Analyzing the transmission of SVCV among zebrafish populations by compartment mathematical modeling

Abstract

There are many studies of freshwater pathogen microorganisms aiming to elucidate the mechanism of infection and the individual immune responses. However, few of these studies focus on the transmission of the pathogens among freshwater fish populations. In this work, we performed experiments by introducing the zebrafish (Danio rerio) infected with spring viremia of carp virus (SVCV) to conduct the infectious process among zebrafish populations. Based on the collected data in the transmission experiment with PCR testing and tissue histology, an SEIR (susceptible-exposed-infected-removed) compartment mathematical model was established to quantitively characterize the propagation of SVCV among fish populations. After deriving the basic reproduction number R0 by this SEIR model, the temperature and density effects were preliminarily investigated. It was found that at lower temperatures between 15 and 21 °C, the transmission rate increased. The culturing density also played a vital role in R0 at certain temperatures. By reducing the culturing density, the determined reproduction number at 18 °C is substantially reduced, implying an effective slowing down of the transmission at this temperature. But the reductions in R0 are less effective for 15 °C and 21 °C. In all, this study proposed a new approach to quantitively analyze the virus transmission in the freshwater aquaculture. By supplementing with the individual immune research tools, it can not only provide effective containment strategies to control epidemics for freshwater fisheries, but also be used to optimize the culturing conditions to avoid the outbreak of transmissible diseases.