EVD is caused by four of five viruses classified in the genus Ebolavirus, family Filoviridae, order Mononegavirales: Bundibugyo virus (BDBV), Ebola virus (EBOV), Sudan virus (SUDV), and Taï Forest virus (TAFV).
ພະຍາດໄວຣັດອີໂບລາເກີດຈາກໄວຣັດສີ່ໃນຫ້າຊະນິດທີ່ຈັດຢູ່ໃນສະກຸນ Ebolavirus ວົງ Filoviridae ອັນດັບ Mononegavirales ໄວຣັດທັງສີ່ຊະນິດນັ້ນໄດ້ແກ່: ໄວຣັດບັນດີບູກຽວ (Bundibugyo virus, BDBV), ໄວຣັດອີໂບລາ (Ebola virus, EBOV), ໄວຣັດຊູດັງ (Sudan virus, SUDV) ແລະ ໄວຣັດປ່າຕາອີ (Taï Forest virus, TAFV).