Virus Fate and Transport (Virulo) Model

Virulo is a probabilistic screening model for predicting leaching of viruses in unsaturated soils. It employs Monte Carlo methods to generate ensemble simulations of virus attenuation due to physical, biological, and chemical factors. The model generates a probability of failure to achieve a user-chosen degree of attenuation. Virulo can be used based on limited information such as boring logs, climate data, and soil survey reports for a particular site of interest.

Virulo can be used to predict probability of leaching of viable viruses when the following assumptions can be used:

  • The soil layer of interest is homogeneous in texture
  • Water flow in the layer is due to gravity only
  • The percolating water does not contain surface active agents
  • The soil layer does not induce preferential flow

The particulars of these assumptions are described in detail in the model documentation.

Version 1.0
Release Date August 2002
Operating System Windows, UNIX

Minimum System Requirements

For a Windows installation, a Pentium-like grade processor is needed with at least 100 MHz speed and at least 32 MB of RAM. If your system does not already have the Java Virtual Machine (JVM), version 1.2 or greater, you'll need about 35 MB hard disk space. If you already have the JVM, you'll need only about 2 MB for Virulo itself. Virulo has been tested with the following operating systems:

  • Windows 95, 98, NT Workstation 4.0, and 2000 Workstation
  • Apple Mac OS-X
  • Red Hat Linux 7.2
  • Solaris versions 7 and 8

It should work without problems just as well on any other system that has a JVM with Swing component capability.

The Virulo model requires a computer system that has the JVM, version 1.2 or greater. If your system does not have the JVM, you may download one of the platform-specific installers for Virulo listed below. They will install a recent version of the JVM on your computer during the Virulo installation. Later, if you choose to uninstall Virulo, the JVM will be removed as well.


US EPA. (2002) "Predicting Attenuation of Viruses During Percolation in Soils – 1. Probabilistic Model" Publication EPA/600/R-02/051a.

US EPA. (2002) "Predicting Attenuation of Viruses During Percolation in Soils – 2. User’s Guide to the Virulo 1.0 Computer Model" Publication No. EPA/600/R-02/051b.

Installers If You Do Not Have a JVM

VIRULO Windows 95, 98, NT Workstation 4.0, and 2000 Workstation (No JVM) (EXE)(1 MB)

Virulo Linux (No JVM) (ZIP)(1 MB)

Virulo Solaris (No JVM) (ZIP)(1 MB)

Virulo HP Unix (No JVM) (ZIP)(1 MB)

Installers If You Have a JVM

Virulo Windows (JVM) (EXE)(2 MB)

Virulo Linux (JVM) (ZIP)(2 MB)

Virulo Mac OS-X (JVM) (ZIP)(1 MB)

Virulo Solaris (JVM) (ZIP)(1 MB)

Virulo HP Unix (JVM) (ZIP)(3 MB)

If you are familiar with Java and you have the JVM, you may wish to run Virulo directly from Virulo .jar (ZIP)(86 K)  file.

Source Code Snapshot

Virulo 1.0 Code Snapshot

ASCII text Java files (ZIP)(180 K)

Class Documentation (ZIP)(111 K)