Thursday, June 12, 2014

Is a single rabies vaccination enough to protect dogs from infection?

Edgar catches the news (NB this is not an official entrant in our David Attenborough giveaway as I took the photo...but how could anyone resist?)

A study just published in the Veterinary Record looked at the efficacy of antirabies vaccination in dogs and found that only 39.67 dogs demonstrated protective antibody levels.

This raises major questions about stray dogs vaccinated against rabies. A single vaccination is no guarantee, though a number of aid programs are designed to deliver one vaccine to all animals. This is important - but not enough to establish protective immunity. 

We are very fortunate not to have rabies in Australia, but it’s a scary disease. I should at this point state that rabies is NOT a core vaccination in Australia for companion animals and is only given by Government and AQIS certified vets to animals for the purposes of export to other countries.

Interestingly the factors found to play a role in immunity and maintenance of a protective antibody titre in dogs were regular vaccination, regular exercise, companionship, non-descript breed, desexing, and being over one year old. Stressed, poorly cared for animals are less likely to mount an effective immune response.

The study looked at 300 serum samples from dogs vaccinated for rabies at Madras Veterinary CollegeTeaching Hospital in Chennai, India – a rabies endemic area. To be included in the study, dogs had to be three months old, clinically well and have had at least one rabies vaccination.

Animals less than one year old were less likely to have a protective antibody titre, possibly because they are less capable of mounting an effective immune response following vaccination – a good incentive to revaccinate these animals.
Interestingly, desexed animals were better able to maintain a protective antibody titre than entire animals. A previous study found that castrated mice responded to antigenic stimulation better than entire mice, with twice the number of T lymphocytes, but it isn’t known if this is the explanation here.

Dogs fed a variety of food – rather than a monotonous and likely deficient diet – were also more likely to have a protective antibody titre suggesting that better nutrition leads to better immunity.

Antibody titres were significantly higher in animals receiving multiple rabies vaccinations. Except in adult dogs that had a history of previous immunisation, a single dose of antirabies vaccine was not enough to maintain a good protective antibody titre for twelve months in 50 per cent of adult dogs and puppies.

It’s a reminder of the importance of re-vaccination, especially in endemic countries.

Meanwhile would you believe that there are some insanely irresponsible people out there who are falsifying rabies vaccination certificates? The impact of such an act could be huge – ranging from leading to human and animal deaths to introducing rabies into a non-endemic country. You can read more about it at the Worms and Germs blog here. It is totally unacceptable to play Russian Roulette with infectious diseases.

Reference

Yale G, Ganesan PL, Tirumurugaan KG, Madhusudana SN, Vijaya Bharathi M, Thangavelu A, Yajaman Belludi A, Sanyal S and Taj S (2014). Factors affecting duration of immunity of rabies vaccination in dogs. Vet Rec Open 2014;1:e000023 doi 10.1136/vropen-2013-000023

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