This is a multi-site, observational, cross-sectional clinical study that includes geographically diverse sites within and outside the United States.

Capillary and venous whole blood specimens will be prospectively collected from consented individuals who present with acute febrile illness and clinical suspicion of infection with fever-causing agents

Inclusion Criteria:

• Presents with AFI as defined for endemic populations or fever as defined in non-endemic populations or presents with fever as defined for nonendemic populations
• Clinical suspicion of disease caused by at least one of the following: Plasmodium spp, dengue virus, Zika virus, chikungunya virus, or Leptospira (endemic population)
• History of residence in or travel to an endemic geographic region within 3 months prior to specimen collection (endemic population)

Exclusion Criteria:

• Self-reported or known antibiotic or antimalarial use (oral or intravenous) within 3 days prior to enrollment (endemic and nonendemic population)
• History of residence in or trael to endemic geographic region as defined by protocol ≤ three months prior to specimen collection (nonendemic population)
• Clinical suspicion of infection caused by any of the following: Plasmodium spp., dengue virus, Zika virus, chikungunya virus, or Leptospira spp. (nonendemic population)

Whole blood specimens collected from individuals with AFI and infection caused by fever-causing pathogens