I just had a recent adventure with rabbits. Like the experience of many suburbanites, rabbits like to eat all our ornamental vegetation. My wife oversees that department, and she does not like to see that vegetation depleted. She has tried all the repellants and the rabbits keep coming. She has talked about shooting them like her father used to, but I convinced her that was not a good idea. She settled on the idea of live trapping the animals and releasing them in an area far away from the house – like a park or wildlife reserve.
I researched the legality of it all. I was surprised to find out that rabbits are
considered a nuisance animal in the state of Minnesota. As such you can kill them by various means
other than poisoning without a license and at any time. There are obstacles to
both relocating rabbits or how to dispose of them. I contacted both the county
and city natural resource departments. They told me it was illegal to relocate
rabbits onto city, county, or state lands including parks and wildlife areas. The officials confirmed that I did not need a
hunting license to kill them, but that if I did kill a rabbit, I needed to
report it to the DNR. I did not let
anyone know I thought that killing a rabbit was bad karma and I had no
intention of killing them.
I was advised that if I did kill a rabbit, I needed to
handle it with nitrile gloves and double bag it in plastic. Even then I must contact my garbage hauler to
make sure that I could dispose of it in the trash. There were no further
instructions from officials on the next step if the garbage hauler refuses to
take it – but based on how the conversations were going I thought it was
probably digging a deep hole in the yard.
Minnesota is populated by one true rabbit species – the
Eastern Cottontail (Sylvilagus floridanus) and two hare species – the
Snowshoe Hare (Lepus americanus) and the White-tailed Jack Rabbit (Lepus
townsendii). The hares are probably
more common in the north. The defining
characteristics of rabbits versus hares include fewer chromosomes (44 versus
48), altricial birth state versus precocial, shorter gestation (30-31 days
versus 42 days), smaller bodies and shorter ears, highly social versus
solitary, and softer food preference (grass and leafy vegetables opposed to
bark, twigs, and buds). An altricial
birth state means offspring are born in a state where they are unable to feed
or regulate body temperature and as a result need a prolonged period of close
parenting. In the past 10 years there have also been cladistic analyses based
on nuclear and mitochondrial DNA. Like
all taxonomy there is some mismatch of classification. Jackrabbits are hares and Rock hares are
rabbits.
Even before I heard those biosecurity measures from public
officials, I researched the issue of rabbit to human disease transmission (1). Domestic pet rabbits were noted to spread the
expected pathogens like E. coli, Salmonella spp, Yersinia
pseudotuberculosis, and Cryptosporidium. They can also be a source of Hepatitis
E. Pasteurella multocida and Bordetella
bronchiseptica can be spread as respiratory infections in humans. Rabies was detected in one group of rabbits
thought to have been infected by a wild animal.
Dermatophytes and rabbit fur mites can cause localized infections in
humans.
Wild rabbits harbor Francisella tularensis the infectious bacteria causing tularemia. Tularemia is a systemic multisystem disease that can be difficult to diagnose and treat. In the worst case it can cause shock and death. It has also been implicated as an agent that could be used for bioterrorism. Rabbits can also have Babesia spp and Anaplasma phagocytophilum the infectious agents that cause babesiosis and human granulocytic anaplasmosis.
Babesiosis is caused by the obligate intraerythrocytic protozoan
parasite Babesia microti (2).
Severity of the illness is related to degree of parasitemia
(concentration of parasites in the bloodstream) and host factors that lead to
compromised immune response including age. In the extreme cases it can lead to
life threatening complications that require acute care like acute renal
failure, disseminated intravascular coagulation (DIC), congestive heart
failure, acute respiratory distress syndrome (ARDS), and others.
Human granulocytic anaplasmosis is caused by intracellular
bacteria from the Anaplasmataceae family – in this case Anaplasma
phagocytophilum (3). It is a tick-borne
disease meaning that the major reservoir for the agent is small mammals who
transmit it to humans via a tick vector.
Most people who are infected present with an acute flu-like illness that
can progress to involved multiple systems (rash, pneumonitis, myocarditis,
meningoencephalitis, secondary infections, coma).
Most of the infections identified from rabbits come from
direct contact, contact with infected surfaces, and contact with blood, feces,
or other bodily fluids. People raising rabbits as pets, as a food source, or
hunters would appear to be at highest risk and the suggested biosecurity
measures would be protective. In talking
with the local wildlife officials their concern was that rabbit relocation
could be a significant source of disease spread – specifically Rabbit
Hemorrhagic Fever – a viral illness that results in most rabbits dying of
hepatic necrosis 48-72 hours post infection.
Rabbit Hemorrhagic Disease Virus (RHDV) was first described
in China in 1984 and has spread worldwide (4).
It is a small non-enveloped RNA virus about 40 nm in diameter. The genome is about 8 kilodaltons is size. It
is taxonomically classified in the Calciviridae family. That family has 11 genera (Norovirus,
Nebovirus, Sapovirus, Lagovirus, Vesivirus, Nacovirus, Bavovirus, Recovirus,
Salovirus, Minovirus, and Valovirus). (Smertina) (5). Of the major genera Norovirus and Sapovirus
cause acute gastroenteritis in humans.
The etiological agent can only be distinguished by laboratory testing. The
Lagovirus genus also includes European brown hare syndrome virus (EBHSV) (6). While the original RHDV virus was species
specific – there is a newer strain (RHDV2 (GI.2) that infects both rabbits and
hares and is lethal to both.
All these details build a compelling story far beyond
suburban landscapers wanting to protect their plants. The recent pandemic and likely crossover of a
bat coronavirus into the human population as well as past crossovers like human
immunodeficiency virus and avian influenza highlight the dangers of proximity
to animals with high levels of infection. There have been two recent worldwide
epidemics of rabbit hemorrhagic disease virus (RHDV) initially from 1984 to the
1990s and more recently from 2010 to present.
At no point in my medical career was I made aware of this viral spread
despite hearing about viral spread in other species like elk wasting disease.
Evolutionary biologists have suggested the RHDV virus has been in existence for
150 years (7-10).
The pathogenesis of the virus is known at this point. It
causes apoptosis of hepatic cells and hepatic necrosis. One of the main protective mechanisms’
antioxidant suppression of oxidative stress is overwhelmed. Apoptosis of endothelial cells leads to
procoagulant activity and disseminated intravascular coagulopathy (DIC) and
resulting hemorrhage and shock. RHDV2 has enhanced virulence factors and
previous infection with RHDV does not confer immunity.
The risk of RHDV crossover to human is estimated to be low
based on several factors. First, in a large
study of human exposure of 269 people exposed to infected rabbits there were no
episodes of disease or antibody formation to the virus in any of those
people. Second, there is continued host
specificity to lagomorphs with limited documented crossovers to other species
(Alpine musk deer, Eurasian badgers).
Third, there is limited ability for viral replication in other mammalian
models including mice with immune deficits (interferon 1 receptor deficits).
Fourth, high specificity for histo-blood group antigens (HBGAs) (11-12) – that
is the virus binds to rabbits specific HBGAs and cell receptor
specificities. Fifth, the molecular
biology of the rabbit versus human HBGAs are such that there are no functional
binding sites for RHDV virus.
In my efforts to understand why rabbits are considered a
nuisance animal and a biohazard, I uncovered an interesting set of factors.
Given the rabbit exclusive pandemics that have occurred I can understand why
wildlife officials are concerned about the spread of disease from transported
rabbits. The concern about disease
transfer to humans from feces, saliva, other bodily fluids, and rabbits
carcasses also makes sense. One of my colleagues pointed out that there is a
tularemia vaccination for dogs. Other rabbit
predators may be as susceptible as humans to many of these diseases and they
are probably relatively protected from RHDV because of the aforementioned
factors. This post also highlights the
need for veterinary virologists and epidemiologists to track the evolution and
crossover potential of these viruses.
That used to happen in an organized way for Influenza viruses through
the World Health Organization (WHO) but the current anti-science and
anti-medicine administration has pulled the US out of that organization and had
probably negatively impacted the viral surveillance necessary to prevent
zoonoses.
At the practical level, if you are a suburbanite interested
in protecting your hastes from rabbits, barriers like wire cages are
recommended by the public officials I talked with. Be sure to check with them about live
trapping and relocation or other means of controlling rabbits. The literature I
reviewed on live trapping recommended always using gloves when handling the
trap to avoid contaminants and prevent the transfer of human scent to the
trap. Rabbit waste and carcasses should
also be avoided by homeowners and pets.
Some of the pathogens in the table are transmitted by ticks – so the
same precautions to prevent Lyme Disease apply. In terms of surveillance, your state
department of natural resources is probably the best resource. They
directed me to the problem of RHDV that is not listed in the human literature
but is an ongoing global problem for rabbits at the epizootic level.
The lesson from rabbits so far is that non-humans also have epidemics
or epizootics. The only epizootics that humans seem to pay attention to affect domesticated
animals or potential high risk crossover situations like avian influenza. Those
contacts of humans and animals in suburbia bear watching both for the immediate
threats and implications for handling biological materials – but also the
potential long term consequences. (13-16).
George Dawson, MD, DFAPA
Supplementary 1: I thought this was an excellent graphic but could not figure out where to put it in the above essay. It is an estimate of worldwide mortality due to infectious diseases. Zoonotic origins are on the left of the diagram and non-zoonotic on the right. The authors point out that boundary is not as clear cut as it seems since common causes of crossover like bats, rats, and mice occupy the same biosphere. In the case of rabbits I would say the backyard is the same biosphere.
60% of human diseases have animal origins. Based on the lab origins rhetoric of the
past few years Mother Nature is by far the most significant bioterrorist. It also speaks to why any reasonable approach to prevent these outbreaks requires infectious disease and epidemiology expertise in both human and veterinary medicine.
The graph also contains the implicit information on the
non-zoonotic side. The increasing candida
auris infections are thought to be due to man-made climate change. Warm blooded animals were thought to have
natural resistance to fungal infections based on higher body temperature where
fungi could not survive. That evolutionary advantage is vanishing due to
increasing ambient temperatures and fungal adaptation. There are also 5 vaccine preventable diseases.
There is an active anti-vaccination campaign that has reduced access to some of
these vaccinations.
References:
1: Cotton CN. Zoonoses: Animals other than dogs and cats. UpToDate.
Accessed March 31, 2026. https://www.uptodate.com/contents/zoonoses-animals-other-than-dogs-and-cats
2: Krause PJ. Babesiosis: Clinical manifestations and
diagnosis. UpToDate. Accessed March 31, 2026. https://www.uptodate.com/contents/babesiosis-clinical-manifestations-and-diagnosis
3: Dumler JS.
Biology of Anaplasmataceae.
UpToDate. Accessed March 31,
2026. https://www.uptodate.com/contents/biology-of-anaplasmataceae
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cuniculus.
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Epidemics of Rabbit Hemorrhagic Disease (RHD) in Poland Due to the Co-8: 8:
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