Infectious disease 2 Flashcards
Viral diseases,
Describe the neurological signs of canine distemper
- Circling, head tilt, nystagmus
- Paralysis
- Convulsions, fitting, involuntary “chewing”
- Viral inclusion bodies in CNS (skin, GIT, bronchi etc)
- Death in 2-4 weeks
Outline the effect of canine distemper on teeth
- Enamel hypoplasia
- Most of enamel on teeth gone, poor teeth
- Epithelium laying down enamel on teeth affected
- Infection attacks developing adult teeth
Describe old dog encephalitis and how this relates to canine distemper
- Dementia, blindness, circling
- Often in distemper vaccinated dogs
- CSF normal - virus come in and gone again by the time signs are seen
What is the cause of feline infectious peritonitis?
Feline coronavirus
Which cats are more susceptible to feline infectious peritonitis?
- Younger cats (<1yo)
- More common in pure breed cats (e.g. Bengal, Birman)
- History of stress e.g. neuter, trauma
What are the 2 types of feline infectious peritonitis?
Wet and dry
Outline the pathogenesis of feline infectious peritonitis
- Infection with FCoV
- Either mild or subclinical enteritis OR FIPV
- FIPV able to replicate in macrophages
- Immune complex formation which leads to vasculitis
- Either get effusions (wet) or pyogranulomatous lesions (dry) developing
Describe the clinical signs of wet FIP
- Ascites
- Pleural effusion
- Fever
- Anorexia
- Depression
Describe the clinical signs of dry FIP
- Signs may be vague
- Fever
- Anorexia
- Depression
- Ocular lesions (uveitis)
- Neurological signs
- No effusion
Describe the neurological signs that may be seen with FIP
- Variable, depends on site of inflammatory lesions (cranial, cerebellar, spinal cord)
- Paresis, ataxia, hyperaesthesia, convulsions, beahvioural changes
- Look for involvement of other body systems (ocular, renal, intestinal)
- Uveitis
Discuss potential reasons for the conversion from FCoV to FIP
- Reason unknown
- Probably mutation of virus (recombination or spontaneous)
- Stress
- Viral load
- Inappropriate immune response (poor cellular immune response)
Outline the treatment of FIP
- Generally palliative
- Treat secondary bacterial infections
- Corticosteroids may reduce clinical signs by reducing immune complex formation
- Interferon suggested but lack of evidence in favour
- Polyprenyl immunostimulant
Outline the diagnosis of pestiviruses
- History of abortion etc. in flock/herd
- Clinical signs
- Detection of serum/milk antibody suggests exposure
- Detection of virus
- Post mortem
Describe methods for the detection of pestiviruses
- ELISA for virus antigen, RT-PCR, virus isolation
- Pooled blood samples, ear tag samples (when apply tag produce small circle of skin)
- Pooled samples indicated if there is need for individual sampling
Outline the control of pestiviruses
- Control programs in place
- Cull PIs as soon as identified
- Aim for BVD free status in herd
- National Voluntary Industry led scheme in England
Describe the diagnosis of feline parvovirus
- Clinical signs
- History
- MRI (not usually needed, will not change management)
- PM
Outline the control of parvovirus
- Vaccination (attenuated live and inactivated virus available) once MDA weans after ~8 weeks
- Boost every 1-3 years
- Cannot use live in pregnant queens
- Vaccinate dams to cover early period of neonatal development
- Prevent exposure of kittens to FPV in environment
- Use effective disinfectant (bleach 1:32 dilution) and maintain quarantine in vet practie
Describe the diagnosis of Schmallenberg virus
- Serology (ELISA) so antiviral antibody
- RT-PCR for virus in tissue at PM
- RT-PCR on blood (EDTA) to detect virus RNA in acute phase of infection
What samples can be used for serology to test for Schmallenberg?
- Paired samples collected 2-3 week interval to demonstrate rising antibody titre in order to diagnose individual cases
- Single sample to show exposure
- Bulk milk sample good for herd screening
What is the main disadvantage of using RT-PCR on blood for Schmallenberg virus?
Difficult, will only get positive result prior to clinical signs as virus will be gone once these emerge
Outline the prevention of Schmallenberg virus
- Inactivated live virus vaccine available but poor uptake by farmers
- Used in non-pregnant animals
- Duration of immunity not yet determined
What methods are used in the diagnosis of Borna virus?
- Histopathology
- RT-PCR
- Confirmation on PM examination
Describe the PM findings that would indicate the animal was positive for Borna virus
- Non-suppurative polioencephalomyelitis
- Medullary, cerebellar, pons, thalamic lesions
- Demonstrate virus antigen in lesions by using antibody staining
Outline the control of Louping ill
- Vaccination of lambs before onto pasture after MDA has waned, and any new lambs brought in
- Following vaccination probably protected for life due to natural re-infection
- Vector control
- Max period of tick activity in Spring, once temps are over 70degreesF, lasts 1-2 months
Describe the diagnosis of canine distemper virus
- Virus isolation from smears and swabs from conjunctiva
- Immunofluorescence using Ab to detect viral antigen in ocular/nasal smears
- RT-CR
- Serology (IgM, rising IgG titre)
- Histopathology showing inclusion bodies on histopath PM
- Inclusion bodies on blood/conjunctival smears
Describe the prevention of canine distemper
Vaccination very effective, usually modified live vaccine
Describe the diagnosis of FIP
- History and clinical signs may be suggestive
- Histopath shows cahracteristic lesions
- Peritoneal/pleural fluid
- FCoV antibody titre
- Albumin:globulin ratio
- Alpha1 acid glycoprotein (ACP)
- Haematology
Describe the peritoneal/pleural fluid findings in FIP
- High protein content (elevated gamma globulins)
- Viscous yellow fluid, may clot
Discuss the use of FCoV antibody titre in the diagnosis of FIP
- Titre of 0 makes FIP unlikely
- NB in very end stage of effusive, all antibodies tied up in immune response and may get very low titres, but this is rare
- Only indicates FCoV infection
- Healthy cat with titre of FCoV does not have FIP
Describe the albumin:globulin ratio in FIP
- Serum A:G<0.4 suggestive, ruled out by ratio >0.8
- Rise in globulin, fall in albumin
Describe the alpha1 acid glycoprotein (ACP) in FIP
- > 1500ug/ml is suggestive
- Non-specifically raised in inflammation, goes very high with FIP
Describe the haematology findings in FIP
Anaemia, netrophilia (left shift), lymphopaenia
Describe the control of FIP
- Maintain FCoV free catteries (isolation, use of seronegative stud males)
- Manage catteries effectively: early weaning of kittens from infected dams at 5 weeks before MDA wanes, prevents exposure to virus from dam if removed early
- Vaccination not available in UK and poor efficacy
List the notifiable diseases with neurological signs
- Rabies
- SEs
- Aujesky disease
- Teschen disease
- West Nile Virus
- Equine encephalomyelitis
- Classical Swine Fever
List the main reservoirs for genotype 1 (classical rabies) viruses
- Fox (western Europe)
- Dog (middle east, Africa, eastern Europe)
- Bat (north and south America)
- Raccoon (North America)
- Skunk (North America)
Describe the pathogenesis of rabies
From bites, travels up sensory nerve into brain
List the clinical signs of furious rabies
- Restlessness, anxiety
- Loss of fear of humans
- Aggression, biting
- Hyperaesthesia
List the clinical signs of dumb rabies
- Salivation
- Dysphagia
- Depression
- Paralysis of limbs, neck and head
Describe the diagnosis of rabies
- History and clinical signs
- Isolation of suspected case and send for PM
- Histopathology of CNS tissue, PCR, staining for viral antigen
- Virus isolation in cell culture or by intracerebral injection into mice
Describe the histopathology findings that indicate rabies
- Inclusion bodies, encephalitis
- Viral antigen staining
Outline the control of rabies
- Quarantine
- Vaccination of dogs and cats
- Neutering of stray dogs
- PetTravel schemes
- Vaccine baits for control in wild populations
Describe the control of BSE
- Feed bans
- Removal of SRM
- Over 30 months rule for slaughtered animals
Describe the clinical signs of BSEs
- Highly variable
- nervous, hyperexcitable, aggressive
- Weight loss
- Drop in milk yield
- Ataxia, hypermetria
- Bruxism
Describe the clinical signs of scrapie
- Nervous, excitable, head tremors
- Pruritus, alopecia
- Scratch reflex (nibbling)
- Weight loss
- Goats can also be affected
Describe the control of TSEs
- Legal requirement to report animal suspected of being affected
- Compulsory Scrapie Flock Scheme
- Flock genotyping
- Culling
- 2 year period of TSE testing with negative results before a flock or herd is free of movement restrictions
What is Aujesky’s disease?
Aka pseudorabies, Alpha-herpesvirus
Describe the clinical signs of Aujesky’s disease in pigs and how this varies by age
- Reproductive (abortion, still birth, resorption) and enurological signs
- Neonatal pigs more severely affected: listless, tremors, incoordination, hypersalivation, convulsions, death in 1-2 days
- Suckling pigs: less severe but high mortality, circling, paddling of legs, V/D
- Weaners: lower death rate, respiratory signs, fever, death rate <10%
e
Describe the epidemiology of Aujesky’s disease
- Endemic in Asia, South and central America
- Canada, USA, UK, Denmark etc. disease free but risk of reintroduction
- Spread via oronasal secretions, milk, semen, transplacental
- Pig movement
- Windborne spread over short distances
- Secondary infection of sheep/cattle by aerosols, dogs/cats by ingestion of meat
Describe the clinical signs of Aujesky’s disease in cats
Sudden death
Describe the clinical signs of Aujesky’s disease in dogs
- Jaw and pharyngeal paralysis
- Salivation
- Scratching
- Death
Describe the clinical signs of Aujesky’s disease in cattle
- Mad itch: biting, licking, rubbing
- Often unilateral
- Staggering
- Aggression
- Circling
- Death
Describe the control of Aujesky’s disease
- UK free of disease, if found, slaughter quickly
- In endemic areas have vaccines with attenuated marker vaccine
What is Teschen disease?
Porcine enteroviral encephalomyelitis
Describe the clinical signs of Teschen disease
- Fever and depression
- Followed by: incoordination, paraplegia, paralysis
Evaluate the risk of Teschen disease in the UK
- Never reported in UK
- No recent outbreaks worldwide
What is West Nile Virus?
ssRNA Flavivirus
Describe the epidemiology of West Nile Virus
- Maintained in mosquitos and birds
- Problem when passed to dead end hosts e.g. humans, horses
- Spread to USA from Africa, now endemic
- In UK and Europe mainly sporadic cases
Describe the clinical signs of West Nile virus
- Most horses no dsiease following bite by infected mosquito, silent, seroconvert
- Encephalitis and/or meningitis in 33% of sick animals
- Ataxia, lethargy, facial paralysis, blindness, seizures, recumbency
Describe the diagnosis of West Nile Virus
- Clinical signs
- Detection of anti-iviral antibodies with ELISA
- PM examination of brain
Outline the treatment of West Nile Virus
Supportive Therapy only
Describe the control of West Nile Virus
- Vaccination of horses with killed virus vaccine or canarypox recombinant vaccine
- Reduce opportinities for insect vectors to flourish
- Insect repellents
- Stabling to avoid exposure
- Use of animals as sentinels of disease
What is equine encephalomyelitis caused by?
Alphavirus - WEE, VEE, EEE
Describe the clinical signs of equine encephalomyelitis
- Fever/depression
- Fatal febrile encephalomyelitis
- Photophobia, head pressing, blindness, dysphagia, ataxia
Outline the control of equine encephalomyelitis
Vaccination and vector control
What is classical swine fever caused by?
Pestivirus
Describe the epidemiology of classical swine fever
- Spread by movement of pigs, mechanically or in infected pig products
- Feeding of swill implicated as part of spread
- Present in wild boar in some parts of EU
- Most recent UK outbreak 2000
Describe the clinical signs of classical swine fever
- Erythema, petechiae
- Fever >40degreesC
- Depression, anorexia
- Piglets show convulsions, tremors
- Constipation, diarrhoea
- Abortions, stillbirths
- Haemorrhagic lesions on multiple organs
List the differentials for classical swine fever
- Porcine dermatopathy and nephropathy
- African swine fever
List the notifiable causes of neurological disease that are also zoonotic
- Equine encephalomyelitis
- West Nile Virus
- TSEs
- Rabies
