Arbovirus

Definition and Classification

Arboviruses (arthropod-borne viruses) are a heterogeneous group of viruses transmitted to humans through the bite of infected arthropods, primarily mosquitoes and ticks. The term is epidemiologic rather than taxonomic and includes viruses from multiple families, most notably:

  • Flaviviridae: West Nile virus, Dengue virus, Zika virus, Yellow fever virus, Japanese encephalitis virus
  • Togaviridae (Alphaviruses): Chikungunya virus, Eastern/Western equine encephalitis viruses
  • Bunyavirales: La Crosse virus, Rift Valley fever virus
  • Reoviridae: Colorado tick fever virus

Epidemiology

  • Geographic distribution depends on vector ecology, climate, and seasonal factors
  • Endemic and emerging arboviruses are increasingly reported due to:
    • Climate change
    • Urbanization
    • Global travel
  • Many arboviruses are reportable diseases, with public health implications

Transmission and Pathogenesis

  • Transmission occurs via inoculation of virus-containing saliva during arthropod feeding
  • Humans are often incidental or dead-end hosts
  • After initial replication at the inoculation site, viruses disseminate via viremia
  • Neuroinvasive disease occurs when viruses cross the blood–brain barrier, either through endothelial infection or immune-mediated mechanisms

Clinical Syndromes

Arboviral infections classically present in one of the following patterns:

  1. Undifferentiated febrile illness
    • Fever, myalgia, headache, rash
    • Common with dengue, Zika, chikungunya
  2. Neuroinvasive disease
    • Aseptic meningitis
    • Encephalitis
    • Acute flaccid paralysis (e.g., West Nile virus)
  3. Hemorrhagic or capillary leak syndromes
    • Dengue hemorrhagic fever
    • Dengue shock syndrome
  4. Chronic or post-viral sequelae
    • Persistent arthralgia (chikungunya)
    • Neurocognitive impairment

Diagnosis

  • RT-PCR: Preferred early in illness (during viremic phase)
  • Serology (IgM/IgG): More useful later; cross-reactivity common among flaviviruses
  • CSF analysis (neuroinvasive disease):
    • Lymphocytic pleocytosis
    • Elevated protein
    • Normal glucose

Pharmacists should be aware of false positives and interpretation challenges, especially in vaccinated or previously exposed patients. Treatment and Pharmacotherapy Considerations

  • No specific antiviral therapy approved for most arboviral infections
  • Management is supportive, focusing on:
    • Hydration
    • Antipyretics
    • Pain control

Key pharmacist considerations:

  • Avoid NSAIDs and aspirin in suspected dengue due to bleeding risk
  • Monitor for:
  • Counsel on appropriate analgesic selection (e.g., acetaminophen)
  • No role for empiric antibacterials once arboviral etiology is established
  • Ribavirin and interferons have no established clinical role in most arboviral infections

Vaccines and Prevention

  • Vaccines available for selected arboviruses:
  • No licensed vaccines for dengue in many regions or for most arboviruses
  • Prevention relies on:
    • Vector control
    • Personal protective measures (repellents, clothing, bed nets)
    • Travel counseling

Special Populations

  • Pregnancy: Certain arboviruses (e.g., Zika) associated with congenital abnormalities
  • Older adults and immunocompromised patients: Higher risk of severe neuroinvasive disease
  • Transplant recipients: Increased morbidity and mortality reported

Pharmacist Role Summary

  • Support diagnostic stewardship and lab interpretation
  • Guide safe medication use and avoid contraindicated agents
  • Educate healthcare teams and patients on prevention
  • Participate in antimicrobial/antiviral stewardship
  • Assist with public health reporting and outbreak response
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