (calculated from the last case) • Date and person which will declare the outbreak eradication, and the analysis of the actions taken (preventional programmes).

V. Preparation of the epidemiological nquiry sheet • The epidemiological inquiry sheet (EIS) = the most important methodological document elaborate at the occurrence of the transmissible disease • Used for epidemiological data collection, but also as a forensic document • Base for the Reporting System of Notifiable Diseases • in TD ~ has 7 chapters: - information about the ill person - pathogenic agent source - ways of transmission - receptivity level - intervention of the favouring factors - prevention and control measures - conclusions (source ~ nominal/non-identified; MWT; measures taken; duration of the outbreak surveillance).

Type A VIRAL HEPATITIS Model

I. The Epidemiological Process Virus source: • Humans - ill ~ children < 15 years; - carrier: pre-infectious (very contagious through his/her feces along 8 -10 days before the onset of the disease); healthy (persons in close contact with the ill or pre-infectious carrier); post-infectious (eliminates small doses of virus for a few days of the convalescence) • Animals ~ non-human primates (monkeys). ~ type A hepatitis virus is eliminated through feces or blood (viremia)

I. The Epidemiological Process Ways of transmission: • direct - in communities with a low level of hygiene - natural (floods, earthquake) or social (war) disasters - sexual contact - blood transfusions • indirect - food (seafood) - contaminated water, objects, hands, flies - rats (who mechanically circulate the virus)

I. The Epidemiological Process Receptivity: • general ~ for persons which don’t have specific antibodies; • passive immunity (transplacental) ~ very evident because almost all women at fertility age have high levels of antibodies (repeated immunizations with small doses of virus along their lives). Favouring factors: behaviour. crowd and non-hygienic

II. Control measures in VHA outbreak Measures for ill people: • • detection; hospital isolation; nominal reporting; decontamination of the outbreak with substances containing chlorine. Measures for suspects: • the same as in the case of the ill people until the diagnosis is clarified.

II. Control measures in VHA outbreak Measures for contacts: • • isolation at home epidemiological, clinical and laboratory surveillance, for 30 -40 days excluded from blood donation for 6 months standard immunoglobulin Measures for convalescents: • • • follow up for 6 months clinical and laboratory examination: liver size, transaminases, bilirubin excluded from blood donation for the entire life

B. Special epidemiological investigations • any epidemiological operational one investigation outside • used in epidemiological surveillance activities • they refer to certain indicators: - morbidity, mortality, incidence, prevalence - extensivity and severity of an epidemic - immune background of the population the

OBJECTIVES 1. Measuring the morbidity 2. Study of the natural history of the disease 3. Health status characteristics → normal values are those: • • • located in the median interval (statistically normal) observed for people without morbid manifestations (clinically normal) proven by previous studies as being the normal status of the individual 4. Formulating and checking the aethiological hypotheses

DISEASE OUTBREAK INVESTIGATION 1. Establish the existence of an outbreak 2. Confirm the diagnosis - case definition - case identification and count cases 3. Perform descriptive epidemiology - characteristics of person, place, time - epidemic curve → type of source 4. Determine who is at risk 5. Develop aetiological hypotheses - null hypothesis - alternative hypothesis

DISEASE OUTBREAK INVESTIGATION 6. Verifying the hypothesis through study - type of study: → case-control (→ useful in epidemiological emergencies) → study design (hypothesis; definition of study groups; subjects; variables; statistical analysis; resources; ethical aspects; accord – collaboration; calendar; dissemination of information) 7. As necessary, execute additional studies - investigations in collaboration with veterinary specialists - other types of studies – laboratory, environmental 8. Communicate findings - written report - presentations 9. Implement prevention and control measures

CONTROL – measures: 1. Epidemiological investigation 2. Detection of the ill persons with typical/atypical disease 3. Isolation at home or in hospital 4. Reporting the number or name of cases 5. Isolation / quarantine 6. Contacts surveillance – epidemiological, clinical and laboratory → for those receptive - prevention 7. Follow up for convalescents

CONTROL – measures: 8. Decontamination, deratization 9. Hygiene measures (environment, individual, food etc. ) 10. Education for health of those involved 11. Evaluation of pathogenic agents carriers 12. Instruction of the health workers 13. Outbreak surveillance: - maximum period of incubation calculated from the detection of the last case