The role of maternal antibodies in the emergence of severe disease as a result of fragmentation

Abstract

Population fragmentation is a major problem for the conservation of mammalian species. Since the spread of an infectious disease is related to the intensity of contacts between individuals, fragmentation destabilizes the way the parasites circulate in their host population. Recently, Zinkernagel has proposed that a reduction in the frequency of infections by a parasite could lead to the emergence of severe forms of the disease, previously avoided because the disease was contracted early in life and attenuated by maternal antibodies. However, it is still unclear whether this change in disease expression increases the global mortality it induces because the disease becomes more severe and also less frequent. Here, we use a mathematical model to link population fragmentation with the hypothesis of Zinkernagel. Firstly, we show that there is a change in the severity of the disease during the fragmentation process, especially at a local scale, suggesting that host population fragmentation could be a widespread mechanism of disease emergence. Secondly, we show that the emergence of the severe form of the disease can lead to a significant increase in its induced mortality. Finally, we determine the types of interactions for which the fragmentation of the host population could be the most dangerous.

Impact of myxomatosis in relation to local persistence in wild rabbit populations: The role of waning immunity and the reproductive period

“…In a more recent paper, Fouchet et al (2007) have presented results that support this theory. They studied the impact of a disease potentially attenuated by maternal antibodies during the course of fragmentation of the host population.…”

“…Asymptomatic and mild infections are becoming increasingly studied in mathematical modelling (Codeco and Luz, 2001;Fouchet et al, 2006Fouchet et al, , 2007Grenfell, 2003, 2004;Gomes et al, 2004;Mossong and Muller, 2003). Here, using the example of the rabbit-myxomatosis interaction, we show that attenuated infections can have important consequences for the host population.…”

“…Second, we connect a set of subpopulations with homogeneous mixing to form a metapopulation. To explore alternative possibilities to those tested by Fouchet et al (2007), we analyse the case where persistence times are varied without altering the subpopulation size. We show that the suggestion intuited from the deterministic model provided by Fouchet et al (2006), i.e.…”

Hantavirus infections in fluctuating host populations: the role of maternal antibodies

“…Mills et al 1997Mills et al , 1999Borucki et al 2000;Escutenaire et al 2000;Calisher et al 2007;Dearing et al 2009). However, their role in infection dynamics has largely been neglected in studies on hantaviruses and on natural populations generally, despite recent acknowledgement of the potential of MatAbs to influence disease dynamics in wildlife populations through altering the amount of susceptible individuals (Gasparini et al 2001;Staszewski et al 2007;Bouliner & Staszewski 2008), and their recent inclusion in theoretical studies (Fouchet et al 2006(Fouchet et al , 2007(Fouchet et al , 2008.…”

Timing and severity of immunizing diseases in rabbits is controlled by seasonal matching of host and pathogen dynamics

“…These are not independent, because birth and mortality determine the pool of individuals accessible to infections and infectious disease can significantly reduce host populations or the reproductive behaviour of individuals. Consequently, changes in either demographic or epidemiological traits in space and time can strongly influence coupled host-pathogen dynamics [1][2][3][4].…”