 The EEHVs are members of the Proboscivirus genus , a novel clade most closely related to the mammalian betaherpesviruses that have been responsible for as many as 70 deaths of both zoo and wild Asian elephants worldwide , especially in young calves . There are currently six known species / types of the probosciviruses , and the most commonly encountered and most pathogenic form EEHV1 also has two chimeric subtypes , 1A and 1B . , as well as numerous distinct strains . 
