Dr. Thomas Müller

Laborleiter
Institut für molekulare Virologie und Zellbiologie
……………………………………………………………
Friedrich-Loeffler-Institut
Bundesforschungsinstitut für Tiergesundheit
Federal Research Institute for Animal Health

Your experience with rabies:

What is your education? How long have you been working with rabies? Why did you start working with rabies?

 

I am a veterinarian by background. I have been working with rabies for 27 years. Rabies was my topic when I was a PhD student and it was by coincidence that I stuck with it.

WORLD RABIES DAY

September 28th is the World Rabies Day (WRD), a day dedicated to rabies prevention. What is the role of the rabies scientific community in increasing awareness about rabies? What is its significance to you? Are you doing something to increase awareness about rabies?

The main objective of the rabies scientific community is to increase knowledge and understanding of the benefits and impact of rabies research collaboration by the general public and politicians.

The enormous wealth of knowledge gathered by rabies scientists for rabies prevention and control in our daily lives is often overlooked and public opinion is often only mobilized when rabies hit those who usually do not have to fear it.

Increasing of awareness is one of our terms of reference as a WHO CC. For example, we issue joint press releases with our cooperation partner and the OIE and promote the WRD on our Rabies Bulletin Europe website.

Awareness:

Do you think people, in general, know what rabies is? Do you think there is a need to increase awareness among the general population?

Yes, in principle I think people know what rabies is. However, most of the people think locally (in their environment) rather than globally. As a result, the true burden of rabies in great parts of the world is often taken is as granted by the great majority of the general public, something the little man cannot do much about it.

Burden:

The global burden of rabies is estimated to be around 60.000 death per year. Do you think the global burden of rabies might be higher?

No, I think the figures are pretty accurate.

Geographical burden:

Why is it a problem of mainly Asia and Africa? What countries experience the most number of rabies cases?

Rabies is a neglected disease of poverty, affecting under-privileged communities. This is why rabies is a problem of mainly Asia and Africa.

Dogs are the problem:

Some people believe that if we eliminate rabies from stray dogs, rabies will no longer be a problem. Do you think targeting stray dogs is the way to go?

No. There is no evidence that stray dogs alone are responsible for maintaining the disease and that just by solely focusing on this subpopulation the problem will be solved.

This would be the wrong message. In my opinion, to successfully eliminate canine rabies it is of utmost importance to make sure that there is a high vaccination coverage throughout the dog population no matter whether they are confined or non-confined. In any case, however, vaccination of stray dogs should be included in any dog rabies elimination program. Here, oral vaccination of dogs could be an alternative method.

Transmission:

How is rabies transmitted? Do we have to worry about airborne transmission? Can we contract rabies by eating meat of a rabid animal or drinking unpasteurized milk?

In most cases the disease is transmitted via the bite of rabid animals, which shed infectious virus with their saliva. The virus enters the body through transdermal inoculation (i.e. wounds) or direct contact of infectious material (i.e. saliva, cerebrospinal liquid, nerve tissue) to mucous membranes or skin lesions. The virus cannot penetrate intact skin. Airborne transmission does not play a role in the field at all. Also, I am not aware of any human rabies case caused by eating meat of a rabid animal or drinking unpasteurized milk.

Pets:

Is rabies a problem in pets?

No. In most European and North American countries vaccination of pet animal is compulsory as integrated part of the implemented rabies control program. Also, for the non-commercial movement of pets vaccination of such in the frame of pet travel scheme is mandatory.

Sick bats:

Bats are the second most important source of rabies. How can you recognize a bat with rabies?

Due to the neurotropism of lyssaviruses (viruses that cause rabies), in principle clinical symptoms in bats are not different to those seen in other mammals.

Other animals:

Certain animals are less at risk of contracting rabies, such as rabbits, squirrels or rats. Whys is that? What about rabies in non-mammals, such as chicken and birds?

In principle, all mammals are susceptible to rabies infection. The risk of contracting rabies, however, depends on biological, biogeographical, population demographic and behavioral characteristics of animal species. Also, host pathobiological constraints may limit the dissemination of the virus from the Central Nervous System to the salivary glands and additional replication at this site, such that most mammalian taxa are unable to efficiently transmit the virus. Despite a few questionable reports, it is commonly accepted that birds are not susceptible to rabies.

Research agenda:

What in your opinion should scientists focus their research on?
  • Diagnostics: Development of reliable broad spectrum immunochromatographic (lateral flow tests) and molecular pen-side tests for rapid detection of rabies viral antigens and/or viral RNA in the field to improve surveillance across regions.
  • Vaccines: Development of affordable multivalent vaccines with a broader protection spectrum either using classical methods in cell culture or by molecular techniques (recombinant virus expressing chimeric G protein, protein vaccines).
  • Vaccines: Research on novel vaccine carriers and adjuvants that activate innate immune response when used for post-exposure prophylaxis.
  • Post-exposure intervention: More research, development, and assessment of immunoglobulins or alternatives, such as human monoclonal antibodies, for use in rabies prophylaxis to ensure wider access to passive immunization at a reduced cost.

Which types infect dogs:

Dogs are known to only transmit one type virus, type 1. Why are the other types not endemic in dogs? How does the virus persist in the dog population if dogs eventually die from rabies?

From a taxonomic point of view rabies viruses are no longer segregated into genotypes but are divided into virus species. But yes, it is true that dogs only transmit rabies virus. The fact that certain virus species are associated to different reservoir hosts including dogs is a result of virus evolution and long-term host adaptation. For reasons unknown, spillovers of other bat-associated lyssaviruses to humans and other mammals including dogs is very rare.

Climate change:

Do you think that increased deforestation or climate change leading to increased forest-fire could increase rabies transmission by other animals, such as other carnivores or bats?

I do not think that increased deforestation or climate change will increase rabies transmission by carnivores. Such a scenario, however, might affect transmission of rabies by bats and because of habitat loss those species would need to explore new habitats. There are a few examples showing that human encroachment in rain forests (the way how people alter the landscape), clearly increased prevalence of causative agents in bat species that had to adapt to fragmented landscape compared to intact rain forests. As a result, diseases are likely to spill over into humans more easily.

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