This video turns to perhaps the best case of helping large numbers of animals who live in the wild: vaccinating them. There have already been large successful vaccination campaigns which have completely eliminated the disease rinderpest and greatly reduced the prevalence of rabies in large areas. These vaccination programs were not done for the sake of the animals themselves, but they still greatly helped those animals and they can help to inform future vaccination programs.
Also available as a chapter of our companion ebook to the video course Introduction to wild animal suffering: A guide to the issues
Diseases have the potential to kill animals in very large numbers. We have already seen the great amount of suffering that disease can cause to animals in the wild. Apart from helping 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 successful cooperative effort is the vaccination campaign against rabies, which has been carried out in several countries on a large scale. Vaccinations against many other diseases that wild animals suffer from have also been developed.
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. One paradigmatic example of wild animal immunization is the vaccination of animals against rabies that successfully eradicated the disease in most of Europe by 2010 and in large areas of North America. This is done in order to prevent the disease from spreading and being passed on to animals living with humans, such as dogs, or to humans. The vaccination is done through the aerial dispersal of baits containing the rabies vaccine which are then eaten by the animals.1
In the US, attempts to eliminate the disease started in the 1970s and it has been achieved in large areas of the northeastern United States and Canada. One such program was the prevention of its spread in raccoons in Massachusetts by orally vaccinating 63% of the population, which was sufficient for a successful eradication of the disease in the area. Another example is the oral rabies vaccination program for coyotes in Texas which led to a large reduction of rabies cases as well as stopping its growth in the affected area. A coordinated effort between the USA, Mexico, and Canada has been proposed in order to eradicate rabies from other areas.2 Similar programs have been implemented all over the world.3 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.
While the animals in the cases above were vaccinated not for their own good, but to protect human interests, 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.
Brucellosis is a contagious disease caused by various bacteria of the Brucella family. It affects cows and other ruminants 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 cause arthritis.4
Brucellosis is prevalent among the wild elk and bison populations living in the Greater Yellowstone Area. It has been estimated that more than 14,000 of those animals in the area are infected.5 Since Brucellosis can be transmitted between species, these animals in Yellowstone act as “reservoir” species for the disease. To combat this, a vaccine (RB51) has been developed for the bison population in Yellowstone.
Sylvatic plague is an infectious bacterial disease that affects rodents such as prairie dogs. It is caused by the same bacteria 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%. Symptoms include fever, dehydration, low energy, lack of appetite, difficulty breathing, enlarged spleen, and swollen lymph nodes. 95% of prairie dogs die within 78 hours of infection.6
In 2019 in South Dakota, the plague decimated a population of prairie dogs and, since then, has 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.7 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.
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. In gorillas, the mortality rate may be as high as 90%. Since the 1990s, the Zaire strain of Ebola has killed many thousands of gorillas and chimpanzees. One study suggests that an outbreak in 2002-2003 killed over 5,000 gorillas. It seems that vaccination would be an obvious solution to fight this disease. In fact, this has been proposed 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 they could be treated similarly.
Pilot vaccination programs have been also developed against anthrax in animals. Vaccination has been shown to be effective in black rhinos, zebras, and cheetahs.8 So far they have only been vaccinated for conservationist reasons, but such vaccination programs could be extended to all animals who suffer from anthrax, regardless of their perceived use or value to human beings.
Tuberculosis is still an active disease infecting both human and nonhuman individuals. In 2011, an oral vaccine was delivered in bait to free-living wild boars under natural conditions of transmission.9 Badgers have also been vaccinated against this disease.
Like other animals, insects suffer from disease. 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 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.10 The sheer number of insects in the world means that the welfare potential of vaccination is huge.
The United Kingdom provides a good example of how to begin implementing a vaccination program. It 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 and Newcastle Disease in birds. 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.11
The examples above show that vaccination is a feasible way to dramatically improve the welfare of animals in the wild. We can vaccinate animals against horrific diseases such as rabies, tuberculosis, and even the plague. We even have the ability to totally eradicate certain diseases from the entire surface of the earth. And these abilities will only increase as we learn more. In the future, much more progress can be made towards larger scale prevention of harms suffered by animals in the wild.
1 The procedure of oral vaccination of foxes is described in 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.
2 Baer, G. M.; Abelseth, M. K. & Debbie, J. G. (1971) “Oral vaccination of foxes against rabies”, American Journal of Epidemiology, 93, pp. 487-490; 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; 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; MacInnes, C. D. & LeBer, C. A. (2000) “Wildlife management agencies should participate in rabies control”, Wildlife Society Bulletin, 28, pp. 1156-1167; MacInnes, C. D.; Smith, S. M.; Tinline, R. R.; Ayers, N. R.; Bachmann, P.; Ball, D. G. A.; Calder, L. A.; Crosgrey, S. J.; Fielding, C.; Hauschildt, P.; Honig, J. M.; Johnston, D. H.; Lawson, K. F.; Nunan, C. P.; Pedde, M. A.; Pond, B.; Stewart, R. B. & Voigt, D. R. (2001) “Elimination of rabies from red foxes in eastern Ontario”, Journal of Wildlife Diseases, 37, pp. 119-132; Slate, D.; Rupprecht, C. E.; Rooney, J. A.; Donovan, D.; Lein, D. H. & Chipman, R. B. (2005) “Status of oral rabies vaccination in wild carnivores in the United States”, Virus Research, 111, pp. 68-76.
3 Childs, J. E.; Robinson, L. E.; Sadek, R.; Madden, A.; Miranda, M. E. & Miranda, N. L. (1998) “Density estimates of rural dog populations and an assessment of marking methods during a rabies vaccination campaign in the Philippines”, Preventive Veterinary Medicine, 33, pp. 207-218; Pal, S. K. (2001) “Population ecology of free-ranging urban dogs in West Bengal, India”, Acta Theriologica, 46, pp. 69-78; 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; 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.
5 Kreeger, T. & Plumb, G. (eds.) (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 [accessed on 15 September 2019].
6 Abbott, R. C. & Rocke, T. E. (2012) Plague: U.S. Geological Survey circular 1372, Madison: National Wildlife Health Center [accessed on 10 September 2019]; Prairie Dog Coalition (2018) Prairie dogs, people and plague, Boulder: The Humane Society of the United States.
7 Leggett, H. (2009) “Plague vaccine for prairie dogs could save endangered ferret”, Wired, 08.04.09 [accessed on 25 July 2013].
8 Turnbull, P. C. B.; Tindall, B. W.; Coetzee, J. D.; Conradie, C. M.; Bull, R. L.; Lindeque, P. M. & Huebschle, O. J. B. (2004) “Vaccine-induced protection against anthrax in cheetah (Acinonyx jubatus) and black rhinoceros (Diceros bicornis)”, Vaccine, 22, pp. 3340-3347.
9 Garrido, J. M.; Sevilla; I. A.; Beltrán-Beck, B.; Minguijón, E.; Ballesteros, C.; Galindo, R. C.; Boadella, M.; Lyashchenko, K. P.; Romero, B.; Geijo, M. V.; Ruiz-Fons, F.; Aranaz, A.; Juste, R. A.; Vicente, J.; Fuente, J. de la & Gortázar, C. (2011) “Protection against tuberculosis in Eurasian wild boar vaccinated with heat-inactivated Mycobacterium bovis”, PLOS ONE, 6 (9) [accessed on 28 September 2019].
10 Raukko, E. (2018) “The first ever insect vaccine PrimeBEE helps bees stay healthy”, University of Helsinki, 31.10.2018 [accessed on 8 September 2019].
11 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.