EPIDEMIOLOGY, INFECTIOUS DISEASES. Department of Microbiology and Infectious Diseases Budapest, XIV. Hungária krt. 23-25. Telephone: 251.9900 Internal

EPIDEMIOLOGY, INFECTIOUS DISEASES

Department of Microbiology and Infectious Diseases

Budapest, XIV. Hungária krt. 23-25.

Telephone: 251.9900

Internal phone: 8090, 8091

Fax: 251.9260

E-mail: [email protected]


Lectures

• Bakonyi, Tamás: Associate Professor

• Fodor, László: Professor

• Makrai, László: Associate Professor

• Tuboly, Tamás: Professor

• Varga, János: Professor

• invited speakers


Plenary practicals

• Bakonyi, Tamás: Associate Professor

• Fodor, László: Professor

• Hornyák, Ákos: Head of Department

• Makrai, László: Associate Professor

• Tuboly, Tamás: Professor

• Varga, János: Professor

Diagnostical practical

• 4 weeks

Importance of infectious diseases

• all areas of veterinary medicine

• great economic impact (avian influenza 20 bn $)

• trade of animal and animal products

• zoonoses

• food hygiene, food safety

• 25% of human death cases is because of infective agents

Subject of „Epidemiology, infectious diseases”

• Structure

• lectures

• plenary practicals (from 10th October, 2011)

• practice at diagnostic institute

• midterm exam (24th October, 21st November)

• Content

• general epidemiology

• diseases caused by viruses

• diseases caused by prions

• diseases caused by bacteria

Literature

• Hagan and Brunner’s Microbiology and Infectious Diseases. 8th

Ed. Comstock Publishing Associates 1988.

• Kahn (Ed.): The Merck Veterinary Manual. 10th Ed. Merck & Co.

2010. www.merckvetmanual.com

• http://www.oie.int

• Straw, B. et al. (Eds.): Diseases of swine. 9th Ed. Blackwell. 2006.

• Saif, Y.M. (Ed.Ch.): Diseases of poultry. 12th Ed. Blackwell. 2008.

• Radostits, O.M. (Ed.): Veterinary Medicine 10th Ed. Elsevir. 2007.

HISTORY OF INFECTIOUS DISEASES

• Varro (2nd cent B.C.): living agents

• Fracastoro (16th cent.) „contagium vivum”

• Leeuvenhoek (17th-18th cent.): microscope

• Pollender (19th cent.): bacteria in the blood of animals with anthrax

• Pasteur-Koch (19th-20th cent.)

• Ivanovsky (19th cent.): virus

• Löffler and Frosch (1897): foot and mouth disease virus

• Jenner (1796): pox

• Mechnikov (1884): phagocytosis

• Behring (1890): antibodies in the blood

• eradication of infectious diseases

Infectious disease

• agent (lower ranked)

• host (higher ranked)

• exposition - disposition

• phases of infection

Sources of infection

• source: generally infected animals / humans

• direct

• indirect

•excretions, secretions (blood, faeces, urine, saliva, milk,

semen,)

•products of animal origin (meat, milk, skin, wool, hair)

•drinking water, feed

•soil, environment

• aerogenic

• arthropods

• iatrogenic infections

•nosocomial

Transmission of diseases

• vertical

• germinative

• intra uterine

• galactogen

• horizontal

Zoonoses

• orthozoonoses

• cyclozoonoses

• metazoonoses

• sapronoses

Infection

• ways of infection

• per os, intra nasal, genital tract, udder

• conjunctiva,

• per cutan, wound

• optimal entrance

• source of infection: animal (carrier), environment, feed, water, etc.

Forms of infection

• reinfection

•exacerbation

•superinfection

• secondary infection

• mixed infection

Outcome of the infection (agent – host – environment)

• agent

• relationship of the agent and the host (pathogenicity, virulence)

• amount of the agent

• way of infection

• host

• species, age

• species related resistance

• non specific resistance

• specific resistance

• environment

• nutrition

• management

Outcome of the infection (agent – host - environment)

Agent

• host-parasite relationship

• normal microflora

• pathogenicity (euryxen / stenoxen, obligate / facultative pathogen)

• virulence (virulence factors, MLD, LD50, change of the virulence)

• invasiveness (intra cellular, extra cellular)

• amount of the agent

• way of infection (optimal!)

• Henle-Koch postulates


Host

• species, age (species specific resistance)

• race, individual resistance (lines)

• production (feeding, laying)

• non specific resistance

• skin, mucous membranes, excretions (HCl, fatty acids, bile, etc.

• macrophag-phagocyte system (MPS)

• complement, properdin, opsonin

• IL, IF, TNF

• specific resistance

• passive immunity (natural, induced)

• active immunity (natural, induced)

•specific resistance

• humoral resistance (IgA, IgG etc.)

• cellular resistance (i.c. bacteria, viruses)

• effect of immune suppression (toxicosis, medicine,

micotoxins, some agents, parturation etc.)

• foetal immune reaction (hierarchy, age)

• immune reaction of newborns (age related)

•calf: Ig 4-32 days

•calf, piglet: local immune reaction immediately

(disappears, no immune memory)

•cellular immune reaction: 0-2 weeks weaker


Environment

• survival in the environment

• environmental effects on animals

• predisposes to facultative pathogens

• nutrition

• management

• technology (weaning, grouping, treatment, castration, sheering,

transport)

• physiological effects, use of animals

Course of an infectious disease

1. local infection

2. infections of different organs (localised)

3. generalised infections

• incubation: infection, colonisation, replication

• generalisation: spreading (blood, lymphatic vessels,

perineural)

• foetus:

• resorption, embryonic death, abortion

• teratogenic

• decreased resistance

• tolerated infections

• manifestation: clinical signs, lesions (virulence factors)

Course of infectious diseases caused by viruses

• replication at the place of entry and in the regional lymph node

• localisation by macrophages

• replication in infected macrophages, lymphocytes, blood

(viraemia)

•replication in lymphoid cells: immune suppression, damage of

blood vessels

• secondary replication in tissues

•damage of cells: clinical signs

• reactive inflammation, allergic reactions

•clinical signs

Start and course of infectious diseases

Course of the disease

• incubation time

• course of an infection in time

• peracute

• acute

• subacute

• chronic

Outcome of the disease:

• recovery (full or partial), carrier

• death

Infections without clinical signs

• forms of infections without clinical signs

•abortive infection

•inapparent (sub clinical) infection

•persistent infection (virus)

•latent infection (virus)

•tolerated infection (virus)

• importance of infections without clinical signs

Epidemiology of infectious diseases

Characteristic of infectious diseases

• infectious diseases

• contagious diseases

• soil infections

Statistical evaluation of infectious diseases

• morbidity

• mortality

• lethality

• incidence

• prevalence

Analysing methods of infectious diseases

• data collection to diagnostic work

•monitoring

•surveillance (passive, active)

•screening

• control of hypothesis

•statistical methods

•blind examinations

Extension of infectious diseases

• endemic diseases (enzootia)

• epidemic diseases (epizootia)

• pandemic diseases (panzootia)

Notification

International cooperation regarding infectious diseases

• OIE (Office International des Epizooties, World Organisation for

Animal Health) 1924.

• FAO (Food and Agricultural Organisation) 1948.

• WHO (World Health Organisation) 1948.

Factors influencing infections

• geographical factors (island, desert, mountain, river, soil)

• climatic factors (sunshine, wind, vapour content, season)

• management (overcrowding, mixing, contact, draught, NH3)

• nutrition (pasture, stable, starvation)

• transport (road, rail, harbour)

• biological factors (mating, leave of the offspring)

Diagnostics of infectious diseases

• complex

• epidemiological data

• clinical signs

• pathological lesions

• allergic examination

• laboratory examinations (diagnostic institutions)

• evaluation, diagnosis


• epidemiology – clinical signs – pathological lesions

• allergic tests (tuberculin, mallein)

• laboratory diagnosis

•sampling, letter

•histological examination

•microscopic examination (smear)

•electron microscopic examination

•isolation (medium – cell culture – egg – laboratory animal)

•serological tests

•classical: agglutination, precipitation, elfo, PAGE, CFT

•virus serology: VN, HAI

•marked immunological methods: IF, ELISA, RIA, IRMA


• cellular tests

•lymphocyte stimulation test

•immune rosette formation

•cytotoxic reaction

•macrophage migration

• -interferon test

• methods detecting nucleic acids (DNA hybridisation, PCR)

• more diagnostic methods have to be used

• complex evaluation

Treatment of diseased animals

• aetiological treatment

• symptomatic treatment

• bacteria: antibacterial treatment (appropriate medicine)

• individual / mass treatment

• treatment of certain diseases is not allowed

• some chronic diseases cannot be treated or treatment is not

reasonable

• prevention of complications (diseases caused by viruses)

• hyperimmune serum

Prevention and control of infectious diseases

1. veterinary administration, rules

• general rules

• specific measures

2. immune prophylaxis

3. chemoprophylaxis


1. rules, veterinary administration

• international transport, certificates

• import restrictions

• quality requirements

• localisation


• general rules

•all in, all out, disinfection

•isolated keeping of different animal species / age groups

•closed keeping, limited traffic (personal, vehicles, avoiding mixing)

•isolation from wild animals, rodents, birds

•rendering dead animals, waste

•rules of hatching, transport of day-old chicken

•excluding carrier people


1. veterinary administration

• general rules

• specific rules

• specific measures concerning a certain disease


1. passive immunisation

2. active immunisation

3. chemoprophylaxis

Immune prophylaxis

Passive immunisation

• hyperimmune serum

• maternal immunity

• epitheliochorial: colostrum

• syndesmochorial: mainly colostrum

• endotheliochorial: diaplacentar + colostrum

• immuno globulin content of the colostrum is decreasing

1st day 3rd day Commercial milk

Protein 18.8 7.5 3.25

Ig 13.1 1.0 0.09

Colostrum (%)

• enteral absorption of Ig is decreasing

• enteral lymphocytes can be transferred

• bisection time

• effect of the antigen on the amount of maternal antibodies

• can inhibit immunisation

Immunprophylaxis

Active immunisation

• factors influencing efficacy

• live vaccines (attenuated)

• inactivated vaccines

New generation vaccines

• live vaccines

•deletion vaccines

•vector vaccines

• not living vaccines

• subunit vaccines

• inactivated deletion vaccines

• ISCOM vaccines, virus like particles

• synthetic vaccines

• nucleic acid vaccines (DNA, ss+RNA)

• transgenic plant vaccines

• not replicating vector vaccines

• anti-idiotype vaccines

•DIVA: Differentiation Infected and Vaccinated Animals


1. veterinary administration

• general rules

• specific rules

• specific measures concerning a certain disease


1. passive immunisation

2. active immunisation

3. Chemoprophylaxis

• antibacterials

Control, eradication

• selection (test and remove) (+ vaccine)

• generation shift

• herd replacement

• SPF method

• embryo transfer

Eradication of human infectious diseases

• smallpox (1959-1979)

• polyomyelitis (some years)

• rubella, mumps (target: 2010-2015)

Eradication of infectious diseases of animals

• Rinderpest (2011): 2010-2015)

Documents

EPIDEMIOLOGY, INFECTIOUS DISEASES. Department of Microbiology and Infectious Diseases Budapest, XIV. Hungária krt. 23-25. Telephone: 251.9900 Internal