Notifiable diseases affecting the GI tract_060325.1_w20

Notifiable Diseases

• Legally obliged to report any suspected animal infections to the Animal and Plant Health Agency (APHA)
• Defined as diseases named in Section 88 of the Animal Health Act 1981, or an order made under that Act

OIE-Listed Diseases

• Single list of notifiable terrestrial and aquatic animal diseases
• Animal diseases are identified as important to animal health, welfare, public health, and international trade
• The OIE World Assembly of Delegates reviews the list regularly
• There were 116 animal diseases, listed in 2024

Bluetongue (BT)

• A non-contagious viral disease
• Domestic and wild ruminants are affected and sheep are the most affected, and cattle as a main reservoir
• Transmitted by Culicoides midges
• Part of the Reoviridae virus family, Orbivirus genus, with 29 recognised serotypes
• Found globally, wherever Culicoides are present
• Causes significant economic impact through the loss of stock, production, trade, and the costs of surveillance/control
• Significant UK outbreak in 2007-2008 due to serotype 8
• More recent cases of serotype 3 in SE England in 2023/24 and 2024/25 and serotype 12 was first seen in the UK in Feb '25
• OIE Listed Disease

Bluetongue Transmission

• Not contagious by casual contact
• Some midges of the genus Culicoides transmit it
• The replication period in the insect's salivary gland is 6–8 days
• Infected midges are infective for life
• BTV-8 shows evidence of transplacental transmission
• Spread via contaminated fomites with blood of infected animals, windborne infected midges, and movement of infected livestock

Clinical Presentation of Bluetongue in Sheep

• Varies depending upon the viral strain and sheep breed
• Clinical signs develop in a small percentage of sheep
• Incubation is usually 4-12 days
• Signs include fever (up to 42.0 °C), stiffness, and reluctance to move
• Ulcerations, mucus discharge, and drooling from the mouth, nose, and eye are clinical signs
• Other symptoms include swelling of the mouth, tongue, head, and neck
• Lameness occurs with inflammation at the junction of the skin and the coronary band
• Causes difficulty breathing, and abortion
• May result in death within 8–10 days or long recovery with alopecia, hoof deformities, sterility, and growth delay

Clinical Presentation of Bluetongue in Cattle

• Most adults show mild or no clinical signs
• Incubation is usually 4-12 days
• Subclinically infected cattle can become viraemic 4 days post-infection
• Symptoms include fever (up to 40.0°C), stiffness, reluctance to move, swelling of the head and neck, and nasal discharge
• Can cause redness of the mouth, eyes, and nose
• Causes reddening of the skin above the hoof, erythema, and ulcers on the teats
• Can cause abortion, but deaths are uncommon

Diagnosing and Treating Bluetongue

• FMD, VS, PPR among others are used in differential diagnosis
• Reverse transcriptase-polymerase chain reaction (RT–PCR) tests on clinical samples are used to identify the virus and serotype
• Enzyme-linked immunosorbent assay (ELISA) can identify animals that have been infected or exposed to BTV
• Antibodies appear within 7-14 days post-infexction and are persistent
• Treatment is limited to antibiotic therapy to control secondary bacterial infections

Preventing and Controlling Bluetongue

• Involves good biosecurity and animal care practices
• Ensure animals come from responsible sources
• Involves the monitoring of the disease situation in Europe and internationally
• Risk-based import conditions and testing should be in place
• Increase farmer awareness, monitoring and surveillance of live animals
• Culling of infected animals depends on the disease scenario
• Implement movement restrictions on animals, carcasses, ovum, embryos, & semen
• Vaccination with inactivated vaccines is possible in areas without Bluetongue restrictions and the BTV-3 vaccine is now available in England

Rinderpest

• Contagious viral disease that affects domestic and wild cloven-footed animals, such as cattle and buffalo
• Part of the Paramyxoviridae family, Morbillivirus genus
• Causes high mortality in cattle
• Transmitted mainly by direct contact and aerosol/fomite transmission is insignificant
• Eradicated worldwide and declared as such in 2011
• OIE Listed Disease

Clinical presentation of Rinderpest in cattle

• Incubation ranges from 3-15 days, 4-5 is typical
• Fever (up to 41.5 °C) develops with depression, loss of appetite and increase of respiratory rate
• Animals may be constipated in the early stages
• Grain-like bumps develop in the nostrils and inside the lips and cheeks that often develop into ulcers
• Discharge of watery mucus also develops from eyes and nostrils, occasionally with blood
• Causes reduced milk production, profuse diarrhoea, and dehydration in the late stages
• High mortality reaches 80-90% when infected with the more virulent strains with deaths appearing within 6-10 days

Diagnosing and Treating Rinderpest

• Diagnosis is based on identifying the virus from blood or tissues using RT-PCR
• No specific therapeutic treatment exists
• Treatment is limited to antibiotic therapy for secondary bacterial infections and fluid replacement therapy

Preventing and Controlling Rinderpest

• Rinderpest was previously controlled by annual vaccination of all cattle and domesticated buffalo over a year old
• Vaccination for one strain protects against all strains
• Controlled through quarantines, movement control, euthanasia of infected and exposed animals
• Also, through intensive focal vaccination, and decontamination of infected premises

Pestes des petits ruminants (PPR)

• A highly contagious viral disease, also called 'Sheep and Goat Plague'
• A virus in the Paramyxoviridae family, Morbillivirus genus
• Affects goats and sheep mainly with high morbidity and mortality
• Transmitted mainly by aerosols or direct contact between animals, as well as fomites
• Occurs in large parts of Africa, the Middle East, and Asia
• Causes severe socio-economic impacts on livelihoods and food security of vulnerable rural communities
• OIE Listed Disease

Clinical presentation in sheep and goats

• Incubation ranges from 3-6 days
• Fever (up to 41 °C) develops with severe depression, loss of appetite, and clear eye and nasal discharges
• Tissues in the mouth can swell and ulcers form on the lower gums, dental pad, hard palate, cheeks, and tongue
• Causes severe diarrhoea in some animals, leading to dehydration and weight loss
• Causes pneumonia in later stages
• Pregnant animals may abort
• High mortality rates reach 90% in the peracute form, dying within 5-10 days of fever onset

Diagnosing and Treating PPR

• PPR virus (PPRv) antigens are detected by immunocapture ELISA and RT-PCR for confirmation
• No specific treatment exists, although supportive care and treatment of bacterial and parasitic coinfections may decrease mortality

Preventing and Controlling PPR

• A Global Control and Eradication Strategy of PPR (led by OIE + FAO) is in place with goals for eradication by 2030
• Import controls, movement restrictions, testing, and quarantine are used to exclude the virus in nonendemic areas
• Control in non-endemic areas includes quarantines, movement controls, euthanasia of infected/exposed animals, and disinfection
• Monitoring of wild and captive animals and possibly vaccination are necessary
• In endemic areas, control and vaccination of wild and captive animals is necessary, to avoid contact with sheep and goats

Classical swine fever (CSF)

• Highly contagious viral disease of pigs
• Causes high morbidity and mortality rates in acute forms
• Part of the Flaviviridae family, Pestivirus genus
• Main transmission is oral and oronasal, either by direct or indirect contact
• Endemic in parts of Asia, South and Central America
• Last UK outbreak was in East Anglia in 2000 and 74,793 pigs were slaughtered
• OIE Listed Disease

Classical swine fever transmission

• Transmitted mainly by oral or oronasal routes, either by direct or indirect contact
• Direct contact occurs through animal secretions, excretions, semen, or blood
• Indirect contact occurs through ingestion of contaminated pork, fomites, or transplacental infection and aerosol transmission

Clinical presentation of Classical swine fever

• Almost identical to the clinical presentation of African swine fever (ASF)
• Varies depending on the strain, age, and susceptibility of pigs

Acute form of Classical swine fever

• Presents with incubation ranges from 3-7 days
• Fever (up to 41 °C) develops with anorexia and lethargy and conjunctivitis
• Causes transient constipation followed by diarrhoea
• Also, ataxia, paresis, convulsion, occasional vomiting, dyspnoea, and coughing
• Multifocal hyperaemia and/or haemorrhagic lesions of the skin and cyanosis of the skin can develop
• Causes enlarged, and swollen lymph nodes
• Leads to birthing problems such as, mummification, stillbirth & abortion
• Death occurs within 5–25 days of the onset of illness with Mortality in young pigs approaching 100%

Chronic form OF Classical Swine Fever

• Incubation ranges from 2-15 days
• Presents with dullness, capricious appetite, pyrexia, and diarrhoea for up to 1 month
• Causes growth retardation and poor reproductive performance
• Results in apparent recovery with eventual relapse and death within 3 months

Diagnosing and Treating Classical swine fever

• Laboratory diagnosis necessary to distinguish CSF from ASF
• Blood or tonsil swabs are collected from febrile animals, or tissue samples from necropsy
• Reverse transcriptase polymerase chain reaction (RT–PCR) tests on viral nucleic acids should be performed
• There is no specific treatment other than supportive care

Preventing and Controlling Classical swine fever

• Involves good communication between stakeholders, a reliable disease reporting system, import controls, biosecurity, and testing
• For CSF-free areas, stamping out policy should be implemented by slaughtering affected and at-risk animals, cleaning affected premises, and surveilling
• Buying animals from CSFV-free herds, quarantining the new stock, & vaccination are the key control for endemic areas

African swine fever (ASF)

• A highly contagious haemorrhagic viral disease of the pig family (Suidae)
• Causes high morbidity and mortality rates
• Large DNA virus of the Asfarviridae family, genus Asfivirus
• Transmitted via the oral/oronasal routes (direct/indirect contact), and by ticks (Ornithodoros)
• Present in wild and/or domestic pigs in regions of Asia, Europe & Africa
• Causes serious economic and production losses
• Never seen in the UK
• OIE Listed Disease

African swine fever transmission

• Direct contact between infected animals through secretions, excretions, semen, or blood
• Indirect contact through contaminated pork or fomites such as vehicles and clothing
• Can transmit through aerosol routes in close confinement
• Biological vectors include the soft tick genus Ornithodoros
• Feeding uncooked swill containing infective tissues to pigs and illegal transport of animals transmits infection

Clinical presentation of African swine fever

• Symptoms vary with the strain and pig type or species
• Incubation ranges from 4-19 days
• Peracute form presents with sudden death
• Acute form is similar to CSF with highly virulent virus

Subacute form of African swine fever

• Less intense clinical signs appear with slight fever, reduced appetite, and depression
• Duration of illness extends from 5-30 days
• Pregnant sows can abort and death occurs within 15-45 days
• Mortality rates vary, from 30–70%

Chronic form of African swine fever

• Intermittent low fever, appetite loss, and depression are symptoms
• Some pigs develop respiratory problems, swollen joints, arthritis, and skin ulcers
• Develops over 2–15 months with low mortality
• Survivors can become virus carriers

Diagnosing and Treating African swine fever

• Laboratory diagnosis is necessary to distinguish ASF from CSF
• Take samples of blood from live animals, or tissue samples from an animal’s necropsy
• Detect ASFV genomic DNA by polymerase chain reaction (PCR) or real-time PCR
• Perform serological test: Enzyme-linked immunosorbent assay (ELISA) and immunoblotting
• No specific treatment for ASF exist, other than supportive care

Prevention and Control of African swine fever

• No approved vaccine exists
• Use Prevention (sanitary prophylaxis) through good communication between stakeholders
• A reliable disease reporting system, import controls, biosecurity, testing and quarantine
• Slaughter confirmed and contact animals, cleaning infected premises, follow carcass disposal, movement controls, quarantines & surveillance
• Should implement strict biosecurity measures, manage wild boar populations, and control ticks

Porcine Epidemic Diarrhoea (PED)

• Contagious viral disease of pigs; causes mortality up to 100% in piglets
• Caused by an RNA virus of the Coronaviridae family, Alphacoronavirus genus
• Transmitted via the faecal-oral route by direct contact with infected pigs
• First reported in the UK in 1971
• Causes economic and production losses in naïve populations
• Notifiable in the UK but notifiable in the EU
• Not an OIE Listed Disease

Aetiology and current PED situation

• Two genotypes: Classical genotype 1 (GI) and Epidemic genotype 2 (GII)
• GI primarily affects growing pigs and forms a low level endemic disease in the UK
• GII affects all ages and highly virulent genotype
• High virulent variant is responsible for the USA and Asia epidemics and 100% mortality in piglets below 7 days of age
• Has never been seen in the UK (pigs have no immunity)
• Confirmed PED cases in European countries in Austria, Belgium, France, Germany, Italy, Netherlands, Ukraine and Slovenia

Clinical Presentation of Porcine Epidemic Diarrhoea

• Dependent on virulence of the strain, age of the pigs, previous exposure, etc.
• Incubation ranges from 1-4 days
• Infectious period extends from 6-35 days of clinical signs
• Can cause anorexia, dehydration, metabolic acidosis, watery diarrhoea and vomiting
• Rapid spread of diarrhoea is observed across the farm
• Morbidity in piglets reaches up to around 100%.
• Mortality varies as follows: 100% in suckling piglets; less than 10% in piglets older than 10 days; less than 5% in adult and fattening pigs

Diagnosis and Treatment of Porcine Epidemic Diarrhoea

• Detect PED virus (PEDv) RNA using RT-PCR after the first 14 days following the onset of the disease
• Perform ELISA, immunofluorescence, immunohistochemistry and antibodies for surveillance with serum
• Serum antibodies of infected pigs persist for over 1 year
• There is no specific treatment for the disease aside from the symptomatic treatment for diarrhoea

Prevention and Control of Porcine Epidemic Diarrhoea

• Practicing strict biosecurity is most effective
• Introduce pigs of known health status and have on-farm movement control of pigs, material and people
• Disinfect vehicles & equipment and dispose of dead pigs and slurry properly
• All-in-all-out practice breaks the transmission cycle within a farm
• PEDv vaccines have been produced but their efficacy is controversial and unlicenced in the UK