Infectious diseases Flashcards
What are the clinical signs of feline panleucopaenia virus?
Early to mid stage in utero infection can result in foetal death, resorption or abortion. infection in the late stage of gestation or in neonatal kittens may result in kittens with profound and permanent suppresion of their immune system., thymic atrophy and cerebellar hypoplasia, tremors and wide based stnce. Infections in older kittens typically follow incubation period and range from subclinical to peracute death. mild forms include self limiting diarrhoea, panleucopenia. Other kittens may show profound diarrhoea, panluecopaenia, secondary bacterial infection, sepsis/death. Affected kittens often present with a sudden onset of depression, anoreia, pyrexia and apparent thirst - but do not actually drink.
Describe the transmission of feline Panleucopenia virus
Ubiquitous in the environment and highly contagious, almost all cats exposed, seen most freq in unvaccinated kittens 3-5 mths, may also be seen in kittens from well vaccinated pedigree breeding cats - high levels of environmental contamination, disease results from superinfection with gut bateria. FPV transmitted via oro faecal route, direct contact, envinronmental contamination. Virus very stable and can survive long time in organic material. On entry to the cat the virus repilicates in rapidly dividing cells particularly the lymphoid tissue bone marrow and intestines.
How is feline panleucopaenia virus diagnosed?
Presumptive based on presence of clinical signs, vaccinal status, age and environment accompanied by profound panleucopaenia, particularly neutropenia. Serology should show a rising titre in a non vaccinated kitten. Virus isolation or PCR tests can be performed in faeces samples, oropharyngeal swabs in transport media or post mortem material.
What is the treatment for feline panleucopaenia virus?
Treatment relies on supportive care. This includes intensive fluid therapy, broad spectrum antibiotics, anti emetics, gut protectants, B vitains, provision of warm clean environment and good nursing care. Severely panleucopaenia kittens may benefit from a blood transfusion. Parenteral feline interferon omega can be very helpful or oseltamivir.
How can feline panleucopaenia be prevented?
all kittens should be vaccinated against FPV, beggining at 8-12 weeks of age, with a second dose 3-4 weeks later, and a final dose >16 weeks of age. cats older than 16 weeks of age need be given 1 dose only. colostrum deprived kittens can be vaccinated regardless of age.
Describe the aetiology of ‘cat flu’
Common name for infectious acute upper respiratory tract disease. Seen freq in unvaccinated cats and kittens when they are kept in large groups. Can be caused by feline calicivirus, feline herpes virus, Other organisms may also be involved, bordatella bronchiseptica, pasturella multiocida and mycoplasma species and chlamydophila felis.
Describe feline herpes virus (causing cat flu)
FHV-1 is a labile DNA virus of a single serotype and consistent pathogenicity that is readily destroyed outside the host. up to 80% of recovered cats may become viral carriers and excrete virus under stress, concurrent disease or following the use of corticosteroids.
describe Feline calicivirus (causing cat flu)
An RNA virus with variable virulence and pathogenicity that is more resistent within the environment to disinfection. all affected cats shed this virus for variable periods of time after resolution of the clinical signs. the most important sources of these viruses are clinical cases followed by healthy carriers.
What is B bronchiseptica?
A gram negative coccobacillus that can act as a respiratory pathogen in a number of species, including pigs, dogs, cats and humans. It can cross species and has potential zoonotic risk Affected cats may remain persistently infected and shed bacteria.
What is C felis?
It has a special predilection for the conjunctiva. In the Uk up to 30% of cats with conjunctivitis have a C felis infection. It is an obligate intracellular bacterium. Affected cats may remain persistently infected and shed bacteria.
Describe the pathogenesis of cat flu
Most are transmitted by aerosol and or direct contact of the eyes, noses and mouths. FHV-1 replicated in the epithelial cells of the nasal chambers, tonsils, conjunctiva and trachea. It causes local necrosis of mucosa and leads to a serous then mucopurulent discharge FCV targets similar cells but more often causes ulceration of the tongue, hard palate, soft palate, pharynx and external nares. These ulcers form from vesicles which burst due to tissue necrosis and cellular infiltration with neutrophils. An acute immune complex mediated synovitis can occur occasionally.
What are the clinical signs of cat flu?
young cats, although any age group can be affected. Incubation period around 6 days. Morbidity is high while mortality should be low with appropriate treatment. Disease more serious in pure breeds. Sneezing first clinical sign, followed by serous occular and nasal discharge which rapidlyy becomes mucopurulent due to secondary bacterial infection. Cats are depressed and pyrexic. Conjunctivitis, keratitis and corneal ulceration may occur. Coughing and dyspnoea seen less comonly. Ulceration of the oral cavity leads to salivation nd loss of appetite. C felis is associated with conjunctivitis. Coughing seen with FHV-1 and b bronchiseptica. FHV-1 causes more severe disease than FCV with more conjunctivitis, perfuse nasal discharge and obvious coughing and FCV tends to be associated with milder signs and oral ulceration.
How is cat flu diagnosed?
Presumptive diagnosis - clinical signs and history of exposure. Not usually possible to determine which organisms are involved. Nasal or oropharyngeal swabs can be taken for isolation and culture and in the case of fhv-1 and c felis PCR tests. Bacteriology of little value. Serology can test whether a cat has previously exposed to FCV or FHV-1.
What is the treatment for cat flu?
Antivirals and immune stimulants - Feline IFN omega as antiviral, oral famcyclovir, oral L lysine. Antibiotics - selected by culture and sensitivity or broad spectrum 2-3 weeks. For b bronchiseptica - doxycycline. Nutritional and fluid support - iv fluids, feeding tube. supportive nursing care, multivitamins, ucolytics - ease respiratory tract congestion e.g bromhexine, nebulised air - use of steam or or nebulised air can help clear airways. Decongestants. Do NOT use corticosteroids.
How can cat flu be controlled?
Suitable vaccination - against C felis, B bronchiseptica. Decrease stockign density a nd increase ai r flow, ensure good sneeze barriers, hygiene, disinfectant, have individual cats and wean kittens in isolation, have suitable quarantine facility, stop breeding.
Describe the aetiology of feline infectious Anaemia?
The organism that causes - haemobartonella felis ( renamed mycoplasma haemofelis, M turicensis, and mycoplasma haemominutum - non pathogenic. The parasites adhere to red blood cells changing their cell surface and making them antigenic so they are removed by the RE system of the spleen and liver. the replication cycle of this parasite takes 2-8 weeks so clinical disease tends to be cyclic. infection may be subclinical, most likely to result in disease when the cat is coinfected with FeLV.
Describe the pathogenesis of feline infectious anaemia?
Route of transmission believed to via saliva through biting and fleas. Transmission from queen to kittens either in utero or via milk may also occur. Persistent infections, clinically normal carriers and recurrent infections can all occur.
What are the clinical signs of feline infectious anaemia?
Cats may be asymptomatic, just show fever or other cats develop acute disease with signs of lethargy, pale mucus membranes, tachypnoea, tachycardia and dyspnoea, splenomegaly is common and pyrexia is variable. Where the anaemia is severe a haemic murmur may be detected and jaundice may develop. Autoimmune haemolytic anaemia usually develops concurrently.
How is feline infectious anaemia diagnosed?
Parasitaemia waxes and wanes but giemsa or acridine orange stained blood smears can be used for detection of the organism attached to red ccells. the organism may appear as rods, cocci or chains. detection of the organism is variable and repeat smears may be required. Small peripheral vein best. Regenerative anaemia should be present with polychromasia and normoblasts. AIHA is often present (autoimmune haemolytic anamia) resulting in autoagglutination or positive coombs test.
What is the treatment for feline infectious anaemia?
Doxycycline or oxytetracycline - which may actually be able to clear the infection. Where AIHA is present give prednisoline tapering over 8 weeks. Use of steroids may lea to increased risk of generating a chronic carrier. Blood transfusion in severe cases of anaemia. no vaccine available.
Describe Feline leukaemia virus
a retrovirus with an RNA genome surrounded by a protein core and an external envelope. The most abundant of the core proteins is p27 which is the antigen detected in the FeLV test. The envelope has glycoprotein spikes which contain the antigens which induce production of the viral neutralising antibodies. Three subgroups of FeLV exist - A,B and C - dependent on the type of glycoprotein spike present. Subgroup A is found in all infected cats and is important in the generation of B and C in vivo by gene recombination and mutation.
Describe the transmission and pathogenesis of feline leukaemia virus?
FeLV is transmitted by cat to cat contact with the virus being excreted in saliva (biting, licking and mutual grooming), urine, faeces and milk. Congenital infection can also occur. FeLV is labile and indirect spread of the virus is not thought to occur.
What are the possible outcomes of infection with feline leukaemia virus?
30% progressive infection, 40% latent infection, 30% regressive or abortive infection. Progressive and latent infection may show FeLV related disease.
Describe abortive infection of feline leukaemia viirus
Following infection the virus is eliminated by an effective early immune response so there is no viral replication and no FeLV infection of cells. These cats test PCR negative.
Describe regressive infection cased by feline leukaemia virus?
The virus replicates in the cats oropharynx. In these cats the antigebaemia is only transient since the virus is then reduced to very low levels by an effective immune response. the duration of the transient viraemia which can be detected by p27 elisa/rim test is variable and can last from a day to 12 weeks. These cats may maintain low levels of viral replication for protracted periods of time before eventual elimination and conversion to abortive status.
Describe latent and focal infections of feline leukaemia virus?
In about a third of cats which appear to eliminate the virus the infection is maintained in bone marrow or other tissues such as the intestines or mammary tissue. This is because moderate initial proviral load and viral replication leave a residual viral infection. Inadequate virus is present to reslt in a viraemia and these cats are usually n egative on conventional FeLV elisa/ RIm and IFA tests. In latent infections the virus can sometimes be identified on bone marrow samples. Cats are not thought to excrete virusa.
Describe progressive infections of feline leukaemia virus?
Where the immune response is inadequate the virus is transferred to the bone marrow via the blood. Following replication in the bone marrow large amounts of virus are released into the plasma and from here can gain access to other organs. Multiplication of the virus in the salivary glands allows excretion of the virus in saliva. the incubation period between infection and the appearance of virus in the blood can vary between 4 and 30 weeks.
What is the epidemiology of Feline leukaemia virus?
The outcome of infection depends upon a number of factors, particularly the age of the cat and the dose of the virus. the younger the cat the mroe susceptible it wil be to persistent infection and therefore development of clinical disease. Cats <16 weeks of age are most likely to develop persistent viraemia. Prolonged or recurrent exposure to the virus aids effective transmission of FeLV making transfer likely in large multicat households. With increased use of FeLV screening and vaccination FeLV infection is now less common in multicat households and infection is being seen more common in older adult males related to fighting.
describe immunosuppression related to FeLV?
Many of the diseases due to FeLV are related to its immunosuppressive actions. FeLV can result in immunosuppression by numerous mechanisms including cytopenia, neutrophil and lymphocyte dysfunction, Thymic atrophy. this may result in non specific infections; predispose to opportunist infections, exacerbate pre existing disease and ,make treatable disease slower to respond to appropriate treatment.
Describe anaemia caused by feline leukaemia virus?
Anaemia in association with felv is seen commonly. Regenerative anaemia can occur due to FeLV associated immune mediated haemolytic anaemia or due to M haemofelis infection whilst marrow disorders can result in non regenerative anaemia. A pure red cell aplasia can result from FeLV subgroup C infection but this is quite rare.
Describe the neoplastic diseases seen with FeLV?
Lymphoma most common, infection may have occured years before but left damage,LSA can be generalised or localised. Generalised can b e multicentric or disseminated. multicentric form is seen as LSA affecting several separate sites, such as kidneys, nose and nervous system. Disseminated form occurs in young to middle aged cats with up to 60% being feLV positive. Localised LSA involving the thyymus + intrathroacic lymph nodes. Most cases are now FeLV negative and typically seen in young siamese or oriental cats.
What other disorders can feline leukaemia virus cause?
FeLV can cause severe Haemorrhagic enteritis similar to FPV infection, a progressive deforming polyarthritis in young male cats, infertility in queens, plus foetal resorption and neonatal death, and neurological signs such as ataxia and pupil changes.
Describe the ELISA test for detection of FeLV infection
Snap, cite test, commercial labs - detects the FeLV p27 antigen detected in the plasma.
What is the prognosis for cats infected wwith FeLV?
High risk of developinig FeLV related disease. In one study 85% of viraemic cats died within 3.5 years of diagnosis compared to 15% of recovered or uninfected cats.
How should FeLV be controlled?
Testing in a household for all cats for FeLV. Negative and positive cats should be separated and the house qarantined with no new cats. good hygiene measures regardng litter trays, feeding bowls etc should be followed and cats then retested 3 months later. Cats positive on both occasions are considered to be persistently viraemic and should be kept in isolation permanently. Cats which are neative on both occasions are considered to be FeLV negative. If any previously negative cats are now positive they are retested 3 months later.
What treatment considerations must be used for cats with FELV or FIV
Isolate the cat to reduce exposure to pathogens and to reduce the risk of it transmitting its infection to other cats. Ideally the cat should be kept on its own and not allowed to roam freely outside. it that is not possible then feed cat separate. if access is permitted outside, instigate a night curfew. avoid overcrowding, vaccinate regularly, feed separately, give essential fatty acids, control parasites especially fleas, have regular health and weight checks., do not use griseofulvin in FIV cats.
Describe feline immunodeficiency virus?
Prevalent in cat populations throughout the world and is important cause of disease, FIV belongs to lentivirus family of retrovirus group. Increase in Prevalence with age and a higher prevalence in male cats compared to females. It is the older male cat free to roam outdoors. Major route of transmission is via saliva, biting, and territorial aggression most at risk. Vertical transmission can also occur. Venereal transmission not been reported. level of infection variable.
Describe the pathogenesis of FIV
FIV falls into four phases - the acute primary phase occurs as the virus replicates rapidly in lymphoid tissue. This begins approx 3 weeks after infection. This phase may be subclinical. more typically > pyrexia, malaise and lymphadenopathy. Most infected cats then become asymptomatic, levels of circulating virus are low but viral replication continues within infected tissues. Immunosuppression develops as the virus causes a reduction in CD4+ T helper cells. Both cell mediated immunity and humeral immunity become defective as T and B lymphocyte function is suppressed. Initial signs of immunosuppression are usually seen as secondary infections, skin and mucosal surffaces. OVer time infections become repeated and chronic.
What are the clinical signs Of Feline immunodeficiency virus?
Related to secondary infections - including gingivitis, stomatitis, weight loss, rhinitis, diarrhoea, skin disease, occular signs such as uveitis, fever, lymphadenopathy, respiratory disease, otitis, recurrent abscesses, chronic entertis or chronic renal insufficiency. Mild behavioural changes due to meningoencephalitis. Opportunistic pathogens whch healthy cats would usually show greater resistance. such as ; toxoplasmosis, salmonellosis, FIA, demodicosis and dermatophytosis. Evidence tat the incidence of neoplasia is increased in FIV cats. Tumours include lymphoma, scc, mammary gland carinoma, mast cell tumours, bronchoalveolar carcinoma.
What are the clinical laboratory findings of FIV?
While clinicopathological abnormalities are common in FIV infected cats, none are pathognomonic. in the acute phase, many cats show neutropenia and lymphopenia. These usually resolve as the cats b become asymptomatic but often recur intermittently. Clinicall ill cats may show neutropenia lymphopenia, anaemia, monocytosis or thromocytopenia. Analysis of serum biochem reveals hypergammaglobulinaemia.also may include azotaemia, raised liver enzymes, hypercholesterolaemia, hyperglycaemia or prolonged coagulation times.
Describe why FIV specific testing may be carried out?
There are a number of reasons for a cat to be tested for FIV. the cat has clinical signs suggestive of a retrovirus infection, the cat has been in contact with a retrovirus infected cat, the cat comes from a high risk group (feral, rescue centre), pre breeding testing.
How is a definitive diagnosis of FIV determined?
Made by detecting either the virus or FIV specific antibodies in the blood or saliva. In the UK, diagnostic kit to detect anti FIV antibodies are currently based on elisa or rapid immuno migration methodologies. ELISA tests detect antibodies to the core protein FIV p24 while RI tests detect antibodies to the envelope protein gp40. PCR used to detect integrated provirus DNA is used as a confirmatory test by some laboratories as are immunofluorescent antibody tests and western blotting.
Describe false positive antibody results that may occur.
since prevalence of infection is low in healthy cats and none f the assays are 100% specific, occasional false positive results will occur. technical error may result in occasional false positive results particularly when whole blood or saliva are used rather than serum or plasma. Equivocal results should not be over interpreted they are unreliable and affected cats should be re tested. Kittens born to an FIV infected queen will gain MDA via the colostrum, they may therefore test positive with tests designed to detect antibodies. while MDA usually declines to undetectable levels by the time the kittens are twelve weeks of age, occasional kittens will test positive beyond this time.
Describe false negative antibody results that may occur?
up to 20% of FIV infected cats do not have detectable levels of antibody. this may be due to early infection (it can take up to 8 weeks for antibodies to develop, terminal immune collapse, a relative or absolute lack of antibody, a failure in the test system to identify antibody. these cases must be diagnosed by PCR - available in certain specialist laboratories.
describe the management of FIV?
Depends on nature and severity of clinical signs, type of environment it lives, and willingness of owner, cat should be exposed to as few in infectious organisms as possible, ideally should be isolated or kept in small groups, should be fed separately on high quality diet. stress will accentuate immune dysfunction exposure to stressful situations should be minimized. Care must be taken w hen vaccinating. clinically unwell animals should not be vaccinated. Treatment based on managing problems associated with immunosuppresion. Use of corticosteroids appears to be contraindicated.
What is the prognosis for FIV?
Long term prognosis is guarded, but some cats will survive for many years following diagnosis. an FIV positive result is not an indication for euthanasia necessarily. it is not possible to give an accurate prognosis but generally/ the more severe and chronic the clinical signs, the worse the prognosis.
What is feline infectious peritonitis?
One of the major viral infectious diseases in cats. Although sporadic it is usually fatal. FIP is caused by infection with feline coronavirus. Able to survive in environment under certain circumstances for several weeks. up to 40% of the general cat populatioin have antibodies against FCoV and in catteries and muti cat households this rises. Many FCoV are harmless and only cause mild enteric signs however it is believed that when FCovs are able to replicate rapidly they undergo mutation which can lead to increased pathogenicity. This enables the virus to infect macrophages and in some causes, cause FIP.
How does transmission of feline infectious peritonitis occur?
transmission of FCoV occurs via the faeco oral route. there is a higher incidence of FIP in cats housed in colonies and the burmese, persian, birman and bengal reeds appear to be predisposed. F IP is seen most frequently in cats <2 years of age and in geriatrics.
What is the pathogenesis of FIP
Immune mediated. Inflammatory lesions occur as small white nodules all over the visceral and parietal peritoneum and various organs. These nodules consist of neutrophils and macrophages in so called pyogranulomatous lesions. These are usuall centred on small blood vessels resulting in a vasculitis. Tw forms are recognised - both wet and dry.
Describe the two forms present of FIP
Effusive or wet form, fluid accumulates in the peritoneal or pleural cavities with lesions on the peritoneum and pleua. In the non effusive or dry form small focal lesions develop in the peritoneum, kidneys, liver, and mesenteric lymph nodes and pancreas. In addition, thoracic lesions may involve the pleura, diaphragm, lungs and myocardium. The eyes are often involved presenting as anterior uveitis and posterior uveitis where the CNS is involved inflammation of the meninges may produce ataxia and seizures.
Describe the clinical signs of FIP?
While signs of FIP may be acute, they are more commonly chronic and insidious. the History usually includes anoreexia, weight loss, pyrexia and dullness. Int he wet form ascites or hydrothorax are common. in the dry form clinical signs depend on the organs affected and can include renomegaly, jaundice, anterior uveitis and CNS signs. gut involvement may result in vomiting o diarrhoea and a mass at the ileocaecal junction.
How is a diagnosis of FIP made?
Clinical signs. Lymphocytic holangitis is a major differential for cats presenting with ascites and jaundice. Haematology most commonly reveals lymphopaenia and Neutrophilia with anaemia. serum biochemistry may reveal Hyperglobulinaemia and or bilirubinaemia. The serum albumin to globulin ratio is often low, tpically <0.4 serum acid 1 alpha glycoprotein. In the effusive form appearance of any ascitic or pleural fluid is characteristic - non septic exudate high in protein and cells which is usually viscous and yellow in nature. Cytology reveals neutrophils. Serology can be used to identify antibody to FcO b ut this is not specific to pathogenic strains. A negative titre can rule out dry fp but not wet FIP.
What is the treatment and prognosis of FIP?
Treatment usually ineffective although rFeIFN and steroids and supportive care have been advocated. Prognosis is extremely poor and euthanasia generally recommended once diagnosis has been made.
How can FIP be controlled?
Hygiene measures, stress should be m inimised as this may increase a cats susceptibility to FIP. Any concurrent diseases such as FeLV or FIV which may also increase susceptibility should be addressed, no cats should be moved into or out of household for 6 months.
