An Israeli group has a commentary that starts:
In a conference held on March 6, 2017, to commemorate the Martyr Day in Tehran, the head of the Martyrs Foundation... said that the number of fatalities among the fighterssent by Iran to Syria and Iraq had reached 2,100 (Mehr, March 6, 2017). The number of fatalities announced .. does not refer only to fighters of Iranian nationality, but to all fighters sent on behalf of Iran to Syria and Iraq. These fighters include Lebanese Hezbollah operatives as well as Shiites of Afghan, Pakistani and Iraqi descent, handled by the IRGC.
They also refer to WINEP research:
In Syria, 473 Iranian fighters, 1,045 Hezbollah operatives, and 801 operatives of the Shiite militias operating in Syria(Pakistanis, Afghans, and Iraqis)were killed. Thus, the total of fatalities among the Iranian forces and Iran’s proxy organizations in Syria has reached 2,319. In Iraq,Alfoneh identified 38 Iranian fighters and 246 operatives of the Iraqi Shiite militias. Thus, the total of fatalities in Iraq has reached 248
Link:http://www.terrorism-info.org.il/en/article/21176