This document discusses the risks of communicable diseases spreading between domesticated animals and wildlife. It provides examples of diseases that have spread in this way, such as avian influenza between poultry and wild birds, bovine tuberculosis between cattle and wildlife like possums and deer, and African swine fever between domestic pigs and wild boar. The author argues that minimizing contact between domestic and wild animals, quickly controlling outbreaks in domestic populations, and avoiding disturbing, gathering or feeding wild animals can help curb the cycle of infection at the wildlife-domestic animal interface.

1. Combating communicable diseases at the farm – wildlife interface
Global communicable animal disease burden on the rise
With an ever growing population of humans and a rising standard of life in developing countries
the required amount of animal protein is increasing. So the number of chickens and other poultry,
pigs, sheep, goats and cattle worldwide is also on the rise. When you put climate change and
changing husbandry systems in the mix, you can imagine that the chances of wildlife coming into
contact with domesticated animals are higher than ever before. Therefore the chances of exchange
of infectious organisms is also increasing.
In this article I’m going to share my perspective on these phenomena and try to outline a way to
deal with these challenges.
Infectious agents typically need a sufficiently large and well connected population to thrive in,
combined with ways to find new populations to infect. For this reason the connections between
livestock and wildlife are vital for their dispersal. Furthermore these connections can undo all
efforts man makes to curb infections in livestock.
HPAI
When we look at the spread of
Avian Influenza last year we see
an overwhelming spread of this
disease in wild birds across central
and western Europe in a matter of
weeks. That spread lead to massive
outbreaks of avian influenza in farms
across Europe. Where did that virus
come from, you may ask. Well, the
virus had already been spotted in
Russia, in the summer breeding
grounds and lakes of migrating birds.
Before that outbreaks of this virus
had been seen in China and South
Korea, where a lot of avian influenza
types can be found.
It is in my opinion probable that the
combination of wild birds and captive
poultry has been vital for the
increased occurrence of HPAI viruses
these last two decades. Captive birds
provide the dense population that causes the virus to multiply, whereas wild birds provide long
distance spread. Especially when you take into account that every multiplication can cause genetic
mutation and every simultaneous infection can cause genetic reassortment, a prolonged presence
of endemic HPAI in a country will the increase the chance of emergence of new HPAI viruses. In

2. this context it is not opportune to “blame” either wild birds of poultry, but it is vital for the
protection of global animal, public and wildlife health that biosecurity is enhanced so that poultry
will not come into contact with wild birds and that transport of possibly infected poultry is
prevented.
Bovine Tuberculosis
Bovine tuberculosis (bTB) is also a disease that can jump between captive and wild animals. A
large variety of mammals is susceptible to the different varieties of the Mycobacterium
Tuberculosis complex. In the case of bTB, next to cattle, the common brushtail possum (New
Zealand), badger (Great Britain) and deer (USA, central Europe) serve as a reservoir.
Whereas HPAI in its speed of transmission is a global problem, bTB has more regional effects. It is
not the speed of transmission that is the problem with bTB, but the resistance of the bacterium,
the duration of infection, coupled with the low sensitivity and specificity of the tests that are used
that make this disease very hard to eradicate. Especially when a proportion of the reservoir of
disease is not in the farm, but outside, breakthroughs can not be attributed to a specific source
and can therefore be very frustrating for the stakeholders.
African Swine Fever
When we look at African Swine Fever the relationship between wild and domesticated pigs is
evident. During the outbreak that is still ongoing in eastern Europe the disease probably originated
in domesticated pigs and was spread to wild boar. In that group it spread for thousands of
kilometres to the north, unimpeded by any actions of man. During this outbreak we have seen
many incursions of disease from wild boar to domesticated pigs, so the threat continues.
When you look at these examples it is obvious that domesticated animals can pose a threat for
wild and vice versa. The point is that we need to find a way to intervene in key places to curb the
cycle of infection.
I think an intervention strategy should be based on three points:
http://www.tbhub.co.uk/biosecurity/wildlife/biosecurity-guidance-farm-buildings/
1. Minimise directandindirectcontactbetweendomesticatedandwildanimals.
2. If a communicable diseaseshouldbreakoutindomesticatedanimals,curbitas soonas possible.

3. 3. Don’tdisturb,gatheror feedwildanimals.
Ad 1: Biosecurityisextremelyimportanttokeepinfectiousdiseasesfromenteringthe farm. The
measuresthatneed tobe taken dependonthe extentof the threatthat ispresent.Forinstant
duringan episode of HPAIinwildbirdsitisnotprudentto letpoultryrange outside.Also
changingfootwear,washinghands,showeringbefore enteringthe premisesbecome more
importantduringtimesof heightenedprobabilityof contaminationof the surroundingarea.
Generallyspeakingitisimperative todenywildanimalsaccesstobarnsand feedstock,and
preventdirectcontactbetweendifferentanimal groups.
Ad 2: Quickreactionto a notificationof acommunicable disease isimperative tominimisespreadof
infectiontootheranimals,wildordomesticated. The firststage isa fastnotificationtothe
authorities.Animal ownersshouldbe aware andhave anincentive tonotifypossible disease
outbreakstothe government.The nextstepisa swiftresponse. Thisnecessitatesaquick
reactionforce inplace at all times,able toreactat a moment’snotice. The reactioncanmean
culling,vaccinating,orquarantining,dependingonthe diseaseandpossibilitiesof the
stakeholders.
Ad 3: Gatheringwildanimalstogetherincreasesthe numberof contactsina population,while
disturbance mixespopulationsup,bothcanbe instrumental inspreadof disease.Althoughitis
sometimesinthe bestinterestof animalstobe fed,forinstance duringthe harshwintermonths,
one mustalwaysbe aware that diseasesare presentancan be spreadin thisway.So when
animalsare fed,theyinfact become adomesticatedpopulationandtherefore needtobe
subjecttopoint1 and 2. Feedingwildanimalsnotalwayshappenspurposefully. Oftenwildlife
will scavenge feedthatwasmeantfordomesticanimals.Itisinthe bestinterestof the farmerto
keepwildlife away fromfeed,bothfinanciallyandto prevent(in)directcontactwithcarriersof
disease. Feedingwildlifewillalsocreate apopulationof wildanimalslargerthanthe load
bearingcapacityof the environment.