Low-coverage vaccination strategies for the conservation of endangered species.

Division of Environmental and Evolutionary Biology, University of Glasgow, Glasgow G12 8QQ, UK.
Nature (Impact Factor: 42.35). 11/2006; 443(7112):692-5. DOI: 10.1038/nature05177
Source: PubMed

ABSTRACT The conventional objective of vaccination programmes is to eliminate infection by reducing the reproduction number of an infectious agent to less than one, which generally requires vaccination of the majority of individuals. In populations of endangered wildlife, the intervention required to deliver such coverage can be undesirable and impractical; however, endangered populations are increasingly threatened by outbreaks of infectious disease for which effective vaccines exist. As an alternative, wildlife epidemiologists could adopt a vaccination strategy that protects a population from the consequences of only the largest outbreaks of disease. Here we provide a successful example of this strategy in the Ethiopian wolf, the world's rarest canid, which persists in small subpopulations threatened by repeated outbreaks of rabies introduced by domestic dogs. On the basis of data from past outbreaks, we propose an approach that controls the spread of disease through habitat corridors between subpopulations and that requires only low vaccination coverage. This approach reduces the extent of rabies outbreaks and should significantly enhance the long-term persistence of the population. Our study shows that vaccination used to enhance metapopulation persistence through elimination of the largest outbreaks of disease requires lower coverage than the conventional objective of reducing the reproduction number of an infectious agent to less than one.

1 Bookmark
  • [Show abstract] [Hide abstract]
    ABSTRACT: Although little studied in natural populations, the persistence of immunoglobulins may dramatically affect the dynamics of immunity and the ecology and evolution of host-pathogen interactions involving vertebrate hosts. By means of a multiple-year vaccination design against Newcastle disease virus, we experimentally addressed whether levels of specific antibodies can persist over several years in females of a long-lived procellariiform seabird—Cory’s shearwater—and whether maternal antibodies against that antigen could persist over a long period in offspring several years after the mother was exposed. We found that a single vaccination led to high levels of antibodies for several years and that the females transmitted antibodies to their offspring that persisted for several weeks after hatching even 5 years after a single vaccination. The temporal persistence of maternally transferred antibodies in nestlings was highly dependent on the level at hatching. A second vaccination boosted efficiently the level of antibodies in females and thus their transfer to offspring. Overall, these results stress the need to consider the temporal dynamics of immune responses if we are to understand the evolutionary ecology of host-parasite interactions and trade-offs between immunity and other life-history characteristics, in particular in long-lived species. They also have strong implications for conservation when vaccination may be used in natural populations facing disease threats.
    The American Naturalist 12/2014; 184:764-776. · 4.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Parasites can reduce host body condition, impair reproduction, and cause mortality. However, parasites are a major source of biodiversity, are a fundamental component of a healthy ecosystem, and could be the group most affected by the modern-day biodiversity crisis. Parasite control may cause immunological naivety, unbalance parasite-mediated apparent competition between hosts, and destabilize the host–parasite arms race. Here, we rank parasite control strategies according to their potential impact on ecosystems. We argue that, as the threat that a parasite poses to host survival increases, the need for parasite control increases, and, therefore, control measures that have a greater impact on ecosystems can be justified. However, because host-specific parasites may be more endangered than their hosts, there is often the need for active parasite conservation strategies such as establishing parasite refugia. Although the principles proposed here are predominantly intuitive, there are numerous examples in which they have not been applied.
    BioScience 10/2014; 64(10):932-937. · 5.44 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Many endangered wildlife populations are vulnerable to infectious diseases for which vaccines exist; yet, pragmatic considerations often preclude large-scale vaccination efforts. These barriers could be reduced by focusing on individuals with the highest contact rates. However, the question then becomes whether targeted vaccination is sufficient to prevent large outbreaks. To evaluate the efficacy of targeted wildlife vaccinations, we simulate pathogen transmission and control on monthly association networks informed by behavioural data from a wild chimpanzee community (Kanyawara N = 37, Kibale National Park, Uganda). Despite considerable variation across monthly networks, our simulations indicate that targeting the most connected individuals can prevent large outbreaks with up to 35% fewer vaccines than random vaccination. Transmission heterogeneities might be attributed to biological differences among individuals (e.g. sex, age, dominance and family size). Thus, we also evaluate the effectiveness of a trait-based vaccination strategy, as trait data are often easier to collect than interaction data. Our simulations indicate that a trait-based strategy can prevent large outbreaks with up to 18% fewer vaccines than random vaccination, demonstrating that individual traits can serve as effective estimates of connectivity. Overall, these results suggest that fine-scale behavioural data can help optimize pathogen control efforts for endangered wildlife.
    Journal of The Royal Society Interface 08/2014; 11(97). · 3.86 Impact Factor

Full-text (2 Sources)

Available from
May 23, 2014