▁sla ugh ter ▁of ▁ 5 0 0 , 0 0 0 ▁p igs . ▁The ▁out break ▁was ▁l abeled ▁the ▁" most ▁alarm ing ▁event " ▁of ▁ 1 9 7 1 ▁by ▁the ▁United ▁Nations ▁Food ▁and ▁Agricult ural ▁Organ ization . ▁Six ▁years ▁after ▁the ▁event , ▁the ▁newspaper ▁News day , ▁cit ing ▁un trace able ▁sources , ▁claimed ▁that ▁anti - Cast ro ▁sab ote urs , ▁with ▁at ▁least ▁the ▁t ac it ▁backing ▁of ▁U . S . ▁Central ▁Int elligence ▁Agency ▁officials , ▁introduced ▁African ▁sw ine ▁fe ver ▁virus ▁into ▁Cuba ▁six ▁weeks ▁before ▁the ▁out break ▁in ▁ 1 9 7 1 , ▁to ▁dest abil ize ▁the ▁Cub an ▁economy ▁and ▁encou rage ▁domestic ▁opposition ▁to ▁F idel ▁Castro . ▁The ▁virus ▁was ▁alleg edly ▁delivered ▁to ▁the ▁oper atives ▁from ▁an ▁army ▁base ▁in ▁the ▁Pan ama ▁Canal ▁Zone ▁by ▁an ▁un named ▁U . S . ▁intelligence ▁source . ▁Ev idence ▁linking ▁these ▁inc idents ▁to ▁bi ological ▁war fare ▁has ▁not ▁been ▁confirmed . ▁ ▁Acc us ations ▁have ▁continued ▁to ▁come ▁out ▁of ▁Hav ana ▁charg ing ▁U . S . ▁use ▁of ▁bio - we ap ons ▁on ▁the ▁island , ▁after ▁the ▁official ▁end ▁of ▁the ▁US ▁bi ological ▁weapons ▁program ▁in ▁ 1 9 7 3 . ▁The ▁Cub an ▁government ▁bl amed ▁the ▁U . S . ▁for ▁a ▁ 1 9 8 1 ▁out break ▁of ▁den gue ▁fe ver ▁that ▁sick