IEF is continuing its long-term funding of research to understand and combat the devastating acute hemorrhagic disease caused by some strains of Elephant Endotheliotropic Herpesvirus (EEHV). This novel group of mammalian herpesviruses discovered in 1999 has been responsible for the deaths of 20% of all Asian elephant calves born in human care in North America and Europe over the past 25 years. The same virus types have also been confirmed to be present in 86 lethal cases in wild, orphan and camp-reared Asian elephant calves within at least six different Asian elephant range countries over the last ten years and thus represent another of the many difficult to control factors threatening the long-term breeding success and survival of the highly threatened Asian elephant worldwide. This project conducts extensive genetic analyses of virus positive samples from Asian and African elephants and has thus far revealed that these infections are endemic in both host species. Most, if not all, elephants may become latently infected with different types of EEHV in their lifetimes, therefore it is important for this research to not only identify and categorize the strains of EEHV but understand the differences between types and understand why one type (EEHV1A) is far more dangerous to calves than the others. This research has served as the foundation for most EEHV research around the world.