Question

Zika virus exposure during pregnancy has been associated with microcephaly in newborns. Koch’s postulates are traditionally used to link a pathogen to a disease. List three reasons why Koch’s postulates are not completely applicable in this case.

Answer 1

• It has been modified over the years to encompass viruses that cause symptoms in an infected host long after the original infection and which progress slowly.
• Under circumstances, the parasite can account for the pathological changes and clinical course of the disease where it occurs in every case of the disease in question.
• Fortuitous and non-pathogenic parasite occurs in no other disease.
• The parasite can induce the disease a new after being fully isolated from the body and repeatedly grown in pure culture.
• There should be association with pathogenic members of a genus or pathogenic strains of a species where phenotype under investigation.