Non-systemic transmission of tick-borne diseases: a network approach

TL;DR

This paper models non-systemic transmission of tick-borne diseases using network theory, revealing how heterogeneity in tick aggregation influences pathogen persistence without systemic infection of hosts.

Contribution

It introduces a bipartite graph model to mathematically analyze non-systemic transmission and identifies conditions that facilitate pathogen persistence based on network heterogeneity.

Findings

Higher variability in tick aggregation promotes pathogen persistence.

Fragmented networks can still support disease transmission.

Analytical and computational results confirm the role of heterogeneity.

Abstract

Tick-Borne diseases can be transmitted via non-systemic (NS) transmission. This occurs when tick gets the infection by co-feeding with infected ticks on the same host resulting in a direct pathogen transmission between the vectors, without infecting the host. This transmission is peculiar, as it does not require any systemic infection of the host. The NS transmission is the main efficient transmission for the persistence of the Tick-Borne Encephalitis virus in nature. By describing the heterogeneous ticks aggregation on hosts through a \hyphenation{dynamical} bipartite graphs representation, we are able to mathematically define the NS transmission and to depict the epidemiological conditions for the pathogen persistence. Despite the fact that the underlying network is largely fragmented, analytical and computational results show that the larger is the variability of the aggregation, and the easier is for the pathogen to persist in the population.