I REMEMBER being horrified as a new graduate, back in the days when BSAVA congress was held in the Hammersmith Novotel and when having three concurrent lecture streams was considered novel and daring, to see delegates not sitting attentively in the lectures and taking notes, but rather standing in the commercial exhibition, drinking coffee (or something stronger!) and chatting to each other.
Outrageous! And yet now I find myself doing exactly that. Not all the time of course – I do attend some lectures and several of the clinical research abstracts. But now catching up with old friends and being introduced to new ones is a key part of congress.
That’s been legitimised these days by calling it networking, hasn’t it? And it’s by no means worthless – not merely a social gathering by any manner of means. Let me give you an example. I chanced to bump into an old friend and over a coffee he waxed lyrical about a paper in the Transactions of the Royal Society of Tropical Medicine and Hygiene.
That’s not a journal that’s on my regular reading list I must admit and the paper to which I was directed, “Heterologous and sex differential effects of administering vitamin A supplementation with vaccines”, would not have leapt out of the page at me I have to say!
Its take-home message, that the success or failure of vaccination depends critically on the health and immune status of the individual, was not surprising. What was novel to me at least was a key finding that vaccination against measles and tuberculosis using the BCG immunogen reduced mortality caused by other diseases.
This seems to occur since immunity linked to natural killer cell activity is increased, having a beneficial effect against many other pathogens quite apart from the target organism. Well, you might ask, what on earth has this to do with veterinary medicine, interesting though it may be with regard to disease in human patients in the third world? The striking thing for me was that a day or two earlier in our pre-congress ophthalmology meeting, Professor Mike Lappin from Colorado State had been talking about exactly the same area, but concerning his findings in cats.
Immunisation using a modified live feline herpesvirus-1 and feline calicivirus vaccine protected cats against disease caused by Bordetella bronchiseptica.
Now that was something I hadn’t heard before so I quickly popped “vaccination”, “heterologous” and “immunity” into PubMed. Encouragingly there were only 860 papers – quite often such general searches call up tens of thousands of references!
The most recent ones included one from Mike Lappin’s group but also interesting papers on diseases from tuberculosis through influenza to tuleraemia. I like seeing where it all started, so I scrolled to the first of those 860 papers. I expected to see something maybe back in the ‘90s so imagine my surprise to find the first paper, “Non-specific immunity by heterologous vaccination” in the American Journal of Public Health back in 1933! If you’ve nothing better to do over coffee today, why not read it at www.ncbi.nlm.nih.gov/pmc/articles/PMC1558353/pdf/amjphnation00933-0054.pdf. The wonders of modern technology, hey?!
It’s a beautifully written piece that starts by reminding us that back in Pasteur’s day it was recognised that recovering from one disease protected you from others. The authors continue with a great literature review emphasising the point.
Calmette’s work with BCG, for instance, showed that vaccination protected not only against tuberculosis but reduced mortality in young infants more generally. Well I never knew that even though I did my first degree and a PhD in immunology – how hopeless is that?
The researchers back in the 1930s clearly had no clear understanding of the innate versus the acquired immune system and the part natural killer cells play as we have now. But they knew that this non-specific vaccination gave a “mobilization, strengthening and training of the immune system”. And that was 80 years ago!
Vaccination issues
We have quite an issue from many quarters these days with the regular vaccination of cats and dogs, don’t we? A quick Google search comes up with quotations such as, “There is no scientific data to support a recommendation for annual administration of vaccines … repeated administration of vaccines may be associated with a higher risk of anaphylaxis and autoimmune diseases.”
Can we find support for this online? Type “vaccination” and “autoimmunity” into PubMed and sure enough up come one or two fascinating papers. Ever heard of ASIA in sheep? Well I hadn’t, but it turns out that vaccination can cause this autoimmune/auto-inflammatory syndrome induced by adjuvants such as mineral oils giving weakness, cachexia, tetraplegia and death. But this seems only to have been seen after bluetongue virus vaccination in 2013.
Multiple vaccinations in farmed salmon can give rise to auto-antibody-associated thrombosis hepatitis, and glomerulonephritis. So ASIA can affect salmon as well as sheep, and it can be induced by injection of adjuvants in laboratory rodents too.
We have no well-documented series of cases in these companion animal species, however, maybe because mineral oil adjuvants aren’t used in those vaccinations.
There’s more information available through the WSAVA’s vaccination guidelines at www.wsava.org/sites/default/files/WSAVA_OwnerGuidelines_September2010.pdf. But do we have evidence for benefits of regular vaccination apart from the obvious ones of protecting against specific infectious diseases?
Maybe the heterologous effects we talked of earlier might be important for diseases quite different from those against which the animal has been vaccinated but we do need more evidence for that. Are there data showing other benefits of vaccination?
Evaluations reported
At BSAVA we reported findings on a thousand vaccination examinations at 10 different clinics, evaluating the number of consultations at which a condition was found which would otherwise have been missed. In animals from middle-age onwards, 20% had dental disease, 15% had dermatological problems and almost 15% had weight issues noted.
Sadly, it was difficult to assess the benefit of alerting the owner to weight problems as we did not have longitudinal data on weight changes after the consultation. That’s an interesting topic for future work! Now of course it could be said that such examinations could be done without vaccination, but it seems to be a fact of life that people need an enticement to visit for an examination of their dog or cat.
Or maybe not: two of the clinics we visited managed to persuade owners that routine examinations were essential without vaccinations every year. So maybe there is more research to do on reasons people bring their pets to the vet and how we can persuade them that routine examinations are essential.
Hopefully, our study presented at BSAVA might help – I must go and write it up!
