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


Version 1.0
Release Date August 2002
Development Status general release
Development Information  
Operating System Windows, UNIX, Mac
Development Language  
Intended Audience  
Key Words  
Related Web Sites  

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:

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.


Unzipping SoftwareExit EPA disclaimer

You will need unzipping (compression) software to uncompress ZIP files. If you need to load unzipping software on your computer, free software is available for download on the internet at the following sites:

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

Windows 95, 98, NT Workstation 4.0, and 2000 Workstation (EXE) (12 MB)

Linux (BIN) (36 MB)

Solaris (BIN) (32 MB)

HP Unix (BIN) (53 MB)

Installers If You Have a JVM

Windows 95, 98, NT Workstation 4.0, and 2000 Workstation (EXE) (1.4 MB)

Linux (BIN) (1.5 MB)

Mac OS-X (ZIP) (1.1 MB)

Solaris (BIN) (1.5 MB)

HP Unix (BIN) (1.5 MB)

If you are familiar with Java and you have the JVM, you may wish to run Virulo directly from its .jar file.

Source code snapshot

Virulo 1.0 Code Snapshot (PDF) (100 pp, 168 KB) November 2002

ASCII text Java files (ZIP) (176 KB)

Class Documentation (ZIP) (109 KB)


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See EPA's PDF page to learn more.


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