− | The consideration of non-Poissonian infection or recovery processes does not lend itself easily to analytical approaches <ref>Lambiotte R, Tabourier L, Delvenne J C. Burstiness and spreading on temporal networks[J]. The European Physical Journal B, 2013, 86(7): 320.</ref>. Some simple forms for the distribution of infectious periods, such as the Erlang distribution, which can be described as the convolution of identical Poisson processes <ref>Cox D R. Renewal Theory, 2-nd Edn[J]. 1967.</ref>, can be tackled analytically by postulating an extended epidemic model with different infective phases and Poissonian transitions among them <ref>Lloyd A L. Destabilization of epidemic models with the inclusion of realistic distributions of infectious periods[J]. Proceedings of the Royal Society of London. Series B: Biological Sciences, 2001, 268(1470): 985-993.</ref>. However, general non Poissonian forms lead to convoluted sets of integrodifferential equations <ref>Keeling M J, Grenfell B T. Disease extinction and community size: modeling the persistence of measles[J]. Science, 1997, 275(5296): 65-67.</ref>. As a consequence there are not many analytical results for non-Poissonian transitions in complex networks. We mention the results of Min, Goh, and Kim (2013)<ref name="Min2013">Min B, Goh K I, Kim I M. Suppression of epidemic outbreaks with heavy-tailed contact dynamics[J]. EPL (Europhysics Letters), 2013, 103(5): 50002.</ref> which consider the SIR process on a network in which infection events follow an interevent distribution P aðτaÞ. Assuming that infected nodes remain in that state for a fixed amount of time τi, it is possible to compute <ref name="Min2013"></ref>(Min, Goh, and Kim, 2013) the disease transmissibility as | + | The consideration of non-Poissonian infection or recovery processes does not lend itself easily to analytical approaches <ref>Lambiotte R, Tabourier L, Delvenne J C. Burstiness and spreading on temporal networks[J]. The European Physical Journal B, 2013, 86(7): 320.</ref>. Some simple forms for the distribution of infectious periods, such as the Erlang distribution, which can be described as the convolution of identical Poisson processes <ref>Cox D R. Renewal Theory, 2-nd Edn[J]. 1967.</ref>, can be tackled analytically by postulating an extended epidemic model with different infective phases and Poissonian transitions among them <ref>Lloyd A L. Destabilization of epidemic models with the inclusion of realistic distributions of infectious periods[J]. Proceedings of the Royal Society of London. Series B: Biological Sciences, 2001, 268(1470): 985-993.</ref>. However, general non Poissonian forms lead to convoluted sets of integrodifferential equations <ref>Keeling M J, Grenfell B T. Disease extinction and community size: modeling the persistence of measles[J]. Science, 1997, 275(5296): 65-67.</ref>. As a consequence there are not many analytical results for non-Poissonian transitions in complex networks. We mention the results of Min, Goh, and Kim (2013)<ref name="Min2013">Min B, Goh K I, Kim I M. Suppression of epidemic outbreaks with heavy-tailed contact dynamics[J]. EPL (Europhysics Letters), 2013, 103(5): 50002.</ref> which consider the SIR process on a network in which infection events follow an interevent distribution P aðτaÞ. Assuming that infected nodes remain in that state for a fixed amount of time τi, it is possible to compute <ref name="Min2013"></ref> the disease transmissibility as |
− | For a power-law distribution $P_a(\tau_a)~\tau_a^{-\alpha}$, it is found that $\tau_{ic}$ diverges as $\alpha\to2$, implying that only diseases without recovery are able to spread through the network (Min, Goh, and Kim, 2013). An important step forward in the treatment of generic nonexponentially distributed recovery and transmission times in the SIR model is the application of a message-passing method, as reported by Karrer and Newman (2010). This approach leads to an exact description in terms of integrodifferential equations for trees and locally treelike networks, and to exact bounds for non-tree-like networks, in good agreement with simulations. | + | For a power-law distribution $P_a(\tau_a)~\tau_a^{-\alpha}$, it is found that $\tau_{ic}$ diverges as $\alpha\to2$, implying that only diseases without recovery are able to spread through the network <ref name="Min2013"></ref>. An important step forward in the treatment of generic nonexponentially distributed recovery and transmission times in the SIR model is the application of a message-passing method, as reported by Karrer and Newman (2010)<ref>Karrer B, Newman M E J. Message passing approach for general epidemic models[J]. Physical Review E, 2010, 82(1): 016101.</ref>. This approach leads to an exact description in terms of integrodifferential equations for trees and locally treelike networks, and to exact bounds for non-tree-like networks, in good agreement with simulations. |
− | Finally, Cator, van de Bovenkamp, and Van Mieghem (2013) proposed an extension of the SIS IBMF theory for nonexponential distributions of infection or healing times.Using renewal theory, their main result is the observation that the functional form of the prevalence in the metastable state is the same as in the Poissonian SIS model, when the spreading rate $\lambda=\beta/\mu$ is replaced by the average number of infection attempts during a recovery time. The theory by Cator, van de Bovenkamp, and Van Mieghem (2013) also allows one to estimate the epidemic threshold in non-Markovian SIS epidemics. | + | Finally, Cator, van de Bovenkamp, and Van Mieghem (2013)<ref name="Cator2013">Cator E, Van de Bovenkamp R, Van Mieghem P. Susceptible-infected-susceptible epidemics on networks with general infection and cure times[J]. Physical Review E, 2013, 87(6): 062816.</ref> proposed an extension of the SIS IBMF theory for nonexponential distributions of infection or healing times.Using renewal theory, their main result is the observation that the functional form of the prevalence in the metastable state is the same as in the Poissonian SIS model, when the spreading rate $\lambda=\beta/\mu$ is replaced by the average number of infection attempts during a recovery time. The theory by Cator, van de Bovenkamp, and Van Mieghem (2013)<ref name="Cator2013"></ref> also allows one to estimate the epidemic threshold in non-Markovian SIS epidemics. |