Outbreaks of human infections mainly occur in low-income countries with intensive pig production, which is largely due to close contact of humans to pigs and lack of awareness of the disease within the population at risk.
Izbruhi okužb pri ljudeh se pojavljajo predvsem v državah z nizkimi dohodki in intenzivno prašičerejo, predvsem zaradi tesnega stika ljudi s prašiči in nezadostnega poznavanja bolezni pri ogroženi populaciji.