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Providing evidence to improve practice

Action: Use vaccination programme Terrestrial Mammal Conservation

Key messages

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  • Seven studies evaluated the effects on mammals of using vaccination programmes. Three studies were in the UK and one study was in each of Belgium, Spain, Poland and Ethiopia.

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (7 STUDIES)

  • Abundance (1 study): A before-and-after study in Poland found that following an anti-rabies vaccination programme, red fox numbers increased.
  • Condition (6 studies): Five studies (including three replicated, three controlled and two before-and-after studies) in Belgium, Spain and the UK found that following vaccination, rabies was less frequent in red foxes, numbers of Eurasian badgers infected with tuberculosis was reduced and European rabbits developed immunity to myxomatosis and rabbit haemorrhagic disease. One of the studies also found that vaccination reduced the speed and extent of infection in infected Eurasian badgers. A study in Ethiopia found that following vaccination of Ethiopian wolves, a rabies outbreak halted.

BEHAVIOUR (0 STUDIES)

Supporting evidence from individual studies

1 

A study in 1989–1991 in a rural region of Luxembourg, southern Belgium (Brochier et al. 1991) found that vaccinating red foxes Vulpes vulpes against rabies reduced the occurrence of rabies. After one vaccination attempt, six out of nine (67%) rabid and 11 of 14 (79%) healthy foxes tested had consumed the bait. After the second attempt, 25 of 31 (81%) adult foxes and 27 of 55 (49%) juvenile foxes tested had consumed bait, and all 86 were healthy. After the third vaccination phase, 64 of 79 (81%) foxes had consumed bait and only one tested positive for rabies (authors note that it was found at the edge of the vaccination area, and had not taken bait). Additionally, the number of cases of rabies reported in livestock every six months fell from 7–61 before the second vaccination attempt (January 1985–June 1990) to zero in the year afterwards (reporting of rabies in livestock is mandatory in Belgium). In November 1989, April 1990 and October 1990, a total of 25,000 field vaccine-baits containing VVTGgRAB and a tetracycline biomarker were dropped by helicopter across a 2,200 km2 area at a density of 15/km (excluding urban areas). After each vaccination period (January–March 1990, April–October 1990, November 1990–April 1991) a total of 188 foxes which were found dead or shot by hunters were tested for both rabies and the presence of tetracycline (which would indicate that they had consumed the bait).

2 

A replicated, before-and-after study in 1999–2002 in Cadiz province, Spain (Cabexas et al. 2006) found that most vaccinated European wild rabbits Oryctolagus cuniculus developed immunity to myxomatosis and rabbit haemorrhagic disease. Of 32 rabbits which initially had no immunity to myxomatosis, 26 (81%) had developed immunity 2–4 weeks after vaccination. Of 81 rabbits which initially had no immunity to rabbit haemorrhagic disease , 68 (84%) had developed immunity 2–4 weeks after vaccination. The development of immunity did not differ between males and females, nor did it vary with time spent in captivity. Between November 1999 and March 2002, six groups of 14–46 wild-caught rabbits (some of which already had natural immunity to one or both diseases) were vaccinated against myxomatosis and rabbit haemorrhagic disease with commercial vaccines, and held in captivity for two, three or four weeks. Blood samples were taken from each rabbit both before vaccination, and two days prior to release, to test for immunity to each disease.

3 

A before-and-after study in 1980–2005 in a rural area near Rogów, Central Poland (Goszczyński et al. 2008) found that following an anti-rabies vaccination programme, red fox Vulpes vulpes numbers increased. The density of fox tracks was higher after the start of the vaccination programme than before (11.0 vs 5.9 snow tracks/km/day). The same pattern held for fox density as recorded by surveys from vehicles (2.6 vs 1.2 foxes/km2) and for active dens (15.0 vs 9.3 dens with young/year). However, there were fewer cubs/den after vaccination (3.4) than before (3.8). Anti-rabies vaccinations started in 1995-1996. Between 1980 and 2005, fox densities were estimated annually within an 89-km2 area. Estimates were from counts of tracks in snow (average annual transect length was 90 km before and 55 km after the vaccination programme), individuals seen from vehicles in forest habitats, and location of dens and number of cubs within the dens.

4 

A study in 2003–2004 in alpine habitat in a national park in Ethiopia (Knobel et al. 2008) found that vaccinating Ethiopian wolves Canis simensis successfully halted a rabies outbreak. Of 69 wolves vaccinated in the “intervention zone” (beyond the boundaries of the outbreak) between one to four months after rabies was confirmed, all 19 animals sampled one month later had protective levels of rabies antibodies. Six months after initial vaccinations, two wolves that received a booster vaccination at 30 days still had protective levels of antibodies while one wolf that did not receive a booster had levels below those regarded as providing protection. Of five wolves sampled 12 months after initial vaccinations, one that received a booster still had protective levels of rabies antibodies while four that received only initial vaccinations did not have protective levels. The last confirmed rabies death was two months after the start of the vaccination programme. Rabies was first confirmed on 28 October 2003 from wolf mortalities since mid-August. Sixty-nine wolves were vaccinated in the intervention zone, between November 2003 and February 2004. A further eight were vaccinated during follow-up recapture (March–November 2004). Mortality in the affected sub-population was 76%.

5 

A replicated, controlled study in 2006–2009 on 15 wild-caught, captive Eurasian badgers Meles meles in England, UK (Chambers et al. 2011) found that vaccinating badgers against tuberculosis reduced the likelihood of tuberculosis infection, and reduced both the speed and the extent of infection in infected animals. Three out of nine badgers vaccinated with Bacillus Calmette-Guérin (BCG) became infected with tuberculosis, compared to six out of six badgers which had not been vaccinated. The time taken for infection to develop was longer in vaccinated badgers (two, eight and 12 weeks), than in non-vaccinated badgers (2–4 weeks). Vaccinated badgers had fewer lesions (median score: 4) than non-vaccinated badgers (median score: 9–12.5). Fifteen tuberculosis-free wild badgers were caught and housed in groups of up to four. Nine badgers were injected with 1 ml of Bacillus Calmette-Guérin (BCG) Danish strain 1331 vaccine and six were not vaccinated. After 17 weeks, all 15 badgers were infected with tuberculosis. Every 2–3 weeks badgers were anaesthetized and examined for tuberculosis infection and, 29 weeks after vaccination, the badgers were killed and examined for tuberculosis infection. (Years of study assumed from information provided, as not specified).

6 

A replicated, randomized, controlled study in 2006–2009 in an area of mixed woodland and farmland in Gloucestershire, UK (Chambers et al. 2011, same experimental set-up as Carter et al. 2012) found that vaccinating Eurasian badgers Meles meles against tuberculosis reduced the number of animals infected. Vaccination with Bacillus Calmette-Guérin (BCG) reduced the number of badgers with tuberculosis in vaccinated groups (15/179 infected, 8%) compared to non-vaccinated groups (18/83 infected, 22%). In 2009, badgers were caught in cage traps, set for two consecutive nights, twice a year, at every active sett in a 55 km2 study area. Badgers were tested for tuberculosis using three tests. Social groups were randomly allocated to “vaccinated” or “not vaccinated” treatments. Every badger caught in a vaccination group was injected with 1 ml of Bacillus Calmette-Guérin (BCG) Danish strain 1331 vaccine once per year. A total of 179 badgers from 38 social groups were vaccinated, while 83 badgers from 26 social groups were unvaccinated.

7 

A randomized, controlled, before-and-after study in 2006–2009 in an area of mixed woodland and farmland in Gloucestershire, UK (Carter et al. 2012, same experimental set-up as Chambers et al. 2011) found that vaccinating Eurasian badgers Meles meles against tuberculosis reduced the number of animals infected. Three years after vaccination with Bacillus Calmette-Guérin (BCG) began, the number of badgers infected with tuberculosis (119 of 342 tested, 35%) was lower than before vaccination began (156 of 294 tested, 53%). Vaccination reduced the likelihood of individual badgers testing positive for tuberculosis by 54%. Unvaccinated badgers from vaccinated social groups were less likely to have tuberculosis (adults: 35%, cubs: 21% infected) than badgers from unvaccinated social groups (adults: 52%, cubs: 33% infected). Additionally, unvaccinated cubs were 79% less likely to become infected with tuberculosis when at least one third of the adults in their social group were vaccinated. However the probability of an unvaccinated adult having tuberculosis did not change when more group members were vaccinated. From June 2006–October 2009, badgers were caught in baited steel mesh traps, set for two consecutive nights, twice a year at every active sett in a 55 km2 study area. Badgers were tested for tuberculosis using three tests. Social groups were randomly allocated to “vaccinated” or “not vaccinated” treatments. Badgers in vaccination groups were injected with 1 ml of Bacillus Calmette-Guérin (BCG) Danish strain 1331 vaccine once/year.

Referenced papers

Please cite as:

Littlewood, N.A., Rocha, R., Smith, R.K., Martin, P.A., Lockhart, S.L., Schoonover, R.F., Wilman, E., Bladon, A.J., Sainsbury, K.A., Pimm S. and Sutherland, W.J. (2020) Terrestrial Mammal Conservation: Global Evidence for the Effects of Interventions for terrestrial mammals excluding bats and primates. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.