Viremia

Definition

The presence of virus particles in the bloodstream of a host, representing the stage at which hematophagous arthropods can acquire infection during blood-feeding and subsequently transmit the pathogen to new hosts.

Etymology

From Latin virus (poison, slimy liquid) + Greek haima (blood)

Example

In yellow fever, sufficient viremia in a human or non-human primate allows infective Aedes aegypti mosquitoes to ingest virus during feeding; after extrinsic incubation in the mosquito, the virus can be transmitted to subsequent hosts.

Synonyms

• viraemia

Related Terms

• bacteremia
• parasitemia
• extrinsic incubation period
• vector competence
• Transovarial transmission
• Arbovirus

Usage Notes

Viremia is typically quantified as viral titer (e.g., plaque-forming units per milliliter) and must reach threshold levels for vector infection. Primary viremia follows initial infection; secondary viremia occurs after viral replication in target tissues. Contrast with localized infection where virus remains confined to entry site or lymphatic tissue. The duration and magnitude of viremia are key determinants of vector-borne disease ecology.