Learning objectives
- Knowledge and understanding.
At the end of the module the student is expected to know and understand:
the role and purposes of epidemiology; the scientific method and the epidemiological approach to the quantitative analysis of the circumstances under which health events occur in animal populations; the criteria for characterizing the causality of associations; the applications of epidemiology in evaluating the efficacy and efficiency of prophylactic and therapeutic treatments and diagnostic tests.
- Applying knowledge and understanding.
At the end of the module the student is expected to be able to: determine the extent and impact of a disease; identify risk factors; compare the different research strategies and the different epidemiological study designs, evaluating their strengths and weaknesses. Furthermore, the student is expected to be able to critically evaluate the scientific literature concerning the subject.
- Making judgements.
At the end of the module the student is expected to be able to apply the skills acquired in order to make decisions based on evidence, in consideration of clinical, economic and possibly political aspects, in a defined epidemiological context.
- Communication skills.
At the end of the module the student is expected to have acquired the ability to communicate with adequate language skills and to be able to present the topics in a clear, linear and coherent manner.
- Learning skills.
At the end of the module the student is expected to have developed skills that allow independent learning through the critical evaluation of the scientific literature concerning the subject.
Prerequisites
First year course “Applied physics, basic mathematics for biomedical sciences, Informatics”.
Basic competence in using Excel.
Desirable technical requirements: internet access and possession of a PC with Office package.
Course unit content
Study of the methods applied to the understanding of the epidemiology of diseases of veterinary interest.
Full programme
1. Introduction to the study of epidemiology. Historical considerations and basic concepts. Differences between epidemiology and other diagnostic disciplines. The concept of disease determinant. Primary determinants. Secondary determinants. The concept of "population". Levels of populations. Basics of computational epidemiology. Descriptive and analytical epidemiology. Evidence based medicine, example of systematic review and meta-analysis, the forest plot.
2. Tasks and aims of epidemiology. Tasks of veterinary epidemiology. Natural history of disease. Classic iceberg concept of infection. Prevention, control and eradication of diseases. Basic reproduction number and herd immunity. The aims of epidemiological studies. Analytical studies for demonstrating causality. Observational (cohort, case-control and cross-sectional) and experimental studies (uncontrolled, randomized and non-randomized controlled), prospective and retrospective studies.
3. From association to causality. Demonstration of causality in observational studies. Statistical significance and causality. Chi-square test for comparing two percentages. Statistical significance tests. Association and causality: types of association. General model of causal and non-causal associations. Examples of causal and non-causal associations. Confounding and effect modification.
4. The epidemiological approach to the causes of disease. Henle-Koch's postulates. Evans's postulates. The Rules of John Stuart Mill. Demonstration of causality. Criteria of causality. Prevalence rate, relative risk and odds ratio. Linear simple regression.
5. Biological variability: basic concepts in epidemiology. Frequency distribution. Cumulative, median and centile frequencies. Central tendency indices. Variation indices.
6. Sampling in veterinary practice. Aims of sampling. Characteristics of a good sample. Sampling errors. Sampling methods. The variability of an estimate and confidence limits. Sample size.
7. Measuring disease frequency. General concepts. Morbidity and mortality. Survival and lethality. Prevalence and incidence. Attack rate. Relationship between incidence and prevalence. Epidemic, endemic and sporadic diseases. Other methods for measuring disease frequency. Standardization of measures.
8. Screening tests for sub-clinical diseases. Population screening. Test performance assessment. Sensitivity, specificity, positive and negative predictive value. Methods for improving the predictive value of a test. Multiple tests: use of two tests simultaneously or in succession; serial or parallel interpretation. Concordance index between two tests.
9. Transmission and maintenance of infectious diseases Transmissible diseases. The cycle of a transmissible disease. Latent infection and carrier status. Horizontal and vertical, direct and indirect transmission. Host types. Mechanical and biological vectors. Factors associated with the spread of infections. The spread of infections and host characteristics: receptiveness and contagiousness. The spread of infections and agent characteristics. The spread of infections and contact efficiency. Routes of infection. Transmission modes. Long distance transmission of disease agents. Vertical transmission of disease. Maintenance and survival strategies of the agent.
Bibliography
BOTTARELLI E., OSTANELLO F. (2011). Epidemiologia. Teoria ed esempi di medicina veterinaria. Edagricole, Milano;
oppure (disponibile online):
BOTTARELLI E. Quaderno di Epidemiologia Veterinaria (http://www.quadernodiepidemiologia.it);
testi di consultazione:
PFEIFFER D.U. (2002). Veterinary Epidemiology - An Introduction (PDF reperibile liberamente online);
THRUSFIELD M. (2018). Veterinary epidemiology. Wiley Blackwell (disponibile presso la biblioteca di Medicina Veterinaria);
LOPALCO P.L., TOZZI A.E. (2003). Epidemiologia facile. Il Pensiero Scientifico Editore, Roma (disponibile presso la biblioteca di Medicina Veterinaria);
SIGNORELLI C. (2000) Elementi di metodologia epidemiologica. Società Editrice Universo, Roma, V ed. (disponibile presso la biblioteca di Medicina Veterinaria);
BEAGLEHOLE R., BONITA R., KJELLSTROM. (1997). Epidemiologia di base. Edizione italiana a cura di G. Agazzotti, Editoriale Fernando Folini, Casalnoceto (disponibile presso la biblioteca di Medicina e Chirurgia).
Teaching methods
The lectures will be carried out through the prevalent use of slideshow or multimedia presentations.
Practical teaching will be carried out partly independently through guided exercises using a spreadsheet.
Assessment methods and criteria
Written exam, lasting one hour, at the end of the module.
Composition of the written test:
Two open questions. The maximum score achievable for each question is 5.
Four questions with multiple choice answers. The score is assigned according to the following criteria: 2 points for correct answers; 0 points for the answers not given; there is no penalty for incorrect answers.
Two exercises. The maximum score achievable for each exercise is 6.
The student can use a calculator (no smartphone, smartwatch or PC) during the test.
The final score is given by the sum of the scores acquired for each question/exercise. The student must achieve a minimum score of eighteen to pass the exam. The use of appropriate terminology will be taken into account in the evaluation.
Students with certified disabilities pursuant to article 16 of law n. 104/1992 or learning disabilities (law n. 170/2010), will be provided with proper specific support and additional times.
Other information
