Importance of Vaccination for Prevention and Control of Feline Rabies : A Short Review
Dr. Ayesha S Mujawar1 and Dr. Sajid Hussain2
- Junior Veterinary Surgeon, nPAWS Organization, Nagpur, Maharashtra, India.
- Veterinary Officer, Suguna Foods Pvt. Ltd.,Safidon, Jind, Haryana, India.
ABSTRACT
Felines are a very popular pet animal worldwide and in India. In addition, there are a large number of non-owned cats living next to human populations in India. Vaccination is an important measure for preventing infectious diseases among cats and when possible, preventing the spread of zoonotic diseases to humans, as in the case of rabies. Although feline vaccination has been a standard of care for cats for many years, there are changes in the vaccines available, current concepts of when and how to vaccinate cats, and what is considered as core vaccination for a cat versus what can be considered as non-core vaccination which should only be recommended in certain circumstances. Vaccination guidelines for cats must be tailored to the animal’s environment, geographical location, and be updated regularly as knowledge progresses and new products are available. The purpose of this review was to evaluate and describe the vaccines available and used in India to prevent feline rabies, and to update on this disease. This short review highlights their pathogenicity, modes of transmission, symptoms and the type of vaccines produced for their prevention and control.
Key words: Feline, Rabies, Pathogenesis, Clinical Signs, Vaccination. - INTRODUCTION
Vaccination is the exposure of an animal or human to antigen of a pathogen and the induction of an immune response that will protect the host when it encounters the virulent pathogen. Vaccination of cats is intended to prevent them from becoming infected with some of the most common feline infectious diseases. Cats are often protected against some infectious diseases by maternally derived antibodies in their blood, but the levels of these antibodies decrease gradually after birth and eventually kittens must mount their own immune responses in order to avoid being infected and becoming ill (Claus et. al., 2006; Baneth, 2020). Vaccination of cats is extremely important for prevention of infections with severe and life-threatening infectious diseases and in some cases also for protecting the cat’s environment and owners, as in the case of rabies vaccination. (Kass, 2018; Baneth, 2020). Feline and canine vaccines have been divided by the World Small Animal Veterinary Association (WSAVA) vaccination guidelines group (VGG) as core or non-core, with the core vaccines defined as vaccines that all cats or dogs throughout the world must receive (Day et al., 2015; Baneth, 2020).
Rabies is a fatal zoonotic disease of man and other mammals. The dog and cat are high risk species for the transmission of the virus to man. Rabies virus is a member of the Rhabdoviridae family. The genus Lyssavirus contains 14 species (Lefkowitz et al., 2017). Rabies virus is almost always transmitted through saliva via a bite or other skin wound. Cats are more resistant to some strains of rabies virus, but not all strains when compared to the dog. The cat becomes a more important source of rabies virus for man where rabies is well controlled in the dog by vaccination (WSAVA-VGG-Pictorial-Fact-Sheets-June-2015). The present short review describes the transmission, pathogenesis, clinical signs, diagnosis, vaccination, prevention and control of this important viral pathogen in felines having high public health concerns.
TRANSMISSION & PATHOGENESIS
Rabid animals are the only source of virus. It is shed in the saliva some days before the onset of clinical signs, and the agent is transmitted through a bite or a scratch of the skin or mucous membranes (eyes, nose, mouth). The average incubation period in cats is two months, but can range from 2 weeks to several months or even years, depending on the dose of virus transmitted and the severity and site of the wound (Charlton et al., 1997; Jackson, 2002). 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, hence the greater the distance from the central nervous system, 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), which must be taken into account when evaluating wound history, especially in free-roaming cats exhibiting sudden behavioral change and/or signs of motor neuron dysfunction that may initiate the clinical phase. The virus replicates in striated muscle and 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 peripheral nerves directly, spreading to the central nervous system via the axonal route.
The virus then travels 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 that time, 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). The rabies virus glycoprotein probably plays a 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).
CLINICAL SIGNS
There are two disease forms can be identified in cats that is furious and dumb form. The furious form has three clinical phases (prodromal, furious or psychotic and paralytic) but they are not always distinct in cats. The dumb form has two phases prodromal and paralytic. During the very short prodromal phases (12-48 hours) of both forms, a wide range of quite non-specific clinical signs like fever, anorexia, vomiting and diarrhea may occur, sometimes accompanied by neurological signs. Behavioral changes may be noticed first, such as an unusually friendly or otherwise shy or irritated behavior and increased vocalization. Altered behavior depends on forebrain involvement and may be associated with other neurological signs reflecting the infection site (O’Brien and Axlund, 2005).
DIAGNOSIS
The serious public health risk particularly for veterinarians requires a careful differential diagnosis. Any CNS disease characterized by sudden onset and rapidly evolving clinical signs must include rabies for free roaming, unvaccinated cats. Routine laboratory diagnosis should be undertaken using only the techniques specified by the OIE (Terrestrial Manual – OIE 2017) and the WHO (Laboratory Techniques in Rabies). The Fluorescent antibody test is the primary method recommended (Bourhy et al., 1989; Birgham and Merwe, 2002). The confirmation test should use rabbit tissue culture inoculation test. The mouse inoculation test can be used only if rabbit tissue culture is not available. ELISA is used for testing vaccinated animals (Servat et al., 2007).
VACCINATION & PREVENTION
A strong immune response is the only effective defense against rabies. Standard rabies vaccination, when administered through proper protocols, affords protection against all variants. Vaccine failure does occur, but is very rare. Vaccines are either inactivated (killed) or recombinant. Most rabies vaccines are first administered at age 3 months, boostered a year later, and then every one or three years thereafter. The vaccine label should be reviewed carefully for the exact protocol required. Adult cats being vaccinated for the first time should have a booster a year later. An animal is considered immunized about four weeks after its first rabies vaccination, or immediately after a booster. Indoor‐only cats should be vaccinated against rabies. The risk of injection‐site fibrosarcoma exists when vaccinating cats. Recombinant vaccinations appear to be associated with a lower risk than killed vaccines (Beeler and Ehnert, 2020)
Table 1: Guidelines and recommendations for core (recommended), non-core (optional) and not recommended vaccines for cats. Adapted from the WSAVA recommendations.
Vaccine Initial kitten vaccination Initial adult vaccination Revaccination recommendation
Rabies (canary pox virus-vectored recombinant, non-adjuvanted, parenteral) Administer a single dose as early as 12 weeks of age, with revaccination 1 year later. Administer a single dose with revaccination at 1 year of age. Revaccination (booster) as per licensed DOI or as required by local regulations. Core in areas where the disease is endemic.
Rabies (1- and 3-year killed, adjuvanted products are available, parenteral) Administer a single dose as early as 12 weeks of age, with revaccination 1 year later. Administer a single dose with revaccination 1 year later. Revaccination (booster) as per licensed DOI or as required by local regulations. Core in areas where the disease is endemic.
References:
Baneth, G. (2020). Feline Vaccination Guidelines in Israel. Israel Journal of Veterinary Medicine: Vol. 75 (3).
Beeler E. and Ehnert K. (2020). Rabies in Dogs and Cats. Clinical Small Animal Internal Medicine Volume II, First Edition. Edited by David S. Bruyette: www.wiley.com/go/bruyette/clinical.
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 Methods, 101, 85-94.
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.
Claus, M.A., Levy, J.K., MacDonald, K., Tucker, S.J. and Crawford, P.C.: Immunoglobulin concentrations in feline colostrum and milk, and the requirement of colostrum for passive transfer of immunity to neonatal kittens. J. Feline. Med. Surg. 8:184-191, 2006.
Day, M.J., Karkare, U., Schultz, R.D., Squires, R. and Tsujimoto, H.: World Small Animal Veterinary Association (WSAVA) Vaccination Guidelines Group (VGG). Recommendations on vaccination for Asian small animal practitioners: a report of the WSAVA Vaccination Guidelines Group. J Small Anim. Pract. 56: 77-95, 2015.
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, 2147-2153.
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.
Jackson AC (2002): Pathogenesis. In Rabies (Eds Jackson AC, Wunner WH). Academic Press, San Diego, 245-282.
Kass, P.H.: Prevention of Feline Injection-Site Sarcomas: Is there a scientific foundation for vaccine recommendations at this time? Vet. Clin. North Am. Small Anim Pract. 48:301-306, 2018.
Lefkowitz EJ, Adams MJ, Davison AJ, Siddell SG, Simmonds P (editors) (2017): Classification and Nomenclature of Viruses; 10th Online Report of the International Committee on Taxonomy of Viruses. https://talk.ictvonline.org/ictv-reports/ictv_online_report/negative-sense-rna-viruses/mononegavirales/w/rhabdoviridae/795/genus-lyssavirus.
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, 1-16.
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.
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 (2017): Rabies. In Manual of Diagnostic Tests and Vaccines for Terrestrial Animals. Chapter2.1.17 http://www.oie.int/fileadmin/Home/eng/Health_standards/tahm/2.01.17_RABIES.pdf
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, 1-10.
World Health Organisation (WHO). http://www.who.int/rabies/epidemiology/en/
The World Small Animal Veterinary Association (WSAVA) at: https://www.wsava.org/WSAVA/ media/PDF_old/WSAVA-Vaccination-Guidelines-2015-Full-Version.pdf.
The Advisory Board for Cat Diseases (ABCD) at: http://www.abcdcatsvets.org/vaccines-andvaccination-an-introduction/.
