EEHV1A (originally just known as EEHV1) was the first species/type identified, which causes an acute hemorrhagic disease with a very high mortality rate in Asian elephants.[5][9][10] This form of the virus was originally believed to occur naturally in African elephants (occasionally producing skin nodules), and to be transmitted to Asian elephants within captivity, but more extensive studies have since largely disproved this concept because several other species/types of EEHV (e.g. EEHV2, EEHV3 and EEHV6) instead have been identified in African elephants.[3][11] A second lethal subtype, EEHV1B, was identified in Asian elephants in 2001.[5] EEHV3, EEHV4 and EEHV5 have also each been responsible for the deaths of at least one Asian elephant calf.[12][13]