Notifiable diseases Flashcards
What are the reasons for a disease being notifiable?
- Internation trade
- Public health (but not always zoonosis)
- Animal welfare
- Wider society
- Due regard for cost to the community and availability of appropriate solutions
What are the criteria for the inclusion of a disease, infection or infestation in the OIE notifiable disease list?
1: Proven international spread of agent
2: At least one country has demonstrated freedom or impending freedom from the disease in a population of susceptible animals, based on provisions of Terrestrial Code
3a: natural transmission to humans proven, associated with severe consequences
3b: disease causes significant morbidity/mortality in domestic animals at level of zone/country
3c: disease shown to/indicated to cause significant morbidity/mortality in wild animal populations
4: reliable means of detection and diagnosis and precise case definition available
What must be included when informing the OIE of an important epidemiological event by sending an Immediate Notification?
- Reason for notification
- Name of disease
- Affected species
- Geographical area affected
- Control measures applied
- Any laboratory tests carried out or in progress
What is the role of the OIE regarding disease?
- Support Member Countries’ efforts to prevent transboundary spread of important animal diseases incl. zoonoses
- Transparent and consistent reporting
- Harmonisation of disease detection, prevention and control
Describe the list of Human Notifiable Infectious Disease UK
- Medical practitioners have statutory duty to notify the “proper office” at local council or local health protection team of suspected cases of certain diseases
- Aims to detect outbreaks of disease and epidemics as rapidly as possible
- Some are zoonoses that are not notifiable when affecting animals
- Includes syndromes as well as disease agents
Outline the WHO system of notifiable diseases
- International Health Regulations 2005
- Member states notify WHO of events of urgent and international importance, instead of disease specific notification
- Consult with WHO in circumstances not at time requiring notification or where related guidance is needed
- Aim to catch emerging/new diseases/syndromes
- Algorithm used to decide whether to report
What actions are required following identification of a potential zoonotic disease?
- Report to appopriate authority e.g. APHA, FHI (fish health inspector), OIE, regional bee inspector or NBU (national bee unit)
- e.g. FMD, duty VO discuss case over phone, must stay on farm, movement restrictions effective immediately samples sent to lab, farm declared Suspect Premises
Describe Rinderpest
- AKA cattle plague
- Eradicated globally in 2011
- Morbillivirus, closely related to: measles, canine distemper, pest de petit ruminants
- Affects ruminant and swine
Describe peste de petit ruminants
- Goat plague (affects sheep and goats)
- Morbillivirus
- fever and depression, severe discharge from eyes and nose, coughing, diarrhoea, death
- Does not usually kill goats and sheep, does cause severe disease and loss of production
- Spreading to Greece and Turkey
Describe Classical Swine Fever
- Aka hog cholera, pig plague
- Pestivirus
- Transmitted in bodily fluids and tissues of sick or dead animals
- Vertical transmission outcome depends on strain and stage of gestation
- Congenital infection can be persistently viraemic, shed for 6-12 months before dying
- Fever, huddling, blotchy skin lesions, convulsions and death
Describe African Swine Fever
- Asfaviridae
- Sub-saharan Africa, Sardina, Caucasus, Northwest Russia
- Severe disease, high mortality
- (Sometimes bloody) V/D, reddening/darkening of skin (esp. ears, snout), gummed up eyes, laboured breathing and coughing, abortion, still births, weak litters, weakness, unwillingness to stand
- Spread by direct contact, faeces, body fluids, fomites, Ornithodoros ticks
Describe Capropoxvirus
- Poxviridae
- Lumpy skin disease
- Spread to Greece and other parts of Eastern Europe, now under control and spread prevented
Describe Foot and Mouth Disease
- Apthavirus (picornavirus)
- Quick mutation
- Survives 1 month in environment
- Transmitted on fomites and wind
- Can cause sub-clinical to severe disease
- Some concern over zoonosis (not shown in practice)
- Vesicles/ulcers in mouth, on tongue, feet, lameness, fever, markedly reduced production
- Pigs produce large amounts of virus as aerosol
Outline the steps following suspicion of an FMD case
- Report to APHA by telephone, discuss with duty VO, visit to farm
- Sample taken, sent to Pirbright, farm declared “Suspect Premises”
- Formal confirmation by Chief Veterinary Officer, informs OIE and EC, reports regularly to both
- England loses FMD free status, exports of cattle and cattle products stop (min. from within control zone)
- Protection zone, surveillance zone and restricted zone put in place
Where is the protection zone in an FMD outbreak?
Minimum of 3km radius from the IP
Where is the surveillance zone in an FMD outbreak?
Minimum of 10km radius from IP
Where is the restricted zone in an FMD outbreak?
National movement ban across GB
Describe the requirements placed on suspected premises of FMD
- Warning/keep out signs
- Records of animals, bedding etc on site
- Isolation of animals
- Prevention of movement of animals and any movements on and off farm that may spread infection
- Disinfectants at entrances and exits
- Rodent control
Describe the requirements placed on infected premises of FMD
- Restrictions imposed on premises remain in force
- Susceptible animals humanely culled
- Carcasses disposed of and preliminary disinfection carried out on farm
- Epidemiological investigation continues to establish where the disease came from and where it may have spread
Describe carcass disposal in FMD
- Normally commercial incineration, rendering or licensed commercial landfill
- Ensure on-farm pyres or mass burial not used in future (but cannot be ruled out if demand exceeds capacity of preferred disposal options
Describe pre-emptive culling in FMD
- Animal Health Act allows culling of animals NOT exposed to FMD infection where at risk
- Only where disease control (slaughter) protocol published, vaccination considered
- Vaccination preferred, aim to avoid pre-emptive culling
Outline the requirements placed on contact premises in an FMD outbreak
- If high risk: premises considered dangerous contact, animals culled
- If low risk: premises and animals under restriction, health status monitored for 3-4 weeks from last known contact with IP, sampled on epidemiological basis
Explain what is meant by contact premises in FMD
- Premises where disease may have come from or spread to
- Can arise through: movement of animals, people, farm equipment, vehicles, slurry/manure, geographical location
- When contact premises identified, assessment made about level of risk (high/low)
What are the impacts of an FMD outbreak?
- Significant economic costs to farmer and government
- Welfare culling if movement restrictions prevent access to food
- Employment of temporary staff
Describe bovine tuberculosis epidemiology
- Combination of diseases, M. tuberculosis, bovis and microti
- Zoonotic, controlled by pasteurisation
- Mainly older animals
- Most long and short distance transmission is between cattle
- In some areas, badgers are main source of bTB outbreaks
List the potential tests for bTB
- Single and comparative skin tests
- Gamma interferon tests
- Post-mortem examination and culture of all positive tests for gamma-interferon and comparative skin tests
- Others
Describe the skin tests for bTB
- Single Intradermal Comparative Cervical Tuberculin (SICCT)
- Clip 2 sites at border of anterior and middle third of neck, 12.5cm apart, 10cm below crest, measure thickness of skin fold with calipers
- Avian tuberculin inoculated into top site, bovine tuberculin into lower
- 72 hours later measure thickness
- Delayed hypersensitivity reaction causes thickening of skin if there is a reaction
Describe the bTB blood test
- Into laboratory within 5 hours of sampling
- Measure interferon gamma released by WBCs
- WBC production increased on stimulation, if exposed before (i.e. positive) leads to increased release of IFN-y
Describe bTB testing monitoring in abattoirs
- Testing important for surveillance
- Skin-test positive cattle sent to designated abattoirs
- If only 1 lesion found in lymph node then nodes and viscera condemned but rest is fit for human consumption
- Widespread and larger lesions likely to be found in non-reactor cattle
- Skin test positive animals detected early so have few or no lesions usually
What is spoligotyping and what is it used for?
- Specific Oligonucleotide Typing
- Looks for presence/absence of variable length “spacers” between repeated sequences
- Consider as bar code
- Used in bTB epidemiology investigations
What is WGS and what is it used for?
- Whole Genome Sequencing
- Looks for mutations (single nucleotide polymorphisms)
- Used in bTP epidemiology investigations
Describe the epidemiology of rabies
- Zoonotic
- Group of viruses of genus and family Lyssavirus
- Largely bat disease exccept Calssical Rabies Virus
- Some covered by vaccination
- Clinically divided into furious and dumb rabies
- Urban and syvaltic forms
Describe urban rabies
- Mainly domestic animals
- Feral, pet or community held dogs
- Asia, Africa and Turkey mainly
Describe sylvatic rabies
- Foxes mainly
- Started in Russia, now in South Eastern Europe
- Vaccine in food in woods used to control presence in wild populations of foxes
Describe human rabies
- Largely disease of childhood
- Preventable by cheap vaccine
- Common in developing countries, poverty areas
- Once show clinical signs death will follow
Describe rabies in the UK
- No rabies in UK foxes
- Do have Bat Lyssavirus, identical clinically to that caused by Classical Rabies Virus
- European Bat Lyssavirus type 2 carried by Daubenton bats
Outline control measures for rabies
- Muzzles, culling quarantining
- Only quarantine from some parts of the world, imported animals require passport, vaccine and serological test
- No treatment in non-humans
- Vaccine is killed vaccine (or live recombinant in wild animals)
- If bitten, administer another dose of vaccine if low risk, high risk administer dose of antiserum
Describe Avian influenza epidemiology
- Genetic drift, shift and reassortment of segmented influenza syndrome A means that is constantly changing
- RNA viruses with segmented genome
- Highly pathogenic and low pathogenic H5 and H7 are notifiable
- Lots of birds carrying AI at all times
- Migratory birds introduce strange strains and infect chickens
- Can be zoonotic
What are the steps following identification of avian influenza on farm?
- Zone set up around primary site
- In IP, birds culled
- In primary zone, active surveillance including visits, sampling, movement restrictions
- In secondary zone, increased awareness, surveillance, some movement restrictions
- Tracing and risk based sampling carried out
Describe the control measures for avian influenza
- Biosecurity measures for hobby as well as commercial keepers
- Make area unattractive to wild birds
- Feed and water birds in enclosed area, prevent access for wild birds
- Minimise movement in and out of bird enclosures
- Clean and disinfect footwear, keep areas where birds live clean and tidy
- Reduce existing contamination, fence off wet/boggy areas
Describe the epidemiology of bluetonge
- RNA virus spread by Culicoides midges, blown over channel from Europe
- Affects all ruminants
- Production losses significant, not found in UK
Describe the clinical signs of Blutongue
- Nasal discharge
- Salivation
- Oedema of muzzle
- Coronitis and laminitis causing lameness
- Rise in temperature is first sign, then hyperaemia of oral cavity and mucus membranes, then oedema of lips, tongue and face
How can Bluetongue virus be controlled?
Vaccines available, monitor situation in Europe to gauge risk of disease in UK
Why is Bluetongue virus notifable but not Schmallenberg?
There are no reasonable steps that can be taken to control the incidence or spread of Schmallenberg, but there are for Bluetongue
Describe the epidemiology of Anthrax
- Bacillus anthracis, Gram +ve rod, vegetative state causes disease, spores resistant for many years in soil and other materials
- Infects wide range of herbivores, some omnivores and some birds
- Peracute, acute, chronic states
- High susceptibility in ruminants, moderate in pigs and horses, low in carnivores and negligible in bids
- More of a problem in tropics
- Quickly leads to death but can be treated with antibiotics
Describe the clinical signs of anthrax in cattle and sheep
- Sudden death most important
- Staggering
- Difficulty breathing
- Fever
- Disorientation
- Abortion
- Bloody discharge from mouth, nose and anus
Describe the clinical signs of anthrax in horses
- Sudden death most important
- Fever
- Chills Anorexia
- Depression
- Colic
- Bloody diarrhoea
Describe the clinical signs of anthrax in pigs/carnivores
- Sudden death most important
- Swelling of throat
- Difficulty breathing and swallowing
Describe the symptoms of anthrax inhalation
- Incubation 2-60 days but quick progression once started
- Stage 1: fever, cough headache, vomiting, chills, weakness, abdominal pain, shortness of breath, chest pain
- Stage 2: fever, difficulty breathing, sweating, bluish discolouration of skin, shock and death
Describe the steps following identification of anthrax
- Report to APHA
- Do not open carcass
- Movement of animals, waste products, feed and bedding from affected and adjacent premises if prohibited
- PPE for personnel, use sporicidal disinfectants
- Formalin fumigation go contaminated buildings
- Immediate disposal (incineration) of carcasses, bedding, feed, contaminated animal
- Prevent access of scavenger animals (insecticides)
- Isolate in-contact animals and keep under close observation for at least 2 weeks
What is the causative agent of BSE, vCJD and CWD?
Prions
What are the main pieces of legislation that regulate notifiable diseases?
- For bees, Bee Diseases and Pest Control Order 2006
- International Health Regulation 2005 (requires member states to notify WHO in events or urgent and international importance)
List enteric zoonoses
- Hepatitis E
- Campylobacter, Salmonella, E.coli (VTEC and AMR)
- Yersinia
- Cryptosporidium
- Giardia
- Toxoplasma
- Cestodes
- Toxocara
- Trichinella
Describe Coxiella burnetti
- Respiratory zoonosis
- Worldwide, common in ruminants
- Different strains with different pathogenicity, human infection uncommon
- Rare in UK
- Abortion in sheep and goats and other species
- Flu like disease in most people, abortion possible
- Can cause severe systemic disease and may become chronic and debilitating
