This text is about ways we can protect animals in the wild against disease. We can vaccinate animals against diseases and provide medical aid to animals who get sick. For information about other ways we can help animals, see our website section about helping animals in the wild. For more information about the suffering caused by disease among wild animals, see our page on diseases in nature.
Disease is one of the sources of misery for nonhuman animals living in the wild. Diseases in nature examines this further. Fortunately, however, this is one of the areas in which we already know ways to help them. The technology to vaccinate and cure many of the diseases that plague animals living in the wild already exists. Generally, vaccines and medicines are given to animals living in the wild only when it benefits human beings, for example by stopping the transmission of diseases from wild animals to farmed animals and to humans, or out of conservationist motives. It is seldom done for the sakes of the individual animals themselves. But the results that have been obtained thus far show it is possible to do vaccinate animals even when doing so doesn’t benefit humans.
White nose syndrome is a disease caused by the fungus Pseudogymnoascus destructans. Since 2007, it has killed more than six million bats in North America.1 The mortality rate is more than 90% in some species. The disease disrupts bats’ hibernation, causing them to either starve to death by using up all of their fat stores, or to die of exposure while trying to find food in winter.2 A 2019 field experiment tested the efficacy of a probiotic bacterium Pseudomonas fluorescens in reducing the impact of the disease in infected bats. They found that the bats treated with the probiotic had a survival rate of 46.2%, while the survival rate of the untreated bats was just 8.4%.3 Although the motivation to find a cure comes from conservationist interests, widespread application would nonetheless significantly reduce suffering and premature death among bats.
Probiotic treatment may also be valuable in treating disease in other species. The chytrid fungus Batrachochytrium dendrobatidis has had a devastating effect on amphibians, killing millions of animals across more than 500 species.4 Infected amphibians show symptoms such as low appetite, lethargy, and thickening of the skin which leads to death because affected individuals are unable to take in nutrients and release toxins through their skin. Some amphibians breathe only through their skin, and once infected, they may be unable to breathe.5 A 2016 study on boreal toads showed that those treated with the probiotic janthinobacterium lividum before exposure to batrachochytrium dendrobatidis had a 40% increase in survival rates compared to untreated toads.6 Probiotics may be used in the future to treat or protect amphibians susceptible to the disease.
Research on the possibility of probiotic treatments for snake fungal disease caused by Ophidiomyces ophiodiicola,7 and for infestation of Nosema ceranae in honeybees8 are also underway. Successful experiments have also been done on using probiotics to inhibit zoosporic infections in fish.9 Probiotics have the potential to significantly improve the welfare of animals living in the wild, by protecting them against disease or by mitigating its effects.
Sarcoptic mange is a skin disease caused by burrowing parasitic mites. It affects several species of nonhuman mammals, including dogs, cats, coyotes, bears, and wombats. Wombats are especially badly affected by mange. It is believed that this is due to conditions inside wombat burrows being especially conducive to the survival and transmission of sarcoptic mites.10 Infested wombats lose hair, their skin becomes crusted and infected, and even their eyes and ears become crusted over. In severe cases, it can lead to death.11 Dr. Carver, a researcher at the University of Tasmania who has a great deal of experience with the disease and its sufferers, believes that the disease is one of the most painful diseases afflicting nonhuman animals.12
Infested wombats are generally treated with cydectin. The work is mostly carried out by volunteers. The stress of capture can kill wombats, especially when they are in a weakened state. The chemical treatment must be applied for several weeks, and is usually administered using a specially designed flap placed above the entrance to the wombat’s burrow. A new treatment being developed by Dr. Carver and his team will offer longer lasting treatment for wombats. If it can be used effectively in the field, it will make it much easier to treat individual wombats over time. It should be noted that this intervention, the research being carried out by Dr. Carver and the work of volunteers in Tasmania, seems to be motivated by concern for the suffering animals themselves rather than out of conservationist or economic motives. There are no reports of transmission of the disease from wombats to domesticated animals, and according to Dr. Carver mange is unlikely to cause extinction of wombats.13
Apart from assistance to animals who are already sick, an important way we can protect animals in the wild from disease is through vaccination. There are many examples of large-scale vaccinations of animals living in the wild. Perhaps the most important of these is vaccination against rabies, which has been carried out in several different countries on a large scale. Vaccinations against many other diseases that wild animals suffer from have also been developed.
One paradigmatic example of wild animal immunization is the vaccination of animals against rabies14 that successfully eradicated the disease in most of Europe by 2010 and in large areas of North America. This was done in order to prevent the disease from spreading and being passed on to animals living with humans, such as dogs, or to humans themselves. The vaccination was administered through the aerial dispersal of baits containing the rabies vaccine which were then eaten by the animals.15
In the US, attempts to eliminate the disease started in the 1970s16 and it has been achieved in Parramore Island, Virginia,17 Williamsport, Pennsylvania18 and Cape May, New Jersey.19 One program was the prevention of the spread of rabies in the free-ranging raccoons of Massachusetts by orally vaccinating 63% of the population, which was sufficient for a successful eradication of the disease in the area.20 Another example is the oral rabies vaccination program for coyotes in Texas which led to a significant reduction of rabies cases as well as stopping its growth in the affected area.21 Further efforts have been made in other parts of North America, such as Canada.22 A coordinated effort between the USA, Mexico, and Canada has been proposed in order to eradicate rabies in other areas.23
Similar programs have been implemented all over the world, including dog vaccination in Africa24 and Asia,25 and vaccination of wolves in Ethiopia.26 The data from these programs provide evidence of efficacy and specifics of implementation that will make it easier to vaccinate more animals in the future.
Rabies is an appalling disease for those animals affected by it. Spread by bites, it causes inflammation of the brain. Symptoms can include fever, pain, tingling/burning sensations, hydrophobia, aggression, confusion, and muscle paralysis. Once symptoms are apparent, death is generally inevitable.27 The video below shows a stray cat suffering from rabies. Note the aggression, difficulty moving, and confusion she displays.
The animals in the cases above were vaccinated not for their own good, but to protect human interests by preventing the transmission of rabies to domesticated animals and humans, or to conserve populations of endangered species. Nevertheless, vaccinating animals in the wild against rabies benefits them immensely by protecting them against a terrible disease. The lessons we have learned in our ongoing struggle against rabies can be used in future vaccination programs aimed at promoting the wellbeing of individual animals in the wild. Furthermore, our successes in this fight should inspire optimism about future vaccination efforts. Despite the great difficulties in vaccinating animals in the wild, we have managed to eradicate rabies from terrestrial mammals in large areas of the world, and vastly lowered its occurrence in others. There is no reason to think that we cannot be similarly successful in vaccinating animals in the wild against other diseases.
Brucellosis is a contagious disease caused by various bacteria of the Brucella family. It affects cows and other ruminants such as bisons and elks, as well as some marine mammals and humans. Its main effects in nonhuman animals are on the reproductive system, causing infertility, abortions, stillbirth or birth of offspring unable to survive. It can also cause swelling of the testicles in males, and the bacteria can get into the joints and causes arthritis.28
Brucellosis is prevalent among the wild elks and bisons living in the Greater Yellowstone Area. It has been estimated that 12.5 thousand elks and 2.5 thousand bisons in the park are infected (10% and 50% respectively).29 Since Brucellosis can be transmitted between species, elks and bisons in Yellowstone act as ‘reservoir’ species for Brucellosis. To combat this, a vaccine (RB51) has been developed for use on bisons in Yellowstone. It is unclear to what extent bisons actually suffer from Brucellosis and whether the currently existing vaccines are effective enough.30 In any case, further research on the welfare effects of Brucellosis on bisons, and into possible interventions (e.g. vaccination) is required. It is believed that brucellosis can be transmitted to captive cows, and to placate farmers, park officials in Yellowstone kill hundreds of bisons every year.31 If it could be shown that brucellosis transmission from bisons isn’t a threat to domesticated animals, or if an effective vaccine could be developed, these killings would be stopped. In either case, the welfare of wild bisons would be significantly increased.
Sylvatic plague is an infectious bacterial disease that affects rodents such as prairie dogs. It is caused by the bacterium Yersina pestis, the same bacteria that is responsible for bubonic plague in humans. The devastating effects of “Black Death” pandemics on human populations are familiar to almost everybody. Not so familiar are the mortality rates of wild rodents who still succumb to sylvatic plague. Outbreaks among prairie dogs can reach mortality rates of close to 100%.32 Symptoms include fever, dehydration, low energy, lack of appetite, difficulty breathing, enlarged spleen, and swollen lymph nodes.33 95% of prairie dogs die within 78 hours of infection.34
Recently, in South Dakota, the plague decimated a population of prairie dogs and has consequently affected black-footed ferrets who eat prairie dogs. A mass immunization of prairie dogs was undertaken, primarily because humans value the ferrets who are at risk of infection. Prairie dogs have shown a survival rate of more than 95 per cent of those infected after they are vaccinated.35 Even though the aim of the vaccination is the protection of ferrets, prairie dogs also benefit from it. At least, that is, until they are preyed upon by healthy ferrets.
In 2017, biologists in Montana started distributing the oral vaccine baits using drones. This allows them to cover much more ground than they could by hand delivering the baits. With the drones, it’s possible to vaccinate 4,000 prairie dogs in a single day. The video below shows the drone taking off.
Anthrax is an acute and lethal disease caused by the bacteria Bacillus anthracis. When exposed to oxygen, the bacteria forms spores which are extremely resistant, capable of surviving for years in the soil or on the fur of an infected animal. The spores enter the body through ingestion, inhalation, or through an open wound. Herbivores can ingest the spores while grazing. Once infected, symptoms can include high fever, muscle tremors and difficulty in breathing. Predatory animals can become infected by eating the flesh of an infected animal.36 Anthrax can have devastating effects on animals living in the wild. Wild herbivores are especially vulnerable to anthrax outbreaks, with mortality rates between 21 and 55% in hippos, and up to 90% in impalas and kudus.37 An outbreak in Namibia in 2017 killed over 100 hippos,38 and more than 2,300 reindeers died in an outbreak in Siberia in 2016.39 The video below is a news report on the effects of the anthrax outbreak on hippos in Namibia.
Given the high risk of the disease spreading to humans, particularly due to the consumption of the flesh of hunted animals, immunization trials have already been carried out. A pilot vaccination program was developed for vaccination against anthrax of animals typically hunted in so-called African “game parks.” Guinea pigs were orally and subcutaneously vaccinated, and they developed successful levels of resistance to the infection.40 Vaccination has been shown to be effective in black rhinos and cheetahs.41 So far vaccinations have only been given to those wild animals who are considered worthy of conservation. For example, the Kenyan Wildlife Service vaccinated the rare white and black rhinos after an outbreak of anthrax among buffaloes in Lake Nakuru National Park.42 An outbreak in 2005-2006 killed 53 Grevy’s zebras. To protect the remaining 650 Grevy’s zebras in Kenya, Kenyan wildlife officials vaccinated them using darts. After the vaccination, no more zebras died.43 Although for now vaccines are distributed only to serve human interests, there is no reason such vaccination programs couldn’t be extended to all animals who suffer from anthrax, regardless of their perceived value to human beings.
There are other serious diseases, more often associated with human beings, which also cause a great deal of suffering and death for wild animal populations. Hepatitis B and tetanus are common diseases among gibbons, along with measles and rabies. In order to reduce the risk of transmission, both from humans to gibbons and vice versa, the Wild Animal Rescue Foundation of Thailand recommends the vaccination of gibbons and human workers for all these diseases.44
In 2013, The European Commission backed a proposal for the vaccination of wild boars in order to improve the health of domestic pigs. The breakout of swine fever in 1997 resulted in the deaths of over 10 million pigs. An orally administered vaccine will give preventive immunity to wild boars and, it can also be used for emergency inoculations of domesticated pigs.45
Since the 90s, the Zaire strain of Ebola has killed approximately one third of the world’s gorilla population and around the same proportion of chimpanzees.46 One study suggests that an outbreak in 2002-2003 killed over 5,000 gorillas.47 It seems that vaccination would be an obvious solution to fight this disease. In fact, this is precisely what has been suggested by organizations such as Vaccinape, which proposes vaccination to save the lives of African great apes. The vaccination procedure consists of either vaccines in bait, as used for rabies vaccines, or hypodermic darts.
There is more interest in treating great apes because their species is generally highly valued, and also because of recent threats to human health that have spread through contact with or consumption of infected apes. Other animals may not receive the same attention, but could be treated similarly.
Ebola is a horrible disease causing a range of symptoms including fever, internal bleeding, muscle weakness, difficulty breathing and swallowing, vomiting and diarrhea. In humans, it is fatal in about 50% of cases.48 In gorillas, the mortality rate may be as high as 90%.49 An effective vaccination campaign would significantly reduce suffering and death among animals vulnerable to Ebola.
The United Kingdom is probably the place where the immunization of animals against disease is most normalized. Vaccination is widely implemented to protect animals from diseases such as Avian Influenza or Newcastle Disease in birds. Despite its name, Newcastle Disease has long been proliferating outside Newcastle. For example, recently in China, 1,989 peacocks were vaccinated in Yunnan Wild Animal Park against avian influenza virus and Newcastle disease.50
In the UK, there is a Vaccine and Antigen Bank where the government keeps supplies to be used in potential outbreaks, or to be deployed for conservation such as for penguins and parrots. The UK also contributes to the EU Vaccine Bank for Classical Swine Fever as well as to the high priority Foot and Mouth antigens bank, where antigens and vaccines are kept ready to be used when needed.51
Tuberculosis is still an active disease acting on both human and nonhuman individuals. In 2011, an oral vaccine was delivered in bait to free-living wild boars under natural conditions of transmission.52 In the UK, badgers often carry TB which can spread to domesticated cows. Unfortunately, the UK government has implemented a policy of killing badgers in parts of the UK in an attempt to minimize the spread of the disease. Since 2013, 68,000 badgers have been killed in the UK.53 The killings are controversial, however. The National Trust, a major landowner in the UK with many farming tenants, doesn’t allow killing of badgers on their land.54 In some areas, volunteers capture, vaccinate, and release badgers, and research is ongoing into an oral vaccine that wouldn’t require trapping animals.55 The video below shows vaccination of wild badgers.
Like other animals, insects suffer from disease. For example, butterflies suffer from a deadly disease called “Black Death” caused by the nuclear polyhedrosis virus,56 and crickets and other insects are affected by the cricket paralysis virus.57 Until recently, it was believed that insect vaccination wasn’t possible, because insect immune systems, though similar in some ways to mammalian systems, don’t use antibodies. Recent research at the University of Helsinki has shown that it is possible to vaccinate honeybees. When a queen bee eats something containing pathogens, the pathogen’s signature molecules are bound by a protein called vitellogenin. Vitellogenin carries these signature molecules into the queen’s eggs, where they act as inducers for immune responses. This means that we can vaccinate thousands of bees simply by vaccinating the queen. Research is being done to develop a vaccine for American foulbrood, a bacterial disease that can devastate honeybee colonies.58 The sheer number of insects in the world means that the welfare potential of vaccination is huge.
In some cases, it is not possible to stop the spread of a disease by vaccinating animals, and other measures are needed to stop it. This is the case, for instance, with diseases that are transmitted by animals such as ticks or insects.
One way to prevent the spread of such a disease would be to kill the insects carrying it, but this would obviously be harmful to them. There are other ways of reducing the populations of insects which do not involve killing animals and that are actually more successful. This can be done by sterilizing them or by a treatment that causes more males to be born than females. Some people might think this is immoral, but this can hardly be so when the alternative is the agony and death many animals would otherwise face because of the disease, in addition to the death of a huge number of the insects themselves due to their population dynamics.
One technique used for this purpose, inherited sterility, consists of relocating individuals from a certain species whose progeny will be sterile into a target area.59 The males are treated in a way that causes them to have fewer offspring, most of whom will be sterile. This also causes more males than females to be born.60
The sterilization of insects has already been carried out on a global scale. It was initially developed in the 1940s61 and has been evolving since then.
Examples of successful uses of this technique are the following:
Of course, this may have some consequences for the natural processes that occur in these areas. Nevertheless, it is widely assumed that it is worth carrying out these measures, because it will save the lives of a great number of human beings. Because it is human lives at stake, this measure is generally accepted as fully justified. Because of the speciesist bias that exists, measures such as vaccination and the sterilization of insects is considered fully acceptable when it benefits humans but not when it only aids nonhuman animals.62 However, because speciesism is morally unjustified, we have to reject this way of thinking.
Rinderpest was an infectious viral disease that affected cows, buffaloes, wildebeests, giraffes, antelope, warthogs and other even-toed ungulates. Symptoms included fever, loss of appetite, discharge from the nose and eyes, constipation followed by acute diarrhea, and erosions in the mouth, the lining of the nose, and the genital tract. The mortality rate was high, approaching 100% in previously unexposed populations. Death occurred between 6 and 12 days after the first onset of symptoms. An outbreak in the 1890s killed 80-90% of all cows in southern and eastern Africa.
After a long and difficult vaccination campaign, the World Organisation for Animal Health officially announced the global eradiaction of the disease in June 2011. Rinderpest had become the second disease to be completely eradicated by humans, and the first affecting nonhuman animals. Although wild animals weren’t vaccinated against rinderpest, its eradication was of great benefit to them as well. For example, the wildebeest population in the Serengeti in the 1957 was around 100,000. The population was maintained at this low level because of transmission of rinderpest from cows and steers to wildebeests. By 1971, just 10 years after the introduction of the rinderpest vaccine, the wildebeest population had grown to 770,000.63 Wildebeest, especially newborns, were very vulnerable to rinderpest. Its eradication has saved thousands of wildebeests from suffering and death, albeit unintentionally as a side effect of the vaccination of domesticated animals.
The eradication of smallpox showed humans that disease is not an essential part of life – it is simply a (very difficult) technical problem, and through co-operation and hard work we can fight it, and thereby increase human wellbeing. The eradication of rinderpest shows us that the same is true in the case of animal diseases. With the right motivation, funding, co-operation, and effort, we can eliminate diseases that plague nonhuman animals. The results obtained to date show us that this is possible. Already the OIE has drawn up plans to eliminate ovine rinderpest, a related disease that affects smaller ruminants, both domesticated ones such as goats and sheep, and wild ones like the saiga antelope.64 45 countries have committed to eradicating the disease by 2030.65
The examples above show that human beings have the capacity to dramatically improve the welfare of animals in the wild. We can treat and cure painful diseases like sarcoptic mange and white-nose syndrome. We can vaccinate animals against horrific diseases such as anthrax, rabies, and even the plague. We even have the ability to totally eradicate diseases from the entire surface of the earth. And these abilities will only increase as we learn more, and develop our technologies. What will we do with that ability? For now, we are motivated mainly by self-interest and the desire to conserve endangered species, so our interventions don’t help as many animals as they could. When we learn to reject speciesism, and couple our knowledge and technological ability with a will to improve the lives of all sentient beings on the planet, our interventions will be reach much farther.
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1 Hopkins, M. C. & Soileau, S. C. (2018) U.S. Geological Survey response to white-nose syndrome in bats: U.S. Geological Survey Fact Sheet 2018–3020, Reston: U.S. Geological Survey [accessed on 9 September 2019].
2 O’Neill, K. (2019) “Spraying bats with ‘good’ bacteria may combat deadly white nose syndrome”, Science News, July 15 [accessed on 9 September 2019].
3 Hoyt, J. R.; Langwig, K. E.; White, J. P.; Kaarakka, H. M.; Redell, J. A.; Parise, K. L.; Frick, W. F.; Foster, J. T. & Kilpatrick, A. M. (2019) “Field trial of a probiotic bacteria to protect bats from white-nose syndrome”, Scientific Reports, 9 [accessed on 9 September 2019].
4 Scheele, B. C.; Pasmans, F.; Skerratt, L. F.; Berger, L.; Martel, A.; Beukema, W.; Acevedo, A. A.; Burrowes, P. A.; Carvalho, T.; Catenazzi, A.; De la Riva, I.; Fisher, M. C.; Flechas, S. V.; Foster, C. N.; Frías-Álvarez, P.; Garner, T. W. J.; Gratwicke, B.; Guayasamin, J. M.; Hirschfeld, M.; Kolby, J. E.; Kosch, T. A.; La Marca, E.; Lindenmayer, D. B.; Lips, K. R.; Longo, A. V.; Maneyro, R.; McDonald, C. A.; Mendelson, J.; III; Palacios-Rodriguez, P.; Parra-Olea, G.; Richards-Zawacki, C. L.; Rödel, M.-O.; Rovito, S. M.; Soto-Azat, C.; Toledo, L. F.; Voyles, J.; Weldon, C.; Whitfield, S. M.; Wilkinson, M.; Zamudio, K. R. & Canessa, S. (2019) “Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity”, Science, 363, pp. 1459-1463.
6 Kueneman, J. G., Woodhams, D.C., Harris, R., Archer, H. M., Knight, R. & McKenzie, J. (2016) “Probiotic treatment restores protection against lethal fungal infection lost during amphibian captivity”, Proceedings of the Royal Society B: Biological Sciences, 283 (1839) [accessed on 9 September 2019].
7 Hill, A. J.; Leys, J. E.; Bryan, D.; Erdman, F. M.; Malone, K. S. & Russell, G. N. (2018) “Common cutaneous bacteria isolated from snakes inhibit growth of Ophidiomyces ophiodiicola”, EcoHealth, 15, pp. 109-120.
8 El Khoury, S.; Rousseau, A.; Lecoeur, A.; Cheaib, B.; Bouslama, S.; Mercier, P.; Demey, V.; Castex, M.; Giovenazzo, P. & Derome, N. (2018) “Deleterious interaction between Honeybees (Apis mellifera) and its microsporidian intracellular parasite Nosema ceranae was mitigated by administrating either endogenous or allochthonous gut microbiota strains”, Frontiers in Ecology and Evolution, 23 May [accessed on 9 September 2019].
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15 The procedure of oral vaccination of foxes is described here: Department for Environment, Food and Rural Affairs (2010) Vaccination as a control tool for exotic animal disease: Key considerations, London: Department for Environment, Food and Rural Affairs [accessed on 10 August 2013].
16 Baer, G. M.; Abelseth, M. K. & Debbie, J. G. (1971) “Oral vaccination of foxes against rabies”, American Journal of Epidemiology, 93, pp. 487-490.
17 Hanlon, C. A.; Niezgoda, M.; Hamir, A. N.; Schumacher, C.; Koprowski, H. & Rupprecht, C. E. (1998) “First North American field release of a vaccinia-rabies glycoprotein recombinant virus”, Journal of Wildlife Diseases, 34, pp. 228-239.
18 Hanlon, C. A. & Rupprecht, C. E. (1998) “The reemergence of rabies”, in Scheld, D.; Armstrong, J. M.; Hughes, J. B. (eds.) Emerging infections I, Washington, D. C.: ASM Press, pp. 59-80.
19 Rosatte, R.; Donovan, D.; Allan, M.; Howes, L. A.; Silver, A.; Bennett, K.; MacInnes, C.; Davies, C.; Wandeler, A. & Radford, B. (2001) “Emergency response to raccoon rabies introduction into Ontario”, Journal of Wildlife Diseases, 37, pp. 265-279.
20 Robbins, A. H.; Borden, M. D.; Windmiller, B.S.; Niezgoda, M.; Marcus, L. C.; O’Brien, S. M.; Kreindel, S. M.; McGuill, M. W.; DeMaria, A., Jr.; Rupprecht, C. E. & Rowell, S. (1998) “Prevention of the spread of rabies to wildlife by oral vaccination of raccoons in Massachusetts”, Journal of the American Veterinary Medical Association, 213, pp. 1407-1412.
21 Fearneyhough, M. G.; Wilson, P. J.; Clark, K. A.; Smith, D. R.; Johnston, D. H.; Hicks, B. N. & Moore, G. M. (1998) “Results of an oral rabies vaccination program for coyotes”, Journal of the American Veterinary Medical Association, 212, pp. 498-502.
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24 Cleaveland, S.; Kaare, M.; Tiringa, P.; Mlengeya, T. & Barrat, J. (2003) “A dog rabies vaccination campaign in rural Africa: impact on the incidence of dog rabies and human dog-bite injuries”, Vaccine, 21, pp. 1965-1973. Kitala, P. M.; McDermott, J. J.; Coleman, P. G. & Dye, C. (2002) “Comparison of vaccination strategies for the control of dog rabies in Machakos District, Kenya”, Epidemiology and Infection, 129, pp. 215-222.
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29 United States Animal Health Association (2006) Enhancing brucellosis vaccines, vaccine delivery, and surveillance diagnostics for elk and bison in the Greater Yellowstone Area: A technical report from a working symposium held August 16-18, 2005 at the University of Wyoming, Laramie: The University of Wyoming Haub School and Ruckelshaus Institute of Environment and Natural Resources [accessed on 28 November 2019].
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43 Ndeereh, D.; Obanda, V.; Mijele, D. & Gakuya, F. (2012) “Medicine in the wild: Strategies towards healthy and breeding wildlife populations in Kenya”, The George Wright Forum, 29, pp. 100-108 [accessed on 22 October 2019].
45 He, T. (2010) “1,989 peacocks vaccinated in Yunnan Wild Animal Park”, Kunming , 2010-11-26.
46 Torres, E. (2012) “Should we vaccinate wild apes?”, February 16 [accessed on 2 July 2013]. Ryan S. J & Walsh, P. D. (2011) “Consequences of non-intervention for infectious disease in African great apes”, PLOS ONE, 6 (12) [accessed on 5 September 2019].
49 Wildlife Conservation Society (2019) “Study: Community-based wildlife carcass surveillance is key for early detection of Ebola virus in Central Africa”, WCS Newsroom, August 28 [accessed on 5 September 2019].
50 He, T. (2010) “1,989 peacocks vaccinated in Yunnan Wild Animal Park”, op. cit.
51 Department for Environment, Food and Rural Affairs (2010) Vaccination as a control tool for exotic animal disease: Key considerations, op. cit.
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55 Dalton, J. (2018) “Badger culling: How much does it cost and is it really working?”, Independent, Tuesday 13 November.
57 Reinganum, C.; O’Loughlin, G. T. & Hogan, T. W. (1970) “A nonoccluded virus of the field crickets Teleogryllus oceanicus and T. commodus (Orthoptera: Gryllidae)”, Journal of Invertebrate Pathology, 16, pp. 214-220.
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61 This method was initially implemented to fight parasitism, and has been used for this purpose also since then. It has been applied in the case of New World screw-worm fly (Cochliomyia hominivorax) in places including the US (Florida and Texas), Central America, the Netherlands Antilles and Lybia.
62 See Loftin, R. W. (1985) “The medical treatment of wild animals”, Environmental Ethics, 7, pp. 231-239.
65 World Organisation for Animal Health (2018) “Countries reaffirm political will to globally eradicate Peste des petits ruminants”, oie.int, 7 September [accessed on 9 September 2019].