rabies in cats - · pdf filerabies in cats the following recommendations have been formulated...

RABIES IN CATS

The following recommendations have been formulated by the

European Advisory Board on Cat Diseases.

The European Advisory Board on Cat Diseases is an independent panel of 17 veterinarians from ten European countries, with an expertise in immunology, vaccinology and/or feline medicine.

The ABCD was set up to compile guidelines for the prevention and management of major feline infectious disease in Europe based on current scientific knowledge and available vaccines.

This work would not have been possible without the financial support of Merial.

© June 2008 by the European Advisory Board on Cat Diseases. All rights reserved.

June 2008

Guidelines on Feline Infectious Diseases

Reprinted in the IVIS website with the permission of ABCD Close window to return to IVIS www.ivis.org

ABCD Guidelines on Feline Immunodeficiency Virus 1/22

ABCD GUIDELINES ON:

6. RABIES IN CATS..................................................................................3 6.1 Virus properties ..............................................................................................................................3 6.2 Epidemiology ..................................................................................................................................4

6.2.1 Rabies-free Countries ...............................................................................................................4 6.2.2 Developing Countries................................................................................................................4 6.2.3 Industrial Countries ...................................................................................................................5

6.3 Pathogenesis...................................................................................................................................5 6.4 Immunity ..........................................................................................................................................6

6.4.1 Passive immunity acquired via colostrum ...............................................................................6 6.4.2 Active immune response ..........................................................................................................7

6.5 Clinical signs...................................................................................................................................8 6.6 Diagnosis ...................................................................................................................................... 12

6.6.1 OIE recommendations ........................................................................................................... 12 6.6.2 Direct viral detection methods ............................................................................................... 12 6.6.3 Indirect detection methods .................................................................................................... 13

6.7 Rabies control in cats ................................................................................................................. 14 6.7.1 Treatment (post-exposure vaccination) ................................................................................ 14 6.7.2 Prophylaxis (preventive vaccination) .................................................................................... 14

6.8 Disease control in specific situations...................................................................................... 16 6.8.1 Shelters ................................................................................................................................... 16 6.8.2 Breeding catteries .................................................................................................................. 16 6.8.3 Vaccination of immunocompromised cats............................................................................ 16

6.9 References.................................................................................................................................... 18

The following recommendations have been formulated by the

European Advisory Board on Cat Diseases.

The European Advisory Board on Cat Diseases is an independent panel of 17 veterinarians from ten European countries, with an expertise in immunology, vaccinology and/or feline medicine.

The ABCD was set up to compile guidelines for the prevention and management of major feline infectious disease in Europe based on current scientific knowledge and available vaccines.

This work would not have been possible without the financial support of Merial.

© June 2008 by the European Advisory Board on Cat Diseases. All rights reserved.


ABCD Guidelines on Feline Immunodeficiency Virus 2/22

ABCD Panel members Marian Horzinek Former Head, Dept of Infectious Diseases, div. Immunology & Virology, Faculty of Veterinary Medicine; Director, Graduate School Animal Health; Director, Institute of Veterinary Research; Utrecht, (NL). Founder President European Society of Feline Medicine. Research foci: feline coronaviruses, viral evolution. Diane Addie Director, Feline Institute Pyrenees, France. Honorary Senior Research Fellow, University of Glasgow Veterinary School, UK. Research foci: eradication of feline coronavirus (FIP); cure for / prevention of chronic gingivostomatitis. Interested in all feline infectious diseases. www.catvirus.com Sándor Bélak Full professor, Dept of Virology, Swedish University of Agricultural Sciences (SLU) & The National Veterinary Institute (SVA), Uppsala (S); OIE Expert for the diagnosis of viral diseases (Sweden). Research foci: biotechnology-based diagnosis, vaccine development, the genetic basis for viral pathogenesis, recombination and virus-host interaction. Corine Boucraut-Baralon Associate professor, Infectious Diseases, Toulouse Veterinary School; Head, Diagnostic Laboratory Scanelis, France. Research foci: poxviruses, feline calicivirus, feline coronavirus, and real-time PCR analysis. Herman Egberink Associate professor, Dept of Infectious Diseases and Immunology, Virology division, Faculty of Veterinary Medicine, Utrecht; Member of the national drug registration board, the Netherlands. Research foci: feline coronavirus (FIP) and FIV, vaccine development and efficacy, antivirals. Tadeusz Frymus Full professor, Head, Division of Infectious Diseases and Epidemiology, Dept of Clinical Sciences, Warsaw Veterinary Faculty, Poland. Research foci: vaccines, Feline leukaemia virus (FeLV), Feline immunodeficiency virus (FIV), Feline Coronavirus (FCoV/FIP) Bordetella bronchiseptica infection, and canine distemper. Tim Gruffydd-Jones Head, The Feline Centre, Professor in Feline Medicine, Bristol University, UK; founder member European Society of Feline Medicine. Research foci: feline infectious diseases, in particular coronavirus and Chlamydophila. Katrin Hartmann Head, Dept of Companion Animal Internal Medicine & full professor of Internal Medicine, Ludwig Maximilian University Munich, Germany; AAFP vaccination guidelines panel member. Research foci: infectious diseases of cats and dogs with special interest in diagnosis and treatment.

Margaret J. Hosie Institute of Comparative Medicine, Glasgow, UK. RCVS Specialist in Veterinary Pathology (Microbiology) Research focus: Feline immunodeficiency virus pathogenesis and vaccine development, feline calicivirus. Albert Lloret Clinician, Veterinary Teaching Hospital, Barcelona University, Spain. Research foci: feline medicine, molecular diagnostics of feline disease, feline injection site sarcomas. Hans Lutz Head, Clinical Laboratory, Faculty of Veterinary Medicine, University of Zurich, Switzerland. Research foci: feline retro- and coronaviruses (pathogenesis & vaccination), epidemiology and molecular diagnostics of feline infectious diseases. Fulvio Marsilio Dept of Comparative Biomedical Sciences, Div. Infectious Diseases, University of Teramo (I). Research foci: PCR as diagnostic tool for upper respiratory tract disease in cats, recombinant feline calicivirus vaccine. Maria Grazia Pennisi Professor, Clinical Veterinary Medicine. Head, Companion Animal Internal Medicine Clinic, Dept Veterinary Medical Sciences, University of Messina, (I). Research foci: clinical immunology, Bordetella bronchiseptica in cats, FIV. Alan Radford Senior Lecturer & Researcher, Dept Small Animal Studies, Liverpool Veterinary School, UK. Research foci: FCV and FHV-1 virulence genes, Bordetella bronchiseptica in cats, parvoviruses and coronaviruses, immune-response variation. Andy Sparkes Head, Feline Unit, Animal Health Trust; Chairman, Feline Advisory Bureau, UK; Editor, European Journal of Feline Medicine and Surgery; AAFP vaccination guidelines panel member. Research foci: feline infectious diseases, lower respiratory tract disease, oncology. Etienne Thiry Full professor, Head of Veterinary Virology, Dept Infectious Diseases and Virology, Liege Veterinary Faculty (B); Member, Committee of Veterinary Medicinal Products (B); Agencies for animal health and food safety (F, B). Research foci: herpesviruses, caliciviruses, emerging feline viruses, host-virus interactions. Uwe Truyen Head of the Institute for Animal Hygiene & Veterinary Public Health, University of Leipzig, Germany, Head of the German standing vaccination committee Vet. Research foci: Animal Hygiene, epidemiology, parvoviruses, feline calicivirus.


ABCD guidelines on Rabies in cats 3/22

6. Rabies in cats

6.1 Virus properties

Rabies is the cause of one of the oldest and most feared diseases of humans and animals

- it was recognized in Egypt before 2300 BC and in ancient Greece, where it was well

described by Aristotle. Perhaps the most lethal of all infectious diseases, rabies also has

the distinction of having stimulated one of the great early discoveries in biomedical

science. In 1885, before the nature of viruses was comprehended, Louis Pasteur

developed, tested, and applied a rabies vaccine, thereby opening the modern era of

infectious disease prevention by vaccination.

Rabies virus is one of the Rhabdoviridae, which encompass over 175 viruses of

vertebrates, invertebrates and plants.

Based on virion properties and serologic relationships four genera containing animal

viruses have been recognized in the family Rhabdoviridae.

The rabies virus belongs to the genus Lyssavirus, together with the Mokola virus, Lagos

bat virus and Duvenhage virus from Africa and European bat viruses 1 and 2 and

Australian bat lyssavirus. Each of these viruses is considered capable of causing rabies-

like disease in animals and humans. All lyssaviruses use bats as reservoir hosts.

Rhabdovirus virions consist of an outer envelope with large peplomers and an inner,

helically coiled cylindrical nucleocapsid. The precise cylindrical form of the nucleocapsid

gives the viruses their distinctive bullet or conical shape. The genome is a single

molecule of linear, negative-sense, single-stranded RNA, 11 to 15 kb in size. The genome

encodes 5 genes in the order 3’-N-NS-M-G-L-5’. The viruses generally have 5 proteins.

The glycoprotein that makes up the peplomers contains neutralizing epitopes which are

targets of vaccine-induced immunity as well as epitopes involved in cell-mediated

immunity. Virions also contain lipids, their composition reflecting the composition of host

cell membranes, and carbohydrate side-chains on the glycoprotein. Rhabdoviruses may

be stable in the environment especially at alkaline pH but are thermolabile and sensitive

to the UV irradiation of sunlight. In clinical practice, rabies virus is easily inactivated by

detergent-based disinfectants.

Viral entry into host cells occurs via fusion of the viral envelope with the cell membrane;

all replication steps occur in the cytoplasm.

Virions are formed by the budding of nucleocapsids through cell membranes. Rabies virus

budding takes place mostly upon intracytoplasmic membranes of infected neurons, but

almost exclusively upon plasma membranes of salivary gland epithelial cells. The

replication of rabies viruses is slow and usually non-cytopathic because it does not shut



down host cell protein and nucleic acid synthesis. Rabies virus produces prominent

cytoplasmic inclusion bodies (Negri bodies) in infected cells.

Laboratory-adapted (“fixed”) rabies virus replicates well in Vero (African green monkey

kidney) cells and BHK-21 (baby hamster kidney) cells, which are the most common

substrates for growing animal rabies viruses for vaccine production. Rabies virus also

replicates to high titre in suckling mouse and suckling hamster brain.

6.2 Epidemiology

The disease occurs worldwide, with certain exceptions. Large regions in Europe became

free of terrestrial rabies as a result of wildlife vaccination programmes.

The rabies situation and the regulations are continuously updated on the web sites of OIE

and WHO (see reference section).

The number of human deaths caused each year by rabies is estimated to be

approximately 40, 000 to 100, 000, worldwide, and an estimated 10 million people

receive post-exposure treatments each year after being exposed to rabies suspect

animals [WHO, 2006]. Dog rabies is still very important in many parts of the world and is

the principal cause of human rabies cases. In many countries, wildlife rabies has become

of increasing importance as a threat to domestic animals and humans, and transmission

from vampire bats is an important issue. The red fox, raccoon, skunk and mink are the

main reservoir species of terrestrial rabies in Europe and North and South America.

The control of rabies in various regions of the world poses very different problems,

depending upon the reservoir host and prevalence of infection.

6.2.1 Rabies-free Countries Strictly enforced quarantine of dogs and cats for various periods before entry has been

used effectively to eliminate rabies virus from Japan, the United Kingdom (UK), Australia,

New Zealand and several other islands. Rabies was never endemic in wildlife in the UK

and was eradicated from dogs in the UK in 1902, and again in 1922 after it became

established in the dog population in 1918. Since then, there had been no rabies in the UK

until recently when there were isolated reports of bats infected with European bat virus

1. However, such isolated incidents did not alter the (terrestrial) rabies-free status of the

UK. In contrast, rabies was not recognized in Australia until recently when Australian bat

lyssavirus was discovered, and found subsequently to be endemic in Southeast Australia.

6.2.2 Developing Countries In most countries of Asia, Latin America and Africa, endemic dog rabies is a serious

problem, causing significant domestic animal and human mortality. In these countries,

large numbers of doses of human vaccines are used and there is a continuing need for



comprehensive, professionally organized and publicly supported rabies control agencies.

That such agencies are not in place in many developing countries is a reflection of their

high cost; nevertheless, progress is being made. For example, a substantial decrease in

rabies incidence has been reported in recent years in China, Thailand and Sri Lanka,

following implementation of dog vaccination programmes and improved post-exposure

prophylaxis of humans. Similarly, the number of rabies cases in Latin America is declining

significantly; the Pan American Health Organization has implemented a vaccination

program to eliminate urban dog rabies from the Southern hemisphere.

6.2.3 Industrial Countries In most industrial countries, even those with modest disease burden, publicly supported

rabies control agencies operate in the following areas: (1) programmes of oral

vaccination of wildlife, in Europe of the red fox; (2) stray dog and cat removal and

control of the movement of pets (quarantine is used in epidemic circumstances, but

rarely); (3) immunization of dogs and cats, so as to break the chain of virus

transmission; (4) laboratory diagnosis, to confirm clinical observations and obtain

accurate incidence data; (5) surveillance, to measure the effectiveness of all control

measures; and (6) public education programs to assure cooperation.

The cat is considered in some European countries to be high-risk species for transmission

to human beings. For example, of more than 20, 000 inhabitants in Switzerland that had

to be vaccinated after exposure to rabies in the years from the late 1960s until the early

1990s, around 70% had been either bitten or in close contact with cats [Hohl et al,

1978].

Even if feline rabies is considered to be a by-product of canine or wild rabies [Blancou &

Pastoret 1990], behavioural characteristics of cats and clinical aspects of the disease in

this species render it important for public health reasons. In fact, despite a lower number

of post-exposure prophylaxis treatment for people following cat bites compared to dog

bites, treatment is justified more often [Blancou & Pastoret 1990].

6.3 Pathogenesis

Rabid animals are the only source of virus. Virus is shed in the saliva some days before

the onset of clinical signs and virus is transmitted through a bite or a scratch of the skin

or mucous membranes (eyes, nose, mouth). The blood of rabid animals is not considered

infectious. The average incubation period in cats is two months but may vary from 2

weeks to several months or even years depending on the dose of virus transmitted and

the severity and site of the wound [Jackson 2002, Charlton et al, 1997].

The incubation period is variable because the virus moves along peripheral nerves with

the normal axoplasmic flow from the inoculation site to the central nervous system



(CNS): hence the greater the distance from the CNS, the longer the incubation period;

and the greater the density of innervation of the inoculated tissue the shorter this

duration [Greene and Rupprecht, 2006]. Very long incubation periods have been

described in some experimental cases [Murphy et al, 1980], and this must be taken into

account when evaluating wound history, especially in free-roaming cats exhibiting

sudden behavioural change and/or signs of motor neuron dysfunction that may initiate

the clinical phase.

The virus replicates in striated muscle and in connective tissue at the site of inoculation

and then enters the peripheral nerves through the neuromuscular junction [Murphy et al,

1973]. Alternatively, it can infect directly the peripheral nerves, spreading to the central

nervous system via the axonal route. The virus can then travel to the salivary glands by

the retrograde axonal route. At this time, the animal becomes infectious, i.e. about 3

days before the first clinical signs appear. By the time clinical signs appear, the virus is

widely disseminated throughout the organs. In most cases, death occurs within 5 days so

that a cat or a dog will be shedding the virus in saliva for about 8 days in total.

Most clinical signs are related to the virus-induced central and peripheral nervous system

dysfunction rather than neuronal death and abnormalities in neurotransmission have

been described [Jackson 2002]. Rabies glycoprotein probably plays an important role in

the trans-synaptic spread of the virus between neurons and in the topographic

distribution of virus infections through the nervous system [Etessami et al, 2000].

6.4 Immunity

6.4.1 Passive immunity acquired via colostrum

Kittens from vaccinated queens obtain maternal antibodies (MDA) via colostrum. The

MDA titre in kittens depends on both the antibody titre of the queen as well as the

amount of colostrum ingested during the first day of life. In most kittens, MDA will not

persist for longer than 12 weeks.

MDA have been demonstrated even in sera of fox cubs whelped by orally immunized

vixens [Vos et al, 2003].

Passive immunity may neutralize vaccine antigens, thereby inhibiting the immunoglobulin

production, interfering in the immunization process during the first weeks of life.

Therefore, it is generally recommended to perform the primary vaccination against rabies

in kittens not earlier than at 12 weeks of age.



6.4.2 Active immune response

Although rabies antigens are highly immunogenic and capable of eliciting the full

spectrum of protective immune responses, the virus is not highly cytopathic, since no cell

lysis occurs during replication or maturation. Therefore, little antigen is presented to the

immune system. Neither humoral nor cell-mediated specific responses can be detected

during the early stages of movement of virus from the site of the bite to the central

nervous system [Green 1997]. Hence, infection of naive animals with rabies virus most

often results in disease and death. Such sequelae may be averted by prompt

immunization following exposure, demonstrating that the development of anti-rabies

viral immunity prior to extensive infection of neurons is protective. It is well documented

that virus neutralizing antibody is a crucial factor in this immunity. Rabies is an example

of a “Th-2 healing disease” in which activation of B lymphocytes, with the help of CD4 T

cells, is important for protection [Garenne and Lafon 1998]. When activated, primarily by

the N protein of the rabies virus, CD4 T cells produce cytokines (i.e. IL-4) that stimulate

B cells to produce antibodies. In contrast, rabies-specific CD8 T cells cause neuronal

damage when a Th-1 response (IFN-γ and TNF-α) predominates [Lafon 2002, Hooper

2005]. However, published reports exist that describe vaccinated animals that had no

detectable virus neutralizing antibody and yet survived rabies challenge, indicating that

other mechanisms may also protect against this disease [Aubert 1992, Hooper et al,

1998].

After intramuscular infection, the virus replicates locally for several weeks in the

myocytes or nervous tissue. In vaccinated cats with adequate serum antibody titres, the

virus is often neutralized during this early incubation period. In contrast, unvaccinated

cats exposed to rabies virus can produce an antiviral immune response, usually late in

the clinical course, that fails to prevent disease [Johnson et al, 2006]. However,

protection against the early stages of infection is provided by non-specific immunity, in

which interferon seem to play a critical role. High levels of interferon are detectable in

sera of mice inoculated with rabies virus by peripheral or intracerebral routes [Marcovistz

et al, 1984, 1994; Johnson et al, 2006]. It is not clear how effective these mechanisms

are in naturally exposed naive cats. It is believed that factors, determining morbidity

include the amount and strain of the virus, the age and immunocompetence of the cat

and the bite, such that in unvaccinated cats the risk of developing rabies is higher (and

the incubation period shorter) in a young animal that has been bitten severely in the

head, with a high saliva deposit in the wound, compared to the risk for an adult cat,

bitten in a limb, especially after extensive bleeding [Pastoret et al, 2004].

In natural infections of unvaccinated animals, neutralizing antibody appears usually after

the virus has entered the central nervous system. Hence, once symptoms are evident,

recovery from rabies is exceedingly rare, although there have been reports of humans



and animals that have recovered following confirmed clinical rabies [Bernard 1985,

Fekadu 1991]. Furthermore, antibodies to lyssaviruses have been detected occasionally

in domestic or wild cats with no history of vaccination, consistent with a non-fatal disease

or subclinical infection [Tjørnehøj et al, 2004; Deem et al, 2004].

6.5 Clinical signs

Aggressive behaviour towards humans is

unusual in healthy cats, so any unjustified

aggressive behaviour in cats must be

considered highly suspicious.

Rabies should be suspected not only when

there has been a recent history of a bite

by or exposure to a rabid animal but also

where an unvaccinated cat may have

been in contact with potentially infected

wildlife, such as bats. Indeed, only

recently (November 2007), a cat in France

died of rabies as a result of infection with

bat lyssavirus. However, although rabid bats having been reported in the UK [Johnson et

al, 2003; Fooks 2003; Harris et al, 2007] and the Mammal Society estimates that British

cats could be killing 230, 000 bats a year [Fooks, personal communication], no cases of

cat rabies have been documented in the UK. These findings indicate that the risk of cats

becoming infected with rabies from bats may be low.

Two disease forms can be identified in cats: the furious and the paralytic one. The furious

form of rabies has three clinical phases (prodromal, furious or psychotic and paralytic or

dumb) but they are not always clearly distinct in cats. The other has only two phases:

prodromal and paralytic. During the very short prodromal phase (12-48 hours) of both

forms, a wide range of quite non-specific clinical signs (fever, anorexia, vomiting,

diarrhoea) may occur, sometimes accompanied by neurological signs. Marked

behavioural changes may be noticed at first, such as unusually friendly or shy or irritated

behaviour or increased vocalization. Altered behaviour depends on forebrain involvement

and may be associated with other neurological signs reflecting the inoculation site. If the

bite occurs in the face, clinical signs reflect cranial nerve and forebrain involvement: the

former may produce depressed or absent reflexes (palpebral, corneal, pupillary, etc.),

strabismus, dropped jaw, inability to move whiskers forward, dysphagia, laryngeal

paralysis, voice change, tongue paralysis. Forebrain involvement is responsible for

seizures, muscular twitching or tremors, aimless pacing, exaggerated emotional

responses (irritability, rage, fearfulness, photophobia, attacking inanimate objects, etc).

The tendency to bite may be the consequence of the loss of inhibitory control by cortical

A rabid cats with typical clinical signs of

encephalitis: Seizures, salivation, pupil

dilatation (Courtesy Dr Veera Tepsumethanon).



neurons over the subcortical bite reflex whereby dogs and cats turn and snap at anything

that touches them around the mouth [O’Brien and Axlund, 2005]. If this is the case, the

animal snaps without warning or showing any emotion when doing it. Pruritus at the bite

site can be observed. If the infecting bite was on the limbs, neurological signs start from

the spinal cord and an ascending lower motor neuron (LMN) paralysis occurs before the

brain signs. The encephalitis rapidly spreads throughout the CNS producing severe

ataxia, disorientation, paralysis, seizures, status epilepticus eventually followed by coma

and death from respiratory arrest.

The furious phase is more consistently developed in cats showing behaviour

abnormalities (described above) [Fogelman et al, 1993]. The paralytic phase

(paraparesis, incoordination, generalized paralysis, coma and death) usually begins after

five days of starting first clinical signs.

Isolated reports of survival after a confirmed clinical disease are available in cats, dogs

and humans [Bernard 1985, Fekadu 1991], but death usually occurs after a clinical

course of 1-10 days. Cats often die in 3-4 days [Rupprecht and Childs, 1996] and

according to a more recent report, 25% of deaths occur in cats within 4 days of clinical

course, while in dogs within 2 days only [Tepsumethanon et al, 2004].

Atypical forms with chronic course have been described after experimental infection in

cats [Murphy et al, 1980].

The severe public health risk (veterinarians included!) requires that differential diagnosis

of CNS diseases characterized by sudden onset and rapidly evolving clinical signs, always

includes rabies for free roaming, unvaccinated cats living in endemic areas or travelling

there. In this case, the clinical approach must make safety the priority because the

manipulation and restraint of the cat easily may provoke biting at the time when salivary

Box 1. Clinical signs of rabid cats infected by classical rabies virus (Genotype I) History and clinical signs by the owner: 1. Dramatic changes from normal behaviour. 2. Very aggressive, biting human and/or animal with no apparent reason. http://www.oie.int/eng/normes/mmanual/A_summary.htm General appearance and clinical signs at observation: 1. 90% of rabid cats show clinical signs of the furious form. 2. Thin (the cat cannot eat) 3. Ruffled and dirty coat. (the cat cannot clean itself) 4. Mucous membranes, tongue, nose and footpads are reddish pink, high fever. 5. The chin and front legs are wet from saliva (salivation). 6. Permanent movement and excitement (restlessness). 7. Imbalanced gait due to paresis of the hind legs. 8. Pupil dilatation unresponsive to light. 9. Abnormal water uptake (water runs back out of mouth). (Courtesy Dr Veera Tepsumethanon)



glands are usually already infected and rabies virus is shed in saliva. Guidelines

indicating that a clinical diagnosis of rabies should be included in the differential

diagnosis in live cats with suspected encephalitis based on history and observation of the

cat inside the carrier would help to reduce the risk of exposure for the veterinary team

(see the flow chart below that was adapted for cats from Tepsumethanon et al, 2003).

Vaccine-induced rabies in cats was observed in the past when modified-live vaccines

were available. Neurological signs occurred several weeks after vaccination and were

characterized mostly by progressive upper motor neuron (UMN) limb paralysis and

cranial nerve deficits.



Is the cat from or near to an endemic area, or traveling from there?

Does the cat have outdoor access?

Has the cat been vaccinated against rabies?

Is the cat less than 1 month of age?

Is the cat sick?

Does the cat show at least 1 of the following clinical signs?

• Behavioural changes • Cranial nerve deficits • Seizures • Muscular twitching or tremors • Aimless pacing • Tendency to bite • LMN paralysis • Severe sensorial ataxia • Depressed sensorium

RABIES POSSIBLE

NO

NO YES or unknown

NO or unknown

YES

NO or unknown

YES

YES or unknown NO

YES

NO

Has the onset been sudden (<1 day)?

The clinical signs have progressed (worsened) in the last 3-5 days?

NO or unknown

YES or unknown

yes

NO

RABIES UNLIKELY

YES or unknown



6.6 Diagnosis

Because clinical diagnosis of rabies is not reliable, a definitive diagnosis can only be

obtained by laboratory investigations post-mortem.

However, serological tests are used for surveys and post-vaccinal control in order to test

immunity level in vaccinated animals, especially in the context of international

movements.

6.6.1 OIE recommendations The recommendations from the experts of the OIE First International Conference “Rabies

in Europe” Kiev, Ukraine, 15-18 June 2005 are the following:

i) Routine laboratory diagnosis should be undertaken using only the techniques specified

by the OIE (Terrestrial Manual) and the WHO (Laboratory Techniques in Rabies).

ii) The FAT (Fluorescent antibody test) is the primary method recommended.

iii) The confirmation test should use rabbit tissue culture inoculation test (RTCIT). The

mouse inoculation test can be used only if rabbit tissue culture is not available.

iv) PCR is presently not recommended for routine diagnosis but may be useful for

epidemiological studies or for confirmatory diagnosis only in reference laboratories.

Reference laboratories: The list of reference experts and laboratories can be found on

the OIE web site (http://www.oie.int/eng/OIE/organisation/en_listeLR.htm).

6.6.2 Direct viral detection methods

Only direct detection methods are recommended to confirm rabies in human beings and

animals.

Samples (animal heads, brain tissues or other organs) should be sent according to the

national and international shipping regulations and care should be taken in order to avoid

potential human contamination. Because rabies virus is rapidly inactivated, the specimen

should be shipped (preferably) refrigerated or at room temperature in 50% glycerine in

phosphate buffered saline solution.

Brain tissue (especially thalamus, pons and medulla) is the preferred sample for post-

mortem diagnosis but other organs such as salivary glands can also be used.

6.6.2.1 Fluorescent antibody test Fluorescent antibody test (FAT) is the method recommended by WHO and OIE for fresh

or glycerol samples [Bourhy et al, 1989, Birgham & van der Merwe 2002], but is less

sensitive in formalin-fixed tissues. FAT provides a reliable diagnosis in 95% to 99% of



cases for all genotypes and in fresh samples. It can also be used for rabies detection in

cell cultures and in brain tissue of mice that have been inoculated for diagnosis.

6.6.2.2 Immunochemical methods Other methods available include immunochemical tests (e.g. avidin-biotin peroxydase

system, ELISA, direct blot enzyme immunoassay). The rapid rabies enzyme

immunodiagnosis (RREID) is an alternative to FAT but detects only one genotype.

Correlation between FAT and RREID is between 96 and 99% [Barrat 1993].

6.6.2.3 Inoculation to laboratory animals and cell cultures These tests are used to confirm inconclusive results with FAT in organs or when FAT is

negative if human exposure has been reported.

Intracerebral inoculation of mice is performed in newborn or 3 to 4 week-old mice. FAT is

used to detect virus 5 days to 11 days post-inoculation. Ideally, these inoculation tests

should be replaced by cell culture tests, which are as sensitive, less time-consuming and

more ethical. Neuroblastoma cell lines may be used and presence of the rabies virus is

revealed by FAT, with results being available within 2 to 4 days.

6.6.2.4 Histology – Immunochemistry Since histology and immunohistochemistry to detect Negri bodies are less sensitive

methods than FAT, especially in autolysed tissues, these methods are not recommended

for routine diagnosis.

6.6.2.5 Other direct methods Reference laboratories may identify rabies virus, and especially some variants, using

monoclonal antibodies, nucleic probes or PCR and sequencing. These techniques can

distinguish vaccine and field strains and may identify the geographic origin of the strain.

6.6.3 Indirect detection methods

6.6.3.1 Seroneutralisation Seroneutralisation tests in cell cultures, such as fluorescent antibody virus neutralisation

(FAVN) or rapid fluorescent focus inhibition test (RFFIT) are widely used.

The principle of FAVN is neutralisation in vitro of a rabies CVS strain before inoculating

BHK-21 C13 cells. The titre is expressed in IU/ml and is the reciprocal value of the

dilution at which 100% of the virus is neutralised in 50% of the wells. RFFIT and FAVN

give equivalent results. A titre of 0.5 IU/ml of serum antibodies is considered to be the

minimum titre to correlate with immune protection.



6.6.3.2 ELISA ELISA has recently been developed and is used for testing vaccinated animals.

Commercial kits are now available for the detection of antibodies in sera from vaccinated

cats and dogs. ELISA tests do not require the culture of live virus and the result can be

obtained within 4 hours. The sensitivity and specificity of ELISA tests still need to be

confirmed before it can be accepted as an official method [Servat et al, 2006].

For further details, refer to Barrat et al, [2006] and the OIE Manual of Diagnostic Tests

and Vaccines for Terrestrial Animals [OIE 2007].

6.7 Rabies control in cats

6.7.1 Treatment (post-exposure vaccination) The post-exposure management of cats depend on the national public health regulations,

but is forbidden in many countries. Usually, it is not authorised in case of clinical

suspicion. No supportive or specific treatment has proved to be effective in rabid cats, so

treatment is not recommended [Greene & Rupprecht, 2006].

6.7.2 Prophylaxis (preventive vaccination) Rabies in cats is usually controlled by traditional inactivated vaccines [OIE 2007] and at

present, several inactivated rabies vaccines are available commercially. These products

have been shown to induce protective immune responses following a single vaccination

[Fu 1997, Perez and Paolazzi 1997]. In cats and dogs, the peak of rabies neutralizing

antibodies is generally reached between 4 to 6 weeks after the first immunization

[Cliquet 2006]. Currently available inactivated vaccines are very efficient. Cats and dogs

with a neutralization titre above 0.5 IU/ml, regardless of the period of time elapsed since

vaccination have a very high probability of survival after a rabies infection [Cliquet,

2006]. Cats respond better to rabies vaccination than dogs and as much as 97.4% of

them develop a titre of 0.5 IU/ml or higher after the first vaccination, many even above 5

IU/ml [Cliquet, 2006]. A very small proportion of cats identified with rabies have had at

least one rabies vaccination during their lifetime [Greene et al, 2006]. Since the new EU

regulations in pet movement were put in place in 1993, no single case of vaccine failure

has been documented [Cliquet 2006]. Rabies vaccines are generally considered to be

safe, even in neonatal kittens.

Inactivated vaccines may carry a risk due to the remote possibility of incomplete

inactivation of the virus and the inadvertent spread of residual pathogenic particles of

rabies virus [Schneider, 1995]. Furthermore, inactivated rabies vaccines may be

associated with the development of injection site sarcomas in cats [Dubielzig et al,

1993].



Such problems led to continued efforts to develop safer rabies vaccines. New vaccines

include recombinant subunit proteins [Wunner et al, 1983], recombinant viral vectors

[Paoletti 1996, Xiang et al, 1996] and deoxyribonucleic acid (DNA) based vaccines

[Osorio et al, 1999, Cupillard et al, 2005]. Recombinant live vector vaccines have some

advantages over traditional vaccines: they are innocuous, they induce suitable humoral

immune responses and they do not require rabies virus to be handled [Paoletti 1996].

They also induce less inflammation at the site of injection [Day et al, 2007].

Fortunately, current vaccines are also cross-protective against a number of other

Lyssavirus genotypes. All cat and dog sera with a titre above 5 IU/ml neutralize EBL-1

and EBL-2 regardless of vaccine/virus strain and among sera with a titre between 0, 5

and 5 IU/ml 87% neutralize EBL-1 and 53% EBL-2 [Fooks, personal communication].

However, against some novel lyssaviruses isolated from bats in Eurasia the protection

may be reduced or negligible depending on the genetic distance between the new isolate

and traditional rabies viruses [Hanlon et al, 2005].

Because of the public health risk associated with susceptible domestic cats becoming

infected following exposure to rabid wild or domestic animals, rabies virus vaccines

should be considered as core vaccines in countries where rabies is endemic and should

be administered in accordance with local or state regulations.

In countries where rabies is not present, rabies vaccination may be considered optional,

to be recommended by the veterinarian if the cat should move to an endemic rabies

area.

6.7.2.1 Primary vaccination course In contrast to all other inactivated vaccines, a single rabies vaccination induces a long-

lasting immunity due to the immunogenic properties of the vaccinal antigen.

Kittens should be vaccinated at 12 to 16 weeks of age to avoid interference from

maternal antibodies, with revaccination one year later (depending on data sheet

recommendations for each brand of vaccine). With this schedule, a single vaccination is

sufficient. However, national or regional legislation regarding vaccination type and

interval should be adhered to.

6.7.2.2 Booster vaccinations Although some commercial vaccines provide protection against virulent rabies challenge

for 3 years or longer [Lakshmanan et al, 2006], national or local legislation may require

annual boosters.



6.8 Disease control in specific situations

6.8.1 Shelters

In endemic areas, stray cats should be always considered at exposure risk and handling

and nursing of rescued animals should be considered dangerous even if they are

asymptomatic.

6.8.2 Breeding catteries

Risk exposure is generally almost nil in breeding catteries because usually pedigree cats

are kept strictly indoors, but their vaccination is under local or state regulation.

6.8.3 Vaccination of immunocompromised cats

6.8.3.1 FIV-positive cats

FIV-positive cats should be kept confined indoors to avoid transmission to other cats, to

protect them from other infections and to slower the progression of FIV infection itself.

This is an efficient preventive measure for rabies in areas at risk, but national or regional

legislation should be adhered to. In outdoor cats with risk of exposure to rabies,

vaccination is strongly advised.

6.8.3.2 FeLV-positive cats

In vaccination studies it was demonstrated that FeLV-infected cats may not be able to

mount adequate immune response to some rabies vaccines [Franchini 1990]. FeLV-

infected cats should be confined strictly indoors to prevent spread to other cats in the

neighbourhood: if cats are allowed to go outside in area at risk for rabies, more frequent

vaccination may need to be considered (e.g. every 6 months).

6.8.3.3 Chronic disease

There is general agreement that cats with acute illness should not be vaccinated but cats

with chronic illness such as renal disease, diabetes mellitus or hyperthyroidism should be

vaccinated regularly if they are at risk of exposure.

6.8.3.4 Cats receiving corticosteroids or other immunosuppressive drugs

In cats receiving corticosteroids, every vaccination should be considered carefully.

Depending on dosage and duration of treatment, corticosteroids may cause functional

suppression of immune responses, particularly cell-mediated immune responses, but

studies exploring rabies vaccine efficacy in cats receiving corticosteroids are lacking. In

dogs, corticosteroids do not appear to result in ineffective immunizations if given for



short periods of time at low to moderate doses [Nara et al, 1979]. However, concurrent

use of corticosteroids at the time of vaccination should be avoided if practical.



6.9 References

Aubert MF (1992). Practical significance of rabies antibodies in cats and dogs. Rev Sci

Tech 11, 735-760.

Barrat J (1993). ELISA systems for rabies antigen detection. Proceedings of the Southern

and estern African Rabies Group International Symposium. Pietermaritzburg, South

Africa, 29-30 April 1993, 152-155.

Barrat J, Picard-Meyer E, Cliquet, F (2006). Rabies diagnosis. Dev Biol (Basel) 125, 71-7.

Review.

Bernard KW (1985). Clinical rabies in humans. In Rabies concepts for medical

professionals Ed Winkler WG. Merieux Institute, Miami, FL, 45.

Birgham J, van der Merwe M (2002). Distribution of rabies antigen in infected brain

material: determining the reliability of different regions of the brain for the rabies

fluorescent antibody test. J Virol Methos 101 85-94.

Blancou J, Pastoret P-P (1990). La rage du chat et sa prophylaxie. Ann Med Vet 134,

315-324.

Bourhy H, Rollin PE, Vincent J, Sureau P (1989). Comparative field evaluation of the

fluorescent antibody test, virus isolation from tissue culture, and enzymes

immunodiagnosis for rapid laboratory diagnosis of rabies. J Clin Microbiol, 27, 519-

523

Charlton KM, Nadin-Davis S, Casey GA, Wandeler AI (1997). The long incubation period

in rabies progression of infection in muscle at the site of exposure. Acta

Neuropathol 94, 73-77.

Cliquet F (2006). Vaccination of pets agains rabies in the context of movements in the EU

– Serological testing as a measure to check efficacy of rabies vaccination.

Vaccinology Symposium, Prague, October 10th, 2006.

Cupillard L, Juillard V, Latour S, Colombet G, Cachet N, Richard S, Blanchard S, Fischer L

(2005). Impact of plasmid supercoiling on the efficacy of a rabies DNA vaccine to

protect cats. Vaccine 23, 1910-1916.

Day MJ, Schoon HA, Magnol JP, Saik J, Devauchelle P, Truyen U, Gruffydd-Jones TJ,

Cozette V, Jas D, Poulet H, Pollmeier M, Thibault JC (2007). A kinetic study of

histopathological changes in the subcutis of cats injected with non-adjuvanted and

adjuvanted multi-component vaccines. Vaccine 200; 25(20), 4073-84.

Deem SL, Davis R, Pacheco LF (2004). Serologic evidence of nonfatal rabies exposure in

a free-ranging Oncilla (Leopardus tigrinus) in Cotapata National Park, Bolivia. J

Wildlife Dis 40, 811-815.



Dubielzig RR, Hawkins KL, Miller PE (1993). Myofibroblastic sarcoma originating at the

site of rabies vaccination in a cat. J Vet Diagn Invest 5, 637-638.

Etessami R, Conzelmann KK, Fadai-Ghotbi B, Natelson B, Tsiang H, Ceccaldi PE (2000).

Spread and pathogenic characteristics of a G-deficient rabies virus recombinant: An

in vitro and in vivo study. J Gen Virol, 81, 9, 2147-2153.

Fekadu M (1991). Latency and aborted rabies. In The natural history of rabies, Ed: Baer

GM, CRC Press, Boca Raton, Florida, 191-198.

Fogelman V, Fischman HR, Horman JT, Grigor JK (1993). Epidemiologic and clinical

characteristics of rabies in cats. J Am Vet Med Assoc 202, 1829-1838.

Fooks AR (2003). Isolation of a European bat lyssavirus type 2 from a Daubenton's bat in

the United Kingdom Vet Rec 152(13), 383-7.

Fooks AR, McElhinney LM, Marston DA, Selden D, Jolliffe TA, Wakeley PR, Johnson N,

Brookes SM (2004). Identification of a European bat lyssavirus type 2 in a

Daubenton's bat found in Staines, Surrey, UK. Vet Rec 155(14), 434-5.

Franchini M (1990). Die Tollwutimpfung von mit felinem Leukämivirus infizierten Katzen,

Vet.Diss. Zürich Univ.

Fu ZF (1997). Rabies and rabies research: past, present and future. Vaccine, 15 (Suppl)

20-24.

Garenne N, Lafon M (1998). Sexist diseases. Perspect Biol Med 41, 176-189.

Green SL (1997). Rabies. Vet Clin North Am: Equine Pract 13, 1-11.

Greene CE, Rupprecht CE (2006). Rabies and other Lyssavirus infections. In Greene CE

(ed): Infectious diseases of the dog and cat. Elsevier Saunders, St Louis, Missouri,

167-183.

Hanlon CA, Kuzmin IV, Blanton JD, Weldon WC, Manangan JS, Rupprecht CE (2005).

Efficacy of rabies biologics against new lyssaviruses from Eurasia. Virus Res 111,

44–54.

Harris SL, Mansfield K, Marston DA, Johnson N, Pajamo K, O'Brien N, Black C, McElhinney

LM, Fooks AR (2007). Isolation of European bat lyssavirus type 2 from a

Daubenton's bat (Myotis daubentonii) in Shropshire. Vet Rec 161(11), 384-6.

Hohl P, Burger R, Vorburger C, Steck F (1978). The re-emergence of human rabies in

Switzerland. A case history [in German]. Schweiz Med Wochenschr 108(16), 589-

92.

Hooper DC (2005). The role of immune responses in the pathogenesis of rabies. J

Neurovirol 11, 88-92.



Hooper DC, Morimoto K, Bette M, Weihe E, Koprowski H, Dietzschold B (1998).

Collaboration of antibody and inflamation in clearance of rabies virus from the

central nervous system. J Virol 72, 3711-3719.

Jackson AC (2002). Pathogenesis. In Rabies. Eds Jackson AC, Wunner WH. Academic

Press, San Diego, 245-282.

Johnson N, McKimmie CS, Mansfield KL, Wakeley PR, Brookes SM, Fazakerley JK, Fooks

AR (2006). Lyssavirus infection activates interferon gene expression in the brain. J

Gen Virol 87, 2663-2667.

Johnson N, Selden D, Parsons G, Healy D, Brookes SM, McElhinney LM, Hutson AM, Fooks

AR (2003). Isolation of a European bat lyssavirus type 2 from a Daubenton's bat in

the United Kingdom Vet Rec 152(13), 383-7.

Lafon M (2002). Immunology. In Rabies, Eds Jackson AC, Wunner WH, Academic Press,

San Diego, CA, 351-371.

Lakshmanan N, Gore TC, Duncan KL, Coyne MJ, Lum MA, Sterner FJ (2006). Three-year

rabies duration of immunity in dogs following vaccination with a core combination

vaccine against canine distemper virus, canine adenovirus type-1, canine

parvovirus, and rabies virus. Veterinary Therapeutics 7(3), 223-231.

Marcovistz R, Hovanessian AG, Tsiang H (1984). Distribution of rabies virus, interferon

and interferon-mediated enzymes in the brain of virus-infected rats. J Gen Virol 65,

995-997.

Marcovistz R, Leal EC, Matos DC, Tsiang H (1994). Interferon production and immune

response induction in apathogenic rabies virus-infected mice. Acta Virol 38, 193-

197.

Murphy FA, Bell JF, Bauer SP, Gardner JJ, Moore GJ, Harrison AR, Coe JE (1980).

Experimental chronic rabies in the cat. Lab Invest, 43, 231-241.

Murphy FA, Harrison AK, Win WC, Bauer SP (1973). Comparative pathogenesis of rabies

and rabies-like viruses: infection of the central nervous system and centrifugal

spread of virus to peripheral tissues. Lab Invest 29(1), 1-16.

Nara PL, Krakowka S, Powers TE. (1979). Effects of prednisolone on the development of

immune responses to canine distemper virus in beagle pups. Am J Vet Res;40(12),

1742-7

O’Brien DP, Axlund TW (2005). Brain disease. In Ettinger Eds SJ and Feldman EC,

Textbook of Veterinary Internal Medicine. Diseases of the dog and cat. Elsevier

Saunders, St Louis, Missouri, 803-835.

OIE (2007): Rabies. In: Manual of Diagnostic Tests and Vaccines for Terrestrial Animals.

Chapter 2.2.5. http://www.oie.int/eng/normes/mmanual/A_00044.htm



Osorio JE, Tomlinson CC, Frank RS, Haanes EJ, Rushlow K, Haynes JR, Stinchcomb DT

(1999). Immunization of dogs and cats with a DNA vaccine against rabies virus.

Vaccine, 17, 1109-1116.

Paoletti E (1996). Applications of pox virus vectors to vaccination: an update. Proc Natl

Acad Sci USA, 93, 11349-11353.

Pastoret PP, Brochier B, Gaskell RM (2004). Rabies virus infection. In Feline medicine and

therapeutics Eds Chandler EA, Gaskell CJ, Gaskell RM, Blackwell Publishing, 637-

650.

Perez O, Paolazzi CC (1997). Production methods for rabies vaccine. J Ind Microbiol

Biotechnol, 18, 340-347.

Rupprecht CE, Childs JE (1996). Feline rabies. Feline Pract 24(5), 15-19.

Schneider LG (1995). Rabies virus vaccines. Dev Biol Stand, 84, 49-54.

Servat A, Feyssaguet M, Morize JL, Schereffer JL, Boue F, Cliquet F (2007). A

quantitative indirect ELISA to monitor the effectiveness of rabies vaccination in

domestic and wild carnivores. J Immunol Methods, 318 (1-2), 1-10.

Servat A, Wasniewski M, Cliquet F (2006). Tools for rabies serology to monitor the

effectiveness of rabies vaccination in domestic and wild carnivores (Review). Dev

Biol (Basel) 125, 91-4.

Tepsumethanon V, Lumlertdacha B, Mitmoonpitak C, Sitprija V, Meslin FX, Wilde H

(2004). Survival of naturally infected rabid dogs and cats. Clin Infect Dis 39 (2),

278-80

Tepsumethanon V, Lumlertdacha B, Mitmoonpitak C, Wilde H (2003). Clinical diagnosis

for rabies in live dogs. Proceedings of 28th World Congress of WSAVA, October 24-

27, 2003 – Bangkok, Thailand.

Tjørnehøj K, Rønsholt L, Fooks AR (2004). Antibodies to EBLV-1 in a domestic cat in

Denmark. Vet. Rec 155, 571-572.

Vos A, Schaarschmidt U, Muluneh A, Muller T (2003). Origin of maternally transferred

antibodies against rabies in foxes. Vet Rec 153, 16-18.

World Health Organisation (WHO), http://www.who.int/rabies/epidemiology/en/ and

http://www.who.int/rabies/rabnet/en/

World Health Organisation (WHO) (2006). Fact sheet on Rabies, revised September

2006. http://www.who.int/mediacentre/factsheets/fs099/en/

Wunner WH, Dietzschold B, Curtis PJ, Wiktor TJ (1983). Rabies subunit vaccines. J Gen

Virol, 64, 1649-1656.



Xiang ZQ, Yang Y, Wilson JM, Ertl HC (1996). A replication-defective human adenovirus

recombinant serves as a highly efficacious vaccine carrier. Virology, 219, 220-227.


rabies in cats - · pdf filerabies in cats the following recommendations have been formulated...

Documents