Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
166 Cards in this Set
- Front
- Back
EPIDEMIOLOGY
WHY |
...knowledge of microbiology and parsitology alone is no longer sufficient to plan, organize and carry out an effective prevention and control of epizootics...
So Study UP! |
|
PUBLIC HEALTH
IMPACT |
61% of human diseases (1414)are linked to animals
75% of emerging diseases originate in animals |
|
EPIDEMIOLOGY
MEANING |
epi - about or upon
demos - populace logos - science or theory |
|
EPIDEMIOLOGY
A COUPLE OF DEFININTIONS |
The study of the frequency, distribution and deteriminants of health and disease in populations
Method of reasoning about disease that deals with biological inferences derived from observations of disease phenomena in populations and groups |
|
EPIDEMIOLOGY
8 INVOLVEMENTS |
Focuses on poplulations
Involves a very broad definition of disease - ie health related event Involves and understanding of the interrelationships between agen, host and environment - the holy 3 determinants Involves describing the patterns of disease in relation to individuals, place and time Involves a logical approach to solving disease problems regarding etiology, predisposing factors, prognoses and appropriate intervention strategies Involves understanding of change, and and ability to determine whether chance alone can account for observed associations or patterns of disease Provides and approach for the design, implementation and analysis of observational and experimental research Involves a systematic approach for the critical evaluation of scientific literature |
|
EPIDEMIOLOGY
3 GENERAL GOALS |
Describe the distribution and "size" of disease problems in populations
Evaluate factors affecting the transmission of an organism Evaluate factors associated with clinically recognizable disease amoung those who are infected |
|
VETERINARY EPIDEMIOLOGY
9 SPECIFIC GOALS |
Identify Determinants of Disease
- virtually all clinical disease is multifactiorial Indentify risks in terms of probability statements - ie risk is not fixed Formulate hypothesis about causation - ie BSE before knowledge of prions Determine modes of transmission - tf can fight disease before knowing cause Develop and evaluate interventions for control and prevention - ie erradication program Determine efficacy of new therapeutic and preventive measues - ie clinical trials Studying trends over time to make predictions for the future - ie modeling to develop better responses Monitoring the animal health of a herd, region or nation - ie surveillance systems ~~NAHMS, CAHNET Make the best descision about care of individual patients |
|
EPIDEMIOLOGY
3 INPUTS 3 OUTPUTS |
INPUTS
- Who - When - Where - How - Why - What to do about it OUTPUTS - Descriptive - Analytic - Operational |
|
EPIDEMIOLOGY
DESCRIPTIVE |
Any general observational study of the occurrence of disease of other health related event in a population
Surveys - main - representitive sample Case Reports and Case Studies - new diseases or new clinical signs of old disease - not neccesarily epidemiology |
|
EPIDEMIOLOGY
ANALYTIC |
A hypothesis testing method that investigates the association between a given disease or health releated event and possible causation/factors
Statistics > Association Association vs Causation |
|
EPIDEMIOLOGY
OPERATIONAL 3 ACTIVITIES |
An action oriented epidemiology directly aimed at disease control
Control/Eradication/Prevention Surevillance Epidemiological Evaluation |
|
EPIDEMIOLOGY
THE WORDS BEHIND THE NAME |
Ecology
animal Production socIology Demographics mathEmatics Microbiology statIstics parasitOlogy pathoLogy ecOnomics aGriculture biologY ok that is pretty sad |
|
KOCH'S POSTULATES 5
AND ASSUMPTIONS 2 |
The organism must be present in every case of the disease
The organism must not be present in other diseases, or in normal tissues The organism must be isolated from the tissue(s) in pure culture The oganism must be capable of inducing the disease under controlled experimental conditions The organism must then be recovered from the animal and identified ASSUMPTIONS A particular disease has only one cause A particular cause results in one disease |
|
3 SHORTCOMMINGS OF GERM THEORY
|
Germ theory underestimates the complexity of disease
- multiple etiologic factors - multiple effects of single causes - carrier state Many diseases are not caused by infectious agents - ie non-agent factors ~~age ~~breed, genetics |
|
MILLS RULES OF INDUCTIVE REASONING
WHERE IS THE LOGIC GOOD WHERE IS THE LOGIC BAD |
METHOD OF AGREEMENT
If a disease occures under a vairety of circumstances but there is a common factor, this factor may be the cause of the disease METHOD OF DIFFERENCE If the circumstances where a disease occurs are similar to those where the disease does not occur, with the exception of one factor, this one factor of its absence may be the cause of the disease METHOD OF CONCOMITANT VARIATION If a factor and disease have a dose-response relationship, the factor may be the cause of the disease - not always true because dose response relationships are not allways linear ~~ a little wine is good, a lot is bad METHOD OF ANALOGY If the distribution of the disease is sufficiently similar to that of anothe well understood disease, the disease of cncern may share common causes with the other disease. - sometimes, sometimes not METHOD OF RESIDUE If a factor explains only X% of disease occurrence, other factors must be indentified to explain the remainder, or residue (100-X%) |
|
HILLS CAUSALITY CRITERIA
WHAT IS GOOD WHAT IS BAD |
STRENGTH
Strong ssociations are more likely to be causal - but there are weak associations which are causal CONSISTENCY the repeated observation of an association in different populations SPECIFICITY a cause leads to a single effect, not multiple effects - complete crap, life was so simple in the '50s and '60s TEMPORALITY The cause must procede the effect - very ZEN, very important to remember! BIOLOGIC GRADIENT The presence of a monotonic (unidirectional)dose response curve - not true for all diseases ~~ remember the wine PLAUSIBILITY The biological plausibility of the hypothesis - can you imagine proposing prions in the '70s - ok most of you cant imagine the '70s ~~ they were ok it was before the orange of the 80s COHERENCE A cause and effect interpretation for an association does not conflict with what is known of the natural history and biology of the disease - but if you don't know much about it how can you define a conflict EXPERIMENTAL EVIDENCE the removal of some harmful exposure in an intervention or prevention program should lead to a drop in the number of cases - but disease ar e consequences of many factors what if you miss a few through ignorance or logistics ANALOGY causal relationship similar to other better known diseases |
|
EVAN'S POSTULATES
WHAT DID EVAN INCORPORATE GOOD BAD |
Statistics
The proportion (prevalence) of the desease should be significantly higher in individuals exposed to the putative cause than in non-exposed individuals The exposure should be more common in cases than in those without the disease The number of new cases (incidence) should be significantly higher in individuals exposed to the putative cause than in non-exposed individuals Exposure must precede the disease There should be a spectrum of measurable host responses to the agents (ie antibody response) - this may be difficuslt ~~ie host response to prions not detectable The host response should be repeatable following exposure to the putative cause - can be difficult for some diseases Elimination of the putative cause should result in a lower incidence of the disease - but may have other factors producing same disease Preventing, or modifying, the host's response should decrease of eliminate the expression of disease (vaccination etc) The disease should be reproducable experimentally - difficult with many diseases - may know agents but not mechanisms The relationship should be biologically and epidemiologically plausable - biological ~~ the truth is sometimes stranger than fiction - epidemiologically ~~ may need impractically large sample sizes to show relationships Note - Comparison is the basis of epidemiology - temporality MUST ALWAYS be met but other criteria are often not met |
|
ROTHMAN'S CAUSAL INFERENCE THEORY
CAUSE DEFINITION DISEASE DEFINITION |
CAUSE
An event, condition or characteristic that PRECEDED the disease event and without which the disease event either would not have occurred at all or at that time DISEASE the consequences of multiple causes |
|
ROTHMAN'S CAUSAL INFERENCE THEORY
TYPES OF CAUSES - 3 MAIN |
Sufficent Cause
- set of minimal conditions and events (COMPONENT CAUSES) that inevitably produce disease - disease may be produced by different sets of COMPONENT CAUSES - removal of a particular component cause will prevent a certain amount of disease - sufficient causes can be hard to determine Necessary Cause - one component cause WITHOUT WHICH the dissease cannot occur - elimination of neccesary cause eliminates all disease |
|
ROTHMAN'S CAUSAL INFERENCE THEORY
4 TYPES OF COMPONENT CAUSES |
Predisposing Factors
- increase the level of susceptibility in the hose ~~ age, sex, immune status etc Enabling Factors - facilitate manifestation of a disease ~~ housing, nutrition Precipitating Factors - associated with the definitive onset of disease ~~ most toxic and infectious agents ~~ breach of immune barriers ie tooth eruption Reinforcing Factors - tend to aggravate the presence of the disease ~~ repeated exposure to an infectious agent in absence of an immune response |
|
WEB OF CAUSATION
|
Representation of all factors thought to relate to presentation of disease
|
|
DISEASE DETERMINANTS
THE SINFUL SEVEN |
Primary Determinants
- neccesary cause Secondary Determinants - often component causes Intrinsic Determinants - all factors associated with the host Extrinsic Determinants - environment and agent Host Determinants Agent Determinants Environmental Determinants |
|
EPIDEMIOLOGIC TRIAD PLUS
|
AGENT
HOST ENVIRONMENT Vector Factors - relate agent and environment Husbandry and Management Factors - relate host and environment |
|
EPIDEMIOLOGIC TRIAD
3 AREAS OF OVERLAP |
Host and Agent
- infection - contamination ie body surface - pollution Agent and Environment - Transmission ~~ related to ability of agent of survive in environment and vectors Host and Environment - stress ~~ immunosuppresion |
|
THE AGENT
|
Biological, chemical, physical, mechanical, social or behavioral entity for which the presence, the excess or dprivation influences the occurence of diesase
A disease could result from the action of a single agent, from several agents each acting separately, or from the interaction of at least two different agents |
|
AGENTS
4 TYPES |
INFECTIOUS AGENT
- a living organism that infects a host NON-INFECTIOUS AGENTS - Physical ~~ noise, repetitive motin, violence etc - Chemical ~~ air pollutants, water pollutants etc - Nutritional ~~ obesity, deficiencies, diet changes etc |
|
INFECTIOUS DISEASE
ANOTHER LONG WINDED DEFINITION |
An illness due to a specific infectious agent or its toxic products that arises through transmission of that agent or ists products from an infected person, animal or resivoir to a susceptible host, either directly or indirectly through an intermediate plant or animal host, vector or the inanimate environment
|
|
TWO OUTCOMES WHEN INFECTIOUS AGENTS STAY IN ANIMAL
AND THE UPSHOT |
Animal dies and agent is not transmitted
or Animal kills infectios agent tf TRANSMISSION is required for the survival of infectious diseases |
|
CHARACTERISTICS OF THE AGENT
NAME AND DEFINE 9 |
Host Range
- the number of species - variance of environmental conditions - etc - the greater the range, the more capable th organism is of spreading and developing disease in animals Infectivity - ability of an agent ot establish itself in a host ~~ ie quantity of agent required to create disease Ability to survive in the Environment - agents often have part of life cycle outside of host Pathogenicity - ability of an agent to produce disease ~~ agents that must live in host to survive cant significantly harm host tf low pathogenicity Virulence - measure of severity of disease casued by a specific agent Antigenicity - ability of an agent to elicit immune response Immunogenicity - ability of an agent to elicit protective immune response in host ~~ ie parasites generally have low immunogenicity Toxin Production Resistance Factors Toxicity - ability to cause a harmful effect ~~ ie poisons |
|
THE HOST
|
Organism, usually multicellular, that lodges and maintains in natural conditions a pathogen
|
|
THE HOST
4 INTRINSIC FACTORS |
Intrinsic host factors do not change relative to disease challenge
Age - determines immune status of animal ~~ usually lower in young and old Gender - diseases releated to male/female physiology, structures, organs, production or reproductive status Breed - innate resistance/susceptability ~~local breeds are usually more resistant to disease Species - ie foot and mouth in rumminants but not in horses |
|
THE HOST
8 EXTRINSIC FACTORS |
Extrinsic host factors are modifiable
Use Behaviour Castration/hystorectomy Movement Pervious diseases and medications Feed or Diet Contacts Immunization History |
|
THE HOST
IMMUNITY |
Factors that alter the probability of infection and development of disease in the host after the agent is encountered
Innate Immunity - barriers that prevent invading pathogens from entering the body - primarily determined by genetics Acquired Immunity - resistance developed by the host as a result of previous exposuer |
|
THE HOST
INNATE IMMUNITY |
Physical Barriers
- intact skin - mucosal lining - repiratory tract cilia - cough and gag reflex Chemical Barriers - acidity of stomach and vagina - hydrolytic and proetolytic enzymes in saliva and intestines Cellular and Physiologic Barriers - macrophages - NK cells - inflamation ~~ fever |
|
THE HOST
AQUIRED IMMUNITY |
The result of a highly specific and evolved response on the part of the host
- begins when the host is exposed to the pathogen Cellular and Humoral Immunization - can modify aquired immunity - Active ~~ natural or artifical exposure to antigens - Passive ~~ maternal and therapeutic sources |
|
HOST AGENT INTERACTIONS
4 TYPES |
Mutualism
- symbiotic - beneficial for the host ~~ ie rumen bacteria Comensalism - symbiotic - neutral for the host ~~ ie salmonella in birds Parasitism - symbiotic - detrimental to the host ~~ ie typical disease condition Phoresis - host provides transport ~~ ie surface contamination |
|
WHAT DO INFECTION AND INFECTIOUS DISEASE DEPEND ON
|
Agent and Host Factors
- an agent must be present for an infection to occur - presence of agent is not sufficient cause for an infectious disease |
|
THE ENVIRONMENT
2 CHEESY DEFINITIONS |
Set of natural, social and/or cultural conditions in which organisms live
Everthing that is external to the individual host |
|
THE ENVIRONMENT
8 ABIOTIC FACTORS |
Topography
Temperature Water - including relative humidity Soil - minerals Pressure Gases Air Climate |
|
THE ENVIRONMENT
2 BIOTIC FACTORS |
Flora
- poisons - nutrition Fauna - ie skunks and rabies |
|
THE ENVIRONMENT
EPIDEMIC INFECTIOUS DISEASES SEASONAL CONSIDERATIONS OF 4 TRANSMISSION MECHANISMS |
Direct Physical Contact
- low seasonal affects because infectious agent in environment for very short time - sporatic spread - closed commmunities - involves whole herd Airborne Droplets - travel better when humidity higher - rapid spread - universal - often involves young Arthropod Borne Outbreaks - more prevalent in summer - gradual build up (amplification) - follow population dynamic of vectors - may combine biological and mechanical transmission Vehicular - summer and fall afford better conditions for agent survival - explosive outbreaks - follows economic distribution routes - common source ~~ ie water or feed |
|
THE ENVIRONMENT
SOCIOECONOMIC 3 ELEMENTS |
Cultural Background
- ie old Spanish farmers like to swap rams Political - laws - policies - almost allways involved in disease Economic - prices - subsidies ~~ ie motivated to keep older more susceptable sheep |
|
THE ENVIRONMENT
ANIMAL MANAGEMENT 7 FACTORS |
Farm characteristics
Housing - ventilation - sanitation Husbandry Animal Stocking Density - especially respiratory transmission Animal Movement Environmental Conditions - temperature - humidity Nutrition - protein - energy |
|
THE ENVIRONMENT
ANIMAL MANAGEMENT A COUPLE OF SAGE SAYINGS |
Every care or lack of care effects disease in animals
Bovine mastitis is a disease of man with signs in the cow |
|
PATHOGENS
4 SOURCES |
Living Organisms
Carcasses Animal Products Environment |
|
SUSCEPTIBILITY
|
Susceptability is what makes and animal infected
or The state of being readily infected by a pathgen - ie the infectivity Relative to a given agent hosts are - susceptable - non-susceptable |
|
SUSCEPTABLE ANIMALS
|
May or may not express disease after infection
- agent factors ~~ pathogenicity - individual factors ~~ age, sex etc - species factors ~~ a given agent will manifest disease in some species but not others |
|
GRADIENT OF INFECTION AND DISEASE
STATUS TYPE SPECTRUM |
Status of Animal
Type of Infection Spectrum of Disease Non-Susceptable (immune) - no infection ~~ no signs Susceptable - unapparent infection ~~ no signs -~- no disease -~- subclinical disease - overt infection ~~ clinical signs -~- mild -~- severe ~~ death |
|
INCUBATION PERIOD
|
From infection to the development of the clinical manifestations of disease
|
|
PREPATENT PERIOD
|
aka Latent
Interval between infection and the fist shedding of the pathogen |
|
INFECTIOUS PERIOD
|
Duration of infectiousness of animal
|
|
PREVENTION
3 TYPES AND DEFINITIONS |
Primary Prevention
- activites aimed a halting the occurrence of a disease before it happens ~~ immunization ~~ decontaminations ~~ personel hygiene ~~ eliminationn of reservoirs - occurs in prepatent (latent) period Secondary Prevention - activities directed at detecting carriers of infection ~~ find the asymptomatic - occurs before clinical disease Tertiary Prevention - treatment of affected individuals in order to halt the progression of the disease ~~ limit disability ~~ rehabilitation - occurs after clinical disease |
|
SIX SUSCEPTIBLE ANIMALS
|
UNAPPARENT INFECTION
Healthy Infected Animal - salmonella in chickens - doesn't create disease Incubating Animals - BSE in cattle - very long incubation period - tf infected but not showing disease Recovered/Convalescent Animals - sterilizing immunity ie completely clear virus - harbour pathogen ie do not completely clear virus ~~ continuously or periodically shed Chronic Latent/Persistent Infection - infected in utero tf recognize virus as self - continually shed - eventually develop disease Intermittent Shedders - ie cows sheding E coli 157 when diet suddenly changed |
|
FMD
ROLE OF 3 LITTLE HOSTS |
Pigs
- amplifiers - shed very high levels of virus Cattle - indicators - show clinical signs withing one day Sheep - maintenance hosts - late onset of clinical signs - tf undetected |
|
HOSTS
9 TYPES |
Note Definitions are not mutually exclusive
Reservoir - infectious agent normally lives and multiplies - tf common source of infection to other animals - almost all hosts can act as resevoirs Definitive aka Final - organism undergoes its sexual phase of reproduction ~~ ie parasites - or ends its dynamic process Primary aka Natural aka Maintenance - maintains an infection in an endemic area - host unaffected ~~ ie ASH in wild boars - host unaffected Secondary - species involved in the life-cycle of an agent outside typical endemic areas - ASH outbreaks in European pigs Paratenic - transport infectious stages of a parasite to the definitive host - no development of the parasite occurs - can be mechanical vectors Intermediate - infectious agen undergoes some development ~~ often asexual reproduction Incidental aka Dead End - develop disease but not involved in transmission - infection dies in host - ie WNV in humans and horses Amplifier - produces large quantities or transmission of virus - ie birds with WNV infect 100s of mosquitoes Hibernating - parasite hibernates with host |
|
INFECTED ANIMAL PRODUCTS
8 TYPES |
Amount in products is usually low
- ie subclinical - treatment may amplify pathogen Milk and Milk Products - brucellosis Eggs - salmonellosis Bone, Meat and Bone Meal - BSE Serum - bluetongue virus in canine vaccines Tissue - ovine pestivirus in Aujeszky vaccine Exceta - salmonellosis - avian flu Semen and Embryos - campylobacteriosis - BVDV |
|
TRANSMISSIBLE DISEASES
OBLIGATORY 2 BIT DEFINITION 2 TYPES |
Diseases whose agents can be transferred from one individual host to another
CONTAGIOUS - those requiring contact (direct or indirect)with the individual that is the source of the pathogen - ie rabies, FMD NON-CONTAGIOUS - transmitted through the intermediary of a vector or vehicle - ASH, BSE |
|
MODES OF TRANSMISSION
|
Vetrical Transmission
- infection is passed on to the progeny Horizontal Transmission - between animals that are not necessarily related - contact - vehicle - vector |
|
VERTICAL TRANSMISSION
2 WAYS TO PLAY |
Hereditary
- agent transmitted within the genome ~~ retroviruses ie HIV Congenital - prestented at birth - in utero or in ovo - Germinative Transmission ~~ chicken leucosis viruses -~- infects superficial tissues of ovary - Transplancental Transmission ~~ during gestation ~~ abortions ~~ still births ~~ infected offspring ~~ permanently infected offspring - At Parturition ~~ herpesvirus |
|
HORIZONTAL TRANSMISSION
CONTACT 2 WAYS TO PLAY |
DIRECT CONTACT
- requires physical contact - fragile agents - cutaneous or mucosal contact - venereal transmission - bites INDIRECT CONTACT - urine - feces - salivary - droplets from sneezes, coughs - milk |
|
HORIZONTAL TRANSMISSION
VEHICLE |
Fomites
- Mechanical ~~ physical tranfer agent ~~water, air, equipment - Biological ~~ supporting multiplication and/or development ~~ milk |
|
FOMITE
|
An object or material thai is not in itself harmful, but on which pathogens may be conveyed
- clothing, equipment etc - transmission always depends on ability of agent to survive on fomite - equine strangles |
|
HORIZONTAL TRANSMISSION
VECTOR 2 TYPES |
MECHANICAL aks Passive
- pathogen does not replicate - life of agent on vector is limited BIOLOGICAL - Propagaitve Transmission ~~ must exceed blood threshold ~~ may replicate ~~ no morphological changes ~~ no intermediate hosts ~~ ticks act as vector and reservior ~~ other insects act as vector only - Ciciopropagative (Developmental) Transmission ~~ agent must remain in agent for extrinsic incubation period ~~ may or may not replicate ~~ developmental changes ~~ intermediate host |
|
BLOOD THRESHOLD
|
[] of agent required in blood of host in order to infect vector at a level required to infect another host
|
|
EXTRINSIC INCUBATION PERIOD
|
Time between infection of vector and viability of agent to be capable of infecting new host
- agent requires developmental time in vector |
|
PORTAL OF ENTRY
|
The routes by which an infectious agent can infect a susceptible animal
|
|
PORTAL OF EXIT
|
The routes by which an infectious agent exits its host
- feces - urine - saliva - expired air - blood - semen - urogenital secretions |
|
PORTALS OF ENTRY AND EXIT
13 WAYS MAMMALS CAN LEAK |
Conjunctiva
CNS Circulatory System Skin Urinary System Anus - preg checking can you say iatrogenic Fetus Genital System Mammary Gland Alimentary System Respiratory System Oral Cavity Nasal Cavity |
|
FMD ROUTES OF INFECTION
|
Cattle
- more susceptible to infection by the repiratory route Pigs - more susceptible to infection by the oral route |
|
FMD
DURATION OF VIRUS EXCRETION CATTLE |
11 Days
- Saliva 10 Days - semen 7 Days - urine - nasal discharge 5 Days - blood - milk - aerosol - feces |
|
AGENT MAINTENANCE STRATEGIES
5 HANDY ONES FOR THE MIDTERM |
Avoidance of stage in external environment
- vertical transmssion - arthropod borne - direct contact Development of resistance forms - ie sporulation in anthrax ~~ good for 40 yrs ~~ evil fields Rapid In - Rapid Out - short life in host and environment - tf rapid ~~ infection ~~ multiplication ~~ escape - respiratory diseases - works best in high density conditions Persistence within the host - adapts to host defence mechanisms - long incubation Extension of Host Range - zoonoses our favorite |
|
SPREAD OF INFECTION
MENAGE a TROIS |
Host
- Susceptability - apparent disease - infectiousness Pathogen - infectivity - stability (resistance) Effective Contact - routes of infection |
|
HERD LEVEL
MODES OF TRANSMISSION |
Infection from neighboring farms
- vectors - contact Infection by Introduction - animals - objects - people Infection due to resurgence of the disease - anthrax - intermittent shedders |
|
HERD LEVEL
SPREAD OF INFECTION |
Transmissibility
- agent strategy of maintenance Extent to which animals in the herd are receptive to infection - proportion of susceptible and resistant animals Animal Husbandry - stocking density - loose vs tethered housing - movement within herd |
|
HABITAT AND TRANSMISSION
WHERE WHO HOW |
WHERE
- Sources of Infection ~~ measures aimed at destroying the pathogen in situ WHO - Susceptibility of Host ~~ measures aimed at reducing susceptibiliy to infection HOW - Modes of Transmission ~~ measures aimed at preventing transmission |
|
DISEASE CONTROL MEASURES
2 MAIN DIVISIONS |
Sanitary Measures
- Primary Prevention - eliminate agent from environment - tf avoid infection or exposure of health individuals Medical Measures - only acts on hosts - direct protection of healthy animals - treatment of sick animals |
|
SANITARY MEASURES
3 SOUND BITES |
Detection of the Disease
Offensive measures on infected farms to remove disease - contain disease - control outbreak remove the disease Defensive measures on disease free farms to protect them from disease |
|
DETECTION OF DISEASE
|
Systematic Screening
- active detection - non clincal ~~ looking for disease in apparently healthy animals - clinical - antibody or agent detection - laboratory No Screening - passive detection - mainly based on signs or lesions - farmers, vets, abattoir |
|
OFFENSIVE MEASURES
REMOVING DISEASE |
Measures to CONTAIN MOVEMENT of disease
- animals - tissues - fluids Isolation Trace Back and Action - determine when herd infected ~~ incubation period ~~ pepatent period ~~ infectious period - animal with oldest lesions is usually the index case Follow up and action - materials and animals that have moved since begining of incubation period |
|
OFFENSIVE MEASURES
CONTROL OUTBREAK |
Slaughter
Environmental Sanitation Individual Treatment and Isolation |
|
SLAUGHTER INDICATIONS
5 CRITERION |
Spontaneous Development of Infection
- slaughter when permenant infection - ie chronic wasting disease Treatement Availability - slaughter when treatment not available or economically prohibitive - ie paratuberculosis Potential for Spread - slaughter if risk is high - ie FMD or AI Zoonotic Status - slaughter if major zoonosis - ie brucellosis Epidemiological Status - Exotic or Rare disease - AHS, ASF Epidemiological Mechanism - slaughter if absence of enviornmental or wildlife resevoir - Aujeszky's disease |
|
TOTAL AND IMMEDIATE SLAUGHTER
4 REASONS THAT WORKED FOR MALOSAVICH |
aka Depopulation
- highly contagious diseases - no tests to allow selective slaughter - population inaccessible to perform other measures - no other method of control available |
|
PARTIAL AND PROGRESSIVE SLAUGHTER
|
aka Selective
Disease not highly contageous Indentify infected individuals - reqular testing - remove as soon as possible |
|
DEFERRED SLAUGHTER
|
Form of selective slaughter
Slow spreading diseases keep animal as long as productive - ie through pregnancy |
|
ENVIRONMENTAL SANITATION
3 ELEMENTS |
Disinfection
- destruction of disease agent in environment - limited by ~~ extremely resistant pathogens ~~ latent carrier status -~- sheds after disinfection event ~~ intermedisate host -~- reintroduces agent - steps ~~ cleansing ~~ disinfection ~~ dry out period before restocking ~~ second disinfection Vector Control - vector borne diseases Rodent Control - intermediate or paratenic hosts |
|
CERTIFICATION OF DISEASE REMOVAL
|
Total Slaughter
Partial Slaughter - requires 2 consecutive negative tests |
|
RESTOCKING
3 STEPS TO STOCKING |
Initially introduce small number of animals
Check health status after incubation period has elapsed Introduce remaining stock |
|
DEFENSIVE MEASURES
2 GOALS |
aka BIOSECURITY
Reduce or prevent - introduction of new diseases - movement of infectious diseases |
|
BIOSECURITY
7 SOURCES OF INFECTION |
Wind
Water Animals - purchase - quirantine - screening Humans - boots - clothing Vehicles and Equipment Animal Products Neighborhood - contact with any of above |
|
BIOSECURITY PROGRAM
4 DESIGN COMPONENTS |
Risk Assessment
- level of infectious diseases already present Identification of Priorities - which diseases are important Assessment of Diseases NOT Present Development of Plan |
|
SANITARY MEASURES
4 LIMITATIONS |
Wildlife Reserviors
Soil Reseervoirs Endemic Highly Contageous Diseases Phychological Obstacles - established farms reluctant to cull or make changes |
|
SANITARY MEASURES
ADVANTAGES DISADVANTAGES |
Advantages
- no vaccines required ~~ avoid cost, stress etc - avoid cross reaction of vaccine with tests ~~ allows culling program Disadvantages - must be done on ongoing permanent basis ~~ cost - constant risk of infection |
|
MEDICAL MEASURES
|
Treatment
- reduce shedding period - antibiotics - chemo-prophylaxis Immunization - timing must be appropriate - active ~~ vaccines - passive ~~ sera |
|
VACCINE EFFICACY
5 CONSIDERATIONS |
Vaccine Characteristics
- live - innactivated Proportion of immune competent animals Proportion of animals that actually get vaccinated Vaccine Management - storage specifications ~~ ie how long did it spend on your dashboard in july - label usage Environmental Factors - status of the disease - epidemiology of the disease |
|
VACCINE EFFICACY
TAO OF |
Grasshopper:
Rain is Disease Umbrella is Vaccine |
|
HERD IMMUNITY
EVENING NEWS SOUND BITE |
The indirect protection from infection of susceptible animals of a population and the protection of the population as a whole, which is brought about by the presence of immune individuals
Because disease spreads from animal to animal, the probability of reaching a susceptible animal decreases as the proportion of immune individuals increases |
|
HERD IMMUNITY
POPULATION COMPOSITION THE 10 COMPONENTS |
Compostition of Herd Population
- incubating - infected - sick - convalescent - shedding - vaccinated - recovered - susceptible - alternative hosts - alternative carrier animals Note also have to consider Contact Rate - interaction among animals ~~ behavior ~~ husbandry |
|
HERD IMMUNITY
BASIC REPRODUCTION RATE DEFINITION 3 FACTORS FORMULA 3 VALUES |
The average number of secondary cases directly infected by an infectious individual dureing its ENTIRE infectious period, when it enters a TOTALLY susceptible population
B = risk of transmission per contact - aka probability of transmission or attack rate K = number of contacts per unit of time D = duration of infectivity - infectiousness Ro = B x K x D Ro > 1 = Epidemic Ro = 1 = Endemic Ro < 1 = Eradication |
|
HERD IMMUNITY
HOW MUCH IS ENOUGH |
Require that
p > 1 - 1/Ro Where p = proportion of immune population Ro = basic reproduction rate Average diseases have Ro of about 7 tf a herd immunity of about 85% will do |
|
HERD IMMUNITY
4 REQUIREMENTS |
The disease agent must be restricted to a single host species
Transmission must be relatively direct from one member to another There must be NO outside reservoir - provides alternate means of transmission Infections must induce solid immunity |
|
PREVENTION
WHAT IS IT |
Application of measures designed to exclude disease from unaffected populations
First line of defence against a disease |
|
PREVENTION
STRATEGIES FOR PRESENCE AND ABSENCE OF DISEASE |
Absence
- quarantine Presence - mass immunization - chemoprophylaxis - environmental control and hygiene |
|
CONTROL
WHAT IS IT |
Reduction of the prevalence of a disease to a level where it is no longer considered a major health and/or economic problem
~~ ie acceptable losses to producers |
|
CONTROL
4 STRATIGIES |
Preventing the spread of disease
Decreasing communicability Increasing resistance Early detection and diagnosis |
|
WHY ERADICATE
|
Complete elimination of the agent from a specific region usually has greater econimic benefits than controlling agent
|
|
ERADICATION
5 CRITERIA FOR SUCCESS |
Profitable
Method of Diagnosis Isolation of the Agent Removal of Sources of Infection Protection of Susceptible Animals |
|
CONTROL STRATEGIES
3 FRACTIOUS FACTORS |
Nature of Disease
People Infrastructure |
|
6 IMPACTS OF
NATURE OF DISEASE ON CONTROL STRATEGIES |
Cause
- one necessary cause - or multifactorial disease Host Range and Survival in Environment - wildlife reserviors - intermediate hosts Host Agent Interaction - clinical signs - effective antibody responses Transmission - Vertical - Horizontal - Direct - Indirect Diagnostic Methods - fast - inexpensive - accurate Treatment and Intervention - therapeutic measures - preventitive treatment |
|
3 IMPACTS OF
PEOPLE ON CONTROL STRATEGIES |
Economic Considerations
- cost effectiveness of program Political Issues - production limiting diseases - public heath concern - precautionary principle ~~ if don't know much about the disease and public concern is high must be seen to do something -~- ie cull civet cats for sars, only one of many reservoirs Cultrual and Social Factors - culling cattle in Inida - killing wildlife in Britan |
|
6 IMPACTS OF
INFRASTRUCTURE ON CONTROL STRATEGIES |
Participants
- veterinary authorities - laboratories - livestock industry Veterinary Infrastructure - mobile field service - diagnostic facilities - research facilities Diagnostice Capability - rapid recognition of disease Adequate Surveillance Availability of Replacement Stock Suitable Legislation - enforcement - compensation |
|
INDIVIDUAL HERD CONTROL
6 CRITERIA FOR IMPLEMENTATION |
Spread of agent is stopped by physical barrier
- ie fence Rate of spread is slow enough to permit intervention before entire herd becomes infected Carriers of the disease can be detected on the farm Agent does not harm people Agent causes low to high morbidity with low or no mortality Highly effective vaccine or treatment is available |
|
REGIONAL CONTROL
6 CRITERIA FOR PUSHING THE BIG RED BUTTON OR WHEN NOT TO SHOOT, SHOVEL AND SHUTUP |
Agent readily passes physical barriers
Rate of spread is to fast to permit intervention before the entire herd becomes infected Apparently healthy carriers sisseminate the disease that can be detected only by laboratory tests Agent is a human pathogen Agent causes high morbidity and high mortality Vaccine or treatment is only poorly to moderately effective |
|
PREVENTION, CONTROL AND ERADICATION
8 GENERAL STRATEGIES |
Vaccination
- protect against infection and or disease Removal of reactors combined with vaccination of susceptible animals - high prevalence of moderate contagious diseases - segragation of herds inadequate Removal of reactors only - non highly contagious diseases - long incubation period Herd depopulation - highly contagious diseases - difficult to diagnose diseases - short incubation period Surveillance with/without Vaccination - diseased animals will die or recover without being carriers Barriers or isolation - swine, poultry industries Elimination of carriers or vectors Educational activities - whys and hows |
|
MOSS
|
disease MOnitoring and Surveillance Systems
- pathetic Systems for collection, analysis and dissemination of information on animal health related events |
|
DISEASE MONITORING
|
Ongoing efforts directed at assessing the health and disease status of a given population
focuses on identifying a diseas or group of disease to ascertain changes in prevalence and to determine the rate and direction of disease spread Lacks action to prevent or contral a helath problem |
|
DISEASE SURVEILLANCE
|
Directed at a specific disease
Includes an action to prevent or control the health problem thaat is being monitored Requires - a defined monitoring system - a defined threshold for disease level - predefined directed actions and interventions |
|
WHY HAVE A MOSS
3 PERSPECTIVES |
To minimize the negative effects of health related events in the animal population that affect
Animal health and Welfare - knowledge of the extent of endemic diseases - required as part of any control/eradication program Public Health - eradication of major zoonotic diseases - required as part of any eradication program Trade in animals and animal products - evidence about the absence of dieseases - extent of endemic diseases - early warning systems for FADs (foriegn animal diseases) - minimize political interference ~~ can you say RCALF? |
|
MOSS
3 MAIN OBJECTIVES |
Monitoring and Surveillance of endemic animal diseases and infections
Monitoring and surveilliance of FADs Monitoring of risk factors |
|
MOSS ON FADS
|
Early warining of exotic (aka new) diseases
Spatial-Temporal Distribution of Diseases Detection and surveillance of other countries diseases - if status in other countries is known can take steps to prevent entry Prove the absence of diseases |
|
RAUL'S FAVORITE FAILURE OF A MOSS
|
FMD in Britian
|
|
USING A MOSS TO PROVE ABSENCE OF DISEASE
8 STEPS TO ABSTAINENCE |
Intent to eradicate
No clinical disease Provisional freedom from disease Stop vaccination No clinical disease and no vaccination Observe freedom from disease Serological surveillance Establish freedom from disease |
|
MOSS
MONITORING AND CONTROL OF RISK FACTORS |
Track factors associated with endemic diseases
- ie trends in numbers of vaccine doses administerd Control of factors associated with the introduction of new diseases - ie importation regulations |
|
4 REASONS TO CONSIDER A DISEASE FOR MOSS
|
Zoonotic
- public health role Highly Contagious Severe economic impact Trade impact |
|
DISEASES OF INTEREST IN CANADA
3 CATEGORIES |
Reportable Diseases
- significant importance to ~~ human or animal health ~~ Canadian economy - report every case or SUSPICION of a case - vets report Immediately Notifiable Diseases - diseases exotic to Canada for which there are no control or eradication programs - laboratories report Annually Notifiable Diseases - diseases for which Canada must submit an annual report to the OIE indicating their presence within Canada |
|
MOSS INFRASTRUCTURE
6 ELEMENTS |
Vetrinary Services
Laboratories Livestock Industries Communication Economic Resources Legal Basis - ie Animal Health Act |
|
DESIGNING A MOSS
11 CONSIDERATIONS |
Definition of Objectives
Indentification of indicators of health event - # of cases - incidence and prevalence - production indicators Development of case definitions - serology - symptoms - postmortem lesions etc Indentification of data sources - laboratories or practioners Sampling design - unit of analysis - target population - sampling strategy Amount and frequency of data collection - continous - interval Method of data collection - active - passive - sentinel herds Validation of the system Analysis of survellance data Development of dissemination methods Evaluation of survellance systems - Sensitivity/Specificity - timeliness |
|
MOSS
PASSIVE COLLECTION |
No specific effort to collect data
- tf submitted to central units under obligation - ie reportable diseases |
|
MOSS
7 YESES TO SUCCESS |
Animal shows clinical signs
Suspected clinical case identified by owner Suspected clinical case reported to or indentified by vet clinical suspicion confirmed by vet based on expertise decision by vet to submit biological samples appropriate samples of sufficient quality submitted - can you say anatomy and dashboard? Correct diagnostic procedure performed |
|
MOSS
PASSIVE COLLECTION 5 ADVANTAGES |
Indentification of diseases
Detect outbreaks Response to outbreaks Inexpensive Minimum requirement - OIE |
|
MOSS
PASSIVE COLLECTION 8 DISADVANTAGES |
Need of clinical signs
- long incubations signs Incidence or prevalence Representativeness Geographical distribution Free of disease - not a guarantee Priorities Less motivation - involved people may be unaware of obligations Influenced by awareness and level of knowledge |
|
MOSS
ACTIVE COLLECTION 7 ADVANTAGES |
Not restricted to clinical cases
Proper amount of information Representativeness Estimates of incidence or prevalence Rapid Profitable High Motivation Note active involvement of veterinary health authorities |
|
MOSS
PASSIVE COLLECTION 2 DISADVANTAGES |
Costly
Requires high level of organization |
|
SENTINEL NETWORKS
WHAT ARE THEY ADVANTAGES DISADVANTAGES |
Type of active collection
- based on sentinels ~~ ie big white swans for AI - based on hot spots ~~ ie markets ADVANTAGES - identify outbreaks - changes in prevalence/incidence - evaluation of disease control programs - cost effectiveness ~~ not testing whole country DISADVANTAGES - not population based ~~ tf may not be representative - may be ineffective without prior knowledge of disease distribution |
|
MOSS
DATA ANALYSIS AND INTERPRETATION |
Estimate
- incidence - prevelence Identify Risk Factors - OR - RR Impact - AR - AF Identify temporal and spatial clusters |
|
MOSS
USE OF RESULTS |
Evaluation and/or implementation of programs and stregies
- disease frequency - risk factors - program profitability - ability to eradicate Establish freedom from disease Research Projects - secondary source of data |
|
AVIAN INFLUENZA
10 DEFINING FACTOIDS |
Not emerging disease
- very old Infecitous disease of birds All AI is caused by type A strains of influenza - orthomyxovirus - all A subtypes found in birds - humans have B and C strains Worldwide occurrence Present in > 90 species of birds representing 12 orders Wild birds are usually asymptomatic Clinical signs in poultry range from mild to severe Issue for international trade in poultry and poultry products Costs associated with control in poultry can be high Is really an emerging sense of emergency |
|
INFLUENZA FACTIODS
|
AI is a Zoonotic AI
- H5, H7 and H9 strains transmit from bird to humans - pathogenicity varies from conjunctivitis to rapid pneumonia Seasonal Influenza - contagious respiratory illness - caused by human influenza viruses ~~ H1 - H3 Epidemic Inflenza - large outbreak of illness that spresds easily from person to person ~~ H1 - H3 Pandemic Influenza - global outbreak of illness that spreads easily from person to person (H1 - H3) |
|
AI VIRUS FACTIODS
|
RNA Virus
8 gene segments 10 proteins - H (Hemoglutinin) for docking - N Neurimididase for release of virus 16 H types 9 N types Matrix proteins are used to identify subtypes Polymerase is sloppy - tf high mutation rate via antigenic SHIFT Can mutate to high pathogenicity - especially in intensive poultry operations - note pathogenicity is defined by experimentally infecting chickens not people (we wish) or wild birds |
|
INFLUENZA AGENT AND ENVIRONMENT
|
Weak Virus
Heat inactivated Preseved by cold - tf seasonal in wild populations Cyclical pattern with peaks in cooler months in humans - behavior related Primarily water borne in wild bird cycle - shed in feces Strong seasonal patterns in wild birds - viral surviablility - host behavior |
|
TYPE A INFLUENZA HOSTS
|
Wild Birds
- waterfowl - shore birds Domestic Poultry Swine Horses - existing vaccines Humans Other Mammals - mink - whales - seals - dogs ~~ low pathogenicity ~~ probably jumped from horses |
|
AI
HOST TRIAD ECOLOGY |
Wild Birds
- reservoir for all subtypes - spillover to domestic birds - allways fecal/oral transmission Domestic Birds - Amplifiers ~~ viral numbers ~~ viral mutations - initial tranmission fecal/oral - Backyard Flocks ~~ high risk of exposure ~~ high resistance ~~ low amplification - Commercial Flocks ~~ low risk of exposure ~~ low resistance ~~ high amplification ~~ respiratory transmission - Spillback to wild birds - Zoonotic Humans - transmission usually via exposure to dead birds - possible spillback to domestic birds |
|
HOSTS
MIXING VESSELS |
Pigs
- high stocking densisty drives antigenic shift - receptors for both human an avian viruses - tf potential to combine strains Humans - also act as mixing vessels - tf normal influenza plus H5N1 > pandemic |
|
AI
INCUBATION CLINICAL SIGNS LP AND HP |
Incubation Period
- 3 to 5 days Low Path - slow onset - often undetected - ruffeled feathers - mild respiratory signs - mild reproductive signs - drop in egg production - low mortality rates ~~ ie rise from 5% to 8% High Path - sudden onset - death within 24 to 48 hours - severe systemic disease ~~ colonizes entire body ala ebola - respiratory signs - neuological signs - high mortality ~~ 90 to 100% |
|
AI SHEDDING
3 WAYS IN DOMESTICS |
Feces
Nasal Secretions Saliva |
|
AI TRANSISSION
COMMERCIAL POULTRY SEVEN WAYS TO MAKE THE EVENING NEWS |
Movement of infected birds
Contaminated feed and water Contaminated equipment Egg Flats Feed Trucks Personel Aerosol - up to 5 kms - barn to barn if commercial |
|
HISTORY OF HPAI OUTBREAKS
POULTRY |
24 epizoontics of HPAI since 1959
All H5 or H7 subtypes No concurrent humman infection until 1997 A/chicken/Canada/AVFV/04 H7N3 - Fraser Valley BC - 42 commercial - 11 backyard flocks ~~ including pets - 16 million chickens depopulated - 2 humans develop conjunctivitis - $360 M direct losses - $150 M downstream losses |
|
HISTORY OF AI
IN HUMANS |
8 zoonotic outbreaks since 1959
- not including H5N1 - all H5, H7 or H9 - LP and HP Usually isolated cases of mild disease except - 1997 18 humans in Hong Kong ~~ associated with H5N1 ~~ 6 human fatalities - 2003 88 humans in Holland ~~ associated with H7N7 ~~ conjunctivitis -~- 1 death but it was only a vet - 2003 H5N1 re-emerges in SE Asia |
|
HISTORICAL PANDEMICS
|
Usually 3 - 4 per century
1918 Spanish Flu - AI found way into people - H1N1 ~~ reconstructed from human remains - 20 to 40 die - uniquely pathogenic ~~ tf no human immunity - immunosupression via rationing? - transmission via troop movement - disproportionate mortality ~~ 15 to 45 yo 1957 - H2N2 - contained 3 genes from AI 1968 - H3N2 - H2 disappears ~~ this is common with influenza viruses |
|
H5N1 OUTBREAKS
TEMPERO-SPATIAL |
Jan 04 to Jun 05
- Mainly SE Asia Jul - Dec 05 - moved west to Europe - transasian railway ~~ bird migration is mainly north-south Jan 06 - Most of Europe - Africa via smuggling from Turkey H5 in 50 Countries H5N1 - confirmed 39 countries - lag due to requirement to culture virus to determine N type |
|
H5N1
TOP 3 COUNTRIES WHY |
Veitnam
Thailand Indonesia Socioeconomic - people live with poultry - high human cases ~~ culling |
|
QUINHAI LAKE
|
aka STU
Ground Zero - April June 2005 China - 6345 mortalities - initially spread by fall migration Only second H5N1 panzootic recognized in WILD birds |
|
TELL ME SOMETHING
UNUSUAL ABOUT H5N1 |
Gets into mammals
- cats ~~ free range ~~ captive ~~ experimental Pigs Macaques Rats, Rabbits, Ferrets Stone Martens |
|
H5N1
AND HUMANS A FEW FACTIOIDS |
101 deaths of 180 KNOWN cases since 2003
- 60% mortality or undiagnosed cases? East Asia and the Pacific - Cambodia - China - Indonesia - Thailand - Vietnam Europe and Eurasia - Turkey - Azerbajian Family Clusters - common risk factors - or human to human transmission Major risk factor is contact with live or dead infected poultry - raw poultry products may also pose risk |
|
H5N1
OLD WORLD EPIDEMIOLOGY |
Detection
- thresholds - sentinels Pattern matching - time - space Role of Different Hosts - carriers - amplifiers - bridges - accidnental victims ~~ mammals and humans are dead end hosts Genetics and Phlogenics - Quinhai lake strain widely spread Tipping Points - HK 1997 - Quinhai 2005 |
|
H5N1
IS IT ENDEMIC |
Yes
- has been in China for 10 years |
|
MUTE SWANS
WHY DO WE LOVE EM |
The are
- Big - White - tf highly visble - die from H5N1 tf they make great SENTINALS |
|
AI
MANAGEMENT 3 LEVELS |
Socioeconomic not Scientific
Prevention - NA has a shot at this Control - Perhaps in Urasia Eradication - not a chance - endemic in China |
|
AI
MANAGEMENT 6 TOOLS |
Survelliance
Prevent exposure ~~ biosecurity ~~ trade restrictions ~~ quarantine Vaccination ~~ rarely protective ~~ generally suppressive Controled Marketing ~~ for recoverd countries Depopulation ~~ infected populations Education and Cooperation ~~ between veterinary and human health agencies |
|
AI
VACCINE OPTIONS 4 |
Incactivated Homologous Strains
- H5N1? Inactivated heterologous strains - H5N2 Recombinant Vaccines - vector viruses + H5 Reverse Genetics |
|
AI
VACCINATION ADVANTAGES FOUR |
Reduces susceptibility to infection
Increases neccessary infective dose Vaccinated Birds shed less virus - decreased contamination of the environment - decreased risk of human infections Compliments Culling - slows spread of virus - must be used stragetically |
|
AI
VACCINATION DISADVANTAGES FOUR |
Not in line wtih OIE or EU control stategies
- this may change - Russia could care less Negative impact on trade agreements Clinical signs are reduced - disease may be missed in a flock Vaccinated and naturally infected birds can be difficult distinguish |
|
AI
CONTROL MEASURES FIVE |
Culling of infected or in contact poultry
- not wild birds Biosecurity of poultry operations - all in / all out - quarantine - hygiene Protection and surveillance zones around wild bird refuges Improve veterinary infrastructure Treatement and vaccination - people - poultry? |
|
H5N1
7 CONSEQUENCES |
Embargo on poultry and poultry products from affected countries
Poultry sales falling - 50% in some countries Culling - 200 M domestics so far Livelihood of Farmers - 300 M affected Public Panic - zoo closures - dead birds dumped ~~ garbage cans ~~ streets ~~ Nile Cost to Global Poultry Industry - > 10 B USD Cost of Surveilance of Wild Birds - $7.4 M Alaska - $3.6 M Canada - |
|
H5N1
IMPENDING PANDEMIC COST |
$4 T
2% of Global Economy |
|
H5N1
4 ROUTES INTO CANADA |
Wild Bird Migration
Illegal and legal Trade - poultry and products - pet and captive birds - fighting cocks - mammals ~~ wet markets Movement - infected people - fomites Aerosol |
|
H5N1
FOUR PANDEMIC PONDERANCES |
Could we be blinded by the severity of the HPAI virus in poultry in thinking it would be the next pandemic strain when the actual risk omay be LPAI of various subtypes
Each year up to 500,000 people die of seasonal influenza infections. HFN1 has been circulatiing for 10 years and has caused 98 deaths From 2003-2006 9.1 million people were infected with HIV/AIDS, according to UN AIDS and U.S. Dept of Health and Human Services - so why the big deal about AI? WHO: bird fule pose a greater threat than any infectious human disease, including HIV/AIDS and SARS - but you get to have a great concert afterwards |